Influence of increased blood glucose level on brain injury after hypoglycemia in rats

Objective To explore the influence of the rising blood glucose level on brain injury in rats after insulin-induced hypoglycemia. Methods A total of 30 Wistar rats(weight: (300±50) g, age: 4 months) were simpling randomly divided into three equal groups: experimental group(20 rats), both vehicle control group (group A, 5 rats)and normal control group (group B, 5 rats). According to the blood glucose concentration after reperfusion, 20 rats from the experimental group were sub-divided into four groups: 1 9 mmol/L(group F, 5 rats)(blood sugar=blood glucose level). TUNEL staining was used to detect the neurons undergoing apoptosis, and Fluoro-Jade (FJB)staining was performed to reveal the degenerating neuronal cell bodies and axons. SAS 8.0 software analysis and processing, staining between the two groups of measurement data using single factor analysis of variance data. Results (1) TUNEL staining: the percentage of apoptotic neurons showed an obvious increase from C, D, E, and F group(hippocampal CA1: 40.2±3.1, 38.7±2.4, 36.8±2.6 and 76.4±6.3; hippocampal DG: 62.4±4.2, 59.8±3.7, 68.1±2.8 and 125.4±5.8)compared to group A and group B(hippocampal CA1: 3.2±1.9, 2.8±0.8; hippocampal DG: 4.1±2.4, 3.4±1.2), the difference was statistically significant(hippocampal CA1: F=13.52, P<0.05; hippocampal DG: F=14.29, P<0.05); among the subgroups from the experimental group, the percentage of apoptotic neurons from group F(hippocampal CA1: 76.4±6.3, hippocampal DG: 125.4±5.8)rose more markedly than the other three groups(group C, D, E, hippocampal CA1: 40.2±3.1, 38.7±2.4, 36.8±2.6; hippocampal DG: 62.4±4.2, 59.8±3.7, 68.1±2.8), the difference was statistically significant(hippocampal CA1: F=5.08, P<0.05; hippocampal DG: F=6.52, P<0.05). (2) FJB staining: there was a statistical significance between group A, B and group C, D, E, F (hippocampal CA1: F=18.49, P<0.05; hippocampal DG: F=11.37, P<0.05); furthermore, compared with group C, D, E, the percentage of FJB positive cells in group F was significantly increased., the difference was statistically significant(hippocampal CA1: F=7.83, P<0.05; hippocampal DG: F=14.29, P<0.05). Conclusion Control the rats on the same level of blood glucose and the same duration of the hypoglycemia, the severity of brain injury is closely correlated to the rising blood glucose concentration after hypoglycemia: the higher glucose level is, the more serious imparement brain suffer. Key words: Hypoglycemia; Brain injury; Hippocampus