Temporal changes occur in the neuroendocrine control of gonadotropin secretion in aging female rats: role of progesterone.
Temporal changes occur in the neuroendocrine control of gonadotropin secretion in aging female rats: role of progesterone.
复制标题
老年雌性大鼠促性腺激素分泌的神经内分泌控制发生时间变化：黄体酮的作用。
DOI：
10.1095/biolreprod.104.029090
复制
发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Lu,JohnKH
中科院分区：
文献类型：
--
作者：
Tsai,Houng-Wei;LaPolt,PhilipS;Olcott,AngelicaP;Lu,JohnKH
The present study examined the gonadotropin surge-inducing actions of estradiol (E2), both alone and with progesterone (P4), in middle-aged, early persistent-estrous (PE) female rats that had become PE within 35 days. In addition, we also assessed the effect of P4on the mating-induced gonadotropin surges in these acyclic animals. Early PE rats were ovariectomized and received E2implants (Day 0). On Day 4, an s.c. injection of P4(0.5 mg/100 g body weight) at 1200 h markedly increased plasma P4and elicited both LH and FSH surges, whereas vehicle-treated controls displayed no rise in P4or gonadotropins. This observation confirms that at middle age, female rats no longer respond to the positive-feedback stimulation of E2on gonadotropin surges whenever the estrous cyclicity ceases. As PE continued, such a surge-inducing action of E2plus P4became diminished after 75 days of PE and disappeared thereafter. When caged with males, vehicle-treated early PE rats display a mating-induced increase in P4from the adrenal along with small gonadotropin surges. The amplitude of these mating-induced gonadotropin surges was enhanced by supplementation with exogenous P4in early PE rats. Our findings indicate that during the early phase of PE, the surge-inducing action of E2and P4remains intact but deteriorates as PE continues. Thus, a deficiency in P4secretion during aging may contribute to the diminished gonadotropin surge response in the hypothalamic-pituitary axis and the subsequent cessation of estrous cyclicity.
