Exogenous H2S Protects Against Diabetic Cardiomyopathy by Activating Autophagy via the AMPK/mTOR Pathway

Background/Aim: Autophagy plays an important role in cellular homeostasis through the disposal and recycling of cellular components. Hydrogen sulphide (H 2 S) is the third endogenous gas that has been shown to confer cardiac protective effects. Given the regulation of autophagy in cardioprotection, this study aimed to investigate the protective effects of H 2 S via autophagy during high glucose treatment. Methods: This study investigated the content of H 2 S in the plasma as well as myocardial, ultrastructural changes in mitochondria and autophagosomes. This study also investigated the apoptotic rate using Hoechst/PI as well as expression of autophagy-associated proteins and mitochondrial apoptotic proteins in H9C2 cells treated with or without GYY4137. Mitochondria of cardiac tissues were isolated and RCR and ADP/O were also detected. AMPK knockdown was performed with siRNA transfection. Results: In a STZ-induced diabetic model, NaHS treatment not only increased the expression of p-AMPK in diabetic group but further activated cell autophagy. Following 48h high glucose, autophagosomes and cell viability were reduced. The present results showed that autophagy could be induced by H 2 S, which was verified by autophagic ultrastructural observation and LC3-I/LC3-II conversion. In addition, the mitochondrial membrane potential (MMP) was significantly decreased. The expressions levels of autophagic-related proteins were significantly elevated. Moreover, H 2 S activated the AMPK/rapamycin (mTOR) signalling pathway. Conclusions: Our findings demonstrated that H 2 S decreases oxidative stress and protects against mitochondria injury, activates autophagy, and eventually leads to cardiac protection via the AMPK/mTOR pathway.