Autophagy Is Involved In Neuroprotective Effect Of Alpha7 Nicotinic Acetylcholine Receptor On Ischemic Stroke

The alpha 7 nicotinic acetylcholine receptor (alpha 7nAChR) belongs to the superfamily of cys loop cationic ligand-gated channels, which consists of homogeneous alpha 7 subunits. Although our lab found that activation of alpha 7nAChR could alleviate ischemic stroke, the mechanism is still unknown. Herein, we explored whether autophagy is involved in the neuroprotective effect mediated by alpha 7nAChR in ischemic stroke. Transient middle cerebral artery occlusion (tMCAO) and oxygen and glucose deprivation (OGD/R) exposure were applied to in vivo and in vitro models of ischemic stroke, respectively. Neurological deficit score and infarct volume were used to evaluate outcomes of tMCAO in the in vivo study. Autophagy-related proteins were detected by Western blot, and autophagy flux was detected by using tandem fluorescent mRFP-GFP-LC3 lentivirus. At 24 h after tMCAO, alpha 7nAChR knockout mice showed worse neurological function and larger infarct volume than wild-type mice. PNU282987, an alpha 7nAChR agonist, protected against OGD/R-induced neuronal injury, enhanced autophagy, and promoted autophagy flux. However, the beneficial effects of PNU282987 were eliminated by 3-methyladenine (3-MA), an autophagy inhibitor. Moreover, we found that PNU282987 treatment could activate the AMPK-mTOR-p70S6K signaling pathway in the in vitro study, while the effect was attenuated by compound C, an AMPK inhibitor. Our results demonstrated that the beneficial effect on neuronal survival via activation of alpha 7nAChR was associated with enhanced autophagy, and the AMPK-mTOR-p70S6K signaling pathway was involved in alpha 7nAChR activation-mediated neuroprotection.