title: The OPRM1 A118G polymorphism modulates the descending pain modulatory system for individual pain experience in young women with primary dysmenorrhea.
abstract: The mu-opioid receptor (OPRM1) A118G polymorphism underpins different pain sensitivity and opioid-analgesic outcome with unclear effect on the descending pain modulatory system (DPMS). Primary dysmenorrhea (PDM), the most prevalent gynecological problem with clear painful and pain free conditions, serves as a good clinical model of spontaneous pain. The objective of this imaging genetics study was therefore to explore if differences in functional connectivity (FC) of the DPMS between the OPRM1 A118G polymorphisms could provide a possible explanation for the differences in pain experience. Sixty-one subjects with PDM and 65 controls participated in the current study of resting-state functional magnetic resonance imaging (fMRI) during the menstruation and peri-ovulatory phases; blood samples were taken for genotyping. We studied 3 aspects of pain experience, namely, mnemonic pain (recalled overall menstrual pain), present pain (spontaneous menstrual pain), and experimental pain (thermal pain) intensities. We report that G allele carriers, in comparison to AA homozygotes, exhibited functional hypo-connectivity between the anterior cingulate cortex (ACC) and periaqueductal gray (PAG). Furthermore, G allele carriers lost the correlation with spontaneous pain experience and exhibited dysfunctional DPMS by means of PAG-seeded FC dynamics. This OPRM1 A118G-DPMS interaction is one plausible neurological mechanism underlying the individual differences in pain experience.
authors.affiliation: Institute of Brain Science, School of Medicine, National Yang-Ming University, Taipei, Taiwan.|Integrated Brain Research Unit, Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Shyh-Yuh
authors.initials: SY
authors.lastname: Wei
authors.affiliation: Institute of Brain Science, School of Medicine, National Yang-Ming University, Taipei, Taiwan.|Integrated Brain Research Unit, Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan.|Institute of Biomedical Informatics, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Li-Fen
authors.initials: LF
authors.lastname: Chen
authors.affiliation: Institute of Public Health, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Ming-Wei
authors.initials: MW
authors.lastname: Lin
authors.affiliation: Institute of Brain Science, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Wei-Chi
authors.initials: WC
authors.lastname: Li
authors.affiliation: Institute of Biomedical Informatics, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Intan
authors.initials: I
authors.lastname: Low
authors.affiliation: Institute of Brain Science, School of Medicine, National Yang-Ming University, Taipei, Taiwan.|Integrated Brain Research Unit, Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Ching-Ju
authors.initials: CJ
authors.lastname: Yang
authors.affiliation: Department of Obstetrics and Gynecology, School of Medicine, National Yang-Ming University, Taipei, Taiwan.|Department of Obstetrics and Gynecology, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Hsiang-Tai
authors.initials: HT
authors.lastname: Chao
authors.affiliation: Institute of Brain Science, School of Medicine, National Yang-Ming University, Taipei, Taiwan.|Integrated Brain Research Unit, Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Jen-Chuen
authors.initials: JC
authors.lastname: Hsieh
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging / Q000502:physiology*; D063132:Connectome; D004412:Dysmenorrhea / Q000150:complications / Q000235:genetics* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D010146:Pain / Q000209:etiology / Q000235:genetics* / Q000503:physiopathology; D020641:Polymorphism, Single Nucleotide; D017450:Receptors, Opioid, mu / Q000235:genetics*
chemical_list: C485764:OPRM1 protein, human; D017450:Receptors, Opioid, mu