IS MIGRAINE PROPHYLACTIC ACTIVITY CAUSED BY 5-HT2B OR 5-HT2C RECEPTORBLOCKADE

It has been suggested that activation of 5-HT2C receptors is involved hi the initiation of a migraine attack. The 5-HT2C receptor and the ne wly cloned I-al fundus 5-HT2B receptor show close pharmacological and structural resemblance. Antagonist pA(2) values from the rat stomach a nd pK(D) values from a 5-HT2C receptor binding assay correlated both h ighly significantly (p<0.005) with the daily dose of eight migraine pr ophylactic compounds. Although the small difference in antimigraine po tency between the enantiomers of propranolol agrees with the lack of s tereo-selectivity found on the rat fundus 5-HT2B receptor but not with the 5-HT2C receptor, the evidence available does not allow one to dis tinguish between 5-HT2C and 5-HT2B receptor blockade as possible mecha nisms for prophylactic activity.