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首页> 外文期刊>Progress in brain research >Regulation of prolactin secretion during pregnancy and lactation.
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Regulation of prolactin secretion during pregnancy and lactation.

机译：孕期和哺乳期泌乳素分泌的调节。

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Prolactin plays major roles in maintaining the corpora lutea of pregnancy and in the synthesis of milk during lactation. The hypothalamic mechanisms involved in these functions have been investigated. Mating leads to a surge of prolactin and programs daily surges during early pregnancy. The expression of Fos-immunoreactivity shows that mating activates several hypothalamic nuclei, particularly the arcuate nucleus and medial preoptic area. In the arcuate nucleus, mating is associated with Fos expression in beta-endorphin neurons, and infusion of naloxone blocks both mating-induced and diurnal prolactin surges. Tyrosine hydroxylase-immunoreactive dopamine neurons appear not to participate in surge generation. However, after day 10 of gestation the secretion of placental lactogens suppresses prolactin secretion via activation of dopamine neurons without involvement of beta-endorphin neurons. Intracerebroventricular implantation of placental lactogen-secreting cells will block pregnancy prolactin surges, increase Fos expression in dopamine neurons, and increase tyrosine hydroxylase activity. During lactation the mechanisms regulating dopamine and beta-endorphin neurons are further modified. In early lactation a prolactin-induced increase in tyrosine hydroxylase activity leads to negative feedback, but this effect is lost by mid-lactation. Overriding this negative feedback is the inhibitory effect that suckling has on dopaminergic activity. This may involve beta-endorphin-mediated inhibition of dopamine neurons, as naloxone causes a marked increase in tyrosine hydroxylase activity and suppression of circulating prolactin. However, removal of tonic dopamine inhibition is not sufficient to account for the high levels of prolactin attained during lactation, and additional releasing factors are probably involved. In situ hybrization histochemistry for the most recent candidate, prolactin-releasing peptide, suggests that this may involve brain stem neurons that co-localize noradrenaline. Thus, prolactin secretion during pregnancy and lactation involve complex interactions of regulatory factors and plasticity of neuronal responsiveness.
机译：催乳素在维持妊娠体和泌乳过程中的牛奶合成中起主要作用。已经研究了涉及这些功能的下丘脑机制。交配导致催乳素激增，并计划在怀孕初期每天进行激增。 Fos免疫反应性的表达表明交配激活了几个下丘脑核，特别是弓形核和内侧视前区。在弓形核中，交配与β-内啡肽神经元中的Fos表达相关，纳洛酮的输注会阻止交配诱导和昼夜催乳素激增。酪氨酸羟化酶免疫反应性多巴胺神经元似乎不参与电涌的产生。但是，在妊娠的第10天后，胎盘乳原的分泌可通过激活多巴胺神经元来抑制催乳激素分泌，而不会牵涉β-内啡肽神经元。脑室内植入胎盘分泌乳原的细胞将阻止妊娠催乳素激增，增加多巴胺神经元中的Fos表达，并增加酪氨酸羟化酶活性。在哺乳期，调节多巴胺和β-内啡肽神经元的机制被进一步修饰。在哺乳初期，催乳素诱导的酪氨酸羟化酶活性增加导致负反馈，但是这种作用会在哺乳中期消失。克服这种负面反馈是哺乳对多巴胺能活性的抑制作用。这可能涉及β-内啡肽介导的对多巴胺神经元的抑制，因为纳洛酮会导致酪氨酸羟化酶活性显着增加并抑制循环催乳素。但是，消除强直性多巴胺抑制作用不足以解决泌乳期间达到的高催乳素水平，并且可能涉及其他释放因子。最新候选蛋白催乳素释放肽的原位杂交组织化学表明，这可能涉及共定位去甲肾上腺素的脑干神经元。因此，孕期和哺乳期泌乳素的分泌涉及调节因子和神经元反应性可塑性的复杂相互作用。

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