title: Metformin increases pressure pain threshold in lean women with polycystic ovary syndrome.
abstract: BACKGROUND
  Despite the strong preclinical rationale, there are only very few data considering the utility of metformin as a potential pain therapeutic in humans. The aim of this study was to determine the association between metformin therapy and pressure pain threshold (PPT) in lean women with polycystic ovary syndrome (PCOS). We hypothesized that metformin therapy in lean PCOS women increases PPT.
  
  
  METHODS
  Twenty-seven lean PCOS women with free androgen index phenotype >5 and 18 lean healthy controls were enrolled in the study. Fifteen of the PCOS women were randomly assigned to be treated with metformin 1,500 mg daily for 6 months. PPT and plasma β-endorphin levels were measured in all women at the beginning of the study and after 6 months of observation.
  
  
  RESULTS
  We observed an increase in PPT values measured on deltoid and trapezius muscle in the PCOS with metformin group after 6 months of metformin administration (4.81±0.88 kg/cm(2), P<0.001 on deltoid muscle, and 5.71±1.16 kg/cm(2) on trapezius muscle). We did not observe any significant changes in PPT values in the PCOS without treatment group and in controls. We did not observe any significant changes in serum β-endorphin levels in any studied groups during the 6-month observation.
  
  
  CONCLUSIONS
  We conclude that metformin therapy increases PPT in lean PCOS women, without affecting plasma β-endorphin concentration. Our results may suggest the potential role of metformin in pain therapy. We propose that larger, randomized studies on metformin impact on pain perception should be performed.
authors.affiliation: Department of Gynecological Endocrinology, Jagiellonian University, Medical College, Kraków, Poland.
authors.forename: Marta
authors.initials: M
authors.lastname: Kiałka
authors.affiliation: Department of Gynecological Endocrinology, Jagiellonian University, Medical College, Kraków, Poland.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Milewicz
authors.affiliation: Department of Clinical Biochemistry, Jagiellonian University, Medical College, Kraków, Poland.
authors.forename: Krystyna
authors.initials: K
authors.lastname: Sztefko
authors.affiliation: Department of Clinical Biochemistry, Jagiellonian University, Medical College, Kraków, Poland.
authors.forename: Iwona
authors.initials: I
authors.lastname: Rogatko
authors.affiliation: Department of Epidemiology, Chair of Epidemiology and Preventive Medicine, Jagiellonian University Medical College, Kraków, Poland.
authors.forename: Renata
authors.initials: R
authors.lastname: Majewska
mesh_terms: D005260:Female; D006801:Humans; D008687:Metformin / Q000494:pharmacology / Q000627:therapeutic use*; D017288:Pain Threshold; D011085:Polycystic Ovary Syndrome / Q000188:drug therapy*
chemical_list: D008687:Metformin
keywords: metformin; pain therapy; polycystic ovary syndrome; pressure algometry; pressure pain threshold