[Plasma beta-endorphin and caffeine consumption in chronic hemicrania].

Thanks to recent biochemical and neuroendocrine findings, migraine belonging to the group of primary headaches appears as a pathology of the antinociceptive system with evolutive character. It has been demonstrated, in fact, that right at the early stage of migraine, there is a significant reduction in liquoral concentrations of beta-endorphin (beta-E), endogenous opioid peptide followed by a similar change in the plasma opioid system. The opioid system deficiency is even more evident after stimulation tests that point to reduced reactivity of the hypothalamo-hypophyseal system with respect to stimuli that in normal subjects trigger hypophyseal beta-E incretion. Caffeine, a member of the methyl-xanthine group, is an interesting molecule in the study of migraine patients because the chronic intake of this substance, contained in numerous analgesics, has been related to the chronic nature of the pain. The purpose of the present study is to assess the relationship between caffeine consumption and plasma opioid system. With the administration of a single oral dose of caffeine, normal subjects present an increase in plasma concentrations of beta-E, while in patients with chronic migraine, the response is significantly lower. These data confirm the poor reactivity of the plasma opioid system to pharmacological stimuli in migraine. Average daily consumption of caffeine has also been determined. It was not possible to establish a correlation between consumption of caffeine and plasma concentrations of beta-E whether basal or after stimulus with caffeine.