Menopause in female rhesus monkeys

Area of Science:

• Reproductive endocrinology
• Primate reproductive biology
• Comparative endocrinology

Background:

• Menopause is a natural biological process characterized by the cessation of menstruation and loss of ovarian function.
• Understanding menopause in non-human primates, such as rhesus monkeys, provides valuable insights into human reproductive aging.
• Rhesus monkeys are a widely used model for studying reproductive physiology and aging due to their biological similarities to humans.

Purpose of the Study:

• To characterize the endocrine and menstrual changes associated with menopause in female rhesus monkeys.
• To determine the age at which menopause typically occurs in this species.
• To correlate hormonal profiles with age and ovarian activity.

Main Methods:

• Longitudinal study of 15 female rhesus monkeys over one year.
• Monitoring of menstrual cycles and collection of serum samples for hormone analysis (estradiol and luteinizing hormone).
• Histological examination of ovaries from postmenopausal individuals.

Main Results:

• Premenopausal monkeys (8-11 years) exhibited cyclic ovarian activity and menstruation.
• Perimenopausal monkeys (24-26 years) showed varied patterns, including menstruation, periodic hormone secretion, or elevated LH with low estradiol.
• Postmenopausal monkeys (27-34 years) displayed consistently high LH and low estradiol levels, with limited ovarian folliculogenesis.
• Significant inverse correlation between estradiol and age, and positive correlation between LH and age were observed.

Conclusions:

• Menopause in female rhesus monkeys is established in the latter half of the third decade of life (approximately 27-34 years).
• Hormonal profiles, including elevated LH and low estradiol, are indicative of postmenopausal status.
• Ovulation, when it occurred, was seasonal, primarily in winter and early spring.