Modulation of Mitochondrial Function and Autophagy Mediates Carnosine Neuroprotection Against Ischemic Brain Damage

Background and Purpose-Despite the rapidly increasing global burden of ischemic stroke, no therapeutic options for neuroprotection against stroke currently exist. Recent studies have shown that autophagy plays a key role in ischemic neuronal death, and treatments that target autophagy may represent a novel strategy in neuroprotection. We investigated whether autophagy is regulated by carnosine, an endogenous pleiotropic dipeptide that has robust neuroprotective activity against ischemic brain damage. Methods-We examined the effect of carnosine on mitochondrial dysfunction and autophagic processes in rat focal ischemia and in neuronal cultures. Results-Autophagic pathways such as reduction of phosphorylated mammalian target of rapamycin (mTOR)/p70S6K and the conversion of microtubule-associated protein 1 light chain 3 (LC3)-I to LC3-II were enhanced in the ischemic brain. However, treatment with carnosine significantly attenuated autophagic signaling in the ischemic brain, with improvement of brain mitochondrial function and mitophagy signaling. The protective effect of carnosine against autophagy was also confirmed in primary cortical neurons. Conclusions-Taken together, our data suggest that the neuroprotective effect of carnosine is at least partially mediated by mitochondrial protection and attenuation of deleterious autophagic processes. Our findings shed new light on the mechanistic pathways that this exciting neuroprotective agent influences.This study was supported by National Institutes of Health and American Heart Association grants to Dr Majid. This work was also supported by National Research Foundation of Korea (NRF)-2012M3A9C6049935 and the Daegu Gyeongbuk Institute of Science and Technology Convergence Science Center Program (14-BD-04) to Dr Yu and by NRF-2012R1A1A3013240 to Dr Bae, funded by the Ministry of Science, ICT, and Future Planning of Korea