Endocannabinoids and Related Lipids in Chronic Pain: Analytical and Clinical Aspects

This thesis investigates whether ECs and the related N-acylethanolamines (NAEs) can be used as potential biomarkers for CWP/FM. Specifically, the studies compared the peripheral and systemic levels of ECs and NAEs in 121 women with CWP/FM and in 137 healthy controls in two different cohorts. In addition, the correlation between lipid levels and common pain characteristics such as intensity, sensitivity, and duration were investigated. The EC and related lipid levels were measured using liquid chromatography in combination with tandem mass spectrometry. Multivariate data analysis was used for biomarker evaluation.

Compared to the healthy controls, the CWP/FM patients had significantly higher concentrations of OEA, PEA, and SEA in muscle and plasma (p ≤ 0.05) and significantly higher 2-AG in plasma (p ≤ 0.01). These results may indicate that NAEs, are mobilized differently in painful muscles compared with pain free muscles. Moreover, increased systemic levels of NAEs and 2-AG in patients might be signs of ongoing low-grade inflammation in

CWP/FM. These findings contribute to a better understanding of how peripheral and systemic factors maintain and activate chronic pain. Although the investigated lipids have statistically significant effects but biologically uncertain role in the clinical manifestations of CWP/FM. Thus plasma lipids are not a good biomarker for CWP/FM. Nevertheless, increased lipid levels indicate a metabolic asymmetry in CWP/FM, a finding that could serve as a basis for more research on pain management.