TITLE:
Pregnancy with and without birth trauma modulates the gene expression of proteins involved in elastic fiber homeostasis in the rat vagina
AUTHORS:
K. T. Downing, F. A. Strube, M. S. Mikhail, M. E. DiSanto
KEYWORDS:
Elastic Fiber Homeostasis; Pregnancy
JOURNAL NAME:
Open Journal of Obstetrics and Gynecology,
Vol.3 No.8,
October
14,
2013
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.