Hippocampal neuroinflammation and neuronal injury in the acute phase of pentylenetetrazol induced epilepsy mouse model

ObjectiveTo investigate the activation of microglia and astrocytes, the secretion of pro-inflammatory factors, and the survival of neurons in the hippocampus of mice with acute seizures induced by pentylenetetrazol (PTZ) 24 hours after the onset of seizures. MethodsAdult male C57BL/6 mice were randomly assigned to the control group and the PTZ-induced acute epileptic seizure group using random numbers, with 28 mice in each group. The activation status of microglia and astrocytes in the CA1 region of the hippocampus was evaluated by immunofluorescence 24 hours after the onset of seizures. RNA was extracted from the hippocampal tissue to detect the expression level of inflammatory factor mRNA, and HE staining was used to assess the survival of neurons in the hippocampus. ResultsTwenty-four hours after PTZ-induced acute seizures in mice, the numbers of activated Iba1+ microglia (55.72±4.29 vs 35.71±9.66, P＜0.001) and GFAP+ astrocytes (51.61±8.21 vs 37.64±5.27, P＜0.01) in the CA1 region were significantly increased compared with the control group; the proportion of M1 microglia was significantly increased (0.58±0.02 vs 0.35±0.08, P＜0.0001), while the proportion of M2 microglia was significantly decreased (0.25±0.08 vs 0.44±0.09，P＜0.01); the mRNA level of pro-inflammatory factor IL-1β in the hippocampus was significantly higher than that in the control group (2.49±1.61 vs 1.02±0.68, P＜0.05); the numbers of neurons in the CA1 (284.91±73.32 vs 498.88±176.79, P＜0.05) and CA3 (247.42±50.20 vs 457.78±150.08, P＜0.05) regions during the acute phase was significantly reduced compared with the control group. ConclusionsTwenty-four hours after PTZ-induced acute epileptic seizures in mice, microglia and astrocytes in the CA1 region of the hippocampus are activated, with microglia mainly presenting the M1 phenotype to exert pro-inflammatory effects, secretions of pro-inflammatory factors increasing, and surviving hippocampal neurons decreasing.