Conditioned taste aversion in the adult rat induced by dietary ingestion of cadmium or cobalt.

The potential aversive qualities of dietary cadmium chloride (10, 100 mg/kg) or cobalt chloride (20, 100, 200 mg/kg) were evaluated in a conditioned saccharin aversion task. Male Long-Evans hooded rats (n = 42) were trained to drink tap water and ingest 10 grams of chow during daily 60 minute access tests. During the aversion-acquisition phase, a second bottle containing 0.1% sodium saccharin was introduced and the various metal-adulterated diets (10 grams, dose calculated as mg metal base/kg body weight) offered in place of plain chow. During extinction testing, all rats were fed the plain chow. Diets adulterated with cadmium (10 or 100 mg/kg) or cobalt (100, 200 mg/kg) induced marked conditioned saccharin aversions after 2-3 days of exposure and were found to be profoundly resistant to extinction. Both cadmium (100 mg/kg) and cobalt (100, 200 mg/kg) induced a corresponding suppression of intake of adulterated food and significant weight losses. The relation of these aversive effects to the influence of cadmium and cobalt on operant responding for food reward is discussed.