CHANGES IN PAIN TOLERANCE AND OTHER BEHAVIOR PRODUCED BY SALICYLATES

¹ Department of Medicine (Division of Clinical Pharmacology) and Department of Pharmacology and Experimental Therapeutics, The Johns Hopkins University School of Medicine, Baltimore, Maryland

Parenteral sodium salicylate and oral aspirin raise the level at which rats keep the intensity of an electric shock that periodically rises in intensity while lever presses by the rats reduce this intensity. The rise in shock level is proportional to drug dose. The same doses of sodium salicylate and aspirin that produce changes in tolerated shock level also produce changes in two kinds of positively reinforced responding: timing behavior and variable-interval schedule performance. Ordinary escape performance was not affected at these doses. Sodium pentobarbital has little effect on shock level but depresses positively reinforced behavior. It is not now possible to state whether the effect on shock level is an analgesic one, the result of general CNS depression, or both.