Molecular Mechanism Of Type 2 Diabetes Mellitus-associated Erectile Dysfunction

Erectile dysfunction(ED)is one of the most common chronic complications in diabetic males.With the increase of the population of diabetic patients,the incidence of diabetes mellitus-associated erectile dysfunction(DMED)is increasing year by year.It is characterized by youth,prominent symptoms and difficult treatment,which greatly affects the quality of life of patients.Due to diabetes systemic lesions,the conventional treatment of erectile dysfunction drugs in the treatment of DMED has deficient curative effect,and has certain limitations in clinical practice.So,looking for a new pathological mechanism to help improve the existing treatment,improve curative effect,reduce side effects is our research target.There had been some reports published about microRNAs(miRNAs)participating in the pathological processes of DM and ED.Thus,we studied miRNAs’role in type 2 diabetes mellitus-associated erectile dysfunction(T2DMED).First,using GeneChip array techniques and next generation sequencing(NGS)technology,we detected the differentially expressed miRNAs in the corpus cavernosum(CC)of mice with T2DMED.miR-18a,miR-206,miR-122 and miR-133a appeared distinctly differential expressed(fold change≥3,p ≥ 0.01)and were confirmed by qRT-PCR(p<0.05 and FDR<5%);miR-384 appeared significantly declined in corpus cavernosum(CC)of T2DMED mice(fold change=6.4)and was confirmed by qRT-PCR(fold change=8.8,differences within group P>0.05).According to bioinformatic analysis using TargetScan,DAIAN and DAVID,these 5 miRNAs were speculated to play potential roles via regulating several genes and signaling pathways,including apoptosis,fibrosis,eNOS/cGMP/PKG,and vascular smooth muscle contraction processes,which mainly focused on affecting the functions of the endothelium and smooth muscle(SM)in the CC.Second,we verified the result of bioinformatic analysis via luciferase assay:IGF-1(insulin like growth factor 1)was confirmed as the target of miR-18a&miR-206,and ETA(endothelin receptor type A)was confirmed as the target of miR-384.Third,we detected that IGF-1 decreased in the CCs of T2DMED animals comparing with Negative Control(NC)via ELISA.Smooth muscle cell(SMC)of rat CC was cultured,transfected with miR-384 and verified ETA’s significant decline comparing with NC by western blotting.Thus,miR-18a&miR-206 were believed to down-regulated IGF-1 selectively and obstructed NO production in epithelium cells and then influence the eNOS/cGMP/PKG signaling pathway,lead to diastolic function of SM on the CC injury to cause ED.miR-384 was identified to down-regulated ETA selectively and then enhanced systolic function of SM on the CC to cause ED.Therefore,above-mentioned miRNAs may became new therapeutic or preventive target of T2DMED.Additionally,previous study showed that the major lesions in the early stage of T2DMED are neurocentral lesions.By performing electrical stimulation on the CC of T2DMED mice,no conspicuous erectile lesion was found.Hence,we posed a hypothesis that ED in the early stage may derived from the abnormity of central nervous system.We confirmed the key nucleus which controlled erection process in brain and laid a foundation for the subsequent in-depth study via animal erectile behavioral study and immunofluorescence(IF).