Insulin elicits ingestion in decerebrate rats.

Insulin administered to rats reliably elicits ingestion of food. To determine whether the neural mechanisms sufficient to control insulin-elicited ingestion are located in or caudal to the forebrain, decerebrate rats were treated with insulin and ingestive responses were measured. Insulin treatment produced hypoglycemia that was comparable, in magnitude and duration, in control and decerebrate rats. Decerebrate and control rats ingested significantly more sucrose solution while hypoglycemic than while normoglycemic. In contrast, insulin did not augment the water consumption of either group. These data indicate that neural systems caudal to the forebrain are sufficient to control ingestive consummatory behavior through the integration of metabolic signals generated by insulin treatment and taste afferent input from the oropharynx.