Effect of preoptic administration of angiotensin on lateral hypothalamic unit activity.

The effect of administering angiotensin II to the preoptic region on lateral hypothalamic single unit activity was studied in unanesthetized, freely-moving rats. Angiotensin (100 ng) reliably initiated drinking behavior and caused an increase in the discharge frequency of single neurons located in the perifornical area but had no effect on units in the zona incerta, ventromedial hypothalamus or farlateral hypothalamus. These results suggest that efferent pathways from preoptic receptors for angiotensin pass through the midlateral hypothalamus.