LE300--new results on its ability to antagonize the discriminative stimulus effects of cocaine

LE300, i.e. 7-methyl-6,7,8,9,14,15-hexahydro-5H-benz-[d]indolo[2,3-g]azecine, with nanomolar affinities to the hD1 receptor family, suppresses in vivo spontanous locomotor activity and attenuates locomotor activity induced by cocaine. Therefore in this study, LE300 was investigated for its ability to antagonize cocaine's discriminative effects. LE300 was tested in doses from 0.5 to 10.0 mg/kg and partially antagonized the discriminative stimulus effects produced by 10 mg/kg of cocaine in rats. The partial antagonism (39% drug-appropriate responding) occurred following 5 mg/kg LE300. Response rate was decreased following 5 and 10 mg/kg, with the maximum effect (27% of cocaine control) following 10 mg/kg LE300.