AN NMDA RECEPTOR ANTAGONIST REDUCES ETHANOL PREFERENCE IN UNTRAINED BUT NOT TRAINED RATS

Rats were exposed to a potent antagonist of NMDA receptors, 2-amino-5 phosphonovalerate (AP5) by implanting osmotic pumps delivering AP5 (te st group) or the vehicle for AP5 (control group) into the cerebrospina l fluid through previously implanted cannulas. A week later they were given the choice of 6% ethanol or water for 1 h. The control group had a significantly greater preference for ethanol than the test group af ter the first 5 days. Another group of rats was trained almost to a 10 0% criterion in preferring ethanol to water in the hour the choice was available. Then they were implanted with osmotic pumps and cannulas a nd administered Ape. These trained rats showed no significant differen ce between control and test groups in preference for ethanol after the first 5 days. The results support the hypothesis that activation of N MDA receptors is involved in learning to drink ethanol.