Studies of the functional significance of angiotensin II receptors in the rat olfactory bulb: evidence for alterations in normal fluid intake.

The effects of continuous infusion of angiotensin II (ANG II, 1 microgram hr-1) into the olfactory bulb (O.B.) were studied on rats with chronically indwelling intracerebral cannulae. Chronic infusion (ALZA minipump system) of ANG II into the O.B. elicited a moderate dipsogenesis as compared to saline infused animals. The increased drinking occurred only during the dark phase (6 pm - 6 am) and appeared to be associated with food intake, which also occurred during this time. Removal of the food or disconnection of the minipump reduced water consumption to comparable levels in both groups. Acute injection of ANG II (250 ng) into the O.B. failed to elicit drinking. Since the olfactory bulb has a high concentration of ANG II receptors, these experiments suggest that ANG II may interact with the O.B. to facilitate the drinking associated with food intake.