Comparison of N2O- and chlordiazepoxide-induced behaviors in the light/dark exploration test.

Earlier research has demonstrated similarities in the behavioral effects of nitrous oxide (N2O) and benzodiazepine (BZ) drugs such as chlordiazepoxide (CP). The present research was conducted to compare the behavioral effects of N2O and CP in mice in the light/dark exploration test. When challenged with either N2O or CP, mice exhibited significant dose-dependent increases in the time spent in the light compartment and also in the number of transitions between the light and dark compartments. Pretreatment with BZ receptor antagonist flumazenil (FLU), the GABA(A) receptor antagonist SR-95531 or the selective neuronal nitric oxide (NO) synthase (nNOS) inhibitor 7-nitroindazole (7-NI) all antagonized anxiolytic effects of N20 and CP. Based on these findings, it was concluded that N20 and CP evoke similar behavioral effects in the light/dark exploration test that are similar in their interaction with BZ and GABA(A) receptor antagonists. There also appears to be a specific role for nNOS in generating the NO involved in mediation of these effects.