Kow L-M, Bogun M, Zhang Q, Pfaff D W
Laboratory of Neurobiology & Behavior, The Rockefeller University, 1230 York Avenue, Box 336, New York, NY 10021-6399, USA.
Endocrine. 2007 Dec;32(3):287-96. doi: 10.1007/s12020-008-9046-1. Epub 2008 Feb 2.
To assess how early can estrogens induce female mating behaviors, rat pups 8-29 days old (D8-D29, respectively) were injected twice daily with estradiol benzoate (E) or oil (O) followed by progesterone (P) or oil, and then observed for the estrogen-dependent ear wiggling (EW) and lordosis in response to natural stimulation from male rats. In female pups treated with E + E + P, the incidence of EW appeared as early as D13 and increased gradually to reach maximum at D18, when all pups tested showed EW. EW also occurred in E + E + O females, but never in O + O + P females or in any E + E + P male. Lordosis in E + E + P, as well as E + E + O, female pups occurred later, starting at D15. O + O + P females or E + E + P males never display lordosis. To explore the possibilities that the age and gender differences are due to distribution and/or function of estrogen receptor-alpha (ERalpha) or progesterone receptor (PR), separate pups were used for immunocytochemical (ICC) staining of these receptors in the hypothalamic ventromedial nucleus (VMN). There was no age difference in female pups in the density of ERalpha or the induction of PR between D11/D12, when no sexual behavior was observed, and D19/D20, when almost all pups tested performed the behaviors. There were gender differences: male pups had less ERalpha than females at D19/D20, though not at D11/D12, and did not respond to E in the induction of PR in the VMN. These results show that ERs and their signaling systems in the VMN of rat pups are functional at least after D11 but only in females, and that the gender differences appeared to be due to differences in the molecular biology of ERalpha.
为了评估雌激素多早能够诱导雌性的交配行为,分别给8至29日龄(分别为D8 - D29)的幼鼠每天注射两次苯甲酸雌二醇(E)或油(O),随后注射孕酮(P)或油,然后观察其对雄性大鼠自然刺激产生的雌激素依赖性摆耳(EW)和脊柱前凸行为。在用E + E + P处理的雌性幼鼠中,EW行为最早在D13出现,并逐渐增加,在D18达到最大值,此时所有受试幼鼠均表现出EW行为。EW行为也出现在E + E + O处理的雌性幼鼠中,但从未出现在O + O + P处理的雌性幼鼠或任何E + E + P处理的雄性幼鼠中。E + E + P处理以及E + E + O处理的雌性幼鼠的脊柱前凸行为出现得较晚,始于D15。O + O + P处理的雌性幼鼠或E + E + P处理的雄性幼鼠从未表现出脊柱前凸行为。为了探究年龄和性别差异是否归因于雌激素受体α(ERα)或孕酮受体(PR)的分布和/或功能,使用单独的幼鼠对下丘脑腹内侧核(VMN)中的这些受体进行免疫细胞化学(ICC)染色。在未观察到性行为的D11 / D12和几乎所有受试幼鼠都表现出这些行为的D19 / D20之间,雌性幼鼠在ERα密度或PR诱导方面没有年龄差异。存在性别差异:在D19 / D20时,雄性幼鼠的ERα比雌性少,尽管在D11 / D12时并非如此,并且雄性幼鼠在VMN中PR诱导方面对E无反应。这些结果表明,幼鼠VMN中的雌激素受体及其信号系统至少在D11之后才起作用,并且仅在雌性中起作用,而且性别差异似乎归因于ERα分子生物学的差异。