Role of visceral adipose tissue in aging.

Visceral fat (VF) accretion is a hallmark of aging in humans. Epidemiologic studies have implicated abdominal obesity as a major risk factor for insulin resistance, type 2 diabetes, cardiovascular disease, stroke, metabolic syndrome and death. Utilizing novel rodent models of visceral obesity, studies have demonstrated a causal relationship between VF and age-related diseases. In contrast, surgically removing large quantities of subcutaneous (SC) abdominal fat does not consistently improve metabolic parameters in humans or rodents, suggesting that SC fat accrual is not an important contributor to metabolic decline. There is also compelling evidence in humans that abdominal obesity is a stronger risk factor for mortality risk than general obesity. Likewise, we have shown that surgical removal of VF improves mean and maximum lifespan in rats, providing the first causal evidence that VF depletion may be an important underlying cause of improved lifespan with CR. Given the hazards of VF accumulation on health, treatment strategies aimed at selectively depleting VF should be considered as a viable tool to effectively reduce disease risk in humans. In summary, this review provides both corollary and causal evidence for the importance of accounting for body fat distribution, and specifically VF, when assessing disease and mortality risk.

Huffman DM, Barzilai N.
Biochim Biophys Acta. 2009 Jan 30.

reduced dehydroepiandrosterone sulfate (DHEAS) levels - biomarker of aging in male

Aging in male primates: reproductive decline, effects of calorie restriction and future research potential.

Although less dramatic than in females, male mammals experience decreasing reproductive function during aging. In primates, multiple facets of the hypothalamic-pituitary-gonadal axis show evidence of gradual age-related decline, including behavioral, neuroendocrine and endocrine alterations such as decreased testosterone levels, reduced circulating dehydroepiandrosterone sulfate (DHEAS) levels, increased numbers of sperm abnormalities, and a general decline in physiological responses. In this review we consider a range of age-related changes in males. These measures, including more subtle aging characteristics, are interesting additional indices for detecting the timing of age-related changes in behavioral, neuroendocrine, and endocrine responses. Evidence of potential effects of calorie restriction as an intervention in reproductive aging is also discussed. A discernable decline occurs in both metabolic and reproductive endocrine processes during male aging. This cascade of events includes neuroendocrine and behavioral changes; biomarkers such as circulating DHEAS also show clear age-related decline. The varied changes that occur during male aging are considered in the context of primate aging in general.

Age (Dordr). 2008 Sep;30(2-3):157-68. Epub 2008 Jul 9.

Sitzmann BD, Urbanski HF, Ottinger MA.