Prostaglandin levels, vaginal innervation, and cyst innervation as peripheral contributors to endometriosis-associated vaginal hyperalgesia in rodents

Mol Cell Endocrinol. 2016 Dec 5;437:120-129. doi: 10.1016/j.mce.2016.08.017. Epub 2016 Aug 11.

Abstract

Endometriosis is a painful condition characterized by growth of endometrial cysts outside the uterus. Here, we tested the hypothesis that peripheral innervation and prostaglandin levels contribute to endometriosis-associated pain. Female Sprague-Dawley rats (n = 16) were surgically instrumented by transplanting uterine tissue onto mesenteric arteries within the peritoneal cavity to create a model of endometriosis which forms extra-uterine endometrial cysts and vaginal hyperalgesia. Our results describe a significant positive correlation between endometriosis-induced vaginal hyperalgesia and cyst innervation density (sensory, r = 0.70, p = 0.003; sympathetic, r = 0.55, p = 0.03), vaginal canal sympathetic innervation density (r = 0.80, p = 0.003), and peritoneal fluid levels of the prostaglandins PGE2 (r = 0.65, p = 0.01) and PGF2α (r = 0.63, p = 0.02). These results support the involvement of cyst innervation and prostaglandins in endometriosis-associated pain. We also describe how sympathetic innervation density of the vaginal canal is an important predictor of vaginal hyperalgesia.

Keywords: Cyst; Endometriosis; Innervation; Pelvic pain; Prostaglandin; Vaginal hyperalgesia.

MeSH terms

  • Animals
  • Ascitic Fluid / metabolism
  • Calcitonin Gene-Related Peptide / metabolism
  • Cysts / complications
  • Cysts / pathology*
  • Endometriosis / complications*
  • Endometriosis / pathology*
  • Female
  • Hyperalgesia / complications*
  • Hyperalgesia / pathology*
  • Prostaglandins / metabolism*
  • Rats, Sprague-Dawley
  • Uterus / innervation
  • Uterus / pathology
  • Vagina / innervation*
  • Vagina / pathology*

Substances

  • Prostaglandins
  • Calcitonin Gene-Related Peptide