Leptin, adiposity, and testosterone in captive male macaques

Abstract

Leptin is considered to act as a signal relating somatic energetic status to the reproductive system. However, the nature of that signal and its relationship with male reproductive function across nonhuman primate species are unclear. We suggest that species-specific differences in leptin physiology may be related to the degree of environmental variation and variation in the importance of energy stores for male reproduction. In order to test the role of seasonality in species differences among nonhuman primates, we compared leptin, testosterone, and body composition in male rhesus (n = 69) and pig-tailed (n = 43) macaques. Despite having larger abdominal fat deposits, the rhesus macaques did not exhibit significantly higher leptin levels (rhesus, 2.21 +/- 0.43 ng/ml; pig-tailed, 2.12 +/- 0.39 ng/ml). Both species showed increases in leptin across adolescent, subadult, and adult age-groups (P = 0.036 for rhesus; P = 0.0003 for pig-tailed by ANCOVA). Testosterone was not significantly associated with leptin in either the rhesus (r = 0.039; P = 0.754) or pig-tailed (r = 0.2862; P = 0.066) samples. Comparison of leptin levels across the two species using univariate modeling procedures showed no significant age-group by abdominal fat interaction. These findings suggest little difference in leptin production between these two closely related species, despite the difference in breeding seasonality.

Aging-related sex-dependent loss of the circulating leptin 24-h rhythm in the rhesus monkey

“…Additionally, our data concur with previous non-human primate studies, in that we observed similar plasma concentrations of leptin that increased with age (Urbanski & Pau 1998, Muehlenbein et al 2005. However, this work advances the paucity of data regarding circulating leptin in rhesus monkeys in several ways.…”

“…However, this work advances the paucity of data regarding circulating leptin in rhesus monkeys in several ways. Unlike previous works utilizing rhesus monkeys, we were able to determine the 24-h pattern of release by utilizing a remote blood-sampling system that allowed for frequent sampling (hourly for 25 h) rather than a single daytime only, or a single day and nighttime sample (Plant & Durrant 1997, Urbanski et al 1998, Suter et al 2000, Muehlenbein et al 2005, and this remote sampling technique also eliminated the potential for a stress response that may confound the observed levels of leptin. Much of the previous data on circulating leptin in the nonhuman primate pertained to the relationship between circulating leptin levels and the initiation of puberty (Plant & Durrant 1997, Suter et al 2000.…”

Seasonal variation and sex differences in the nutritional status in two local populations of wild Japanese macaques

“…Such differences in body sizes as reported by Hamada et al (1996) may be partly based on genetic differences between the two populations (Nozawa et al 1996), though no published data are available on the influence of genetic differences demonstrated by isozyme analyses on morphometric measures. However, differences in nutritional condition and its fluctuations in animals are likely to be related to differences in the climates (e.g., temperature, snowfall) and/or vegetation of the habitats of the two populations (Muehlenbein et al 2005). Lower temperature and more snowfall in the Shimane region than in the Boso region may require more energy reserves in animals.…”

“…A primate index is calculated as mass/(crown-rump length) 2 according to Muehlenbein et al (2005). A physique index was also calculated according to Hamada et al (1996) as follows:…”

“…For example, feeding is an activity to gain energy and other nutrients to survive, whereas reproductive behavior such as mating, conception, and lactating offspring entail considerable energy expenditure (McFarland 1997). Many studies have been conducted in nonhuman primates, on nutritional status in terms of reproductive strategies and ecological adaptation (Goldizen et al 1988;Bercovitch 1992;Altmann et al 1993;Dietz et al 1994;Alberts et al 1996;Koenig et al 1997;Kurita et al 2002;Muehlenbein et al 2002Muehlenbein et al , 2005.…”