Effects Of Hydrogen Sulfide On Myocardial Fibrosis In Rats With Abdominal Aortic Coarctation By Inhibiting Autophagy And Its Mechanism

Objective:To study the effects of hydrogen sulfide on myocardial fibrosis in rats with abdominal aorta coarctation under pressure overload and its regulatory mechanism through regulating autophagy.Methods:Forty-four male Sprague-Dawley rats were randomly divided into 4groups:Control group,AAC group,AAC+H₂S group,H₂S group.The AAC+H₂S and H₂S group were treated with exogenous hydrogen sulfide（100umol/kg sodium hydrosulfide）daily after the abdominal aorta coarctation was established by operation.The control group and AAC group received intraperitoneal injection of the same amount of PBS.The blood pressure was examined after 4 weeks,the LVEF and FS was measured by ultrasound.The weight ratio of heart to body weight was calculated.Masson staining and electron microscopy were used to observe the myocardial pathological changes.Western Blot was used to detect the expression of TGF-β,MMP16,TIMP1 and autophagy protein.RT-qPCR was used to detect the expression of miR-1,mi R-34 a,miR-499-3p in myocardium.Results:1.Compared with Control group,Blood pressure in AAC group and AAC+H₂S group was significantly higher（P<0.05）.There was no significant difference between AAC and AAC+H₂S group in blood pressure（P>0.05）.There was no significant difference in the BW,HW,HW/BW of rats and the quantity of urine protein,either the value of left ventricular EF and FS between the groups（P>0.05）.2.Masson staining showed that the collagen fibers in group AAC were significantly increased than those in Control group.The collagen fiber deposition in AAC+H₂S group was significantly lower than that in AAC group,and there was no significant change in H₂S group compared with Control group.3.Transmission Electron Microscope showed that myofilament arrangement was disordered,mitochondria content was abundant and autophagosomes could be found in the AAC group.After treatment with exogenous hydrogen sulfide,the arrangement of myocardial fibers in AAC+H₂S group was similar to that in normal group,and the number of autophagosomes decreased.4.Western Blot showed that the expression of TGF-βwas significantly higher in AAC group than that of Control group（P<0.05）,and the expression of TGF-βin AAC+H₂S group was lower than that in AAC group（P<0.05）.Compared with Control group,the expression of autophagy related factor in AAC group was significantly up-regulated（P<0.05）,.The expression of ATG3,ATG5 and LC3A/B protein were significantly down-regulated in AAC+H₂S group（P<0.05）.5.RT-q PCR results showed that the expression of mi R-1,miR-34 a and miR-499-3p in the AAC group was significantly lower than that in the Control group（P<0.05）,and the miR-1,miR-34 a and miR-499-3p expression level in the AAC+H₂S group was significantly higher than that in the AAC group（P<0.05）.Conclusion:1.Myocardial fibrosis may occur in rats with coarctation of abdominal aorta and obviously up-regulated autophagy,which may be related to the activation of TGF-βsignaling pathway and the regulation of miR-1,miR-34 a and miR-499-3p.2.Exogenous hydrogen sulfide can significantly reduce myocardial fibrosis in rats with abdominal aortic coarctation,which may be related to the inhibition of excessive autophagy by down-regulation of TGF-βand regulation of mi R-1,miR-34 a and miR-499-3p.