Proteomic analysis related to stress urinary incontinence following vaginal trauma in female mice Huey-Yi Chen a, *, Chao-Jung Chen b, **, Yu-Ning Lin c , Yung-Hsiang Chen b , Wen-Chi Chen d , Chuan-Mu Chen e a Department of Obstetrics and Gynecology, Sex Hormone Research Center, China Medical University Hospital, Graduate Institute of Integrated Medicine, China Medical University, Taichung, Taiwan b Graduate Institute of Integrated Medicine, China Medical University, Taichung, Taiwan c College of Life Sciences, National Chung Hsing University, Taichung, Taiwan d Department of Urology, China Medical University Hospital, Graduate Institute of Integrated Medicine, China Medical University, Taichung, Taiwan e Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan 1. Introduction Stress urinary incontinence (SUI) is a disease that is defined as the involuntary leakage of urine under vesical stress conditions [1]. The primary etiological factor of SUI is vaginal delivery [2], usually due to combined muscular, nerve and connective tissue injury [3]. Although progress has been made in the treatment of SUI [4], our understanding of the molecular mechanisms underlying the condition is poor. Because of the limited availability of human tissue for study, animal models are an important adjunct in improving our understanding of SUI [5]. Over the last decade, animal models of SUI have increasingly been used to understand the pathogenesis of the condition [6]. Vaginal distension (VD; simulated birth trauma; vaginal trauma) [7] and pudendal nerve transection [8] have been used for inducing SUI in rats, as evidenced by lowered leak point pressures (LPP) on urodynamic testing. Birth trauma from vaginal delivery may include denervation damage, ischemia and mechanical injuries to the muscular, neural and connective components of the lower urinary tract tissues [3,9–12]. Proteomics aiming at identification and quantifi- cation of the entire protein content (proteome) of tissue at a given time may provide insights into the mechanisms of diseases [13]. Our general goal is to understand the molecular mechanism related to SUI following vaginal trauma. Based on the relevant literature, we designed the present study with the following aims: (1) to examine LPP and maximum urethral closure pressure European Journal of Obstetrics & Gynecology and Reproductive Biology 171 (2013) 171–179 A R T I C L E I N F O Article history: Received 20 April 2013 Received in revised form 28 July 2013 Accepted 13 August 2013 Keywords: Stress urinary incontinence Vaginal distension Leak point pressure Maximum urethral closure pressure Myosin A B S T R A C T Objective: The molecular mechanisms underlying stress urinary incontinence (SUI) are not clear. In light of the limited availability of human tissue for study, we explored the changes in the urethra of C57BL/6 mice with experimentally induced SUI. Study design: Twelve virgin female mice were randomized into two groups: one group undergoing vaginal distension (VD) for 1 h with an 8-mm dilator, and a non-instrumented control group. Four days after VD, leak point pressures (LPP) and maximum urethral closure pressure (MUCP) were assessed in these mice under urethane (1 g/kg, i.p.) anesthesia. After measuring LPP and MUCP, the animals were sacrificed, and the urethras were removed for proteomic analysis using 2-dimensional differential gel electrophoresis (2D DIGE) and liquid chromatography–tandem mass spectrometry (LC–MS/MS) technology. Lastly, interaction between these proteins was further analyzed using MetaCore. Results: LPP and MUCP values were significantly decreased in the 8-mm VD groups compared with the non-instrumented control group. Sixty-eight differentially expressed proteins of urethra from female mice with and without VD were identified. Of these, 19 proteins were up-regulated and 49 were down- regulated. The majority of the VD-induced proteins were involved in generation of precursor metabolites and energy, oxidation of reduction, regulation of apoptosis, and glycolysis. Myosin expression in the urethra was significantly decreased in the 8-mm VD group as compared with the control group. Conclusions: As a model of simulated birth trauma, VD can induce SUI in female mice. Under-expression of myosin plays a plausible role in the pathogenesis of SUI following vaginal trauma. ß 2013 Elsevier Ireland Ltd. All rights reserved. * Corresponding author at: Department of Obstetrics and Gynecology, China Medical University Hospital, No. 2, Yu-Der Road, Taichung 404, Taiwan. Tel.: +886 4 22052121x2063; fax: +886 4 22033295. ** Corresponding author. Tel.: +886 4 22052121x2761. E-mail addresses: d888208@ms45.hinet.net (H.-Y. Chen), ironmanchen@yahoo.com.tw, cjchen@mail.cmu.edu.tw (C.-J. Chen). Contents lists available at ScienceDirect European Journal of Obstetrics & Gynecology and Reproductive Biology jou r nal h o mep ag e: w ww .elsevier .co m /loc ate/ejo g rb 0301-2115/$ – see front matter ß 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ejogrb.2013.08.034