Conditioned Response to Ethanol as Indicated by Spontaneous Motor Activity

A group of rats were given 1.6 g/kg intraperitoneal (IP) injections of either saline or ethanol on 16 successive conditioning days (CD's). During each two-day period of the 16-day sequence, the rats received saline on one day in a specifically "saline-paired" environment and ethanol on the next day in an "ethanol-paired" environment. Visual, olfactory, auditory, and tactile manipulations were utilized to create these two different environments. In order to determine the conditioned response to ethanol, rats were given saline in "ethanol-paired" environments at the end of the 16-day sequence. SMA on this day was compared to that of the previous saline day and the following day, which was specifically conducted as a "reconditioning day". In determining conditioned tolerance, rats were next given ethanol in the "saline-paired" environment. SMA on this day was again compared to that of the previous and following ethanol day in the "ethanol-paired" environment. A robust conditioned response was found as the rats showed much higher SMA on the conditioned response test day than on regular saline conditioning days. Although the rats showed less SMA on the conditioned tolerance test day than on regular ethanol conditioning days, the difference was not statistically significant. However, this non-significant trend in the predicted direction was interpreted as a result of an insufficient number of subjects, or due to unpredictable variations of individual animal physiology in response to ethanol CNS depressant effects. The observation of the conditioned increase in SMA provides further support for the theory that conditioned responses to depressant drugs are usually in a direction opposite to the actual drug effect.