Angiotensin II-induced taste aversion learning in cats and rats and the role of the area postrema.

The capacity of angiotensin II (AII, 1 mg/kg, IP) to produce a taste aversion was studied in cats and rats with and without lesions of the area postrema. Using a one-bottle test, injection of AII produced an aversion in cats but not in rats. Using a two-bottle test, injection of AII produced a slight, but significant, decrease in sucrose preference in intact rats, but had no effect on rats with area postrema lesions. Lesions of the area postrema prevented the acquisition of a taste aversion in cats. These results, which show a clear species difference in the capacity of AII to produce a taste aversion, are discussed as supporting the hypotheses that there is a relationship between the sensitivity of the area postrema to a compound and the capacity of that compound to produce a taste aversion; and that excitation of the area postrema constitutes a sufficient condition for taste aversion learning to occur.