Abstract:

Objective: To observe the changes of neuronal microtubule-associated protein (Tau) and apoptosis related factors in the rat HT22 cells injured by okada acid,and to investigate the protective effect of pilose antler polypeptides (PAP) on the nerve cell injury, and to explore its mechanism.Methods: Okada acid was used to induce the HT22 cell injury in the rats after HT22 cells were cultured in vitro.The HT22 cells were divided into normal control group,DMSO control group,okada acid injury model group and different concentrations of PAP groups (the final concentrations were separately 50,500,and 1 000 mg·L^-1),which were incubated for 24 h at in the condition of 37℃ and 5% CO₂.The levels of Tau phosphorylation and the expressions of apoptosis related factors Bcl-2 and Caspase-3 in the HT22 cels in various groups were detected by immunocytochemical staining, Western blotting and RT-PCR methods.Results: The results of immunocytochemical staining showed that phospho-Tau was colored brown-yellow.The brown-yellow particles in the cells in okada acid injury model group were significantly increased compared with normal control group.The brown-yellow particles in 500 and 1 000 mg·L^-1 PAP groups were significantly decreased compared with okada acid injury model group.The results of Western blotting method showed that the Tau protein expression levels in different concentrations of PAP groups were significantly decreased compared with okada acid injury model (P<0.05 or P<0.01).The expression level of Bcl-2 in 1 000 mg·L^-1 PAP group was significantly increased compared with okada acid injury model group (P<0.05).The expression levels of Caspase-3 in different concentrations of PAP groups had no significant changes compared with okada acid injury model group (P>0.05).The results of RT-PCR showed that the levels of Bcl-2 mRNA in different concentrations of PAP groups were significantly increased compared with okada acid injury model group (P<0.05 or P<0.01);the expression levels of Caspase-3 mRNA in 500 and 1 000 mg·L^-1 PAP groups were significantly decreased(P<0.05 or P<0.01).Conclusion: PAP could protect the nerve cells injured by okada acid through inhibiting the excessive phosphorylation of Tau protein and apoptosis mechanism of cells.

Key words: pilose antler peptid, okada acid, HT22 cells, Caspase-3, microtubule-associated protein, Bcl-2