DISTRIBUTION OF MESSENGER-RNA FOR THE VASOPRESSIN V1A RECEPTOR IN THECNS OF MALE AND FEMALE RATS

The distribution of cells expressing mRNA encoding a vasopressin V-1a receptor (V(1a)R) was examined in Long-Evans male and female rats by i n situ hybridization using a [S-35]cRNA probe. Specific hybridization to the vasopressin V(1a)R mRNA was evident in cells of the frontal cor tex, piriform cortex, internal granular layer and the medial, dorsal, ventral and lateral portion of the anterior olfactory nucleus, zona li mitans of the islands of Calleja, suprachiasmatic nucleus, CA1, CA2, C A3 and dentate gyrus of the hippocampus, paraventricular hypothalamic nucleus, ventromedial hypothalamic nucleus, arcuate nucleus, lateral h abenular nucleus, and the molecular and granular cell layers of the ce rebellum. The cerebellum, olfactory nucleus and the dentate gyrus appe ared to be the most intensely labeled areas, while all other areas exh ibited a lower level of expression. The anatomical distribution and th e amount (as measured by optical density) of V(1a)R mRNA labeling was identical between male and female rats. This indicates that unlike the vasopressin gene itself, the expression of the vasopressin V(1a)R mRN A does not exhibit sexual dimorphism. These data demonstrate a wide sp read distribution in the expression of the vasopressin V(1a)R mRNA in the CNS of male and female rats. This information on the anatomical di stribution of the V,,R mRNA when combined with data concerning the ana tomical distribution of the V-1a binding sites, provides new informati on on the possible pre- and post-synaptic location of these neuropepti de receptors.