Physiological Increases in Uncoupling Protein 3 Augment Fatty Acid Oxidation and Decrease Reactive Oxygen Species Production Without Uncoupling Respiration in Muscle Cells

Abstract

Decreased uncoupling protein (UCP)3 is associated with insulin resistance in muscle of pre-diabetic and diabetic individuals, but the function of UCP3 remains unclear.

Our goal was to elucidate mechanisms underlying the negative correlation between UCP3 and insulin resistance in muscle.

We determined effects of physiologic UCP3 overexpression on glucose and fatty acid oxidation and on mitochondrial uncoupling and reactive oxygen species (ROS) production in L6 muscle cells.

An adenoviral construct caused a 2.2- to 2.5-fold increase in UCP3 protein.

Palmitate oxidation was increased in muscle cells incubated under normoglycemic or hyperglycemic conditions, whereas adenoviral green fluorescent protein infection or chronic low doses of the uncoupler dinitrophenol had no effect.

Increased UCP3 did not affect glucose oxidation, whereas dinitrophenol and insulin treatments caused increases.

Basal oxygen consumption, assessed in situ using self-referencing microelectrodes, was not significantly affected, whereas dinitrophenol caused increases.

Mitochondrial membrane potential was decreased by dinitrophenol but was not affected by increased UCP3 expression.

Finally, mitochondrial ROS production decreased significantly with increased UCP3 expression.

Results are consistent with UCP3 functioning to facilitate fatty acid oxidation and minimize ROS production.

As impaired fatty acid metabolism and ROS handling are important precursors in muscular insulin resistance, UCP3 is an important therapeutic target in type 2 diabetes

http://diabetes.diabetesjournals.org/content/54/8/2343.full

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Into the heart, an air that kills, from yon far country blows.
What are those blue remembered hills, what sphires what farms are those.
That is the land of lost content,I see it shining plain,
The happy highways where I went and cannot come again

More evidence that muscle atrophy requires a possible separate and earliest as possible therapeutic approach until we have a general ALS therapy?


Muscle atrophy induced by SOD1G93A expression does not involve the activation of caspase in the absence of denervation

Abstract
Background: The most remarkable feature of skeletal muscle is the capacity to adapt its morphological,biochemical and molecular properties in response to several factors.

Nonetheless, under pathological conditions, skeletal muscle loses its adaptability, leading to atrophy or wasting. Several signals might function as
physiopathological triggers of muscle atrophy.

However, the specific mechanisms underlying the atrophic phenotype under different pathological conditions remain to be fully elucidated.

In this paper, we address the involvement of caspases in the induction of muscle atrophy in experimental models of amyotrophic lateral sclerosis (ALS) expressing the mutant SOD1G93A transgene either locally or ubiquitously.

Results: We demonstrate that SOD1G93A-mediated muscle atrophy is independent from caspase activity.

In particular, the expression of SOD1G93A promotes a reduction of the phosphatidylinositol kinase/Akt pathway associated with activation of forkhead box O3.

In contrast, the activation of caspases occurs later and is causally linked to motor neuron degeneration, which is associated with exacerbation of the atrophic phenotype and a shift in fiber-type composition.

Conclusion: This study suggests that muscle atrophy induced by the toxic effect of SOD1G93A is independent from the activation of apoptotic markers and that caspase-mediated apoptosis is a process activated upon muscle denervation.

www.skeletalmusclejournal.com/content/pdf/2044-5040-1-3.pdf

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Into the heart, an air that kills, from yon far country blows.
What are those blue remembered hills, what sphires what farms are those.
That is the land of lost content,I see it shining plain,
The happy highways where I went and cannot come again

I suggest we forget about ALS in this thread, to start with, and concentrate on common pathways in muscle atrophy to find common linking factors. Then try to link those common factors back to what mutant SOD1 is doing in muscles.

Separating muscle loss from neuron degeneration to find effective therapies?


This may be one part of the puzzle: Atrogin and it is up regulated in many muscle atrophy pathologies.

This response to training represents a normal response of the muscle to increased use (Salmons and Henriksson 1981).

The beneficial effects of exercise may, at least partly, be brought about by an increase in the expression of myogenin a reduction of the occurrence of apoptosis , and suppression of the muscle specific ubiquitin ligase atrogin .

Furthermore, endurance training may attenuate systemic inflammation and it is thus possible that the beneficial effects of training are partly mediated via a reduction in inflammation. So far, it is not clear whether all patients would benefit from exercise programs as for instance in some elderly people the hypertrophic response is attenuated, indicating a reduced plasticity at old age.

This attenuated response has been shown to be related to elevated baseline levels of soluble TNF-receptors in the elderly. This would imply that chronic patients with a significantly elevated systemic inflammation may have reduced improvements in response to exercise training, particularly when one considers that the inflammatory and oxidative stress response is augmented in muscle-wasted patients

Supporting the notion that exercise may loose its effectiveness when systemic inflammation is present, is the observation that the cellular protein breakdown in patients with a low fat free mass does not decline after an exercise training

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2695204/
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Gene Discovery Linked To Muscle Atrophy In Numerous Conditions

ScienceDaily (Mar. 21, 2002) — HOUSTON-(March 20, 2002) -- A newly identified gene, atrogin-1, is involved in muscle loss associated with cancer, diabetes, fasting and kidney disease as well as in the atrophy occurring with disuse, inactivity, and nerve or spinal injury.

"Through a study of rat muscles, we determined that atrogin-1 is found only in muscle," said Dr. Alfred Goldberg, professor of cell biology at Harvard Medical School and associate leader of NSBRI's team of scientists focusing on muscle loss in space.

"In normal muscles, the amount is low; however, there is a dramatic increase in the production of the atrogin-1 protein in conditions where muscles lose size and strength."

In healthy muscles, there is a continual process of muscle protein production and breakdown.

In healthy muscles, there is a continual process of muscle protein production and breakdown. With muscle-wasting conditions, this cycle gets out of balance.

Protein breakdown occurs more rapidly than protein production, leading to loss of muscle weight.

"Proteins in cells are destroyed in a structure called the proteasome," Goldberg said. "From clues in its gene sequence, we guessed that atrogin-1 was a component of this pathway of protein breakdown and succeeded in proving atrogin-1 targets other proteins for destruction."


"We found a fragment of a messenger RNA that increased dramatically in muscle atrophy," he said. "Cloning techniques allowed us to discover the atrogin-1 gene's full sequence and to produce the protein that it codes for. We then determined that it played a role in atrophy, where it seems to trigger the excessive protein breakdown."

Goldberg's group chose the name, atrogin-1, as short for atrophy-related gene. Their findings appear in the Dec. 4 issue of the Proceedings of the National Academy of Science.

In earlier studies, the group was the first to establish that muscle atrophy is due primarily to excessive protein breakdown and the first to indicate that a similar biochemical process was responsible for muscle loss in many different diseases.
Goldberg feels the atrophy process is similar in humans.

"Almost everything we know about human muscle function was first discovered in experimental animals," he said. "The atrogin-1 gene in humans is almost identical to that in mice and rats."

Many could potentially benefit from drugs designed to block or slow down muscle atrophy, from cancer patients to the bedridden to those losing muscle while in a cast. Even astronauts on long missions, who lose muscle while in space, will need a means to control muscle loss.

"If you could inhibit atrogin-1 or block a cell's ability to make it, you could reduce muscle wasting," Goldberg said.

"Atrogin-1 is an attractive target for drug therapy since it is only found in muscle and plays a critical role in the atrophy process."

http://www.sciencedaily.com/releases/2002/03/020321070908.htm
...................................................

Statin-induced muscle damage and atrogin-1 induction is the result of a geranylgeranylation defect

Abstract
Statins are widely used to treat hypercholesterolemia but can lead to a number of side effects in muscle, including rhabdomyolysis.

Our recent findings implicated the induction of atrogin-1, a gene required for the development of muscle atrophy, in statin-induced muscle damage. Since statins inhibit many biochemical reactions besides cholesterol synthesis, we sought to define the statin-inhibited pathways responsible for atrogin-1 expression and muscle damage.

We report here that lovastatin-induced atrogin-1 expression and muscle damage in cultured mouse myotubes and zebrafish can be prevented in the presence of geranylgeranol but not farnesol.

Further, inhibitors of the transfer of geranylgeranyl isoprene units to protein targets cause statin muscle damage and atrogin-1 induction in cultured cells and in fish. These findings support the concept that dysfunction of small GTP-binding proteins lead to statin-induced muscle damage since these molecules require modification by geranylgeranyl moieties for their cellular localization and activity.

http://www.fasebj.org/content/23/9/2844.full
...........................................

IGF-1 prevents ANG II-induced skeletal muscle atrophy via Akt- and Foxo-dependent inhibition of the ubiquitin ligase atrogin-1 expression

Abstract
Congestive heart failure is associated with activation of the renin-angiotensin system and skeletal muscle wasting.

Angiotensin II (ANG II) has been shown to increase muscle proteolysis and decrease circulating and skeletal muscle IGF-1.

We have shown previously that skeletal muscle-specific overexpression of IGF-1 prevents proteolysis and apoptosis induced by ANG II.

These findings indicated that downregulation of IGF-1 signaling in skeletal muscle played an important role in the wasting effect of ANG II.

However, the signaling pathways and mechanisms whereby IGF-1 prevents ANG II-induced skeletal muscle atrophy are unknown.

Here we show ANG II-induced transcriptional regulation of two ubiquitin ligases atrogin-1 and muscle ring finger-1 (MuRF-1) that precedes the reduction of skeletal muscle IGF-1 expression, suggesting that activation of atrogin-1 and MuRF-1 is an initial mechanism leading to skeletal muscle atrophy in response to ANG II.

IGF-1 overexpression in skeletal muscle prevented ANG II-induced skeletal muscle wasting and the expression of atrogin-1, but not MuRF-1.

http://ajpheart.physiology.org/content/298/5/H1565.full
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Atrogin-1 Affects Muscle Protein Synthesis and Degradation When Energy Metabolism Is Impaired by the Antidiabetes Drug Berberine

CONCLUSIONS
Berberine impairs muscle metabolism by two novel mechanisms.

It impairs mitochonidrial function stimulating the expression of atrogin-1 without affecting phosphorylation of forkhead transcription factors.

The increase in atrogin-1 not only stimulated protein degradation but also suppressed protein synthesis, causing muscle atrophy.

http://diabetes.diabetesjournals.org/content/59/8/1879.full
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Testosterone represses ubiquitin ligases atrogin-1 and Murf-1 expression in an androgen-sensitive rat skeletal muscle in vivo

Skeletal muscle atrophy induced by denervation and metabolic diseases has been associated with increased ubiquitin ligase expression.

In the present study, we evaluate the influence of androgens on muscle ubiquitin ligases atrogin-1/MAFbx/FBXO32 and Murf-1/Trim63 expression and its correlation with maintenance of muscle mass by using the testosterone-dependent fast-twitch levator ani muscle (LA) from normal or castrated adult male Wistar rats.

Gene expression was determined by qRT-PCR and/or immunoblotting.

Castration induced progressive loss of LA mass (30% of control, 90 days) and an exponential decrease of LA cytoplasm-to-nucleus ratio (nuclear domain; 22% of control after 60 days).

Testosterone deprivation induced a 31-fold increase in LA atrogin-1 mRNA and an 18-fold increase in Murf-1 mRNA detected after 2 and 7 days of castration, respectively.

Acute (24 h) testosterone administration fully repressed atrogin-1 and Murf-1 mRNA expression to control levels.

Atrogin-1 protein was also increased by castration up to 170% after 30 days.

Testosterone administration for 7 days restored atrogin-1 protein to control levels.

In addition to the well known stimulus of protein synthesis, our results show that testosterone maintains muscle mass by repressing ubiquitin ligases, indicating that inhibition of ubiquitin-proteasome catabolic system is critical for trophic action of androgens in skeletal muscle.

Besides, since neither castration nor androgen treatment had any effect on weight or ubiquitin ligases mRNA levels of extensor digitorum longus muscle, a fast-twitch muscle with low androgen sensitivity, our study shows that perineal muscle LA is a suitable in vivo model to evaluate regulation of muscle proteolysis, closely resembling human muscle responsiveness to androgens.

http://jap.physiology.org/content/108/2/266.full
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Now coming back to ALS for any links with atrogin...

Human skeletal muscle atrophy in amyotrophic lateral sclerosis reveals a reduction in Akt and an increase in atrogin-1

Confirmation of skeletal muscle atrophy

Skeletal muscle atrophy is a well known characteristic observed in ALS. In the present study skeletal muscle cross sectional area (CSA) of the type I and type II fibers was 35% (P=0.002) and 22% (P=0.03) smaller in the ALS than in control subjects, presenting a severe atrophy of the vastus lateralis muscle. Skeletal muscle atrophy was also confirmed in G93A ALS mice, when compared with control mice, as the mass of the tibialis anterior muscle was ∼50% lower (P<0.001).

2. Atrogin-1 and MuRF1

We observed that in skeletal muscle of the ALS patients, when compared with the healthy control subjects, a significant 170% and 340% increase, respectively, in atrogin-1 mRNA and protein content (Fig. 1⇓ ).

In the G93A mice, when compared with the wild-type mice, atrogin-1 mRNA and protein contents were significantly increased several fold.

There was, however, no difference in MuRF mRNA levels for both the human and rodent groups.

http://www.fasebj.org/content/20/3/583.full

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Into the heart, an air that kills, from yon far country blows.
What are those blue remembered hills, what sphires what farms are those.
That is the land of lost content,I see it shining plain,
The happy highways where I went and cannot come again

Electrical stimulation based on chronaxie reduces atrogin-1 and myoD gene expressions in denervated rat muscle

Abstract

Denervation induces muscle fiber atrophy and changes in the gene expression rates of skeletal muscle.
Electrical stimulation (ES) is a procedure generally used to treat denervated muscles in humans.

This study evaluated the effect of ES based on chronaxie and rheobase on the expression of the myoD and atrogin-1 genes in denervated tibialis anterior (TA) muscle of Wistar rats.

Five groups were examined: (1) denervated (D); (2) D+ES; (3) sham denervation; (4) normal (N); and (5) N+ES.

Twenty muscle contractions were stimulated every 48 h using surface electrodes.

After 28 days, ES significantly decreased the expression of myoD and atrogin-1 in D+ES compared to the D group.

However, ES did not prevent muscle-fiber atrophy after denervation.

Thus, ES based on chronaxie values and applied to denervated muscles using surface electrodes, as normally used in human rehabilitation, was able to reduce the myoD and atrogin-1 gene expressions, which are related to muscular growth and atrophy, respectively.

The results of this study provide new information for the treatment of denervated skeletal muscle using surface ES. Muscle Nerve, 2006

http://onlinelibrary.wiley.com/doi/10.1002/mus.20668/full

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The above shows that ES does not work after denervation but does not mean that it still may work before complete denervation?

---

Into the heart, an air that kills, from yon far country blows.
What are those blue remembered hills, what sphires what farms are those.
That is the land of lost content,I see it shining plain,
The happy highways where I went and cannot come again

I have tried to tease out the relevant pathways of muscle hyper and hypo trophy so as to give us some possible therapeutic targets.

It's a bit of a long read but does highlight some relevant pathways.

One thing I do notice in these papers is how some substances help by modulation of some of these pathways but not all of them.

Thereby possible giving a reason why past clinical trials of said substance have not been conclusive or helped much.

In other words only specific targeting of a substance to all the relevant pathways would do the business.

I suggest you have a read of the original paper as I like others are prone to mistakes and may get my conclusions wrong?



Molecular regulation of skeletal muscle mass

Akt signalling
Studies using pharmacological and genetic manipulation in cellular and rodent models have identified Akt (also called protein kinase B (PKB)), a serine/threonine kinase, as a pivotal point in the hypertrophy8 and, more recently, in the atrophy signalling pathways.

Akt is activated via phosphorylation following a series of intracellular signalling cascades involving insulin-like growth factor (IGF)-1 and phosphatidylinositol 3-kinase.

In addition, Akt phosphorylates and activates the mammalian target of rapamycin (mTOR), with the latter phosphorylating and activating p70S6K, as well as phosphorylating and releasing the inhibitory effect of phosphorylated, heat and acid stable (PHAS)-1/eukaryotic initiation factor 4E binding protein 1 (4E-BP).

Phosphorylation of p70S6K and PHAS-1/4E-BP1 leads to the activation of pathways promoting protein synthesis and translation initiation, respectively.

Hence, the Akt/GSK3β and Akt/mTOR pathways are important for muscle hypertrophy
the Akt/mTOR pathway is involved in load-induced skeletal muscle growth
8 weeks of resistance training exercise results in muscle hypertrophy that is associated with increases in phosphorylated Akt, GSK3β and mTOR.

Other in vivo and in vitro rodent models associated with muscle atrophy, such as ALS, sepsis induced by lipopolysaccharide-induced endotoxaemia or denervation, as well treatments with lovastatin, dexamethasone and serum starving, all result in reduced Akt activation.

In conditions of human muscle atrophy, Akt activity is reduced in ALS and following de-training.

In contrast, Akt is upregulated in atrophied muscle of COPD patients, a possible attempt to try to reduce any further muscle wasting.

In age-related muscle wasting, or sarcopenia, total, but not phosphorylated, Akt is upregulated in elderly compared with young subjects, suggesting a reduced efficiency or capacity to activate their Akt pool.

Increasing Akt activity is seen as a therapeutic strategy to attenuate skeletal muscle atrophy.

Using tamoxifen-inducible transgenesis in mice to activate Akt prevented the muscle damage caused by eccentric contractions in dystrophic mdx mice and force levels were maintained to a similar extent as those observed in muscles from wild-type mice.

This effect is not correlated with increased muscle hypertrophy, nor is it blocked by rapamycin, suggesting an mTOR-independent mechanism.

Along similar lines, doxycycline-inducible Akt in transgenic mice promotes the expression of utrophin and prevents sarcolemmal damage and muscle wasting in mdx mice.

These observations show that Akt can potentially attenuate the loss of muscle mass and function, at least in mdx mice

Atrogin-1 and muscle ring finger-1 (MuRF1) were discovered in 2001 following screening studies for genes upregulated in different models of rodent muscle atrophy.

Based on their sequence structure and results from in vitro experiments, atrogin-1 and MuRF1 were identified as having E3-ligase activities.

E3-Ligase proteins are key components of the ubiquitin–proteasome pathway, which is one of the main pathways involved in skeletal muscle protein degradation.

Knockout of either atrogin-1 or MuRF1 in mice reduces muscle loss following denervation by approximately 50%.

These observations highlight atrogin-1 and MuRF1 as potential targets for combating skeletal muscle atrophy.

The mRNA expression of atrogin-1 and MuRF1 has been shown to be increased in numerous in vitro and in vivo rodent models of muscle atrophy, ranging from treatment with dexamethasone and tumour necrosis factor (TNF)-α to starvation, uraemia, denervation, immobilization, ALS, cancer and statin therapy.

Previous in vitro and in vivo rodent studies have consistently shown that under catabolic conditions the atrogin-1 and MuRF-1 genes are regulated by pathways that activate FoXO.

One study has also shown that MuRF-1 is regulated by the nuclear factor-κB transcription factor.

FoXO1 does not directly increase atrogin-1 levels, but instead blocks the IGF-1 inhibition of atrogin-1 upregulation in catabolic conditions such as dexamethasone treatment.

FoXO3a has been shown to bind directly to the atrogin-1 promoter in mouse muscle and increase its transcription.

Recently, it was shown that FoXO4 is responsible for the increase in atrogin-1 following treatment with TNF-α in mouse myotubes.

In contrast with previous observations, TNF-α activation of FoXO transcription of atrogin-1 was paralleled by an increase in Akt activity; the latter generally believed to inhibit the FoXO/atrogin-1 pathway.

Clearly, the various FoXO family members are regulated via differing catabolic and anabolic signals.

Previous work in human muscle has shown that atrogin-1 and MuRF1 are not always regulated in the same in vivo models as observed in rodents.

For example, fasting increases atrogin-1 in mice, but has no effect in humans.

Paraplegia-induced muscle atrophy in rats resulted in no change in atrogin-1, but increased MuRF1, when measured 10 weeks after injury.

In contrast, atrogin-1 and MuRF1 are increased in human paraplegic patients as early
as 2–5 days after trauma and this increase is transient, with both atrogin-1 and MuRF1 reduced in paraplegic patients when measured as late as 3 months after trauma.


Differences in these genes have also been observed between rodent and human models of ageing, with atrogin-1 and MuRF1 increased in old rats, but no change in these genes observed in muscle from elderly humans.

In human muscle, atrogin-1 mRNA and protein, as well as MuRF1 mRNA, are increased in human atrophy conditions, such as in patients with ALS

At present, studies in humans have not supported the role of FoXO transcription factors in the regulation of atrogin-1 and MuRF1 in human models of muscle atrophy, including ALS, COPD, ageing and spinal cord injury.

Peroxisome proliferator-activated receptor (PPAR) γ coactivator-1α (PGC-1α), a transcriptional coactivator, was first identified as a functional activator of the PPARγ receptor in brown adipose tissue.

In skeletal muscle, PGC-1α has been shown to control the transcriptional programme of genes that regulate mitochondrial biogenesis and fusion,adult skeletal muscle phenotype, glucose transport50 and lipid utilization.

Role of PGC-1α in regulating muscle mass

Skeletal muscle PGC-1α mRNA levels are decreased in several rodent models of muscle atrophy, including diabetes, cancer, cachexia, uraemia, starvation, denervation and heart failure.

It has also been shown that PGC-1α mRNA is downregulated in human models of reduced muscle mass, including COPD, insulin-resistance, and ageing, suggesting that PGC-1α may play a role in regulating skeletal muscle mass.

As mentioned previously, these disease conditions are also associated with perturbations in Akt and/or atrogin-1 levels, suggesting a potential link between PGC-1α, Akt and atrogin-1.

Mice genetically modified to overexpress PGC-1α in their skeletal muscles were protected against denervation- or starvation-induced muscle atrophy.

This sparing of muscle mass is associated with an attenuated increase in atrogin-1 due to PGC-1α inhibiting binding of FoXO3a to the atrogin-1 promoter (Fig. 1); MuRF1 mRNA upregulation was also attenuated by PGC-1α.

Furthermore, PGC-1α inhibits the activity of a constitutively active FoXO3a, a mutant that cannot be phosphorylated and inactivated by Akt.

This suggests that PGC-1α may not act via the Akt signalling pathway.

However, this is yet to be demonstrated.

It has been shown that PGC-1α rescues the lovastatin-induced damage and atrophy of skeletal muscle in zebrafish with an associated reduction in atrogin-1

The mechanisms through which PGC-1α attenuates protein degradation were not established; however, inhibition of proteasomal and lysosomal mechanisms is likely because these process can be regulated via FoXO activity.

In contrast with these protective effects of PGC-1α, Muira et al. demonstrated that genetic overexpression of PGC-1α resulted in skeletal muscle atrophy, especially in muscles with a higher proportion of Type 2B fibres.


These mice also had decreased levels of ATP, a perturbation caused by impaired mitochondrial dysfunction in various inherited and acquired human diseases, such as cardiomyopathy, neuromuscular disorders and diabetes.

The differences between the studies by Sandri et al.25 and Miura et al.61 may be related to the age of the mice.

For example, Sandri et al.25 used mice that were 3 months of age, whereas Miura et al.61 used mice that were 6 months of age, suggesting that long-term stable overexpression of PGC-1α may be toxic.

This possibility, although not validated experimentally, has implications for potential pharmacological or gene therapies for increasing PGC-1α to rescue or maintain muscle mass during catabolic conditions.

It would be of interest to test the effectiveness of transient induction of PGC-1α in skeletal muscle during catabolic stress.

http://onlinelibrary.wiley.com/doi/10.1111/j.1440-1681.2009.05265.x/full

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Into the heart, an air that kills, from yon far country blows.
What are those blue remembered hills, what sphires what farms are those.
That is the land of lost content,I see it shining plain,
The happy highways where I went and cannot come again

Now that I can understand the pathways better (remember I'm still learning) other relevant postings add to the development of a potential cocktail.
It's not complete but this adds some of the possible ingredients:

In this case not only helping with muscle rebuilding but with possible nerve regeneration:

Taken from the thread:

From Mary:

Amelioration of denervation-induced atrophy by clenbuterol is associated with increased PKC-α activity

I'd like to see a trial with the combination therapy, clenbuterol and chondroitinase.

Mary

Pflugers Arch. 2010 Aug;460(3):657-66. Epub 2010 Jun 16.
Partial functional recovery after complete spinal cord transection by combined chondroitinase and clenbuterol treatment.


Abstract
Spinal cord injury not only disrupts axonal tracts but also causes gliotic, fibrotic, and Schwannotic scarring with resulting deposition of chondroitin sulfate proteoglycans (CSPGs) which prevent axonal reconnection and recovery of locomotor function.

Here, we determined whether recovery of locomotor function could be promoted after complete transection, by degrading CSPGs enzymatically within the injury site with chondroitinase ABC (chABC) together with treatment with the beta(2)-adrenoceptor agonist, clenbuterol, a neuroprotective agent which can promote regrowth of lower motoneurons.

Partial recovery of locomotor function was observed 8-12 weeks postinjury only after combined chABC and clenbuterol treatment.

The recovery of locomotor function coincided with the presence of axons caudal to the injury site arising from neurons of the reticular, vestibular, and red nuclei also only with combined chABC and clenbuterol treatment.

Axons myelinated by Schwann cells were most prominent in the transection site in the combined treatment group.

Clenbuterol treatment activated cAMP response element binding protein within retrogradely traced neurons which has been associated with axonal regrowth.

ChABC treatment decreased scarring due to both CSPG and collagen deposition as well as the gap between intact regions of the spinal cord. ChABC also increased numbers of phagocytic cells which remove myelin debris as well as populations of astrocytes thereby aiding blood-spinal cord barrier reformation. Together the results suggest that chABC and clenbuterol can act synergistically to promote recovery of locomotor function.

PMID:20552220[PubMed - indexed for MEDLINE]

.....................................

Chondroitinase ABC treatment opens a window of opportunity for task-specific rehabilitation


Abstract

Chondroitinase ABC treatment promotes spinal cord plasticity. We investigated whether chondroitinase-induced plasticity combined with physical rehabilitation promotes recovery of manual dexterity in rats with cervical spinal cord injuries. Rats received a C4 dorsal funiculus cut followed by chondroitinase ABC or penicillinase as a control.

They were assigned to two alternative rehabilitation procedures, the first reinforcing skilled reaching and the second reinforcing general locomotion.

Chondroitinase treatment enhanced sprouting of corticospinal axons independently of the rehabilitation regime.

Only the rats receiving the combination of chondroitinase and specific rehabilitation showed improved manual dexterity.

Rats that received general locomotor rehabilitation were better at ladder walking, but had worse skilled-reaching abilities than rats that received no treatment.

Our results indicate that chondroitinase treatment opens a window during which rehabilitation can promote recovery. However, only the trained skills are improved and other functions may be negatively affected.

http://www.nature.com/neuro/journal/v12/n9/abs/nn.2377.html

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Again from Mary -

I think a trial with either drug would provide some answers, as both stimulate the AKT pathway. Formoterol due to the reduced cardiac effects and clenbuterol due to the fact that it also inhibits atrogin-1 .

---

Into the heart, an air that kills, from yon far country blows.
What are those blue remembered hills, what sphires what farms are those.
That is the land of lost content,I see it shining plain,
The happy highways where I went and cannot come again

Staying on thread:

Regulation of atrogin-1 and MuRF1 following exercise

Because atrogin-1 and MuRF1 have been shown to increase skeletal muscle atrophy, it was expected that resistance exercise, an intervention known to increase net protein synthesis, would reduce the expression of these atrophy genes.

However, we have shown previously in humans that following 8 weeks of hypertrophy-inducing resistance training, performed at 85–95% of maximum, atrogin-1 and MuRF1 mRNA and protein levels are increased in hypertrophied muscle.

In contrast, performing acute moderate-intensity knee extension exercise, consisting of three to eight sets of 10 repetitions at 60–80% of one maximal concentric lift, results in a decrease in atrogin-1 mRNA approximately 4–24 h after exercise and an increase in MuRF1 mRNA 1–4 h after exercise in human quadriceps muscle.

In contrast, performing 8 × 5 maximal effort leg extensions reduced atrogin-1 by 70% (not significant) in endurance trained subjects, but had no effect in strength-trained subjects.

Exercise, in the form of stepping up (concentric contractions) onto a bench with one leg and stepping down (eccentric contractions) with the other leg, resulted in an increase in MuRF1 3 h after exercise during the concentric phase and a decrease in atrogin-1 mRNA from 3 to 24 h during the eccentric phase.

However, because the amount of concentric and eccentric work was not equal and the effect of combined systemic influences not considered, these observations are difficult to interpret.

Running for 30 min at a moderate-high intensity of 75% of Vo2max results in an increase in both atrogin-1 and MuRF1 mRNA 1–4 h after exercise.

Similarly, cycling at 70% of Vo2 peak for 60 min increased atrogin-1 mRNA by twofold in endurance-trained subjects and by 0.4-fold in strength-trained subjects.

It appears that the regulation of atrogin-1 and MuRF1 depends on the mode and intensity of exercise, as well as the training history of the subjects.

To date, none of these acute exercise studies has established the transcriptional mechanisms regulating atrogin-1 and MuRF1 gene expression, nor have their protein levels been measured.

No rationale has been proposed to explain the opposing regulation of atrogin-1 and MuRF1 with these differing intensities of muscle contraction.

Furthermore, the extracellular signals, or their target receptors and downstream intracellular signalling pathways that control transcriptional and translational regulation of atrogin-1 and MuRF1 in various human catabolic and anabolic situations, have not been well defined.

Understanding the signalling mechanisms by which exercise may up- and/or downregulate atrogin-1 and MuRF1 is vital for our understanding of how these key genes regulate skeletal muscle mass. This knowledge will have implications for clinical rehabilitation and the future development of pharmacological interventions.

......................................

Notice in the above the different actions between concentric and eccentric exercise:


Now look below and it looks like vitamin E is selective in eccentric exercise only.
Maybe another factor indicating a cocktail approach should include vitamin E and on its own it is only partially effective?


Promotion of plasma membrane repair by vitamin E

Also, as motioned above, in humans one of the problems associated with vitamin E deficiency is skeletal myopathy, and low vitamin E levels in the elderly are correlated with 'frailty' syndrome, characterized primarily by loss of muscle strength.

More importantly, vitamin E supplementation protects human muscle from injury by eccentric exercise, a form of muscle contraction known to result in extensive membrane disruption events. Statins, cholesterol-lowering drugs whose main side effect is muscle damage, reduce vitamin E levels in blood, leading to the speculation that this deficiency might explain statin-induced muscle damage.

We also mention above that muscular dystrophy can result from a failure in plasma membrane repair by skeletal muscle myocytes and that plasma membrane disruptions occur not only in disease, such as muscular dystrophy, but also physiologically, in normal muscle, reaching the highest measured levels during exercise-induced eccentric contractions.

These eccentric contractions generate high levels of ROS relative to concentric contractions, and vitamin E supplementation can reduce exercise-induced oxidative damage of phospholipids.

In one case where a positive effect of supplementation was demonstrable in a muscle contraction model, careful analysis showed that the additional vitamin E did not prevent development of a post-contraction force deficit, or reduce the number of injured fibres, but that it did prevent subsequent rises in blood CK levels56, as would be consistent with an action that was reparative, not protective.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3247818/?tool=pmcentrez

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Into the heart, an air that kills, from yon far country blows.
What are those blue remembered hills, what sphires what farms are those.
That is the land of lost content,I see it shining plain,
The happy highways where I went and cannot come again

I have condensed and taken all the information from the relevant postings in this thread to lay them out:

This should show us what the pathways are or in other words what each factor does - good or bad- and some possible self therapeutic approaches.

Post 1: This indicates that mutant SOD1 has a sort of toxin like action that is separate from the nerve degeneration process in muscles.

The results of this study challenge the accepted dogma that motor neuron degeneration, caused by transgenic SOD1 G93A overexpression, is the primary cause of muscle atrophy.
This sequential pattern of degeneration suggests that certain muscle abnormalities precede motor neuron death rather than resulting from it.

Our results confirm that local oxidative stress is a primary determinant of ALS-associated muscle pathology, separating the toxic effects of SOD1 G93A transgenefrom motor neuron degeneration.

Post 2: mitochondrial ROS production decreased significantly with increased uncoupling protein (UCP)3

Post 3: You have to be selective when taking anti-oxidants as accumulation of these in mitochondria increases their efficacy. Note Mito-Q, a derivative of ubiquinone, and MitoVit-E, a derivative of Vit-E, are two promising antioxidants (Fig. 1) that are specifically targeted to mitochondria

Importantly, the accumulation of these antioxidants by mitochondria protected them from oxidative damage far more effectively than untargeted antioxidants, suggesting that the accumulation of antioxidants within mitochondria does increase their efficacy.

Most interestingly, these compounds were several hundred–fold more effective at preventing cell death in fibroblasts from Friedreich Ataxia patients (49a).

Post 4: More evidence in support of the first post. SOD1G93A-mediated muscle atrophy is independent from caspase activity.

Post 5:
1. Could we use it as a possible marker for SOD1 dysfunction - if you have muscle wasting does it happen in other types of ALS like say TDP-43 etc. If it is explicit to SOD1 dysfunction that gives you an indication of what type of therapy to pursue. I realise this is a possible crude biomarker but what else do we have?

2. Any therapy should be looking at specific muscle dysfunction caused by SOD1 and may have to be separate to any therapy for ALS in general.

3. If should not be as difficult as solving or curing ALS to develop a specific muscle therapy based on what we know now. In this case we know what is causing the muscle loss and have a possible pathway.

4. This specific therapy may or may not prolong life but would improve the quality of life.

Post 6: Increase of atrogin-1 causes muscle loss: - The increase in atrogin-1 not only stimulated protein degradation but also suppressed protein synthesis, causing muscle atrophyatrogin-1 is found only in muscle. -

In normal muscles, the amount is low; however, there is a dramatic increase in the production of the atrogin-1 protein in conditions where muscles lose size and strength."

"If you could inhibit atrogin-1 or block a cell's ability to make it, you could reduce muscle wasting," Goldberg said.

Our recent findings implicated the induction of atrogin-1, a gene required for the development of muscle atrophy, in statin-induced muscle damage.

Implication of IGF-1: It inhibits the ubiquitin ligase atrogin-1 expression
IGF-1 prevents ANG II-induced skeletal muscle atrophy via Akt- and Foxo-dependent inhibition of the ubiquitin ligase atrogin-1 expression

Post 7: The role of Testosterone
Testosterone represses ubiquitin ligases atrogin-1 and Murf-1 expression in an androgen-sensitive rat skeletal muscle in vivo

The role of both Atrogin-1 and MuRF1

We observed that in skeletal muscle of the ALS patients, when compared with the healthy control subjects, a significant 170% and 340% increase, respectively, in atrogin-1 mRNA and protein content

Post 8: Muscle Protein Breakdown in Cachexia
One particular gene that we have begun characterizing, which we named atrogin-1, is induced in all states where muscle atrophy occurs and is a central regulator in the process.

Post 9: Electrical stimulation based on chronaxie reduces atrogin-1 and myoD gene expressions in denervated rat muscle.

However, ES did not prevent muscle-fiber atrophy after denervation.

Post 10: Foxo3a transcription factor is critical for muscle atrophy, since it activates the expression of ubiquitin ligase Atrogin-1.

Our results thus suggest that SAPKs are involved in the control of Foxo3a nucleocytoplasmic translocation in C2C12 cells.

Moreover, activation of SAPKs decreases the expression of Atrogin-1, and stable C2C12 myotubes, in which the p38 pathway is constitutively activated, present partial protection against atrophy.

Post 11: Molecular regulation of skeletal muscle mass by Akt signalling.
Other in vivo and in vitro rodent models associated with muscle atrophy, such as ALS, sepsis induced by lipopolysaccharide-induced endotoxaemia or denervation, as well treatments with lovastatin, dexamethasone and serum starving, all result in reduced Akt activation

Using tamoxifen-inducible transgenesis in mice to activate Akt prevented the muscle damage caused by eccentric contractions in dystrophic mdx mice and force levels were maintained to a similar extent as those observed in muscles from wild-type mice.
These observations show that Akt can potentially attenuate the loss of muscle mass and function, at least in mdx mice

Knockout of either atrogin-1 or MuRF1 in mice reduces muscle loss following denervation by approximately 50%.

FoXO1 does not directly increase atrogin-1 levels, but instead blocks the IGF-1 inhibition of atrogin-1 upregulation in catabolic conditions such as dexamethasone treatment.

In human muscle, atrogin-1 mRNA and protein, as well as MuRF1 mRNA, are increased in human atrophy conditions, such as in patients with ALS

Role of PGC-1
Mice genetically modified to overexpress PGC-1α in their skeletal muscles were protected against denervation- or starvation-induced muscle atrophy.
Furthermore, PGC-1α inhibits the activity of a constitutively active FoXO3a, a mutant that cannot be phosphorylated and inactivated by Akt.

This suggests that PGC-1α may not act via the Akt signalling pathway
In contrast with these protective effects of PGC-1α, Muira et al. demonstrated that genetic overexpression of PGC-1α resulted in skeletal muscle atrophy, especially in muscles with a higher proportion of Type 2B fibres.

These mice also had decreased levels of ATP

Post 12: Clenbuterol

clenbuterol unfortunately doesn't do the complete works as it does not act on Akt but it does suppresses the transcription of the lysosomal protease cathepsin L and of atrogin-1/MAFbx and MuRF1....

Clenbuterol suppresses proteasomal and lysosomal proteolysis and atrophy-related genes in denervated rat soleus muscles independently of akt.

Post 13: Amelioration of denervation-induced atrophy by clenbuterol is associated with increased PKC-α activity (see above post 11)

Partial recovery of locomotor function was observed 8-12 weeks postinjury only after combined chABC and clenbuterol treatment.

Possible renervation with combined chABC and clenbuterol treatment.

The recovery of locomotor function coincided with the presence of axons caudal to the injury site arising from neurons of the reticular, vestibular, and red nuclei also only with combined chABC and clenbuterol treatment.

Chondroitinase
Chondroitinase treatment opens a window during which rehabilitation can promote recovery. However, only the trained skills are improved and other functions may be negatively affected.

Post 14: The role of presenilins (PS) in the business of neuron health and disease
PS2, in particular, is necessary for normal expression of the receptor for platelet-derived growth factor (PDGF), and for activation of the neuroprotective Akt and ERK kinase cascades in fibroblasts.

Akt activation in fibroblasts from PS1/2 double knockout mice that had been reconstituted with human PS1 or PS2 alleles.

They found that expression of either gene could restore Akt and ERK activation (and decrease tau phosphorylation) in response to whole serum, but only PS2-expressing cells responded to the individual growth factor PDGF.

Activation of the anti-apoptotic Akt pathway by growth factors with the help of presenilins seems to be required to maintain mouse neurons during aging, and probably human ones, as well.

The role of DHA (in omega 3):
And in another reminder of the importance of Akt activation, a report in last week’s PNAS online, shows that the neuroprotective n-3 fatty acid docosahexaenoic acid (DHA) promotes the speedy membrane translocation and activation of this survival signaling enzyme in neurons from mice fed a diet rich in DHA.

Post 15: Regulation of atrogin-1 and MuRF1 following exercise. It appears that the regulation of atrogin-1 and MuRF1 depends on the mode and intensity of exercise, as well as the training history of the subjects

The role of Vitamin E:
vitamin E is selective in eccentric exercise only. These eccentric contractions generate high levels of ROS relative to concentric contractions, and vitamin E supplementation can reduce exercise-induced oxidative damage of phospholipids.

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Into the heart, an air that kills, from yon far country blows.
What are those blue remembered hills, what sphires what farms are those.
That is the land of lost content,I see it shining plain,
The happy highways where I went and cannot come again

There is supporting evidence that SOD1 G93A
toxic properties are independent of the levels of SOD1 activity in muscles

Small amounts of mutant SOD1 can cause muscle atrophy.

Note also how EDL and soleus muscle are initally affected and in some PALS foot drop is the first signs of ALS?


Mutant SOD1 Alters the Functional Performance and the Contractile and Metabolic Machinery of Skeletal Muscle

To determine whether muscle accumulation of SOD1 G93A mutant protein affected the capacity to produce force a direct comparison of mechanical parameters was performed for the soleus and EDL muscles of both WT and MLC/SOD1 G93A transgenic mice at 16 weeks of age. Muscle atrophy in transgenic mice was associated with decreased tetanic and specific force generation of 37% for EDL and 39% for soleus muscle compared with age-matched WT littermates.

Note: ex-tensor digitorum longus (EDL)
The Extensor digitorum longus is a pennate muscle, situated at the lateral part of the front of the leg. It is involved in foot drop in ALS.

In humans and some other mammals, the soleus is a powerful muscle in the back part of the lower leg (the calf)


This trend was confirmed by the analysis of isotonic fatigue. In the first seconds of fatigue, stimulation of both transgenic EDL and soleus produced work of about 38% less than WT muscles. Furthermore, MLC/SOD1 G93A EDL and soleus stopped shortening about 7 s and 15 s, respectively, before the WT controls. These analyses demonstrate that even low levels of mutant SOD1 G93A transgene expression, such as those in the soleus muscle, were sufficient to compromise the morphological and functional parameters of skeletal muscle
The Peroxisome proliferator-activated receptor gamma coactivator 1a (PGC1a) is one of the major regulators of several crucial aspects of energy metabolism. PGC1a controls many aspects of oxidative metabolism, including mitochondrial biogenesis and it is the master regulatory gene that promotes fiber-type switching from glycolytic toward more oxidative fibers.
Real-time polymerase chain reaction (PCR) revealed that PGC1a expression was significantly increased in EDL muscle of MLC/ SOD1 G93A transgenic mice

Notably the accumulation of PGC1 a was also associated with a shift in the metabolic activity of EDL muscle fibers to a more oxidative phenotype in MLC/SOD1 G93A transgenic mice, as shown by greater content of NADH. Taken together these results demonstrate that oxidative stress significantly alters the metabolic activity of skeletal muscles.

These experiments suggest that alteration of SOD1 protein exclusively in skeletal muscle significantly damages the sarcolemma of muscle fibers, without affecting other targets altered by the ubiquitous expression of SOD1 mutant gene.

http://www.scribd.com/doc/8696012/Skeletal-Muscle-is-a-Primary-Target-of-SOD1-Mediated-Toxicity-Musaro

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Into the heart, an air that kills, from yon far country blows.
What are those blue remembered hills, what sphires what farms are those.
That is the land of lost content,I see it shining plain,
The happy highways where I went and cannot come again

Status of UCP's

UCP2 and UCP3 are overexpressed in ALS mice muscles

1. We systematically studied the expression levels of UCPs in various tissues of ALS affected mice carrying a mutated form of SOD1 (G86R mice) using semiquantitative RT-PCR. We found an increased expression of UCP2 and UCP3 expression in skeletal muscle of G86R mice compared with control littermates. UCP3 expression was increased 2 wk before disease onset (90 days of age) and sustained until death of the animals (105 days of age), whereas UCP2 up-regulation occurred later, close to disease onset.

We did not detect any variation of UCPs in other tissues (liver, spinal cord).

2 UCP2 mRNA levels are up-regulated in mouse gastrocnemius muscles by experimental sciatic nerve axotomy or crush. On the contrary, UCP3 mRNA levels are down-regulated in experimentally denervated muscles, a situation opposite to the one observed in muscles of G86R transgenic mice.

3. UCP2 mRNA levels are unchanged in muscles of a transgenic mouse line overexpressing the wild-type allele of SOD1 (wt-SOD1).

UCP3 mRNA levels are decreased in wt-SOD1 muscles.

The early up-regulation of UCP3 mRNA in the skeletal muscle of G86R animals is thus specifically linked to the expression of the ALS-associated mutant enzyme.

4. UCP3 mRNA and protein levels were up-regulated in human muscular sporadic ALS biopsies compared with various neuromuscular and control patients.

5. Isolated mitochondria of G86R muscles displayed a lower respiratory control ratio while cytochrome c oxidase activity was found unchanged thus suggesting the occurrence of mitochondrial uncoupling.

Furthermore, ATP levels are depleted in skeletal muscles of G86R mice (30% decrease at 90days of age; 38% decrease at 105 days of age) and unchanged in liver and spinal cord tissues, correlating with a UCP pattern of expression.

CONCLUSIONS AND SIGNIFICANCE

Our findings demonstrate that UCP3 is specifically overexpressed in skeletal muscles of ALS patients and an ALS animal model independent from the transcriptional response of the muscle to neuronal death.

Furthermore, this UCP3 overexpression is specific to muscle tissue and correlates with a decrease in mitochondrial respiratory control ratio in ATP levels in this tissue.

Our results thus suggest that UCPs trigger mitochondrial uncoupling, which lowers ATP levels and contributes to the ALS phenotype.

Indeed, UCP2 and UCP3 are both susceptible to trigger mitochondrial uncoupling in vitro and in vivo as shown by the decreased mitochondrial proton leak of isolated mitochondria from UCP3 −/− or UCP2 −/− animals.

However, even if these proteins are susceptible to significantly uncouple mitochondria, their absence has no effect on whole animal metabolic responses: UCP3 and UCP2 knockout animals are neither obese nor show abnormal responses to fasting or cold-induced thermogenesis.

This is probably due to the involvement of UCP2 and UCP3 in an oxidative stress-inducible proton leak rather than to basal proton leak.

In physiological situations where oxidative stress occurs, such as exercise or fasting, UCP2 and UCP3 uncoupling activities are activated by superoxide anion, limiting ROS production by mitochondrial respiratory chain. This in turn decreases superoxide levels and UCP uncoupling activity by a feedback loop.

UCP3 up-regulation thus appears as a primary protective response against oxidative stress.

Our experiments further suggest that in vivo muscular mitochondrial uncoupling is able to be deleterious for skeletal muscle cells.

For example, a possible deleterious effect of a sharp UCP3 up-regulation is its potential effect on general metabolism.

Although UCP3 levels have no effect on the basal metabolism in normal conditions, transgenic mice that overexpress UCP3 in muscles are lean and hyperphagic due to hypermetabolism through mitochondrial uncoupling.

In ALS, weight loss is a common symptom, and a clinical study showed that ALS patients are hypermetabolic.

http://www.fasebj.org/content/17/14/2091.full


Earlier posting

'We studied transgenic mice with muscular overexpression of uncoupling protein 1 (UCP1), a potent mitochondrial uncoupler, as a model of muscle restricted hypermetabolism. These animals displayed age-dependent deterioration of the NMJ that correlated with progressive signs of denervation and a mild late-onset motor neuron pathology.

NMJ regeneration and functional recovery were profoundly delayed following injury of the sciatic nerve and muscle mitochondrial uncoupling exacerbated the pathology of an ALS animal model.

CONCLUSIONS/SIGNIFICANCE:

These findings provide the proof of principle that a muscle restricted mitochondrial defect is sufficient to generate motor neuron degeneration and suggest that therapeutic strategies targeted at muscle metabolism might prove useful for motor neuron diseases.'
So UCP1 up regulation looks bad.....?

New Aspects of Mitochondrial Uncoupling Proteins (UCPs) and Their Roles in Tumorigenesis

Richard et al. reported the presence of UCP2 mRNA with varying intensities throughout the brain.

Marked high intensities were found in the hypothalamus, the ventral septal region, the ventricular region and the cerebellum, suggesting a novel role of UCP in modulating neuroendocrine functions and autonomic responses of the brain.

In addition, UCP2-mediated mitochondrial proton leak has been positively correlated with increased oxygen consumption in brain tissues.

This regulation of oxygen consumption, suggests that UCP2 may modulate ROS production and influence the process of neurodegeneration.

The mRNA expression of UCP2 in the brain suggested neuronal localization .

In an animal model of Parkinson’s disease (PD), in which dopamine neurons are depleted by 1-methyl-4-phenyl-1,2,5,6 tetrahydropyridine (MPTP), UCP2 knockout increased whereas UCP2 overexpression decreased MPTP-induced nigral dopamine cell loss.

Coenzyme Q10 (CoQ10), a cofactor of mitochondrial metabolism and UCP2 activity, induced UCP2-mediated mitochondrial uncoupling in the substantia nigra.

When given orally, CoQ10 was shown to reduce dopamine cell loss in both mouse [25] and primate models of PD [24] and potentially slowed the progression of the disease in human patients.

As mentioned above, UCP2 protects against dopamine cell loss caused by the mitochondrial complex I toxin MPTP.

Consistent with that, degeneration of substantia nigra compacta dopaminergic neurons in human PD is associated with mitochondrial complex I dysfunction and free radical toxicity.

These studies demonstrate the importance of UCP2 in normal nigral dopamine cell metabolism, and suggest that UCP2 is important in regulating cell survival and susceptibility to mitochondrial toxins; and may serve as a novel therapeutic target for the prevention and treatment of PD.

Not surprising, UCP also plays an important role in Alzheimer’s disease (AD).

The expression levels of UCP2, 4, and 5 were significantly reduced in AD patients, which were accompanied by upregulation of nitric oxide synthases (NOS), and resulted in increased oxidative stress and impaired mitochondrial functions.

Therefore, to increase the expression level of UCP may help in the treatment of AD.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3179165/

UCP2
From Wikipedia, the free encyclopedia

Although it was originally thought to play a role in non shivering thermogenesis, obesity, diabetes and atherosclerosis, it now appears that the main function of UCP2 is the control of mitochondria-derived reactive oxygen species.

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Increased uncoupling proteins and decreased efficiency in palmitate-perfused hyperthyroid rat heart


Abstract
The physiological role of mitochondrial uncoupling proteins (UCPs) in heart and skeletal muscle is unknown, as is whether mitochondrial uncoupling of oxidative phosphorylation by fatty acids occurs in vivo.

In this study, we found that UCP2 and UCP3 protein content, determined using Western blotting, was increased by 32 and 48%, respectively, in hyperthyroid rat heart mitochondria.

Oligomycin-insensitive respiration rate, a measure of mitochondrial uncoupling, was increased in all mitochondria in the presence of palmitate: 36% in controls and 71 and 100% with 0.8 and 0.9 mM palmitate, respectively, in hyperthyroid rat heart mitochondria.

In the isolated working heart, 0.4 mM palmitate significantly lowered cardiac output by 36% and cardiac efficiency by 38% in the hyperthyroid rat heart.

Thus increased mitochondrial UCPs in the hyperthyroid rat heart were associated with increased uncoupling and decreased myocardial efficiency in the presence of palmitate.

In conclusion, a physiological effect of UCPs on fatty acid oxidation has been found in heart at the mitochondrial and whole organ level.

http://ajpheart.physiology.org/content/280/3/H977.full
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Palmitic acid
From Wikipedia, the free encyclopedia

Palmitic acid has been shown (in rats fed on a 20% fat (palmitic acid), 80% carbohydrate diet) to alter aspects of the central nervous system responsible for the secretion of insulin, and to suppress the body's natural appetite-suppressing signals from leptin and insulin -- the key hormones involved in weight regulation

Excess carbohydrates in the body are converted to palmitic acid.

Palmitic acid is the first fatty acid produced during fatty acid synthesis and the precursor to longer fatty acids.

Palmitate negatively feeds back on acetyl-CoA carboxylase (ACC), which is responsible for converting acetyl-CoA to malonyl-CoA, which in turn is used to add to the growing acyl chain, thus preventing further palmitate generation.

In biology, some proteins are modified by the addition of a palmitoyl group in a process known as palmitoylation. Palmitoylation is important for membrane localisation of many proteins.

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Into the heart, an air that kills, from yon far country blows.
What are those blue remembered hills, what sphires what farms are those.
That is the land of lost content,I see it shining plain,
The happy highways where I went and cannot come again