AN IMMUNOCYTOCHEMICAL COMPARISON OF THE ANGIOTENSIN AND VASOPRESSIN HYPOTHALAMONEUROHYPOPHYSEAL SYSTEMS IN NORMOTENSIVE RATS

In the present study we investigated the possibility that angiotensin II/III and vasopressin coexist in the hypothalamo-neurohypophysial pathway. For our experiments 8-week-old male rats not treated with colchicine were used. The anatomical orientation of the entire pathway for angiotensin and vasopressin was facilitated by examining a series of subsequent coronal, horizontal and sagittal sections. Arching fibre tracts are formed mainly by projections emanating from cell bodies in the para-ventricular nucleus, the accessory magnocellular nuclei, the supraoptic nucleus and the retrochiasmatic part of the supraoptic nucleus. The majority extend as far as the median eminence and the neurohypophysis, where major terminal fields exist. However, there is a difference between the staining pattern within the suprachiasmatic nucleus and the hypophysis. The results clearly show the colocalization of angiotensin and vasopressin in neurones as well as in fibres of the hypothalamo-neurohypophysial system.