Ethanol does not affect discriminative-stimulus effects of nicotine in rats

The effects of ethanol were evaluated in rats trained to discriminate 0.4 mg/kg of nicotine from saline under a fixed-ratio 10 schedule of food delivery. Ethanol (0.1 - 1 g/kg, i.p.) did not produce any nicotine-like discriminative effects and did not produce any shift in the dose-response curve for nicotine discrimination. Thus, the ability to discriminate nicotine's effects does not appear to be altered by ethanol administration. However, the high dose of I g/kg ethanol, given either alone or in combination with nicotine, markedly depressed food-maintained responding. This later effect was associated in some rats with an attenuation of the discriminative-stimulus effects of the training dose of nicotine. This suggests that previous reports of increased tobacco smoking following ethanol consumption in humans are connected, in some way, with an increase in motivation to consume nicotine that is produced by ethanol, rather than with a decrease in the subjective response to nicotine. (c) 2005 Elsevier B.V. All rights reserved.