Angiotensin-(1–7) reduces α-synuclein aggregation by enhancing autophagic activity in Parkinson's disease

Abnormal accumulation of α-synuclein contributes to the formation of Lewy bodies in the substantia nigra, which is considered the typical pathological hallmark of Parkinson's disease. Recent research indicates that angiotensin-(1–7) plays a crucial role in several neurodegenerative disorders, including Parkinson's disease, but the underlying mechanisms remain elusive. In this study, we used intraperitoneal administration of rotenone to male Sprague-Dawley rats for 4 weeks to establish a Parkinson's disease model. We investigated whether angiotensin-(1–7) is neuroprotective in this model by continuous administration of angiotensin-(1–7) into the right substantia nigra for 4 weeks. We found that angiotensin-(1–7) infusion relieved characteristic parkinsonian behaviors and reduced α-synuclein aggregation in the substantia nigra. Primary dopaminergic neurons were extracted from newborn Sprague-Dawley rat substantia nigras and treated with rotenone, angiotensin-(1–7), and/or the Mas receptor blocker A-779 for 24 hours. After binding to the Mas receptor, angiotensin-(1–7) attenuated apoptosis and α-synuclein aggregation in rotenone-treated cells. Primary dopaminergic neurons were also treated with angiotensin-(1–7) and/or the autophagy inhibitor 3-methyladenine for 24 hours. Angiotensin-(1–7) increased α-synuclein removal and increased the autophagy of rotenone-treated cells. We conclude that angiotensin-(1–7) reduces α-synuclein aggregation by alleviating autophagy dysfunction in Parkinson's disease. Therefore, the angiotensin-(1–7)/Mas receptor axis plays an important role in the pathogenesis of Parkinson's disease and angiotensin-(1–7) has potential therapeutic value for Parkinson's disease. All experiments were approved by the Biological Research Ethics Committee of Nanjing First Hospital (approval No. DWSY-2000932) in January 2020.