Visual evoked potentials and nitrous oxide-induced neuronal depression: role for benzodiazepine receptors.

We have examined the role of benzodiazepine receptors in nitrous oxide-induced neuronal depression in rats. The changes in neuronal excitability induced by nitrous oxide and the benzodiazepine inverse agonist, Ro15-4513, were monitored by measurement of visual evoked potentials (VEP). Administration of Ro15-4513 10 mg kg-1 i.p., in rats breathing air, did not affect the amplitude or latency of VEP. However, the same concentrations of Ro15-4513 antagonized nitrous oxide-induced depression of VEP amplitudes. We conclude that antagonism of nitrous oxide-induced depression by Ro15-4513 indicates that at least part of the decreased neuronal excitability caused by nitrous oxide could be ascribed to interactions with the GABAA receptor complex.