The Variety Of The Function On Microglia In The Glucose And Insulin Models

Objectives: Our formal researches suggested that different insulin concentrations had influence on the function of microglia through affecting the secretion of nerve growth factor(NGF),then based on the formal research,we would like to explore the variety of the function and the expression of TrkA(the high affinity receptor of NGF)on microglia in the glucose and insulin models.Methods: BV2 and PC12 cell line were utilized to stand for microglia and neurons respectively in this study.We use BV2 cell as our research object,the function of them were evaluated by measuring the survival rate of PC12 cell.There were three groups of our research including the low glucose group(GLU 5mmol/L),the control group(GLU 10mmol/L),the high glucose group(GLU 23mmol/L)and fluctuant group(GLU 5mmol/L /23mmol/L).Four different concentrations of insulin(0ng/ml,50ng/ml,100ng/ml and 150ng/ml)were added into the supernatant of BV2 cell in every group respectively,after 24 h,the supernatant was collected to culture PC12 cell.Depending on the different supernatant,PC12 cell were divided into three groups.The supernatant of BV2 cell was added to the PC12 cell.PC12 cell were cultured for 1h.Measuring the survival rate of PC12 cell with the method of MTT.The levels of TrkA were detected by western-blot measurement.Compare the survival rate of PC12 cell and the expression of TrkA among the low glucose group,high glucose group and fluctuant group with that of the control group in the same insulin concentration,to make clear the influence of glucose on the function of BV2 cell and the variety of TrkA.Results:1.The survival rate of PC12 cell was 56.75±0.84% ? 64.06±1.8% ?72.05±0.75% ? 53.91±1.23% respectively in the low glucose group,the control group,the high glucose group,and fluctuant group when the insulin concentration was 0ng/ml;In the corresponding groups,the survival rate of PC12 cell was 58.58±1.80%?68.37±1.25%?74.47±0.21%?56.05±0.34% in the 50ng/ml insulin concentration,61.64±0.61% ? 71.49±1.59% ? 77.16±2.37% ? 58.01±0.82% in the 100ng/ml insulin concentration and 50.66±0.82%?59.72±1.46%?63.15±0.21%?47.69±0.66% in the 150ng/ml insulin concentration.We compared the viability of PC12 cell of the low glucose group,the high glucose group and the fluctuant group with that of the control group in the same concentrations of insulin respectively,it was significantly increased in the high glucose group(P<0.05)and decreased in the low glucose group and fluctuant group(P<0.01).Stable glucose concentration and proper insulin concentration(100ng/ml)makes viability of PC12 cell higher,whereas fluctuant glucose concentration and high insulin concentration(>100ng/ml)makes it lower.2.The amount of TrkA were 7.12±0.89?8.81±0.29?10.01±0.30?7.17±2.64 respectively in the low glucose group,the control group,the high glucose group,and fluctuant group when the insulin concentration was 0ng/ml.In the corresponding groups the amount of TrkA were 22.53±0.40?24.34±0.67?26.34±0.67?21.41±7.24 in the 50ng/ml insulin concentration,55.42±1.01 ? 76.27±0.89 ? 83.10±3.85 ?35.66±0.69 in the 100ng/ml insulin concentration and 50.71±1.59 ? 51.7±0.55 ?54.51±1.09?24.96±0.92 in the 150ng/ml insulin concentration.We compared the amount of TrkA of the low group,high glucose group and fluctuant group with that of the control group in the same concentrations of insulin,it was significantly higher in the high glucose group(P<0.05)and lower in the low glucose group and fluctuant group(P<0.05).The amount of TrkA were increased with the rising of insulin concentrations(?100 ng/ml)(P<0.01).Conclusions:1.Microglia function as neuroprotective effect at certain concentrations of glucose and insulin.However,its neurotoxic effect appears at low(5mmol/L)or fluctuant concentrations of glucose or high concentrations of insulin(>100ng/ml),furthermore that effect becomes the most at fluctuant concentrations of glucose and high concentrations of insulin(>100ng/ml).2.The level of TrkA expressed by microglia rises when it function as neuroprotective effect,and decreases when it function as neurotoxic effect.To a certain extent,it suggests that the variety of the function of microglia is relevant to the amount of TrkA expressed by it.