Iontophoretic application of angiotensin II, vasopressin and oxytocin in the region of the anterior hypothalamus in the rat.

The anterior hypothalamus has been implicated in the regulation of hydromineral balance, drinking, vasopressin release, sodium excretion and blood pressure control. Using anaesthetized rats, we have looked at the activity of cells in this region through using a recording electrode cemented to a 7 barrelled iontophoretic electrode inserted ventrally. Cells were tested for their responsiveness to iontophoretic application (Io) of angiotensin II (AII), vasopressin (AVP) and oxytocin (Ox). Of the 47 cells found to responsive to Io glutamate, 23 increased firing to AII, 18 to AVP and 6 to Ox. Nine cells responsive to AVP also responded to AII. Two cells responded to both Ox and AII. It appears that this rostral diencephalic area has neurons sensitive to more than one of the hormones implicated in the various responses involved in hydromineral regulation.