Abstract
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-ΔΔCt 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.
Highlights
Pelvic organ prolapse (POP) is a major health and quality of life problem that affects women in their reproductive and menopausal years [1]
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
The study used 38 female Sprague-Dawley rats. 10 virgin rats underwent simulated vaginal delivery (SiVD) as follows: under anesthesia a 10 French Foley catheter was inserted into the vagina, the Foley balloon inflated with ~2.5 cc of water, and the catheter placed to gravity off the edge of the lab bench for 3 hours, removed while still inflated. pregnant rats underwent spontaneous vaginal delivery (SpVD). pregnant rats were submitted to cesarean delivery (CD) on gestation day 21 as follows: under anesthesia, a small vertical incision was made in the lower ventral abdominal wall allowing for delivery of the gravid uterine horns
Summary
Pelvic organ prolapse (POP) is a major health and quality of life problem that affects women in their reproductive and menopausal years [1]. The causes of POP common to most women include pregnancy and parturition, and aging. With respect to the former, increasing vaginal parity, and operative vaginal delivery have been identified as the exposures most associated with higher rates of POP; yet, most women who have born children do not develop POP and when they do so it is well after the associated exposure [4,5,6,7]. In recent years a significant advancement in our understanding of the pathophysiology of POP came to light when an important physiologic link between elastic fiber homeostasis and POP was observed in two murine knockout (KO) models (Lysyl Oxidase Like-1 [LOXL-1] and Fibulin 5 [FBLN 5]) that develop POP due to abnormalities in elastic fiber formation [8,9].
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