Nonhuman Primate Models of Menopause (Part 12)

Previous studies of metabolic parameters in middle-aged and older female rhesus monkeys generally provided limited documentation of the hormonal profile or their menopausal status. Furthermore, these studies used a cross-sectional rather than a longitudinal experimental design. Therefore, it is impossible to identify the temporal sequence of events in individual animals and their interrelationships with menopause. A better understanding may be forthcoming when two ongoing studies of caloric restriction (at the NIA Intramural Program and the Wisconsin Regional Primate Research Center) are complete. These studies maintain control groups that will yield substantive information regarding normative aging when completed. The female monkeys in these studies are currently 14-20 yr of age and are approaching a time when menopause-related symptoms and conditions will begin to occur. natural asthma treatment

Baboon. In an unpublished study, a cohort of 26 nondiabetic female baboons (age, 9-18 yr) with body fat greater than 20% and exhibiting regular menstrual cycles as well as normal complete blood counts and serum chemistry profiles was used to examine the effect of increasing age and obesity on fasting lipids, glucose, and insulin levels. When examined 5 yr later, the 15 animals remaining in the cohort were still cycling regularly but exhibiting subtle signs of impending irregular cycles. Both weight and percentage body fat had increased, but only weight had increased significantly. Glucose had increased significantly, so that all animals were hyperglycemic. Despite a significant decrease in insulin, all but two animals remained hyperinsulinemic. Triglyceride levels were normal and did not change. A slight decrease had occurred in serum total cholesterol, but an increase in low-density lipoprotein (LDL) cholesterol, a significant decrease in high-density lipoprotein (HDL) cholesterol, and a significant increase in the LDL:HDL cholesterol ratio had also occurred. Thus, conditions associated with increased risk of coronary heart disease in aging women, such as obesity, altered lipoproteins, and increases in fasting glucose and insulin, also occur in aging female baboons.