[Development of passivity in the rat: effect of tranquilizers and antidepressants]

Following the views on passivity as one of the features of depression-like behaviour in rats developing as a result of unavoidable painful stimulation an attempt was made to eliminate by antidepressant drugs the passivity manifested in an almost complete absence of motor searching reactions in an "open field" and a maze. However tranquilizing drugs rather than antidepressants to a greater extent induced the effect presupposed. Hence the type of passivity under study corresponds more likely to neurotized behaviour than to a special depression-like. In the second series of experiments the action was studied of multiple injections of antidepressants on similar manifestations of passivity as well as on alimentary instrumental conditioned responses in rats with initially expressed passive character of behaviour. In this case too neither the presupposed increase of motor searching reaction was observed nor any significant changes in the rate of instrumental conditioning nor elimination of its failures of a "refuse" type.