Nonhuman Primate Models of Menopause (Part 4)
Ovarian Cycles and Serum Hormones
Characterization of ovarian and pituitary function during female reproductive aging in rhesus monkeys, baboons, and chimpanzees is based on presentations by Dr. Bill Lasley (University of California at Davis), Dr. Firyal Khan (University of Houston), Dr. K.D. Carey (Southwest Foundation for Biomedical Research), Dr. Marc Tatar (Brown University), and Dr. Kenneth Gould (Yerkes Regional Primate Research Center). A moderate number of studies have examined the female reproductive aging process of NHPs, including studies of both captive and free-ranging animals. canadian health & care mall
Rhesus monkey. A recent study revealed that urinary estrogen and progestin profiles of female rhesus monkeys during the menopausal transition are similar to those of women. However, certain hallmarks of the reproductive aging process in women may be absent in regularly cycling, older rhesus monkeys. Specifically, the monotropic rise in FSH, decline in inhibin B, and episodically high estrogen levels seen in regularly cycling, middle-aged women before the onset of irregular cycles are not apparent in middle-aged macaques before the onset of irregular menstrual cyclicity. Using four groups of rhesus monkeys categorized by menstrual cycle status and pattern (three to six animals per group), the investigators concluded that in contrast to women, in whom menopause-related changes in hormonal outputs of the pituitary and ovary appear gradually, starting in middle-aged, regularly cycling women, older female rhesus show more abrupt changes, starting when cycles begin to become irregular. Perhaps age-related changes play a more prominent role in the development of menopause in women than in rhesus monkeys. This type of study should be repeated and extended using larger groups of animals to confirm these interesting findings.