HYPER-REACTIVITY TO AVERSIVE DIETS IN RATS PRODUCED BY INJECTIONS OF INSULIN OR TOLBUTAMIDE, BUT NOT BY FOOD-DEPRIVATION

The effects of exogenous or endogenous elevations of insulin, or food deprivation, on intake of aversive diets by rats was investigated. Rats maintained on 0.2% quinine powder or offered this diet for the first time were hypophagic following injection of 40 U/kg of protamine zinc insulin (PZI) and died. This result was shown not to be an artifact of quinine-insulin toxicity. Rats were habituated to diets adulterated with 0.2% quinine, 20% sucrose octa-acetate, or 20% curry. Following injection of 300 mg/kg of Tolbutamide, a drug which stimulates the secretion of endogenous insulin, or 20 U/kg of PZI, intake of the adulterated diets, but not of plain powder, was suppressed significantly below or remained at control (placebo injection) levels for up to 10 hr. No hyperreactivity to 0.2% quinine powder was observed following fasts ranging from 0 to 72 hr, although following 24, 48 and 72 hr fasts a delayed decrease of quinine powder intake was observed. Since diabetic rats, or rats injected with 2-deoxy-D-glucose also show hyperreactivity to aversive diets, cellular glucoprivation may be the effective stimulus underlying this response. © 1979.