Int J Med Sci 2020; 17(12):1683-1691. doi:10.7150/ijms.44927

Research Paper

Effects of Dexamethasone on Remodeling of the Hippocampal Synaptic Filamentous Actin Cytoskeleton in a Model of Pilocarpine-induced Status Epilepticus

Nuo Yang1,2, Yan Zhang3, Jiang-Tao Wang1, Chen Chen1, Yan Song4, Jian-Min Liang1, Di-Hui Ma2✉, Yan-Feng Zhang1✉

1. Department of Pediatric Neurology, The First Hospital of Jilin University, Changchun, Jilin Province 130021, PR China.
2. Department of Neurology, The First Hospital of Jilin University, Changchun, Jilin Province 130021, PR China.
3. College of Life Sciences, Jilin University; Jilin Province, 130021, PR China.
4. Nursing College, Beihua University, 3999 Huashan Road, Jilin 132013, PR China.

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Citation:
Yang N, Zhang Y, Wang JT, Chen C, Song Y, Liang JM, Ma DH, Zhang YF. Effects of Dexamethasone on Remodeling of the Hippocampal Synaptic Filamentous Actin Cytoskeleton in a Model of Pilocarpine-induced Status Epilepticus. Int J Med Sci 2020; 17(12):1683-1691. doi:10.7150/ijms.44927. Available from http://www.medsci.org/v17p1683.htm

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Abstract

The filamentous actin (F-actin) cytoskeleton is progressively damaged after status epilepticus (SE), which is related to delayed neuronal death, aberrant recurrent circuits and epileptogenesis. Glucocorticoids regulate dendritic spine remodeling by acting on glucocorticoid receptors and the dynamics of the F-actin cytoskeleton. Our previous study showed that administration of dexamethasone (DEX) in the latent period of the pilocarpine epileptic model reduces damage to the hippocampal filamentous actin cytoskeleton and the loss of hippocampal neurons and aids in maintaining the synaptic structures, but it is not sufficient to stop epileptogenesis. In this work, we focused on the role of glucocorticoids in regulating the hippocampal F-actin cytoskeleton during SE. We examined the abundance of synaptic F-actin, analyzed the hippocampal F-actin/G-actin (F/G) ratio and pCofilin, and evaluated the number of hippocampal neurons and pre/postsynaptic markers in pilocarpine-induced status epilepticus mice with or without administration of dexamethasone (DEX). We found that the latency of Stage 3 seizures increased, the mortality decreased, the damage to the synaptic F-actin cytoskeleton in the hippocampal subfields was significantly attenuated, and a greater number of postsynaptic structures were retained in the hippocampal subfields after treatment with DEX. These results indicate that treatment with dexamethasone stabilizes the synaptic F-actin cytoskeleton and reduces the damage to the brain due to SE. This approach is expected to be beneficial in alleviating delayed neuron damage and the process of epileptogenesis.

Keywords: Filamentous actin, Status epilepticus, Dexamethasone, Glucocorticoid receptors, Epileptogenesis, Synapse.