Age-dependent changes in the responsiveness of the reproductive system to pharmacological agents

Effects of Hypothalamic-Pituitary Aging on Reproduction

“…On the other hand, aging of the ovary is clearly influenced by the pituitary gland since ovarian aging is delayed by hypophysectomy. 5 Complex interactions between such networks could result in phase-shifting of certain regulators of reproductive cyclicity, causing asynchrony among elements and perturbations of the usual precise control of cyclic reproductive function.…”

“…[40][41][42] Gonadal and pituitary function in aged, persistently estrous rats can be restored temporarily by pharmacologic neuroendocrine treatment, which lowers estrogen and gonadotrophin levels; under these regimens the animal can sustain levels of endocrine secretion comparable to those of younger cycling females. 43,44 Thus, there appears to be a close association between GnRH neuronal function and the loss of reproductive cycles during aging. The concentrations of LH and FSH in the pituitary gland of aging rats do not differ from those found in younger rats.…”

“…In any case, estrogen administration causes variable increases in serum prolactin and the irregular cycles in middleaged rats are characterized by sustained high circulating levels of estrogen. 42,43 Dopamine concentrations decrease in the arcuate nucleus of aging as well as estrogen-treated rats, and relative dopamine deficiency could trigger increased circulating levels of prolactin during reproductive senescence in rats.…”