A novel test procedure for antidepressants was designed in which a mouse is suspended by the tail from a lever, the movements of the animal being recorded. The total duration of the test (6 min) can be divided into periods of agitation and immobility. Several psychotropic drugs were studied: amphetamine, amitriptyline, atropine, desipramine, mianserin, nomifensine and viloxazine. Antidepressant drugs decrease the duration of immobility, as do psychostimulants and atropine. If coupled with measurement of locomotor activity in different conditions, the test can separate the locomotor stimulant doses from antidepressant doses. Diazepam increases the duration of immobility. The main advantages of this procedure are the use of a simple, objective test situation, the concordance of the results with the validated "behavioral despair" test from Porsolt and the sensitivity to a wide range of drug doses.

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The antagonism of hypothermia induced by two doses of apomorphine (1 to 16 mg/kg) is proposed as an improved screening test for both neuroleptics and antidepressants. Low dose apomorphine-induced hypothermia (1 mg/kg) differentiates sulpiride-like neuroleptics (which better antagonize this effect of apomorphine than other effects such as stereotyped behavior) from haloperidol-like drugs. The latter equally antagonize the two effects of apomorphine. The effects of sulpiride are also distinct from those of chlorpromazine-like drugs which strongly antagonize stereotyped behavior, but not hypothermia induced by apomorphine. Hypothermia induced by a high dose of apomorphine (16 mg/kg) is not antagonized by neuroleptics, but is strongly antagonized by antidepressants (imipramine-like drugs, amineptine, amoxapine, nomifensine, viloxazine) and potential antidepressants (beta-adrenergic stimulants). The use of these two tests rapidly screens both antidepressants and neuroleptics and classifies neuroleptics according to their profile of action on the dopaminergic system.