Abstract: Objective To investigate the mechanism of neurotrophic effect of insulin on SY5Y cells. Wortmannin(a specific inhibitor of PI3'K) was used to inhibit the signal transduction pathway of SY5Y cells, which were cultured in MEM medium that contains 5 mmol/L or 11.5 mmol/L glucose. Methods SY5Y cells were cultured and divided into two large groups. Group one included the control, 5 mmol/L glucose, 5 mmol/L glucose+0.01 U/mL insulin, 5 mmol/L glucose+0.01 U/mL insulin+Wortmannin; the second group included the control, 11.5 mmol/L glucose, 11.5 mmol/L glucose+0.01 U/mL insulin, 11.5 mmol/L glucose+0.01 U/mL insulin+Wortmannin. There were 8～12 wells in each group. MTT metabolism, LDH leakage, length of cell axon and area of cell body were measured and analyzed. Results The metabolism increased, LDH leakage decreased in SY5Y cells of 5 and 11.5 mmol/L glucose+0.01U/mL insulin groups. Length of axon and cell body area increased in SY5Y cells of 5 and 11.5 mmol/L glucose+0.01 U/mL insulin groups. However, the above effects were weakened in the Wortmannin groups. Conclusion Insulin receptors exist in SY5Y cells. Insulin exerts neurotrophic function by activating PI3'K signal transduction pathway.

Key words: insulin, wortmannin, PI3'K signal transduction pathway