Attenuation of the effects of punishment by ethanol: comparisons with chlordiazepoxide.

Ethanol (ETOH), like chlordiazepoxide (CDZ), significantly attenuated the suppressive effect of punishment on licking behavior in water-deprived rats and mice. In rats, the greatest effects of ETOH (1.5 g/kg) were observed between 30 and 60 min following IP administration. tert-Butanol also attenuated the effects of punishment, suggesting that acetaldehyde was not contributing to this effect of ETOH. Since a dose of ETOH that increased punished drinking did not increase unpunished drinking, alteration in thirst motivation would not appear to be responsible for its antipunishment action. However, doses of ETOH or CDZ that significantly increased punished responding increased jump thresholds to aversive shock, suggesting that decreased sensitivity to aversive stimulation may contribute to the anti-punishment action of both agents. In addition to these similarities between ethanol and CDZ, several differences were noted in their effects. For example, CDZ decreased serum corticosterone concentration, whereas ETOH did not. Further, ETOH impaired aerial righting reflex and reduced rectal temperature, whereas CDZ had no effect on these parameters at doses that had anti-punishment activity. Finally, specific binding of [3H]flunitrazepam to crude brain cortical membranes was decreased by CDZ, but not ETOH. Although ETOH and CDZ similarly alter punished behavior, results suggest that ETOH does not act through a direct interaction with a benzodiazepine binding site.