Pregnancy with and without birth trauma modulates the gene expression of proteins involved in elastic fiber homeostasis in the rat vagina

Objectives: Elastic fibers have been linked to the pathogenesis of pelvic organ prolapse. This study used a rat model to examine the effect of mode of delivery on the gene expression of proteins involved in elastic fiber homeostasis. Methods: 38 Sprague-Dawley rats were separated as follows: virgin rats after simulated vaginal delivery, groups A (n = 5) and B (n = 5); pregnant rats after spontaneous vaginal delivery, groups C (n = 5) and D (n = 5); pregnant rats after cesarean delivery, groups E (n = 6) and F (n = 5). Groups A, C and E were sacrificed 2 days after the intervention, groups B, D and F were sacrificed 14 days after the intervention. 7 virgin rats served as controls. Vaginal tissue was harvested for RNA extraction and cDNA conversion. The mRNA expression for lysyl oxidase like 1 (LOXL-1), tropoelastin and fibulin 5 (FBLN 5) was quantified via real-time reverse transcriptase polymerase chain reaction using the 2 method; β-actin was selected as the reference gene. Results: Postpartum day two we observed an up-regulation in the relative mRNA expression of LOXL-1, FBLN 5 and Tropoelastin in all groups compared to controls. In lower vaginal tissue the up-regulation decreased uniformly from postpartum day two to postpartum day fourteen. However, the relative mRNA expression of the target genes in upper vaginal tissue persisted at postpartum day fourteen in the SpVD and CD cohort. Conclusions: Vaginal trauma, whether as a result of spontaneous vaginal delivery or simulated vaginal delivery, resulted in the upregulation of genes involved in elastic fiber homeostasis. In addition, pregnancy and parturition, in the absence of direct vaginal trauma, also resulted in the upregulation of these genes. Our findings leave open the possibility that alterations in elastic fiber homeostasis occurring during pregnancy, regardless of mode of delivery, may play a role in the pathogenesis of POP.