Furudate S, Suzuki H, Sato S
Department of Laboratory Animal Science, Kitasato University School of Medicine, Kanagawa, Japan.
Jikken Dobutsu. 1992 Jan;41(1):47-53. doi: 10.1538/expanim1978.41.1_47.
Two surges of prolactin (PRL) are observed daily during pseudopregnancy (PSP) in the rat: the nocturnal (N) surge at dawn and the diurnal (D) surge in the evening. In order to clarify differences in the controlling mechanisms of the two types of PRL surges, we attempted to examine the turnover rates of dopamine (DA) and norepinephrine (NE) in the preoptic-anterior hypothalamus (PAH) and mid-posterior hypothalamus (MPH) on day 5-6 of PSP. The turnover rates of DA in the hypothalamus were inversely correlated with the serum PRL levels at the D surge when a significant increase in serum PRL was accompanied by not only a marked decrease in turnover rates of DA in the PAH, but also a slight decrease in turnover rates of the amine in the MPH. Contrarily, no significant decrease occurred in the turnover rates of DA in the hypothalamus at the N surge. There was no obvious correlation between the turnover rates of NE in the hypothalamus and the serum PRL levels at either PRL surge. These findings suggest that decreased turnover rates of DA in the hypothalamus are involved in the D surge, and it is most probable that the N PRL surge occurs under the control of another factor such as the hypothalamic PRL-releasing factor.
在大鼠假孕（PSP）期间，每天可观察到两次催乳素（PRL）分泌高峰：黎明时的夜间（N）高峰和傍晚时的日间（D）高峰。为了阐明这两种类型的PRL高峰控制机制的差异，我们试图在PSP的第5至6天检测视前区 - 下丘脑前部（PAH）和下丘脑中部 - 后部（MPH）中多巴胺（DA）和去甲肾上腺素（NE）的周转率。当血清PRL显著升高时，下丘脑DA的周转率与D高峰时的血清PRL水平呈负相关，此时不仅PAH中DA的周转率显著降低，MPH中该胺类的周转率也略有下降。相反，在N高峰时，下丘脑DA的周转率没有显著下降。在任何一个PRL高峰时，下丘脑NE的周转率与血清PRL水平之间均无明显相关性。这些发现表明，下丘脑DA周转率降低与D高峰有关，而N PRL高峰很可能是在另一种因素如下丘脑PRL释放因子的控制下发生的。
