Major tranquillizers can be distinguished from minor tranquillizers on the basis of effects on marble burying and swim-induced grooming in mice.

The effects of psychotropic compounds on grooming and burying were compared in mice. Burying behaviour was provoked by glass marbles and grooming was observed after 3 min swimming. Compounds with minor tranquilizing properties, such as diazepam, chlordiazepoxide, flunitrazepam, clonazepam, meprobamate and ethyl alcohol, were more effective in reducing burying than grooming. Drugs with an anticholinergic effect, e.g. scopolamine and atropine were also more effective against burying. A number of neuroleptic drugs, such as haloperidol, chlorpromazine, perphenazine and trifluperidol reduced grooming more effectively than burying. Non-selective inhibitory effects were observed with clozapine, thioridazine, diphenhydramine, imipramine, mianserin and apomorphine. It is concluded that, with certain limitations, the burying-grooming test described offers a simple tool for identifying novel compounds as potential major or minor tranquilizers.