Study On How Ovary Affects Expression Patterns Of Lox Gene Family And Elastin

[Background and Objective] Pelvic organ prolapse (POP) is prevalent in middle-aged and old women. Uterine prolapse is usually accompanied by urinary incontinence (UI). With the pelvic content of prolapse developing, the risk for urinary incontinence also increases. POP and UI affect the quality of patients'life negatively. At present, the etiology and pathogenesis have not been defined clearly. From epidemiology, pelvic organ prolapse is more prevalent after menopause and age is a high-risk factor. From the anatomy pelvic organs are enveloped and connected loosely to the supportive musculature and bones of the pelvis by endopelvic fascia which is a reticulate structure of connective-tissue. If the formation and remodeling of connective-tissue are dysfunctional, women will have a higher prevalence of prolapse. Elastic fiber is one of the most important compositions of connective-tissue. Lox (Lysyl oxidase) family plays a crucial role during elastic fiber synthesis process. They can activate tropoelastin and mediate the deposition of elastic fiber. Recent study showed that in Loxll (Lysyl oxidase-like-1) gene knock-out mice Loxll deficiency causes an inability of replenishing elastic fiber in reproductive tissues after parturition, leading to pelvic organ prolapse and lower urinary tract dysfunction. Loxll was highly expressed in the reproductive tract of adult mice and its expression decreased with advancing age. We speculated the corelation that was reproduction aging—decrease of Loxl1 expression——the obstruction of elastic fiber formation—POP and UI. There are 5 members in Lox family but attention was mostly paid to the study of Lox and Loxl1. Some other members have high expression in uterus as well. It's required to do many experiments to assess whether they have correlation with pelvic organ prolapse. In our study we gained mice of premature ovarian failure through chemical treatment. We want to study three questions as follow:(1) the alterations of Lox family and Elastin expression in uterus, vagina and bladder during aging; (2) the upregulation factors of Lox family and Elastin; (3) if the phenotype could be rescued through regulated the expression of Lox family and Elastin. We hope that our study may provide a new idea for the prevention and treatment of POP and UI.[Methods](1) The 2 month-old mice were administered cyclophosphamide (CTX) through intraperitoneal injection and busulfan (BUS) through hypodermic injection. The injection amount of CTX was 120 mg/kg and BUS was 12 mg/kg. The mice were raised for 1 month. Then we detected the estradiol level of blood serum as indicator for premature ovarian failure.2 month-old mice were control group.(2) The total RNA was extracted from the uterus, vagina and bladder and purified with clearing away protein and DNA. The total RNA was reversed to cDNA. The amounts of Lox family and Elastin were relatively quantified by real-time PCR.(3) The mice of premature ovarian failure were administered estradiol (E2) through intraperitoneal injection for 3 days and the amount was 50μg/kg. The amounts of Lox family and Elastin were relatively quantified by real-time PCR.(4) The data were represented by mean±SD and analyzed using student's t-test (P<0.05 was statistically valid).[Results](1) The serum estradiol level of the mouse of premature ovarian failure decreased 43.9% compared with the 2 month-old mouse. The decrease was significant (P<0.05).(2) The uterus wall and vagina wall of the mouse of premature ovarian failure were much weaker than 2 month-old mouse. The toughness of uterus was decreased and easily fractured.(3) Compared with 2 month-old mouse, the expression of Lox, Loxl1 and Loxl2 in the uterus, vagina and bladder of the mouse of premature ovarian failure decreased. The alteration was significant (P<0.05). The expression of Loxl3 and Elastin in uterus and vagina decreased significantly (P<0.05). The expression of Loxl4 in bladder decreased significantly (P<0.05).(4) Compared with the mice of premature ovarian failure, the expression of Lox in the vagina of the mice+E2 increased significantly (P<0.05). The expression of Loxll and Loxl2 in bladder of the mice+E2 increased significantly (P<0.05).[Conclusions](1) Ovary regulates the expression of Lox family and Elastin. The expression of most Lox family member and Elastin decrease in uterus, vagina and bladder with the aging of ovary, leading a decrease of elastic fibers. Age is a high-risk factor for pelvic organ prolapse and ovary aging may lead a predominant role.(2) Estradiol increases the expression of Lox in vagina, Loxll and Loxl2 in bladder.