Present study was designed to elucidate serotonergic mechanisms in apomorphine-induced behavioral sensitization upon its repeated administration. Since dopaminergic mechanisms are reported to have well-established role in the pharmacotherapy of Parkinson’s, Alzheimer’s and related disorders as well as in the pathophysiology of addiction, this thesis has been conceived to improve therapeutic utility of apomorphine by attenuating the reinforcement and behavioral sensitization induced by apomorphine.  In the present experiment, repeated apomorphine administration exhibited psychosis in rats upon repeated administration, as observed by monitoring locomotive activities in familiar environment of Skinner’s box. Following the third apomorphine injection, locomotor sensitization was evaluated in the familiar Skinner's box environment. In the novel open field environment, we also recorded the locomotive effects of apomorphine. The hyperlocomotive effects of apomorphine are stated to be greater after the sixth injection than the first, implying the emergence of behavioural sensitization effects in a novel environment.

Keywords: Behavioral Sensitization, Locomotory and Exploratory activity, 5 HT-2C Receptor, Apomorphine