Estrogen and Progesterone Metabolites and Follicle-Stimulating Hormone in the Aged Macaque Female1

Abstract

The study presented characterizes the ovarian and pituitary function of the aged female macaque through a complete annual reproductive cycle to compare hormone dynamics during the human and nonhuman primate menopausal transition. Data collected over an entire year from aged macaque females indicated that urinary FSHbeta subunit baseline levels statistically significantly increased in females after age-related abnormal menstrual cycles occurred. These abnormal cycles were followed by anovulation and complete cessation of follicular activity. No statistically significant difference in urinary FSHbeta subunit levels was seen between females that exhibited year-round normal ovarian cycles and those that exhibited seasonal ovarian cycles followed by an interval of anovulation during the nonbreeding season. Basal urinary estrogen metabolite levels were not observed to decrease until ovarian cycles became abnormal and FSHbeta subunit levels began to rise. Early follicular phase circulating inhibin beta levels were statistically significantly reduced only when ovariectomized females were compared to the year-round normally cycling females. A statistically nonsignificant trend toward decreased inhibin secretion, however, was apparent in aged females with normal cycles, aged females with abnormal cycles, anovulatory aged females, and finally, ovariectomized females. Whereas decreased circulating levels of dehydroepiandrosterone sulfate showed a general decline over the 1-yr study period in all groups, they were lowest in the year-round normally cycling group, progressively higher in the normal-to-anovulatory group and abnormal-to-anovulatory group, and highest in the anovulatory group. Finally, the nonbreeding season was associated with the highest number of abnormal cycles, suggesting that onset of complete ovarian senescence in these study macaques was more likely to occur during that time (i.e., females were less likely to return to normal ovarian cycles the following breeding season and more likely to exhibit permanent ovarian quiescence).

Female reproductive activity and its endocrine correlates in the African lesser bushbaby, Galago moholi

“…Despite the absence of seasonality in terms of food availability, individuals were still exposed to seasonal changes in day length and temperature, both important factors driving seasonal breeding and reproductive hormone secretion (Wingfield 1984). A negative correlation between fertility and age has been observed for a number of primate species including hanuman langurs (Presbytis entellus, Borries et al 1991), rhesus macaques (Macaca mulatta, Gilardi et al 1997;Shideler et al 2001) and olive baboons (Papio anubis, Strum and Western 1982). Although the average age of our captive female group was 3.6 ± 1.3 years (range: 2-5), thus at the chronological age of peak reproductive potential, the biological age of the ovaries could be at an advanced stage, influencing ovarian endocrine activity.…”

Age as a determinant of reproductive success among captive female rhesus macaques (Macaca mulatta)

“…Indeed, Shideler et al (2001) monitored rhesus monkeys for a complete year and found that menstrual cycling in older females frequently ceased during the nonbreeding season. They also reported that the monkeys in their study did not exhibit a rise in baseline FSHb during the transition to menopause, although that has been reported in perimenopausal women (Santoro et al 1996).…”

Plasticity of the zona reticularis in the adult marmoset adrenal cortex: voyages of discovery in the New World

“…Nonetheless, there are also differences, namely the function of the ZR in adults and the female-specific and ovary-mediated controls of ZR function. Yet even these differences may not be as great as they would appear, given that increases in DS have been observed late in the menopausal transition among women (Lasley et al 2002) and female rhesus (Shideler et al 2001), when ovarian function ceases. The very fact that marmoset studies reveal ovarian related changes in adult ZR function and the additional correlation of changes in 17,20-lyase activity with zonal CYTB5 expression substantially underscore the importance of CYTB5 as a major regulator of 17,20-lyase activity in vivo.…”