Lorcaserin is approved for treating obesity and its therapeutic effects are thought to result from agonist activity at serotonin (5-HT)2C receptors. The current study compared the behavioral effects of lorcaserin to the effects of other 5-HT receptor agonists in rats. The 5-HT2C receptor selective agonist mCPP (0.032 - 1.0 mg/kg) and lorcaserin induced yawning that was attenuated by the 5-HT2C receptor selective antagonist SB 242084. The 5-HT2A receptor selective agonist DOM (0.1-3.2 mg/kg) induced head twitching that was attenuated by the 5-HT2A receptor selective antagonist MDL 100907. In rats pretreated with SB 242084, lorcaserin also induced head twitching. At larger doses, lorcaserin produced forepaw treading that was attenuated by the 5-HT1A receptor selective antagonist WAY 100635. While the behavioral effects of lorcaserin in rats are consistent with 5-HT2C receptor agonist activity, these data suggest that, at larger doses, it also has agonist activity at 5-HT2A and possibly 5-HT1A receptors.

See article at J Pharmacol Exp Ther 2015 355:381-385.

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