Suppression by glucocorticoid of the immunoreactivity of corticotropin-releasing factor and vasopressin in the paraventricular nucleus of rat hypothalamus.

The effect of glucocorticoid on the production of corticotropin-releasing factor (CRF) and vasopressin in the paraventricular nucleus of the hypothalamus (PVH) was examined immunocytochemically. Intraperitoneal administration of dexamethasone sulfate in a dose of 0.1 mg/day suppressed the immunoreactivity of CRF and vasopressin in the medial parvocellular divisions of the PVH of the rat subsequent to bilateral adrenalectomy. In the magnocellular divisions, suppression of vasopressin-immunoreactivity was not observed. These results suggest that the vasopressin in the medial parvocellular divisions plays a distinct role from that in the magnocellular divisions, the former having functional significance in the hypothalamo-hypophysio-adrenal axis.