Neuropeptide Y(NPY) co-exists with norepinephrine in the sympathetic nervous system, and NPY may represent the sympathetic-neuronal output. Fibromyalgia syndrome (FMS) patients have perturbations in the hypothalmic-pituitary-adrenal (HPA) axis and in the sympathetic stress axis as well. As opioid peptides, monoamines and sex steroids are integrated in the regulation of stress, it is interesting to further explore the role of NPY in FMS patients, as they show many symptoms that are related to perturbations of those systems.In this study, plasma NPY levels were assessed in subgroups of FMS patients: cyclic (regular menstrual cycles), non-cyclic (post-menopausal), depressed and non-depressed patients. In order to examine whether pain and other symptoms seen in FMS patients are correlated to the NPY levels, the patients were also registering 15 different symptoms daily during 28 days. Sex and age-matched healthy controls were recruited for comparisons. Non-parametric tests were used for the statistical analyses.The results showed that the NPY levels were significantly elevated in the patients compared to the controls. In the luteal phase of the cyclic patients, the levels of the peptide were higher than in the corresponding controls. For the non-cyclic patients, there was a positive correlation between physical symptoms and NPY levels, however, pain per se did not reach the significant level of correlation. The non-depressed patients had the same levels of NPY as the depressed FMS patients, who also had a positive correlation between anxiety and NPY levels.These results suggest that FMS patients have an altered activity in the NPY system, most likely due to prolonged and/or repeated stress, and that the hormonal state and time of the menstrual cycle also may be of importance in the complex pathophysiologic mechanism behind the development of FMS. Copyright 1999 European Federation of Chapters of the International Association for the Study of Pain.
Ethylmorphine is metabolised by N-demethylation (to norethylmorphine) and by O-deethylation (to morphine). The O-deethylation reaction was previously shown in vivo to co-segregate with the O-demethylation of dextromethorphan indicating that ethylmorphine is a substrate of polymorphic cytochrome P450(CYP)2D6. To study further the features of ethylmorphine metabolism we investigated its N-demethylation and O-deethylation in human liver microsomes from eight extensive (EM) and one poor metaboliser (PM) of dextromethorphan. Whereas N-demethylation varied only two-fold there was a 4.3-fold variation in the O-deethylation of ethylmorphine, the lowest rate being observed in the PM. Quinidine, at a concentration of 1 gM, inhibited O-deethylation in microsomes from an EM, but was unable to do so in microsomes from the PM. The immunoidentified CYP2D6 and CYP3A4 correlated with the rates of O-deethylation (r = 0.972) and N-demethylation (r = 0.969), respectively. We conclude that the O-deethylation of ethylmorphine is catalysed by the CYP2D6 in human liver microsomes consistent with previous findings in healthy volunteers.
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