HYPOTHALAMIC CONTROL OF PULSATILE PROLACTIN SECRETION

今天人们很好地认识到，所有的脑下垂体激素，特别是 一般说来，荷尔蒙是以间歇性、搏动性的方式分泌的。 这种特殊的分泌方式似乎对 编码调节信号；即刺激性、抑制性，它们是 在目标器官水平上进行积分以获得确定的目标器官 对信号的响应。最近，我们的小组提供了新的见解 关于搏动性催乳素的特性和调节 分泌物。事实上，搏动性的催乳素分泌变化很大。 根据大鼠发情周期的不同阶段，提示不同的 图案向目标组织传递不同的信号。在尝试解码时 这些假定的信号，我们评估了激素释放的总量 每脉冲(脉冲下的面积)，并借助于频率 分布分析，我们观察到至少有两类不同的 可以定义脉冲；大质量催乳素脉冲和小质量催乳素脉冲。 有趣的是，大质量催乳素脉冲的最大发生率是 在发情的下午观察到的一个发情周期阶段，在这个阶段 催乳素的分泌似乎可以保护黄体免受 黄体生成素在发情期分泌的黄体溶解作用。这一观察结果 告诉我们，事实上，催乳素对黄体的作用 编码在这些大量的催乳素脉冲中。此外，大量催乳素 脉冲似乎受到大脑中零星中断的精确调节。 男性和男性下丘脑施加的多巴胺能抑制张力 雌性老鼠。初步实验，使用D2多巴胺能受体 拮抗剂，显示多巴胺能音似乎需要 观察大量催乳素脉冲。在实验中，多巴胺能 语气要么被完全废除，要么继续呈现意志 证明多巴胺能张力的零星中断是否 与大量催乳素脉冲的形成有关。

It is today well recognized that all pituitary hormones in particular, and hormones in general, are secreted in an intermittent, pulsatile manner. This special manner of secretion appears to be of paramount importance in encoding regulatory signals; i.e. stimulatory, inhibitory, which are integrated at the target organ level to obtain a determined target organ response to the signal. Recently, our group has provided new insights concerning the characterization and the regulation of pulsatile prolactin secretion. In fact, pulsatile prolactin secretion dramatically varies depending on the estrous cycle stage in rats, suggesting that different patterns convey distinct signals to target tissues. In an attempt to decode these putative signals, we evaluated the total amount of hormone released per pulse (area under the pulse), and with the aid of frequency distribution analysis, we observed that at least two different classes of pulses could be defined; big and small mass prolactin pulses. Interestingly, the maximum incidence of big mass prolactin pulses was observed during the afternoon of estrus, an estrous cycle stage in which prolactin secretion appears to protect the corpus luteum from the luteolytic actions of LH secreted during metestrus. This observation suggested to us that, in fact, prolactin actions on the corpus luteum are encoded in these big mass prolactin pulses. In addition, big mass prolactin pulses seem to be precisely regulated by sporadic interruptions in the dopaminergic inhibitory tone exerted by the hypothalamus in both male and female rats. Initial experiments, using D2 dopaminergic receptor antagonists, showed that the dopaminergic tone appears to be required to observe big mass prolactin pulses. Experiments in which the dopaminergic tone is either completely abolished or continuously present will demonstrate whether sporadic interruptions of the dopaminergic tone are involved in the genesis of big mass prolactin pulses.