@article {Grottick1183, author = {Andrew J. Grottick and Paul J. Fletcher and Guy A. Higgins}, title = {Studies to Investigate the Role of 5-HT2C Receptors on Cocaine- and Food-Maintained Behavior }, volume = {295}, number = {3}, pages = {1183--1191}, year = {2000}, publisher = {American Society for Pharmacology and Experimental Therapeutics}, abstract = {The present series of studies were designed to investigate the 5-HT2C receptor agonist Ro 60-0175 on cocaine- and food-maintained behavior in the rat. Ro 60-0175 (0.1{\textendash}3 mg/kg, s.c.) reduced cocaine (15 mg/kg, i.p.)-induced hyperactivity. This inhibitory effect of Ro 60-0175 (1 mg/kg, s.c.) was completely blocked by pretreatment with the selective 5-HT2C antagonist SB 242,084 (0.5 mg/kg, i.p.). In further studies, Ro 60-0175 (1{\textendash}3 mg/kg, s.c.) reduced responding for both food (45-mg Noyes pellet) and cocaine (0.25 mg/infusion) maintained under identical schedules of reinforcement (fixed ratio (5), time out 1 min, 60-min duration). The effect on food-maintained responding was blocked by SB 242,084 (0.5 mg/kg, i.p.). Ro 60-0175 (0.3{\textendash}3 mg/kg, s.c.) also reduced the breakpoint for cocaine self-administration under a progressive ratio schedule of reinforcement. After a period of extinction training, where cocaine solution was substituted with saline, an acute priming injection of cocaine (15 mg/kg, i.p.) but not Ro 60-0175 (1 mg/kg, s.c.) reinstated cocaine responding. In this model of relapse, Ro 60-0175 (1{\textendash}3 mg/kg, s.c.) pretreatment attenuated the priming effect of acute cocaine injection. In a final series of studies to examine the cataleptogenic properties of Ro 60-0175, very mild indices of catalepsy were observed at the 3 mg/kg dose only. These catalepsy scores were significantly lower than that produced by haloperidol (0.5 mg/kg, s.c.). In further tests of motor function using the Rotarod, deficits were again seen at the 3 mg/kg dose, but not at lower doses. Taken together, these studies suggest that, in addition to reducing food intake, 5-HT2C receptor agonists reduce cocaine-reinforced behavior. This would be consistent with electrophysiological and biochemical evidence suggesting an important modulatory influence of 5-HT2C receptor activation on mesolimbic dopamine function. The American Society for Pharmacology and Experimental Therapeutics}, issn = {0022-3565}, URL = {https://jpet.aspetjournals.org/content/295/3/1183}, eprint = {https://jpet.aspetjournals.org/content/295/3/1183.full.pdf}, journal = {Journal of Pharmacology and Experimental Therapeutics} }