Response to angiotensin II after selective lesioning of brain regions believed to be involved in water intake regulation.

The subfornical organ (SFO) and organum vasculosum lamina terminalis (OVLT) are regions of the brain that border the third ventricle (outside the blood-brain barrier) and have been implicated in the control of water intake elicited by angiotensin II (ANGII). Studies were conducted in which the response to injected ANGII following lesions of the SFO (LSFO) or OVLT (LOVLT) in broiler chicks was observed. Three groups of birds were used for each trial: lesioned and ANGII-injected (LI); not lesioned and ANGII-injected (NLI); and not lesioned and saline-injected (NLC). In Experiment 1, water intake of LISFO was decreased through 3 h postinjection (P less than .01). Intakes of LISFO and NLCSFO were not significantly different through 1 h postinjection. The OVLT did not have an effect on cumulative water intake in response to intramuscular ANGII. Water intakes of LIOVLT and NLIOVLT did not differ from each other, but were significantly higher than NLCOVLT (P less than .05) at .5 and 1 h postinjection. Feed intake was unaltered by SFO or OVLT lesions. Feed intake was suppressed and water intake increased by ANGII injection. The present study indicates that the SFO, but not the OVLT, plays a role in ANGII-induced water intake in broiler chicks.