Neuroprotective Effects Of Salidroside Through Activation Of PI3K/Akt/Nrf2 Pathways In Focal Cerebral Ischemia Rat

Objective:(1) To investigate the neuroprotective effects of salidroside in focal cerebral ischemia rat; (2) To study the effects and partial mechanisms of PI3K/Akt/Nrf2 signaling pathway on salidroside neuroprotection.Methods:(1) 60 male SD rats were randomly divided into Sham group, MCAO group and MCAO+Sal group. Rats were administrated salidroside, or vehicle, daily for 6 days, after middle cerebral artery occlusion (MCAO) 2 h and reperfusion 1 h.The TUNEL-positive cells were measured by immunofluorescence technology, the mRNA expression of NogoA and NgR was detected by Real-Time qPCR and the protein expression of Bcl-2, Caspase-3, Cleaved Caspase-3, BDNF, NGF, NogoA, NgR, Nrf2 and HO-1 was assessed by Western Blot.(2) 50 male SD rats were randomly divided into Sham group, MCAO group and (MCAO+Sal) group, (MCAO+LY294002) group and (MCAO+LY294002+Sal) group. The PI3K inhibitor (LY294002) or 25% DMSO in PBS was administered intracerebroventricularly before ischemia under the guidance of brain stereotaxic instrument. Rats were administrated salidroside or vehicle after MCAO 2 h and reperfusion 1 h. After 24 h, the mRNA expression of TNFa, IL-6 and IL-1β were measured by Real-Time qPCR and the protein expression of p-IκBα, IκBα, p65, p-Akt, Akt, Nrf2, HO-1, Bcl-xl and Bax was evaluated by Western Blot.Results:(1) Salidroside attenuated cell apoptosis of MCAO rats, and promoted the protein expression of Bcl-2, BDNF and NGF in MCAO rats. Salidroside inhibited the protein of Cleaved Caspase-3 in MCAO rats, Salidroside reduced the mRNA and protein expression of NogoA and NgR in MCAO rats. Meanwhile, salidroside upregulated Nrf2 and HO-1 protein in MCAO rats.(2) Salidroside downregulated p-IκBa and p65 protein in MCAO rats, and enhanced the protein expression of p-Akt, Nrf2 and HO-1 and these increases were blocked by LY294002 in MCAO rats. Salidroside suppressed the mRNA level of TNFa, IL-6 and IL-1β and these were reversed by LY294002 in MCAO rats. Meanwhile, salidroside upregulated Bcl-xl protein and downregulated Bax protein, which were both reversed by LY294002, in MCAO rats.Conclusion:Salidroside can attenuate apoptosis and promote neurotrophic factor expression and promote neuronal axon growth, reduce proinflammatory cytokine production, have neuroprotective effects in focal cerebral ischemia rat, probably through activating PI3K/Akt/Nrf2 signaling pathways.