Prevention of Cyclophilin D-Mediated mPTP Opening Using Cyclosporine-A Alleviates the Elevation of Necroptosis, Autophagy and Apoptosis-Related Markers Following Global Cerebral Ischemia-Reperfusion

The mitochondrial permeability transition pore (mPTP) is a complex channel of the inner membrane, the opening of which leads to mitochondrial swelling and dissipation of mitochondrial membrane potential (MMP). Here, we aimed to evaluate the role of the cyclophilin D (CypD) as a prominent mediator of mPTP, on necroptosis and autophagy as well as apoptosis, beyond the global cerebral ischemia-reperfusion (I/R) injury. We showed that while cerebral I/R injury is accompanied by loss of MMP, mitochondrial swelling and programmed cell death, pretreatment with cyclosporine-A (CsA) as a potent inhibitor of CypD, led to partial but significant reduction in necroptosis markers, RIP1 and RIP3 as well as activity of glutamate-ammonia ligase (GLUL) and glutamate dehydrogenase 1 (GLUD1), downstream enzymes of RIP3. Administration of CsA also partially decreased autophagy associated proteins. Furthermore, we demonstrated that Bax/Bcl-2 ratio as well as caspase-3 activation, as the executioner of apoptosis, noticeably decreased by CsA pretreatment. Taken together, our results suggest that the CypD alongside the apoptosis regulation plays a partial role in inducing necroptosis and autophagy.