DISTRIBUTION OF PROLACTIN RECEPTOR IMMUNOREACTIVITY IN THE BRAIN OF ESTROGEN-TREATED, OVARIECTOMIZED RATS

Although there is extensive evidence for effects of prolactin (PRL) on the brain, knowledge about the PRL receptor (PRL-R) in the brain is l imited. By using monoclonal antibodies raised against purified rat liv er PRL-R, the distribution of PRL-R was investigated by immunohistoche mistry in brains of the estrogen-treated ovariectomized (OVX+E) rat an d the adult male rat. Immunohistochemistry was performed by using the avidin biotinylated horse radish peroxidase macromolecular complex met hod. In both male and OVX-E rats, strong immunostaining was detected i n the choroid plexus of all cerebral ventricles. This immunostaining w as localized predominately on epithelial cell membranes. In the OVX+E female rat, scattered immunoreactive perikarya were observed in the ar cuate nucleus, periventricular hypothalamic nucleus, preoptic area, su prachiasmatic nucleus, and supraoptic nucleus of the hypothalamus. Imm unostaining in hypothalamic nuclei was localized on neuronal cell bodi es as well as on neuronal processes. In addition, there was extensive PRL-R immunoreactivity throughout the globus pallidus and ventral pall idum. Immunostaining in these striatal regions was not associated with neuronal cell bodies but appeared to be localized on processes or gli al cells. In the male rat, less immunostaining was observed in the hyp othalamus, and there was no immunostaining in the corpus striatum. No significant staining was observed in the cerebral cortex, thalamus, or hindbrain of either male or OVX-E rats. The implication of PRL-R exis tence in these brain regions remains to be investigated. J. Comp. Neur ol. 394:462-474, 1998. (C) 1998 Wiley-Liss, Inc.