Resistance to change of alcohol self-administration: effects of alcohol-delivery rate on disruption by extinction and naltrexone.

A common finding in resistance to change research with food-maintained operant behavior is that the persistence of behavior depends on the rate of reinforcement delivered in the context in which the behavior occurs. The present experiment evaluated the effects of rate of response-dependent alcohol delivery on the resistance to change of rats' alcohol self-administration in the face of disruption produced by extinction and a range of doses of naltrexone (1.0, 3.0, 10.0 mg/kg, subcutaneous). Rats responded for a 10% alcohol solution in a multiple schedule of reinforcement arranging a higher rate of alcohol delivery (variable interval 15 s) in the presence of one stimulus and a lower rate of alcohol delivery (variable interval 45 s) in the presence of another stimulus. Baseline response rates and resistance to extinction were higher in the presence of the stimulus associated with higher rates of alcohol delivery. This finding is consistent with studies of the resistance to change of food-maintained behavior. The rate of alcohol delivered in the components, however, did not systematically affect resistance to disruption by naltrexone. One interpretation of this finding from the perspective of behavioral momentum theory is that naltrexone may decrease the impact of alcohol-associated stimuli on the persistence of drinking by reducing sensitivity to the relative reinforcement conditions arranged in the presence of different stimuli.