The effects of cadmium on ethanol self-administration using a sucrose-fading procedure

Rats were exposed for 70 days to either a diet containing 100 ppm cadmium (Group Cadmium) or a control diet with no additives (Group Control). Subsequently, all animals were trained to lever press for a 20% sucrose solution. Across several phases, sucrose was faded out as the reinforcer and gradually replaced with a 10% ethanol solution. A subsequent operant choice (concurrent) test, during which pressing one lever resulted in a dipper presentation of ethanol and the other lever provided water, was followed by a single-lever test where sucrose was reinstated as the reinforcer. The results showed that although cadmium-treated rats lever pressed more than controls during the early phases of the sucrose-fading procedure, animals exposed to cadmium lever pressed at lower rats than controls for ethanol during the concurrent test. There were no group differences on the final sucrose test. The possibility that cadmium may alter sensitivity to ethanol is discussed.