Plasma cholesterol levels in free-ranging macaques compared with captive macaques and humans

Area of Science:

• Primatology
• Comparative Physiology
• Nutritional Science

Background:

• Plasma total cholesterol (TCH) levels vary significantly between wild and captive primate populations, as well as across species and age groups.
• Understanding these variations is crucial for assessing primate health, metabolic status, and reproductive physiology.

Purpose of the Study:

• To compare plasma TCH levels in free-ranging Japanese macaques (Macaca fuscata) and long-tailed macaques (Macaca fascicularis) with captive macaques and humans.
• To investigate the influence of age, sex, and diet on TCH levels in different macaque populations.
• To explore the potential implications of low TCH on reproductive maturation in wild female macaques.

Main Methods:

• Blood samples were collected from free-ranging Japanese macaques on Koshima islet and long-tailed macaques in Pangandaran, Indonesia.
• Plasma TCH and HDL cholesterol levels were measured and compared with existing data for captive macaques and humans.
• Long-term dietary supplementation with cholesterol was administered to captive long-tailed macaques to assess response.

Main Results:

• Free-ranging macaques exhibited markedly lower plasma TCH than captive macaques and humans.
• While captive macaques had lower TCH than humans, HDL cholesterol differences were minimal.
• In Japanese macaques, TCH decreased with age until young adulthood, then increased in captive adult females, unlike wild females who maintained low levels.
• Dietary cholesterol supplementation increased plasma TCH in captive long-tailed macaques, with post-supplementation levels dependent on baseline values.

Conclusions:

• Wild macaque populations, particularly adult females, may experience low energy intake, potentially impacting reproductive timing.
• Captive macaques appear to have a higher baseline cholesterol status, with potential for cholesterol saturation.
• Further research is needed to fully elucidate the metabolic and physiological consequences of differing TCH levels in wild versus captive primates.