Platelet Alpha2-Adrenoceptor Binding in Migraine

SYNOPSIS
Platelet alpha 2 -adrenoceptor binding was determined in ten migraine patients and sixteen healthy controls using (³H)-yohimbine as radioligand. The mean value of maximum binding (^Bmax ) in the migraine patients was 133 ±55 binding sites/ platelet which is significantly lower than that of 217 ± 76 binding sites/platelet in controls (p<0.01). There was also a significant difference in the mean dissociation constant (K_D ); 2.05 ± 0.44 nM in migraineurs and 2.98 ± 1.15 nM in controls (p<0.05). Platelet alpha 2 -adrenoceptors may constitute valid models for certain characteristics of alpha 2 -adrenoceptors in the brain. An alteration in platelet alpha₂ -adrenoceptor binding may thus reflect similar alterations in central alpha₂ -adrenoceptors. It is also discussed whether the alpha₂ -adrenoceptor abberrations are intrinsic to migraine or a result of endogenous and/or pharmacologically induced modulation.