Platelet 3H-imipramine binding and sulphotransferase activity in primary headache

We investigated platelet 3H-imipramine (3H-IMI) binding, a putative peripheral serotonergic marker, and the activity of sulphotransferase (ST), an enzyme involved in the catabolism of catecholamines and phenolic compounds, in 14 patients suffering from migraine without aura (MWoA) and in 10 with tension-type headache (TH), as compared with a group of controls. The possible relationships between the biological parameters and clinical features were also examined. The results showed that the two groups of patients had a lower number of 3H-IMI binding sites and a lower activity of the thermolabile form of ST, which acts preferentially on monoamine substrates, than the healthy controls, with no intergroup differences. Significant correlations between psychopathological rating scales and characteristics of the illness were observed in the patients with TH. The decreased number of platelet 3H-IMI binding sites is suggestive of a presynaptic serotonergic dysfunction and confirms the involvement of 5HT in primary headaches. The reduced ST activity might produce changes in the level of sulphated biogenic amines, including dopamine and tyramine, which might have an additional role in the pathophysiology of some aspects of primary headache.