title: Are there sex differences in affective modulation of spinal nociception and pain?
abstract: Sex differences in the processing and experience of emotion exist. The present study examined whether sex differences in emotion lead to sex differences in affective modulation of pain and spinal nociception (assessed by nociceptive flexion reflex, NFR). Participants were healthy men (n = 47) and women (n = 73). Prior to affective modulation testing, electrocutaneous pain sensitivity was assessed (NFR threshold, pain threshold, pain tolerance). Affective modulation of pain and NFR was then assessed by presenting pictures that vary in emotional valence and arousal (mutilation, attack, death, neutral, families, adventure, erotica) during which suprathreshold electrocutaneous stimulations were delivered. Subjective emotional reactions were assessed after every picture, and nociceptive reactions were assessed after every suprathreshold stimulus. Results indicated women had greater pain sensitivity and also responded more negatively to attack pictures and less positively to erotic pictures. But despite these differences, affective modulation of pain/NFR was not moderated by sex: erotic pictures inhibited pain/NFR and mutilation pictures enhanced pain/NFR. Together, this implies subjective emotional experience does not completely mediate picture-evoked modulation of pain/NFR, a supposition that was further supported by exploratory analyses that demonstrated picture-evoked modulation of pain/NFR was present even after controlling for intra- and inter-individual differences in emotional reactions to pictures. Implications and limitations of these findings are discussed.
  
  
  CONCLUSIONS
  Evidence suggests that women are more sensitive to experimental and clinical pain, but the mechanisms contributing to these sex differences are poorly understood. Affective processes are known to play a role in regulating pain signaling and pain experience; therefore, the present study examined whether sex differences in affective experience contribute to sex differences in pain. Results indicate that in healthy individuals affective processes may not contribute to sex differences in pain.
authors.affiliation: Department of Psychology, The University of Tulsa, Tulsa, Oklahoma, USA. jamie-rhudy@utulsa.edu
authors.forename: Jamie L
authors.initials: JL
authors.lastname: Rhudy
authors.forename: Emily J
authors.initials: EJ
authors.lastname: Bartley
authors.forename: Amy E
authors.initials: AE
authors.lastname: Williams
authors.forename: Klanci M
authors.initials: KM
authors.lastname: McCabe
authors.forename: Mary C
authors.initials: MC
authors.lastname: Chandler
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Russell
authors.forename: Kara L
authors.initials: KL
authors.lastname: Kerr
mesh_terms: D000328:Adult; D004558:Electric Stimulation; D004644:Emotions / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009619:Nociceptors / Q000502:physiology; D010146:Pain / Q000503:physiopathology / Q000523:psychology*; D017288:Pain Threshold / Q000502:physiology / Q000523:psychology*; D012018:Reflex / Q000502:physiology; D012727:Sex Characteristics