Aim: Evaluation of pressure pain threshold and β-endorphin plasma level in lean women with polycystic ovary syndrome (PCOS) and healthy controls. The associations between β- endorphins and pressure pain threshold were also investigated.
Materials and methods: In 48 lean women with polycystic ovary syndrome and 38 lean women without this disorder plasma β-endorphins and pressure pain thresholds were measured.
Results: The β- endorphins level was higher in the PCOS group compared to the controls (15.5±4.37 pg/ml vs 6.9±2.47 pg/ml, P<0.0001). In PCOS group pressure pain thresholds measured on deltoid and trapezius muscles were higher compared to the controls (9.33±1.3 kg/cm2 vs 5.19±0.57 kg/cm2, P<0.001; 8.23±1.04 kg/cm2 vs 4,79±0.55 kg/cm2, P< 0.001). The β- endorphin levels positively correlated with pressure pain thresholds in polycystic ovary syndrome group. Increase in β- endorphin level of 1 pg/ml was associated with increase of pressure pain threshold value on deltoid muscle of 0.23 kg/cm2 (R=0.632, P=0.011) and of 0.18 kg/cm2 on trapezius muscle (R=0.588, P=0.037).
Conclusion: β- endorphin serum level as well as pressure pain threshold are higher in lean polycystic ovary syndrome group than in lean healthy controls. We found correlations between β- endorphin levels and pressure pain threshold in the polycystic ovary syndrome group. It may suggest the role of endogenous opioids in the pathogenesis of polycystic ovary syndrome and also that increases in circulating plasma β- endorphins concentration can increases pressure pain threshold and consequently may modulate pain perception in PCOS lean women.