The distribution of mRNA for the short form of the prolactin receptor in the forebrain of the female rat.

Prolactin exerts its diverse effects on peripheral tissue and on the brain via receptors that have two forms, a short form and a long form. The distribution of the mRNA for both forms of the receptor has been examined in brain and peripheral tissue regions using methods based on regional dissection. Although the cell-specific distribution of the long form of the prolactin receptor has been examined using in situ hybridization in the rat brain, the cell-specific distribution of the short form has not been described. In this study we mapped the distribution of neurons and other cells expressing the short from of the receptor transcript in the forebrain, ovary, and uterus of the female rat by using in situ hybridization with a 33P-labeled cRNA probe specific for the short form of the prolactin receptor mRNA (PRL-SR mRNA). Neurons expressing the PRL-SR mRNA were located predominantly in the preoptic area and hypothalamus as well as in certain limbic structures. Specific nuclei included the anteroventral periventricular nucleus, paraventricular and supraoptic nucleus, medial preoptic area, suprachiasmatic nucleus, and ventromedial and arcuate nuclei of the hypothalamus, as well as the bed nucleus of stria terminalis and the medial amygdala. Scattered neurons expressing PRL-SR mRNA were also found in the cortex, habenula, zona incerta, and thalamus. Cells in the choroid plexus expressed high levels of PRL-SR mRNA, as did the luteal cells of the corpus luteum and the epithelial cells of the uterine glands. These data confirm previous reports and extend our knowledge of the distribution of the short form of the receptor to the cellular level. The neuroanatomic distribution of neurons expressing PRL-SR mRNA suggests that they may influence the mediation and coordination of prolactin-regulated endocrine and behavioral events.