Response to acute food deprivation in OLETF rats lacking CCK-A receptors.

Otsuka Long-Evans Tokushima Fatty (OLETF) rats lacking cholecystokinin (CCK)-A receptors are hyperphagic and obese, and exhibit deficits in meal size control and in neuropeptide Y (NPY) gene expression in the dorsomedial hypothalamus (DMH). The present study was intended to determine whether these deficits would affect OLETF rat's response to an acute 24-h period of food deprivation. OLETF rats lost more body weight in response to deprivation but recovered their weight more quickly during refeeding than did lean Long-Evans Tokushima Otsuka (LETO) rats. Food deprivation decreased plasma glucose and leptin levels to a similar degree in both strains. Both groups increased intake during refeeding but the magnitude of increase was significantly greater in OLETF rats. Deprivation resulted in a significant elevation in arcuate NPY gene expression (approximately 47%) in LETO rats but only produced a small nonsignificant increase in the already decreased level of expression in OLETF rats (approximately 24%, P>.05). DMH NPY gene expression was not changed by deprivation in either OLETF or LETO rats. Although paraventricular corticotropin-releasing factor (CRF) expression was decreased by deprivation in LETO rats, CRF expression was not affected in OLETF rats. Together, these data suggested that OLETF rats lacking CCK-A receptors are not only capable of increasing their food intake in response to food deprivation, but also exhibit differential sensitivity to the effects of deprivation during both the food deprivation and refeeding periods.