The puzzle of drug-induced conditioned taste aversion: Comparative studies with cathinone and amphetamine

Abstract

The potency of dl-cathinone (the active constituent of the Khat plant) was compared with that of d-amphetamine in the conditioned taste aversion (C. T. A.) procedure and in a test of drug-induced adipsia in rats. Both drugs induced C.T.A., the potency ratio being 1∶17 (amphetamine was more potent). Both drugs induced adipsia in deprived rats given access to water for 120 min. The potency ratio in this procedure was 1∶4. Potency in the C.T.A. procedure did not therefore correlate with potency in inducing adipsia; consequently drug-induced C.T.A. cannot be attributed to conditioned adipsia. In the adipsia test the drugs had similar durations of action, thus factors related to duration of drug action (cf Cappell and Le Blanc 1977) cannot account for the surprisingly low potency of cathinone in the C.T.A. procedure. These data, obtained with stimulant drugs with similar structures and similar actions in a variety of conventional in vivo and in vitro pharmacological tests, illustrate the unpredictable nature of drug actions in the C.T.A. procedure. The low potency of cathinone in inducing C.T.A. could not be predicted from knowledge of the potency of this compound in tests of adipsia (as shown here) or (as reported elsewhere) in tests of anorexia, locomotor stimulation, stereotypy, suppression of operant responding, drug discrimination, release and inhibition of reuptake of dopamine and noradrenaline, lethality and actions on the cardiovascular system. All of these studies have reported potency ratios considerably lower than 1∶17, which were nevertheless similar to the 1∶4 ratio observed in the adipsia test. It is suggested that the weak potency of cathinone in the C.T.A. procedure may be related to its comparatively potent reinforcing actions in the self-administration procedure.