Abnormalities in taste preference in hypothyroid rats.

Rats made hypothyroid by administration of radioactive iodine and age-matched controls were individually caged and offered a choice between either water or varying concentraions of sweet (sucrose), bitter (quinine sulfate), salty (NaCl) or sour HCl solutions to drink ad libitum for 48 h periods. Comparative measurements were made of the volume of test solution consumed to that of total volume consumed and were expressed as taste preferences. Throughout a wide range of concentrations, taste preferences for sucrose were significantly lower (P less than 0.001) and those for quinine sulfate and NaCl significantly higher (P less than 0.001) in hypothyroid animals than in controls. Taste preferences for HCl were generally similar in both groups. Daily intraperitoneal injections of thyroxine, 10 mug/100 g body wt. to hypothyroid rats for 18-24 days eliminated completely the difference between hypothyroid and control rats in taste preference for quinine sulfate. These studies show that significant and reversible changes in taste preferences occur in rats rendered hypothyroid with radioactive iodine.