A further characterization of the effects of AV3V lesions on ingestive behavior.

Rats prescreened for responses to dipsogens received anteroventral third cerebral ventricular (AV3V) or sham lesions (ether anesthesia). Many known effects of AV3V lesions were observed, and new findings include a failure to drink adequately in response to polyethylene glycol (PEG) and water deprivation (regardless of responses to other dipsogens) and abnormally high levels of water intake during food deprivation. The groups did not differ in the osmotic suppression of deprivation-induced feeding. Drinking responses to angiotensin, isoproterenol, and PEG were highly intercorrelated in the experimental animals, perhaps due to destruction of an angiotensin-related substrate. Five months after surgery, rats with lesions were hyperphagic and hyperdipsic per gram of body weight, but actually ate a smaller amount of food than control rats, and absolute levels of water intake did not differ. The range of amount of daily water intake, but not food intake, was significantly greater in the experimental rats. These findings suggest that lower levels of neural organization mediate fluid balance in rats with AV3V lesions.