Role of Elastin Expression in Thickening the Postpartum Vaginal Wall in Virgin and Postpartum Rat Models

Childbirth induces a number of alterations, including ligament weakening and increased vaginal distensibility. The occurrence of vaginal laxity or distensibility is associated with the vaginal wall and introitus overstretching during vaginal parturition while the pathophysiology is due to increased levator dimension and trauma to the levator ani muscle through avulsion (macrotrauma) or overdistension (microtrauma). Elastin is an extracellular matrix protein that confers elastic properties to organs and tissues, particularly those requiring elasticity. Elastin plays a vital role in the functioning of numerous tissues, such as the lungs, blood vessels, heart valves, ligaments, tendons, and skin. It is also a component of the vaginal mucosa. The aim of the present was to evaluate the role of elastin in the thickening of the postpartum vaginal wall composed of epithelial mucosa, and to understand the mechanism underlying vaginal laxity or distensibility within parous and nulliparous animal models. A total of 32 female white rats (Rattus norvegicus) were used in the present study. They were divided into two groups, each group consisting of 16 rats. The control group (C0) consisted of virgin nulliparous rats, which were sacrificed on the second day after vaginal parturition. Pregnant rats (group C1) were sacrificed on the second day after vaginal parturition. The median elastin expression in group C1 was higher (3 ± 0.56) than group C0 (2.85 ± 0.75). The mean thickness of the vaginal mucosal epithelium in group C0 (56,8 931μm) was greater than group C1 (44,98 349μm). The comparison of vaginal mucosal epithelium thickness between the two groups indicated a significant difference between groups C0 and C1. Elastin levels were significantly correlated with epithelial thickness. The expression of elastin significantly affects the vaginal wall thickness, which further affects vaginal laxity or vaginal distensibility.