TASTE REACTIVITY IN RATS SELECTIVELY BRED FOR HIGH VS LOW SACCHARIN CONSUMPTION

Rats selectively bred for high (HiS) vs. low (LoS) saccharin consumpti on were compared on taste reactivity responses to 0.1% saccharin befor e and after continuous access to 0.1% saccharin. The rats were also te sted with other saccharin concentrations (0.01-0.3%) before and after the consumption test. Finally, all rats were tested for reactivity to 0.1 M sucrose, 0.0001 M quinine hydrochloride, and a sucrose + quinine mixture. HiS rats ingested more saccharin than did LoS rats, but the groups did not differ in total ingestive or total aversive reactivity on any of the taste tests. When aversive reactivity was analyzed furth er to distinguish passive drip from other, more active responses, HIS rats made more active responses than LoS rats; the latter showed a con sistent tendency to passive drip more than HiS rats. Overall, aversive responding decreased and ingestive responding increased as saccharin concentration rose and from the first to the second concentration seri es. Because the brain stem-mediated hedonic evaluation of tastes by Hi S and LoS rats appears to be similar, the difference in saccharin cons umption must be mediated by psychological processes whose neural subst rates lie above the brain stem.