Chronic lithium chloride infusions: conditioned suppression of food intake and preference.

A modified learned food aversion paradigm simulated the prolonged food and illness exposure likely to characterize nutrient deficiencies or tumor growth. In this paradigm, a continuously available food was associated with a slow, continuous infusion of LiCl provided by osmotic minipump. Significant aversions were acquired when the available diet was novel but not when it was familiar. Effects of drug infusions on daily food intake were found to parallel those on aversion formation. Marked, persistent suppression of food intake was seen in drug-treated animals consuming a novel diet, but only transient declines were seen in those with a familiar diet. By separating the direct from the conditioned effects on food intake of chronic drug infusions, these studies provided strong evidence that learned food aversions can lead to anorexia.