HYPOTHALAMIC CONTROL OF PULSATILE PROLACTIN SECRETION

以前的研究已经证实，脉动的PRL分泌是 雄鼠和雌鼠都有至少两类 分泌性事件，即大的和小的质量脉冲。这种方式 分泌物似乎都为编码提供了一种生理手段 营养信号传递到外周器官，并受到精致的调控。 在早期的研究中，诱导了多巴胺能完全阻断， 提示大质量的PRL脉冲可能是由于零星的中断 在下丘脑施加的主要抑制性多巴胺能张力中。 如果这个假设是正确的，那么要么通过废除多巴胺能 音调或维持连续的多巴胺能输入，大质量脉冲应该 消失。这一假说最近已在实验中得到证实。 使用多巴胺能激动剂和拮抗剂，由于发病率大 两种治疗方法都显著减少了大量的PRL脉冲。在一个 持续的多巴胺能输入的PRL分泌是搏动性的，表明 其他不同于多巴胺的下丘脑因子(S)参与了 产生搏动性催乳素分泌。在使用频率分布之后 分析，没有大质量的PRL脉冲，因此，在这些条件下 小质量脉冲是唯一一类对 催乳素分泌的搏动性。有趣的是，完全封锁了 多巴胺能输入并不能消除催乳素的搏动性 分泌物。此外，多巴胺能受体阻滞剂也显示出同样的性质 现象，即大质量的PRL脉冲也没有，当动物 用多巴胺能拮抗剂治疗。这些观察结果 证明多巴胺能张力的零星中断调节 一类特定的PRL分泌事件的出现，并表明 其他因素(S)(催乳素)能够推动催乳素的脉动性分泌，即使在 一种强烈的多巴胺能状态。结合被动的研究 免疫中和范式与阻断或增强 多巴胺能音将提供有关 肽能和胺能信号，在整合到 垂体水平，以搏动性的PRL分泌为单位。

Previous studies have established that pulsatile PRL secretion is characterized in both male and female rats by at least two classes of secretory episodes, i.e., big and small mass pulses. This manner of secretion appears to both provide a physiological means for encoding trophic signals to peripheral organs and to be exquisitely regulated. Earlier studies in which a complete dopaminergic blockade was induced, suggested that big mass PRL pulses could be due to sporadic interruptions in the prevailing inhibitory dopaminergic tone exerted by the hypothalamus. If this hypothesis is correct, then either by abolishing the dopaminergic tone or maintaining a continuous dopaminergic input, big mass pulses should disappear. This hypothesis has recently been demonstrated in experiments using dopaminergic agonists and antagonists, since the incidence of big mass PRL pulses is dramatically reduced by both treatments. Under a continuous dopaminergic input PRL secretion is pulsatile, indicating that other hypothalamic factor(s) different from dopamine is involved in the generation of pulsatile PRL secretion. After using frequency distribution analysis, big mass PRL pulses were absent, thus, under these conditions small mass pulses were the only class of pulses contributing to the pulsatile nature of PRL secretion. Interestingly, a complete blockade of the dopaminergic input did not abolish the pulsatile nature of PRL secretion. Moreover, the dopaminergic blockade showed the same qualitative phenomenon, i.e., big mass PRL pulses were also absent when the animals were treated with a dopaminergic antagonist. These observations demonstrate that sporadic interruptions in the dopaminergic tone regulate the appearance of a specific class of PRL secretory events and suggest that other factor(s) (PRF) are able to drive pulsatile PRL secretion even under a strong dopaminergic status. Studies combining passive immunoneutralization paradigms and blockade or enhancement of the dopaminergic tone will provide information on the Interactions of peptidergic and aminergic signals which result, after being integrated at the pituitary level, in pulsatile PRL secretion.