Diet palatability modulates sham feeding in VMH-lesion and normal rats: implications for finickiness and evaluation of sham-feeding data.

The capacity for taste cues to modulate the food intake of ventromedial hypothalamic (VMH) and normal rats was examined. Rats with a chronically indwelling gastric cannula sham fed (cannula open) or normally fed (cannula closed) liquid diets varying in sucrose content. Throughout the study VMH rats were maintained at control body weight levels. The results identified two major aspects of the relationship between palatability and feeding. First, for both groups, the discrepancy in consumption between sham and normal feeding situations depended on the sweetness of the diet. The implications of this finding for studies using sham feeding to assess putative feeding control signals are discussed. Second, VMH lesions were demonstrated to exaggerate the sensory control of food intake. Under sham-feeding conditions, increases in the sweetness of the diet led to disproportionately large increments of food intake in VMH animals relative to controls. These data support the existence of a finickiness component in the VMH syndrome and allude to the nature of the physiological disturbance underlying this behavior change.