Regional distribution of putative vasopressin receptors in rat brain and pituitary by quantitative autoradiography

Quantitative light microscopic autoradiography was used to map and characterize the distribution of [3H]arginine vasopressin [( 3H]AVP) binding sites in the rat brain. HPLC analysis for possible degradation of AVP during binding indicated that addition of specific peptidase inhibitors prevented metabolism of AVP. Binding sites for [3H]AVP were observed in the hypothalamus and pituitary as well as in brain regions where AVP may act as a neuroregulator. Within the hypothalamus, dense AVP binding sites were seen in the suprachiasmatic, supraoptic, and paraventricular nuclei. High specific binding was also apparent in the median eminence tubero-infundibular region and in the posterior lobe of the pituitary. [3H]AVP labeling at possible neuroregulatory sites was observed in the hippocampus, lateral septum, superficial cortex, cerebellum, nucleus tractus solitarious, adenohypophysis, and spinal cord.