Nonhuman Primate Models of Menopause Workshop

The Nonhuman Primate Models of Menopause Workshop was held on the National Institutes of Health campus in January 2001. The purpose of this workshop, sponsored by the National Institute on Aging, was to review what is known about the female reproductive aging process in various species of monkeys (particularly rhesus, baboons, cynomolgus, and chimpanzees), including hormone profiles during the menopausal transition, occurrence of hot flashes, extent of age-related and menopause-associated changes in hormone levels on metabolism, bone loss, and impaired cardiovascular and cognitive function. Many aspects of the female reproductive aging process appear to be concordant between humans and these monkey species, but several important features may be species-specific. Those features that appear to parallel human menopause and aging include general similarity of hormone profiles across the menopausal transition, progression to cycle termination through irregular cycles, declining fertility with age, age-related gains in weight and percentage body fat content (with tendencies toward insulin resistance and glucose intolerance), increased low-density lipoprotein cholesterol and decreased high-density lipoprotein cholesterol, declines in serum dehydroepiandrosterone, similarities in temperature-regulation systems, protective responses to estrogen replacement following ovariectomy in terms of bone metabolism, lipid profiles, and cognitive changes. Important differences include relatively short postmenopausal life span, timing in menopause-related changes in hormone secretion, and seasonal menstrual cycles. In addition, the question of whether ovariectomy in young adults is an appropriate model for the consequences of natural or surgical menopause in middle-aged and older adults is unresolved, and the numbers of older female animals available for research on menopause are very limited. The use of animal models is seen by workshop participants to be crucial for a mechanistic understanding of the human menopausal process and its connections to postmenopausal health problems; however, extensive in-depth and broad-based research is required to determine if nonhuman primates are appropriate models of human menopause.