The acute effects of norharman on cocaine self-administration and sensorimotor function in male Wistar rats

The purpose of the present study was to determine the acute effects of the beta -carboline norharman on cocaine dependence. Male Wistar rats were allo wed to self-administer cocaine for 3 h for seven sessions. A single injecti on of norharman (0.2-20 mg/kg, i.p.) was given 30 min before the onset of t he seventh session. It was shown that norharman decreased the cocaine intak e in a U-shaped manner with the dose of 10 mg/kg having the most potent eff ect. These results indicate that several receptor mechanisms mediate the ef fects of norharman. In addition, 15 min following the administration of nor harman on session 7, motor and sensory skill tests were performed. Six naiv e animals were tested with the dose, which has the most pronounced effect o n cocaine self-administration intake, in order to examine whether the obser ved effects were due to norharman or due to the combination of norharman an d cocaine. It was observed that norharman in both the naive and cocaine-exp osed animals significantly increased the response time in the somato-sensor y orienting test. However, only in the naive animals a significant effect o f norharman on the grasp reflex was observed. (C) 2001 Elsevier Science B.V ./ECNP. All rights reserved.