The discriminability of apsirin in arthritic and nonarthritic rats.

Aspirin, 56 mg/kg IP, was shown to be mildly, but significantly discriminable from saline in a group of 12 nonarthritic rats exposed to a 2-lever fixed ratio 10 drug discrimination protocol for 56 trials. In a concurrently-tested group of 12 rats made arthritic by injection of Mycobacterium butyricum into a hind paw, the discrimination of aspirin from saline was enhanced. The results exemplify how drug discriminability may vary depending on the pathological state of the subjects exposed to drug-discrimination training.