No evidence for endorphin deficiency in fibromyalgia following investigation of cerebrospinal fluid (CSF) dynorphin A and Met-enkephalin-Arg6-Phe7

Abstract The CSF levels of Met-enkephalin-Arg 6 -Phe 7 and dynorphin A were measured in patients with fibromyalgia. The mean CSF Met-enkephalin-Arg 6 -Phe 7 level was 35.1 ± 2.4 fmol / ml ( mean ± S . E . M .). The mean CSF level of dynorphin A was 14.3 ± 0.9 fmol / ml . Regression analysis showed a statistically significant correlation between Met-enkephalin-Arg 6 -Phe 7 and dynorphin A ( r = 0.5369, P = 0.001). When correlated to the previously measured CSF levels of beta-endorphin, a statistically significant correlation was found with Met-enkephalin-Arg 6 -Phe 7 ( r = 0.5055, P = 0.03) but not with dynorphin A ( P > 0.05). The Met-enkephalin-Arg 6 -Phe 7 and dynorphin A levels are elevated compared to the levels available for comparison groups. Therefore, a lack of endorphin secretion does not seem to be the basis for the hyperalgesia observed in these patients.