NITROUS-OXIDE ANXIOLYTIC EFFECT IN MICE IN THE ELEVATED PLUS-MAZE - MEDIATION BY BENZODIAZEPINE RECEPTORS

In earlier research, we have hypothesized that exposure to nitrous oxi de (N2O) produces an anxiolytic effect that is mediated by benzodiazep ine (BZ) receptors. The present research was conducted to characterize pharmacologically the behavioral effects of N2O in comparison with a BZ standard, chlordiazepoxide (CP), in the mouse elevated plus maze. E xposure to increasing levels of N2O produced a concentration-related i ncrease in the percent of total entries into and the percent of total time spent on the open arms, a pattern of response similar to that ind uced by CP. These effects of N2O and CP were both antagonized by pretr eatment with the BZ receptor blocker flumazenil (FLU). In another expe riment, mice made tolerant to CP also exhibited a cross-tolerance to N 2O. These results support the hypothesis that the anxiolytic effect of N2O is mediated by BZ receptors.