Morphine-induced taste aversions: A consideration of parameters

Following consumption of saccharin, groups of rats were injected with various doses of morphine sulfate. Although no aversion was found after one conditioning trial, repeated saccharin-morphine pairings resulted in decreases in consumption of the saccharin solution. On the average, however, the groups of rats showed only a moderate aversion, independent of the dose of morphine. Although there was little variability in consumption among rats that received the smallest dose of morphine, there was considerable individual variability among subjects receiving the larger doses. The differences between morphine-based conditioned taste aversions and aversions based on emetic USs were discussed.