HYPOTHALAMIC CONTROL OF PULSATILE PROLACTIN SECRETION

在过去的四年里，我们的实验室将注意力集中在 荷尔蒙信号的编码具有脉动模式。由于…… 在我们的努力下，我们已经能够建立PRL介导的营养 动情周期的黄体的输入被编码成一个特殊的 PRL发作的亚型，我们将其命名为大质量(BM)PRL 脉搏。这种特定类型的PRL分泌事件，它呈现 发情期下午的发病率最高，似乎是 精心管理，因为BM脉冲是 在主音中恢复一段时间的零星中断 下丘脑多巴胺所表现出的抑制作用。由于 大鼠发情当天的特殊内分泌特征，我们 评估雌激素和/或黄体酮印记是否在 发情前几天可能负责建立 观察BM PRL脉冲所需的多巴胺能音中断。 实验是在长期卵巢切除(OVX)大鼠身上进行的， 在发病前三天注射了雌二醇和/或黄体酮 在流血。在这种药理学范式下，我们能够 证明雌激素是获得催乳素模式所必需的 释放由BM和小质量PRL脉冲组成。黄体酮，在 相反，在给药时，似乎可以减少BM脉冲的发生率 加了雌二醇。为了证实我们的观察结果并将其推广 为了更具生理学意义，我们设计了一系列实验 目的是分析卵巢需要的时间 建立导致BM PRL脉冲的荷尔蒙环境。计时的 卵巢切除术要么在发情间期的早晨进行，要么在 排卵前促性腺激素和促性腺激素分泌高峰后的发情前期下午 PRL已发生。动物在预期的发情期下午流血。 在这种情况下，下丘脑要么接收(大鼠之后) 排卵前激增)或被剥夺(发情的去卵巢大鼠) 发情前期卵巢的内源性影响。卵巢切除术中 动情间期取消BM PRL脉冲入射，表明卵巢 发情前期参与了导致BM脉象出现的机制。 相反，当动物在发情前期的晚上去卵巢时，PRL 分泌模式与假手术组观察到的相同 老鼠。这些数据清楚地表明，在排卵期，卵巢 期间，参与了导致 BM PRL脉冲的起源。

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.