Abstract: Objective: To investigate the changes of expressions of tubulin and endosome-lysosome in the neurons in hippocampus tissue of the mice after status epilepticus (SE), and to elucidate the change rule of microtubule and endosome-lysosome system in the process of delayed neuronal death. Methods: A total of 40 male ICR mice were divided into control group(n=7,given normal saline) and experiment group(n=33, give pilocarpine);the mice in experiment group met the SE standand were divided into SE 1 d, SE 2 d, SE 3 d and SE 7 d groups according to the time after SE(n=5). Nissl and Fluoro-Jade B (F-JB) staining methods were used to detect the damage of neurons in hippocampus tissue of the mice in various groups. The expression intensities of β-tubulin,endosom protein Rab5 and lysosome constitutive protein LAMP1 and the percentages of β-tubulin, Rab5 and LAMP1 positive areas in neurons in hippocampus tissue of the mice in various groups were detected by immunofluorescence method. The relationships between the expression of β-tubulin and the expressions of Rab5 and LAMP1 in hippocampal CA1 area of the mice in various groups were detected by double fluorescence method. Results: Compared with control group, the number of neurons in hippocampal CA1 and CA3 areas of the mice in SE 1 d group was decreased (P<0.01), the number of F-JB positive cells was increased (P<0.01); the number of Nissl positive neurons in hippocampus tissue of the mice in SE 2 d, SE 3 d, and SE 7 d groups was decreased (P<0.01). Compared with control group, the number of F-JB positive neurons in hippocampus tissue of the mice in SE 2 d,SE 3 d and SE 7 d groups was increased (P<0.01). Compared with control group, the percentages of β-tubulin positive areas in hippocampal CA1 and CA3 areas of the mice in SE 2 d, SE 3 d and SE 7 d groups were significantly decreased (P<0.05), and the trend of change was similar to that of neuron damage. Compared with control group, the expression intensities of Rab5 and LAMP1 in neurons in hippocampus tissue of the mice in SE 1 d, SE 2 d, SE 3 d and SE 7 d groups were decreased with the prolongation of time, the percentages of Rab5 positive areas were significantly decreased (P<0.05 or P<0.01),and the percentages of LAMP1 positive areas were increased in a short time on the first day after SE and decreased with the prolongation of time(P<0.05 or P<0.01). The double fluorescence staining results showed that 1 d after SE was the key point for the decrease of endosome and the transient increase of lysosome in the early stage, which was consistent with the occurrence time of microtubule injury. Conclusion: SE can cause delayed neuronal death, at the same time, the tubulin skeleton of neurons is damaged, and the location and function of endosome-lysosome system are also changed abnormally.

Key words: status epilepticus, neuron, tubulin, endosomal-lysosome pathway, delayed neuronal death