Age-related differences in the US preexposure effect on conditioned taste aversion in rats

Abstract

Weanling, young adult, and old Wistar albino rats were used to determine whether the unconditioned stimulus (US) preexposure effect on conditioned taste aversion is age-related. The rats at each age level were given five preconditioning injections of either.15 M lithium chloride or physiological saline. These groups were then subdivided and given either conditioning or control treatments. Conditioning consisted of 10 min access to a saccharin solution followed 20 min later by an injection of.15 M lithium chloride. The control treatment consisted of 10 min access to saccharin followed 20 min later by a saline injection. Twenty-four hours later the animals were given a 24-h two-bottle (saccharin vs. water) test. Results indicated that as age increased the US preexposure was less effective in attenuating conditioned taste aversion. These results were interpreted in terms of age differences in response to the conditioning context.