Mitochondrial-dependent mechanisms are involved in angiotensin II-induced apoptosis in dopaminergic neurons.

INTRODUCTION: We recently demonstrated that angiotensin II (Ang II) was involved in the etiology of Parkinson's disease (PD) via induction of apoptosis of dopaminergic neurons, but the mechanisms are not completely elucidated. Here, we asked whether mitochondrial-dependent mechanisms contributed to the Ang II-induced dopaminergic neuronal apoptosis.

MATERIALS AND METHODS: CATH.a cells were incubated with Ang II in combination with mitochondrial permeability transition pore (mPTP) inhibitors or angiotensin receptor antagonists, and apoptosis rate, caspase-3 activity, cytochrome c levels, and mPTP opening were assessed.

RESULTS: We showed that Ang II triggered apoptosis via a mitochondrial-dependent pathway, as elevated cytochrome c levels were observed in the cytosol. By employing cyclosporin A and sanglifehrin A, two specific mPTP inhibitors, we revealed that cytochrome c release from mitochondria into cytoplasm was ascribed to mPTP opening. Meanwhile, the aforementioned effects could be abrogated by an AT1 receptor antagonist losartan rather than an AT2 receptor antagonist PD123319.

CONCLUSION: This study demonstrates that Ang II triggers mitochondrial-dependent apoptosis via facilitating mPTP opening through an AT1 receptor-mediated fashion in dopaminergic neurons. These findings give insight into the effect of Ang II in the etiology of PD, and reinforce the application of AT1 receptor antagonists for PD treatment.