HYPOTHALAMIC CONTROL OF PULSATILE PROLACTIN SECRETION

在过去的四年里，我们的实验室一直专注于 用脉冲模式编码激素信号。 的结果 通过我们的努力，我们已经能够建立PRL介导的营养 发情周期的黄体输入被编码在一个特殊的 我们命名为大肿块（BM）PRL的PRL发作亚型 脉搏 这种特殊类型的催乳素分泌事件，呈现出 发情期下午发病率最高，似乎是 微妙的调节，因为BM脉冲的结果， 恢复主音中一段时间的零星中断 下丘脑多巴胺的抑制作用。 由于 特别是内分泌特点的一天发情的大鼠，我们 评估是否雌二醇和/或孕酮印迹期间， 在发情期前的几天可能负责建立 需要中断多巴胺能张力以观察BM PRL脉冲。 在长期卵巢切除（OVX）大鼠中进行实验， 注射雌二醇、孕酮或两者， 流血了 在这种药理学模式下，我们能够 证明雌二醇是获得PRL模式所必需的 由BM和小质量PRL脉冲组成的释放。预测， 相比之下，似乎降低了BM脉冲的发生率， 雌二醇 为了证实我们的观察并扩展它们 我们设计了一系列实验 旨在分析卵巢需要的时间， 建立导致BM PRL脉冲的激素环境。 定时 卵巢切除术在动情间期的早晨或动情间期的早晨进行。 排卵前促性腺激素激增后的发情前期下午， PRL发生了。 在发情期的预期下午对动物采血。 在这种情况下，下丘脑要么接受（大鼠后， 排卵前激增）或被剥夺（不动情的OVX大鼠） 动情前期卵巢的内源性影响。 卵巢切除术期间 间情期取消BM PRL脉冲发生率，表明卵巢 动情前期参与导致BM脉冲出现的机制。 相反，当动物在发情前期晚上进行OVX时， 分泌模式与假手术组相同 大鼠 这些数据清楚地表明，卵巢，在排卵期 期间，参与生理机制，导致 BM PRL脉冲的发生。

During the last four years, our laboratory has focused its attention on the encoding of hormone signals with pulsatile patterns. As a result of our efforts, we have been able to establish that PRL-mediated trophic inputs to the corpus luteum of the estrous cycle are encoded in a special subtype of PRL episodes which we have denominated as big mass (BM) PRL pulses. This particular type of PRL secretory event, which presents the highest incidence during the afternoon of estrus, appears to be exquisitely regulated, since BM pulses are the consequence of the instauration of a period of sporadic interruptions in the tonic inhibitory influence exhibited by hypothalamic dopamine. Due to the particular endocrine characteristics of the day of estrus in the rat, we evaluated whether estradiol and/or progesterone imprinting during the days prior to estrus could be responsible for establishing the interrupted dopaminergic tone required to observe BM PRL pulses. Experiments were conducted in long-term ovariectomized (OVX) rats which were injected with estradiol, progesterone or both three days before the bleeding. Under this pharmacological paradigm, we were able to demonstrate that estradiol is needed for obtaining a pattern of PRL release consisting of BM and small mass PRL pulses. Progesterone, in contrast, appears to reduce the incidence of BM pulses when administered with estradiol. In order to confirm our observations and to extend them to a more physiological paradigm, we designed a series of experiments aimed at analyzing the time in which the ovary is required for establishing the hormonal environment leading to BM PRL pulses. Timed ovariectomies were performed either in the morning of diestrus or the afternoon of proestrus after the preovulatory surge of gonadotropins and PRL has occurred. Animals were bled on the expected afternoon of estrus. Under these circumstances, the hypothalamus either receives (rats after the preovulatory surges) or is deprived (diestrous OVX rats) of the endogenous influences of the ovary during proestrus. Ovariectomy during diestrus abolished BM PRL pulse-incidence, indicating that the ovary of proestrus participates in the mechanisms leading to BM pulse appearance. In contrast, when the animals were OVX in the evening of proestrus, PRL secretory patterns were identical to those observed in sham-operated rats. These data clearly show that the ovary, during the periovulatory period, participates in the physiological mechanisms leading to the genesis of BM PRL pulses.