Non reciprocal cross-sensitization between cocaine and BTCP on locomotor activity in the rat

Measurement of locomotor sensitization was employed to characterize the eff ect of intermittent treatment with N-[1-(2-benzo[b] thiophenyl)cyclohexyl]p iperidine (BTCP) and cocaine in the rat. Like cocaine, BTCP possesses high affinity for the dopamine transporter and inhibits dopamine reuptake. Altho ugh both drugs exhibit similar behavioral and neurochemical profiles with a cute administration, there is tentative evidence to suggest that following chronic treatment BTCP does not induce neurochemical sensitization, and can attenuate cocaine-induced neurochemical sensitization in the striatum. Mal e Wistar rats were randomly divided into five groups after determining base line locomotor activity. Three groups were treated with tither saline (sali ne/ saline), cocaine (20 mg/kg; cocaine/cocaine), or BTCP (10 mg/kg; BTCP/B TCP) for 10 days. The remaining two groups were treated with cocaine (20 mg /kg) or BTCP (10 mg/kg) for 3 days, followed by administration of BTCP (10 mg/kg; cocaine/ BTCP) or cocaine (20 mg/kg; BTCP/cocaine) for 7 days. Locom otor sensitization was observed in all groups. However, although cross-sens itization on the day of substitution (day 4) was found in the BTCP/cocaine group, cross-sensitization was not observed in the cocaine/BTCP group. Thes e results suggest that although the locomotor-activating effects of BTCP an d cocaine are similar, the two drugs do not act identically, and different neural mechanisms may underlie BTCP and cocaine-induced sensitization. (C) 2000 Elsevier Science Inc.