Interactions of carteolol and other beta-adrenoceptor blocking agents with serotonin receptor subtypes.

The importance of the anti-serotonergic activity of carteolol and other beta-adrenoceptor blockers in their efficacy as anti-migraine agents has been examined in the membrane fraction of rat brain frontal cortex and pig choroid plexus, using radioligand binding methods. Carteolol and l-propranolol, which are suggested to have anti-migraine activity in man, were found to be active inhibitors of the binding of [125I]ICYP to 5-HT1B recognition sites and of [3H]-8-OH-DPAT to 5-HT1A recognition sites. Carteolol is devoid of activity at 5-HT1C and 5-HT2 recognition sites, whereas l-propranolol shows substantial affinity for these receptor subtypes. Atenolol, another beta-adrenoceptor blocker with anti-migraine activity, is devoid of activity at any of the 5-HT receptor subtypes examined. The possibility that carteolol and other beta-adrenoceptor antagonists exert their pharmacological effects through central 5-HT receptor subtypes is discussed in relation to the potential mechanism of the anti-migraine activity of carteolol.