Protective Effect of Rapamycin on STZ-Induced Injury in HT22 Cells
WANG Yi1, ZHU Mengyao1, GUO Zihe1, YUAN Haiyang1, GONG Yuesong1,2*
This study investigated the neuroprotective effect of rapamycin on STZ (streptozotocin) induced HT22 cell damage. A STZ-induced HT22 cell injury model was established and pretreated with different concentrations of rapamycin. Cell viability was detected by MTT to determine the optimal concentration of pre-protection of rapamycin. The cells were divided into control (con), model (STZ) and rapamycin (Rap) groups, and the neuronal morphology and synaptic structure were observed by HE staining. Cell apoptosis was observed by Hoechst 33342 staining. Cell LDH (lactate dehydrogenase) activity, SOD (superoxide dismutase) activity and MDA (malondialdehyde) content in each group were detected by test kits. The protein expression levels of p-AMPK/AMPK, p-mTOR/ mTOR, NR2B, NR1, and PSD 95 in cells were determined by Western blot. The results showed that STZ significantly induced HT22 cell damage compared with the control group, 1.0 μmol/L rapamycin showed the best protective effect on nerve injury induced by STZ. Compared with the control group, the model group showed severe synaptic structure damage, HT22 cells were induced to apoptosis by STZ, SOD activity significantly decreased (P<0.05), LDH activity (P<0.001) and MDA content significantly increased (P<0.001), p-AMPK/AMPK (P<0.001), NR2B (P<0.001), NR1 (P<0.05) and PSD 95 (P<0.001) protein expression levels significantly decreased, and p-mTOR/ mTOR protein expression levels significantly increased. Compared with the model group, rapamycin protected neuronal morphology and synaptic structure, inhibited cell apoptosis, increased SOD activity (P<0.05), decreased LDH activity (P<0.001) and MDA content (P<0.01), upregulated p-AMPK/AMPK (P<0.001), NR2B (P<0.05), NR1 (P<0.05), PSD 95 (P<0.01) protein expression and downregulated p-mTOR/mTOR protein expression (P<0.01). In conclusion, rapamycin can attenuate oxidative stress injury, inhibit apoptosis, and protect synaptic structure in STZ induced HT22 cells, and the mechanism may be related to the regulation of synaptic protein PSD 95 and NMDA receptor activity by AMPK/mTOR pathway.
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