Lerant A, Freeman M E
Department of Biological Science, Florida State University, Tallahassee 32306-4340, USA.
Brain Res. 1998 Aug 17;802(1-2):141-54. doi: 10.1016/s0006-8993(98)00583-6.
The aims of this study were (1) to identify the possible hypothalamic targets for a short prolactin (PRL) feedback in the adult female rat by identifying DAergic neuron populations expressing PRL receptor (PRL-R); (2) to describe the effect of ovarian steroids on the expression of PRL-R and (3) to compare the distribution of both the extracellular (EC) and ligand binding (LB) domains of the PRL-R on the hypothalamic dopaminergic neurons by applying double label immunocytochemistry for the different domains of PRL-R and for tyrosine hydroxylase (TH). Five- to six-month-old female rats were ovariectomized (OVX) and implanted with either 17 beta-estradiol (E2), progesterone (P4) or received an E2 and a P4 implant (E2 + P4) at the same time. In the periventricular nucleus and in the dorsomedial portion of the middle arcuate nucleus, a dramatic increase in PRL-REC immunoreactivity was observed in E2 implanted rats. This increase was attenuated in E2 + P4 rats, but P4 treatment alone had no effect. Changes in PRL-REC expression were paralleled by changes in serum PRL levels. Interestingly, PRL-REC expression in the rostral arcuate nucleus decreased in P4 implanted rats, however, P4 did not attenuate the E2-induced increase in PRL-REC density. PRL-REC immunostaining was observed on the membrane, in the cytoplasm and in the nucleus. PRL-RLB immunoreactivity was also detectable in the TH positive neurons, but no nuclear staining was observed with this antibody. However, we found a strong PRL-RLB immunostaining in the ependymal lining of the 3rd ventricle and in the processes of tanycytes projecting to the median eminence. These data indicate that (1) all neuroendocrine DAergic cells can be targets for PRL, (2) expression of PRL-R is differentially affected by ovarian steroids in the different TH cell populations, (3) PRL-RLB domain may be involved in trafficking PRL in the median eminence.
(1) 通过鉴定表达催乳素受体 (PRL-R) 的多巴胺能神经元群体，确定成年雌性大鼠中催乳素 (PRL) 短反馈的可能下丘脑靶点；(2) 描述卵巢类固醇对PRL-R表达的影响；(3) 通过对PRL-R不同结构域和酪氨酸羟化酶 (TH) 进行双重标记免疫细胞化学，比较PRL-R的细胞外 (EC) 结构域和配体结合 (LB) 结构域在下丘脑多巴胺能神经元上的分布。将5至6月龄的雌性大鼠进行卵巢切除 (OVX)，并分别植入17β-雌二醇 (E2)、孕酮 (P4)，或同时植入E2和P4 (E2 + P4)。在室周核和中弓状核的背内侧部分，在植入E2的大鼠中观察到PRL-REC免疫反应性显著增加。在E2 + P4大鼠中这种增加减弱，但单独使用P4处理没有效果。PRL-REC表达的变化与血清PRL水平的变化平行。有趣的是，在植入P4的大鼠中，弓状核前部的PRL-REC表达降低，然而，P4并没有减弱E2诱导的PRL-REC密度增加。在细胞膜、细胞质和细胞核中均观察到PRL-REC免疫染色。在TH阳性神经元中也可检测到PRL-RLB免疫反应性，但该抗体未观察到核染色。然而，我们在第三脑室的室管膜衬里以及投射到正中隆起的伸长细胞的突起中发现了强烈的PRL-RLB免疫染色。这些数据表明：(1) 所有神经内分泌多巴胺能细胞都可能是PRL的靶点；(2) 在不同的TH细胞群体中，PRL-R的表达受卵巢类固醇的影响不同；(3) PRL-RLB结构域可能参与PRL在正中隆起的转运。
