The Effects of Minocycline on the Hippocampus in Lithium- Pilocarpine Induced Status Epilepticus in Rat: Relations with Microglial/Astrocytic Activation and Serum S100B Level.

Aim: To investigate possible correlations between serum S100B levels and microglial/astrocytic activation in status epilepticus (SE) in lithium-pilocarpine-exposed rat hippocampi and whether serum S100B levels linearly reflect neuroinflammation. Additionally, to assess the effects of minocycline (M), an inhibitor of neuroinflammation.
Material and Methods: Rats were divided into 4 groups (6/group), namely, control (C), sham, SE, and SE+M. Animals were exposed to lithium-pilocarpine to induce SE in the SE and SE+M groups. Cardiac blood was collected to measure S100B levels, and coronal brain sections including the hippocampus were prepared to examine microglial/astrocytic activation and to evaluate neuroinflammation at day 7 of SE.
Results: Serum S100B levels, OX42 (+) microglia in CA1, and GFAP (+) astrocytes in both CA1 and dentate gyrus (DG) were higher in the SE+M group than in the C group. Most importantly, highly positive correlations were found between S100B levels and microglial activation in CA1, apart from astrocytic activation in CA1 and DG. Unexpectedly, microglial activation in CA1 and astrocytic activation in DG were also enhanced in the SE+M group compared with the C group. Moreover, M administration reversed the neuronal loss observed in DG during SE.
Conclusion: These results suggest that serum S100B is a candidate biomarker for monitoring neuroinflammation and that it may also help predict diagnosis and prognosis.