title: Sex differences in spinal processing of transient and inflammatory colorectal stimuli in the rat.
abstract: Sex differences in the spinal processing of somatic and visceral stimuli contribute to greater female sensitivity in many pain disorders. The present study examined spinal mechanisms that contribute to sex differences in visceral sensitivity. The visceromotor response to colorectal distention (CRD) was more robust in normal female rats and after intracolonic mustard oil compared with that in male rats. No sex difference was observed in the CRD-evoked response of lumbosacral (LS) and thoracolumbar (TL) colonic afferents in normal and mustard oil-treated rats, but there was a sex difference in spontaneous activity that was exacerbated by intracolonic mustard oil. The response of visceroceptive dorsal horn neurons to CRD was greater in normal female rats in the LS and TL spinal segments. The effect of intracolonic mustard oil on the CRD-evoked response of different phenotypes of visceroceptive dorsal horn neurons was dependent on sex and segment. The NMDA receptor antagonist 2-amino-5-phosphonopentanoic acid (APV) dose-dependently attenuated the visceromotor response in normal rats with greater effect in male rats. Correspondingly, there was greater cell membrane expression of the GluN1 subunit in dorsal horn extracts in female rats. After intracolonic mustard oil, there was no longer a sex difference in the effect of APV nor GluN1 expression in LS segments, but greater female expression in TL segments. These data document a sex difference in spinal processing of nociceptive visceral stimuli from the normal and inflamed colon. Differences in dorsal horn neuronal activity and NMDA receptor expression contribute to the sex differences in the visceral sensitivity observed in awake rats.
authors: Department of Neural and Pain Sciences, School of Dentistry, University of Maryland, Baltimore, MD, USA Center for Pain Studies, University of Maryland, Baltimore, MD, USA Program in Neuroscience, University of Maryland, Baltimore, MD, USA.
authors: Yaping
authors: Y
authors: Ji
authors: Bin
authors: B
authors: Tang
authors: Dong-Yuan
authors: DY
authors: Cao
authors: Gexin
authors: G
authors: Wang
authors: Richard J
authors: RJ
authors: Traub
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D003106:Colon / Q000187:drug effects / Q000294:innervation / Q000502:physiology; D004576:Electromyography; D005260:Female; D007509:Irritants / Q000494:pharmacology; D008297:Male; D009149:Mustard Plant; D059225:Nociception / Q000187:drug effects / Q000502:physiology*; D010938:Plant Oils / Q000494:pharmacology; D020671:Posterior Horn Cells / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D012737:Sex Factors; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D017833:Visceral Afferents / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D059265:Visceral Pain / Q000378:metabolism / Q000503:physiopathology*
chemical_list: D007509:Irritants; D010938:Plant Oils; D016760:Proto-Oncogene Proteins c-fos; D016194:Receptors, N-Methyl-D-Aspartate; D015763:2-Amino-5-phosphonovalerate; C027793:mustard oil