DR1-CSE/HS Pathway Upregulates Autophagy and Inhibits H9C2 Cells Damage Induced by High Glucose

In the cardiovascular system, long-term high glucose (HG) can lead to cardiomyocyte damage. Hydrogen sulfide (HS) reduces cell autophagy in cardiomyocytes. Dopamine 1 receptors (DR1), a specific binding receptor for dopamine, which has a significant regulatory effect on cardiomyocytes. However, it is unclear whether DR1 inhibits HG-induced cardiomyocyte damage by regulating endogenous HS production and the level of cell autophagy. The present data indicated that the expression of DR1 and cystathionine-γ-lyase (CSE, a key enzyme for endogenous HS production) and HS content were significantly reduced in HG-induced cardiomyocytes, which was reversed by SKF38393 (an agonist of DR1). NaHS (an exogenous HS donor) only increased HS content and the expression of CSE with no effect on DR1 expression. HG reduced cell viability, the expression of Bcl-2 and Beclin1, the production of autophagosomes and LC3 II/I ratio and increased the cell apoptotic ratio, the expression of cleaved caspase-3, cleaved caspase-9, cytochrome c, P62, and p-mTOR/t-mTOR ratio. SKF38393 and NaHS reversed the effects of HG. PPG (an inhibitor of CSE) and 3MA (an inhibitor of autophagy) abolished the beneficial effect of SKF38393. In addition, AICAR (an agonist of AMPK) and Rapamycin (an inhibitor of mTOR) increased the production of autophagosomes but decreased the p-mTOR/t-mTOR ratio, which was similar to the effects of SKF38393 and 3MA. Our findings suggest that DR1 reduces the HG-induced cardiomyocyte damage up-regulating the CSE/HS pathway, which increases cell autophagy by inhibiting the activation of mTOR.