Effect of hormone replacement and selective estrogen receptor modulators (SERMs) on the biomechanics and biochemistry of pelvic support ligaments in the cynomolgus monkey (Macaca fascicularis)

Objective: To evaluate the effect of selective estrogen receptor modulators and ethinyl estradiol on the biomechanical and biochemical properties of the uterosacral and round ligaments in the monkey model of menopause. Study Design: A randomized, double-blind, placebo-controlled study on 11 female macaque monkeys. Ovariectomized monkeys received 12 weeks of placebo, raloxifene, tamoxifen, or ethinyl estradiol. Biomechanical step-strain testing and real-time polymerase chain reaction was performed on the uterosacral and round ligaments. Results: Tamoxifen and raloxifene uterosacrals expressed differing collagen I /III receptor density ratios, but both selective estrogen receptor modulators showed decreased tensile stiffness compared to ethinyl estradiol and controls. Conclusion: These findings support a possible effect of selective estrogen receptor modulators on biomechanical and biochemical properties of uterosacrals. This may play a role in pelvic organ prolapse.