Calorie restriction in rhesus monkeys favourable to DHEA

[jyb]

Calorie restriction in rhesus monkeys.

The study shows that serum DHEA-S is better preserved throughout the lifespan of calorie restricted monkeys. Wouldn't have one expected the opposite?

I don't know what DHEA does really, other than the fact that it has a physiological purpose on top of having a potential to turn into other steroids like estrogen. From personal experiments so far, strangely, I have found it to be more useful than thyroid, progesterone and pregnelonone at reducing stress and increasing temperatures.

 

[jyb]

Dehydroepiandrosterone sulfate (DHEAS) as an endocrine marker of aging in calorie restriction studies

Actually, the findings that CR helps preserve DHEA are disproved in this newer study. Some possible explanations are given, including the fact that the measurements in the older study were not done properly (didn't control for time of the day variation in DHEA).

 

[Lejeboca]

To add fuel to the flames:

Influences of aging and caloric restriction on the transcriptional profile of skeletal muscle from rhesus monkeys​

The best nugget from the paper is not in the title but in the next to last paragraph:

"An interesting observation of our study is the decrease in expression of genes involved in OXPHOS function in both aged animals receiving the control diets and middle-aged CR animals. We postulate that such alterations have a distinct molecular basis and are induced by mitochondrial dysfunction in aged animals as opposed to lower metabolic rate in CR animals. In particular, the 23-fold lower expression of cytochrome c1, which is particularly sensitive to thyroid status (16, 17), was observed in CR monkeys (Table 4) but not in aged animals (Table 2). Consistent with this hypothesis, long-term (2-year) CR leads to reduced energy expenditure and sleeping metabolic rate in humans (24). The concept that reduced OXPHOS gene expression activity with aging is caused by mitochondrial and metabolic dysfunction is supported by the induction of reactive oxygen species and inflammatory related transcripts in aged skeletal muscle of rhesus monkeys (Table 1), and by the accrual of oxidative damage (22) and high levels of mitochondrial DNA deletions in skeletal muscle of these animals (25).
Surprisingly, we did not observe beneficial effects of adult-onset CR on the progression of age-related transcriptional markers (Table 5)."