Enhanced uterine contractility in an animal model of endometriosis

The uterus is composed of smooth muscle layers allowing its regulation. Endometriosis is defined as the presence of endometrium‐like tissue outside the uterus and is characterized by peritoneal inflammation, cysts, adhesions, infertility and chronic pelvic pain. Aim Investigate the impact of endometriosis on uterine muscle motility. Methods Endometriosis was induced in female Sprague‐Dawley rats by suturing uterine horn tissue next to the intestinal mesentery (Endo). Sham rats had sutures only. All animals were sacrificed in estrous phase and examined for cysts. Tissues were analyzed for macroscopic and microscopic damage, myeloperoxidase (MPO) levels, and mast cell numbers. Uterine strips were mounted in organ baths to study in vitro isometric contractile responses of longitudinal and circular muscle to carbachol (10 −8 –10 −3 M). Results Only Endo rats developed cysts. These animals had increased tension in uterine longitudinal muscle, more colonic damage (macroscopic 1.61 ± 0.26 vs. 1.13 ± 0.57, microscopic 4.89 ± 0.46 vs. 3.55 ± 0.45; p=0.056), more mast cells in the uterus (p<0.05), and higher MPO levels (1.5‐fold and 2‐fold for colon and uterus respectively) than Sham (n = 9 ± s.e.m.). Conclusions Our data indicate that the pathophysiological processes associated with this animal model can influence evoked uterine contractility. R15AT006373, R25GM082406, HPD 335731 & CFRDG 335513 from NSU