Daily caloric intake in intact and chronic decerebrate rats.
Daily caloric intake regulation was studied in chronic supracollicular decerebrate rats with a complete transection of the neural axis at the meso-diencephalic juncture and in intact controls. For 1 week, each rat received 3 intraorally delivered meals per day. They were challenged to maintain their 3-meal daily intake over 1 week in which only 2 meals per day were delivered. Intact rats increased meal size to compensate for the lost opportunity to feed, whereas chronic decerebrate rats did not. Results suggest that, although the caudal brainstem, as previously shown (Grill & Kaplan, 1990), is sufficient to modulate ingestive behavior in taste reactivity and single-meal tests, it is not sufficient to regulate daily caloric intake. Although it is possible that chronic decerebrate rats retain a long-term regulatory competence that is somehow masked under the meal omission paradigm, forebrain-hindbrain interactions appear necessary for the coordination of short- and long-term intake control processes.