| 19501602 |
Fletcher PJ, Tampakeras M, Sinyard J, Slassi A, Isaac M, Higgins GA: Characterizing the effects of 5-HT (2C) receptor ligands on motor activity and feeding behaviour in 5-HT (2C) receptor knockout mice. Neuropharmacology. 2009 Sep;57(3):259-67. Epub 2009 Jun 6.
5-HT (2C) receptor agonists have considerable therapeutic potential, however there is little in vivo data to compare the potency and selectivity of 5-HT (2C) receptor agonists. Since 5-HT (2C) receptor agonists reduce locomotor activity and food intake, changes in these drug-induced behaviours in 5-HT (2C) receptor knockout mice could provide a means to examine receptor selectivity in-vivo. Initially this study compared older 5-HT (2C) agonists mCPP and MK212, to newer, apparently more selective compounds: Ro 60-0175, WAY161503, CP809,101 and lorcaserin (APD356) on motor activity in wild-type, and 5-HT (2C) receptor knockout mice. Two 5-HT (2C) receptor antagonists SB242084 and SDZ SER 082 were also examined. mCPP did not significantly alter activity in wild-type mice, but enhanced activity in knockout animals. MK212 (3 and 10 mg/kg) and Ro 60-0175 (1 and 3 mg/kg) reduced activity in wild-type but not knockout animals. At 10 mg/kg, Ro 60-0175 reduced activity in knockout animals, suggesting loss of 5-HT (2C) receptor selectivity. CP809,101 and lorcaserin reduced activity in wild-type but not knockout mice. In subsequent feeding studies, Ro 60-0175 and lorcaserin reduced food intake in wild-type animals only. Selectivity of effect for mCPP was marginal. The antagonist SB242084 increased activity in wild-type animals but not in knockout mice; SB242084 did not alter feeding in either genotype. SDZ SER 082 reduced activity in both genotypes implying poor selectivity for 5-HT (2C) receptors. The data demonstrate that studying food intake, and particularly motor behaviour, in the 5-HT (2C) receptor knockout mouse is a useful and relatively simple approach for screening 5-HT (2C) receptor ligands in vivo. |
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