Vaginal hyperalgesia in a rat model of endometriosis

This study examined whether a rat model of surgically-induced endometriosis that reduces fertility also evokes vaginal hyperalgesia along with changes in vaginal compliance. In nine rats trained to escape vaginal distention, percent escape responses to different volumes of vaginal distention were me asured for 2.5 months before and after endometriosis or sham surgery. Vagin al pressures were also measured simultaneously to provide an estimate of va ginal compliance. Endometriosis (or sham) was induced by autotransplantatio n of small pieces of uterus (or fat) on mesenteric cascade arteries, abdome n, and ovary. Escape responses were significantly increased only in rats wh ose autotransplants had formed cysts. Vaginal pressures, however, remained unchanged. This vaginal hyperalgesia may involve a process of viscero-visce ral referred hyperalgesia. (C) 2001 Elsevier Science Ireland Ltd. All right s reserved.