, Volume 115, Issue 1-2, pp 167-172

Nitrous oxide anxiolytic effect in mice in the elevated plus maze: Mediation by benzodiazepine receptors

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In earlier research, we have hypothesized that exposure to nitrous oxide (N2O) produces an anxiolytic effect that is mediated by benzodiazepine (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. Exposure to increasing levels of N2O produced a concentration-related increase 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 induced by CP. These effects of N2O and CP were both antagonized by pretreatment with the BZ receptor blocker flumazenil (FLU). In another experiment, mice made tolerant to CP also exhibited a cross-tolerance to N2O. These results support the hypothesis that the anxiolytic effect of N2O is mediated by BZ receptors.

Portions of this paper were presented at the Third International Brain Research Organization (IBRO) World Congress of Neuroscience (Abstracts, p 211, 1991) and the 1992 Fall Meeting of the American Society for Pharmacology and Experimental Therapeutics (ASPET) (Pharmacologist 34: 137, 1992).