| Objectives: To investigate the function of microglia and microglia with the overexpression of Trk A in different concentrations of insulin and underlying mechanism. To explore the effect of overexpression of Trk A protein on the function of microglia.Methods: BV2 and PC12 cell line were used to stand for microglia and neurons respectively in this study. We use BV2 cell, BV2 cell with the overexpression of Trk A(Trk A+BV2) as our research object, the function of them were evaluated by measuring the survival rate of PC12 cell. Five differernt concentrations of insulin(0ng/ml, 10ng/ml, 25ng/ml, 50ng/ml and 75ng/ml) were added into the supernatant of BV2 cell and Trk A+BV2 cell respectively, after 20 h, the supernatant was collected to culture PC12 cell. Depending on the different supernatant, PC12 cell were divided into two groups: BV2 cell group and Trk A+BV2 cell group. The supernatant of BV2 cell was added to the former, and the supernatant of Trk A+BV2 cell was added to the latter. PC12 cell were cultured for 1h, and then added H2O2 to the supernatant. Measuring the survival rate of PC12 cell with the method of MTT. Compared the survival rate of PC12 cell between Trk A+BV2 cell group and BV2 cell group in the same condition, to make clear the influence of the overexpression of Trk A protein on the function of BV2 cell. The levels of NGF and IL-1β secreted by BV2 and Trk A+BV2 cell were detected in corresponding state.Results: 1. The survival rate of PC12 cell was 48.26±0.70%, 52.02±0.67%, 57.30±0.91%, 60.71±1.51% and 69.25±1.79% respectively in BV2 cell group when the concentrationsof insulin were 0ng/ml, 10ng/ml, 25ng/ml, 50ng/ml and 75ng/ml. In the corresponding concentrations of insulin, the survival rate of PC12 cell was 49.34±1.33%, 62.06±0.70%, 68.25±1.56%, 73.19±2.38% and 81.87±1.28% respectively in Trk A+BV2 cell group.The survival rate of PC12 cell was increased with the rising of insulin concentrations. The differernce was statistically significant by One-Way ANOVA; there were differernces between every two differernt concentrations(P<0.01). Compared with BV2 cell group in the same concentrations of insulin(except 0ng/ml), the survival rate of PC12 cell was significantly increased in Trk A+BV2 cell group(P<0.01). 2. The levels of NGF were increased with the rising of insulin concentrations in both BV2 and Trk A+BV2 cell, the values of them were 532.17±8.52ng/L VS 568.27±7.43ng/L(insulin of 10ng/ml), 569.18±9.36ng/L VS 593.17±11.10ng/L(insulin of 25ng/ml), 599.24±15.34ng/L VS 636.40±10.75ng/L(insulin of 50ng/ml) and 635.06±12.35ng/L VS 678.72±13.46ng/L(insulin of 75ng/ml), the differernce was statistically significant by One-Way ANOVA, there were differernces between every two differernt concentrations(P < 0.05).Compared with BV2 cell in the same concentrations of insulin, the levels of NGF secreted by Trk A+ BV2 cell were significantly higher than BV2 cell(P<0.05). The levels of IL-1β were decreased with the rising of insulin concentrations in both BV2 and Trk A+BV2 cell, the values of them were 17.77±0.58ng/L VS 17.87±0.66ng/L(insulin of 10ng/ml), 14.15±0.69ng/L VS 14.80 ±0.41ng/L(insulin of 25ng/ml), 13.67±0.89ng/L VS 14.11±0.10ng/L(insulin of 50ng/ml) and 11.53±1.54ng/L VS 11.76±0.84ng/L(insulin of 75ng/ml), the differernce was statistically significant by One-Way ANOVA, except for the levels of IL-1βbetween 25 ng/ml and 50 ng/ml(P>0.05), there were differernces between other two concentrations(P<0.05). Compared the levels of IL-1β between Trk A+BV2 cell and BV2 cell in the same concentrations of insulin, there were no significant(P>0.05).Conclusions: 1.At the certain range of insulin concentrations(≤75ng/ml), microglia play a neuroprotective role by secreting NGF, the levels of NGF were gradually increased and the neuroprotective effect were gradually enhanced with the rising of insulinconcentrations. 2. Compared with microglia in the same concentrations of insulin(except 0ng/ml)microglia with the overexpression of Trk A showed a stronger neuroprotective effect b secreting more NGF. |
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