Abstract
It is a well-known fact that the repeated administration of psychotropic drugs often leads to the development of tolerance in animals. As to tranquillizers, it has been reported by some investigators that the tolerance phenomenon was observed in rats or cats following the chronic treatment with chlorpromazine (1) and meprobamate (2, 3). The present paper deals with the effect of some tranquillizers on the conditioned avoidance response observed with the use of the Miller-Mowrer-type apparatus as well as the development of tolerance to these drugs in the rat.
