A new sensitive method which unlike the Vogel test detects the anxiolytic effect of tofisopam.

A new, more sensitive than previously used anxiolytic test is described. The test consists in measuring of inhibition by punishment of drinking water necessary to swallow dry food by very hungry rats. This test reveals the anxiolytic properties of tofisopam, a clinically effective benzodiazepine anxiolytic, and of very low doses of chlordiazepoxide, both ineffective in the Vogel test, as well as anxiolytic properties of high doses of chlordiazepoxide and other anxiolytics, and confirms the lack of anxiolytic effects of major tranquilizers. The results suggest that chlordiazepoxide (and possibly other benzodiazepines) acts on two subgroups of benzodiazepine receptors, named BRI (high affinity) and BR2 (low affinity), while tofisopam acts specifically on BRI receptors. The new test is proposed as a tool for a search for drugs specifically acting on high affinity benzodiazepine BRI receptors.