Japanese Clinical Medicine Dynamic Change in Cells Expressing IL-1b in Rat Hippocampus after Status Epilepticus

BACKGROUND: The time course of cytokine dynamics after seizure remains controversial. Here we evaluated the changes in the levels and sites of interleukin (IL)-1b expression over time in the hippocampus after seizure. METHODS: Status epilepticus (SE) was induced in adult Wistar rats by means of intraperitoneal injection of kainic acid (KA). Subsequently, the time courses of cellular localization and IL-1b concentration in the hippocampus were evaluated by means of immunohistochemical and quantitative assays. RESULTS: On day 1 after SE, CA3 pyramidal cells showed degeneration and increased IL-1b expression. In the chronic phase (7 days after SE), glial fibrillary acidic protein (GFAP)—positive reactive astrocytes—appeared in CA1 and became IL-1b immunoreactive. Their IL-1b immunoreactivity increased in proportion to the progressive hypertrophy of astrocytes that led to gliosis. Quantitative analysis showed that hippocampal IL-1b concentration progressively increased during the acute and chronic phases. CONCLUSION: IL-1b affects the hippocampus after SE. In the acute phase, the main cells expressing IL-1b were CA3 pyramidal cells. In the chronic phase, the main cells expressing IL-1b were reactive astrocytes in CA1