Post-training administration of GABAergic antagonists enhances retention of aversively motivated tasks

The effect of sub-convulsive doses of GABAergic antagonists on the retention of two aversively motivated tasks, inhibitory avoidance (IA) and Y-maze discrimination (YMD), was investigated in CFW mice. In the IA task, post-training intraperitoneal injections of picrotoxin and bicuculline induced a dose-dependent enhancement of retention measured 24 h after the training, while retention was not affected by bicuculline methiodide (a GABA receptor antagonist that does not readily cross the blood-brain barrier). In the absence of footshock on the training day, post-training administration of picrotoxin and bicuculline did not affect retention test latencies. In the YMD task, the discrimination was reversed on the retention test and errors made on the reversal trials served as the index of retention of the original training. The reversal error scores of mice given post-training injections of picrotoxin or bicuculline, but not bicuculline methiodide, were significantly higher than those of saline-treated controls. These findings extend previous observations that GABAergic antagonists enhance retention of aversively motivated tasks and suggest the involvement of central GABAergic processes on memory consolidation.