The Number of IgG-Positive Neurons in the Rat Hippocampus Increases after Dosed Traumatic Brain Injury

To evaluate the consequences of traumatic brain injury (TBI), we used a model of lateral fluid percussion brain injury in freely moving male Wistar rats. The immediate response to TBI included development of motor excitation and tonic–clonic seizures. Morphological analysis was performed 7 day after TBI. To localize IgG in the brain, rat brain slices were double stained with antibodies against IgG and NeuN (neuronal marker). To evaluate the state of microglia, we performed staining with Isolectin B4 (a microglial marker). The number of neurons was measured in sections stained using the Nissl method. The results show the IgG accumulation in neurons adjacent to cortical focus of trauma. In the hippocampus, IgG was accumulated in the neurons of the ipsilateral hippocampal CA1 and CA2 fields and the dentate gyrus, while in the contralateral hemisphere IgG was accumulated in the neurons of the CA1 field. These changes were accompanied by activation of microglia in the hippocampus, as well as by a decrease in neuronal density in the dentate gyrus of the ipsilateral hippocampus. The results show that TBI leads to bilateral damage to the hippocampus.