| Objective To make clear the effect of high osmolality on nucleus pulposus cell and the possible role of P38MAPK and JNK/SAPK signal pathways in this process.Methods After treatments with different osmolality and time, MTT test and Flow cytometric assay were done to detect the nucleus pulposus cell apoptosis. Immunofluorescence analysis and Western blot were performed to detect changes in phospho-P38mitogen-activated protein kinases (P-P38MAPK) and phospho-c-Jun N-terminal kinases/Stress-activated protein kinases (P-JNK/SAPK) expression and sub-cellular localization to observe the role of it in apoptosis of nucleus pulposus cells.Results:Hyperosmotic stress (600mOsm) induced nucleus pulposus cell apoptosis and changed phospho-P38MAPK and phospho-JNK/SAPK expression in pulposus cells. A highly hyperosmotic medium (600mOsm) severely reduced nucleus pulposus viability and led mainly to apoptotic cell death compared to isosmotic conditions (P<0.01)and corresponding inhibitor groups apoptotic cell death remarkably descend. While elevating osmotic pressure(400mOsm) and corresponding inhibitor groups caused no changes compared to isosmotic conditions. Immunofluorescence analysis demonstrated that P-P38MAPK and P-JNK/SAPK were expressed in cytoplasm and nucleus. Western blotting showed the expression of P-P38MAPK and P-JNK/SAPK significantly increased after treatments with600mOsm medium compared to isosmotic conditions(P<0.01), and were attenuated significantly in corresponding groups pretreated with their inhibitor respectively.Conclusion:Hyperosmotic stress activated P38and JNK/SAPK signal pathways, which induced nucleus pulposus cells apoptosis and nucleus pulposus cells adapted to gentle osmotic pressure increase in a primary nucleus pulposus cell culture. Postgraduate student:Fang-Hui Li (Orthopaedic Surgery) Directed by Professor:De-Chun Wang... |
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