Patterns of increased and decreased ingestive behavior after injections of lithium chloride and 2-deoxy-D-glucose.

In previous research, 750 mg/kg 2DG yielded a number of effects suggesting a postdrug nausea; and the present experiments revealed that the illness-inducing agent LiCl similarly produced taste aversion learning at 7.5 mg/kg, inhibited drinking in water-deprived animals at 30 mg/kg, depressed feeding in hungry rats at 60 mg/kg, and evoked food intake and pica at 120 mg/kg. The appearance of eating and pica at the same dosage suggested that rats may eat food as well as a nonnutritive substance as a species-specific reaction to illness and that postdrug feeding, including that observed after 2DG, is an insufficient condition for concluding that a treatment produces no internal distress. A liquid diet that reportedly ameliorates the glucoprivic feeding deficits produced by lateral hypothalamic and zona incerta lesions theoretically could produce its effects if lesions made rats more reactive to 2DG-induced malaise and if this diet were more palatable to animals experiencing internal distress. However, this liquid diet failed to facilitate food intake after LiCl, nor did it reduce the inhibited eating produced by LiCl in food-deprived subjects. Liquid diet effects in lesioned animals, therefore, may not be explained by factors related to a 2DG-induced malaise.