Estrogen suppresses epileptiform activity by enhancing Kv4.2-mediated transient outward potassium currents in primary hippocampal neurons

Zhang,Yuwen; Huang,Yian; Liu,Xu; Wang,Guoxiang; Wang,Xin; Wang,Yun

doi:10.3892/ijmm.2015.2287

Estrogen suppresses epileptiform activity by enhancing Kv4.2-mediated transient outward potassium currents in primary hippocampal neurons

Authors:
- Yuwen Zhang
- Yian Huang
- Xu Liu
- Guoxiang Wang
- Xin Wang
- Yun Wang
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Affiliations: Department of Neurology, Zhongshan Hospital, Collaborative Innovation Center for Brain Science, Institutes of Brain Science and State Key Laboratory for Medical Neurobiology, Fudan University, Shanghai 200032, P.R. China
Published online on: July 16, 2015 https://doi.org/10.3892/ijmm.2015.2287
Pages: 865-872

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Abstract

Catamenial epilepsy is a common phenomenon in female epileptic patients that is, in part, influenced by the 17-β-estradiol level during the menstrual cycle, which modulates the strength of the epileptic seizures. However, the underlying mechanism(s) for catamenial epilepsy remains unknown. In the present study, the effect of 17‑β‑estradiol on modulating epileptiform activities was investigated in cultured hippocampal neurons by focusing on the transient outward potassium current. Using the patch clamp technique, 17‑β‑estradiol was demonstrated to have a dose‑dependent U‑shape effect on epileptiform bursting activities in cultured hippocampal neurons; only the low dose (~0.1 ng/ml) of 17‑β‑estradiol had a suppressive effect on the epileptiform activities. The blockade effect of the low dose 17‑β‑estradiol could be suppressed by phrixotoxin2 (PaTx2), a selective channel blocker for voltage‑gated potassium channel type 4.2 (Kv4.2), which mediates the transient outward potassium current. Furthermore, the 17‑β‑estradiol bell‑shape‑like dose‑dependently enhanced the transient outward potassium current, which was inhibited by the estrogen receptor antagonist ICI 182,780. In conclusion, these results indicate that reduced activation of the transient outward potassium current by a high (or none) 17‑β‑estradiol level may enhance the epileptiform bursting activities in neurons, which may be one of the triggering causes for catamenial epilepsy, and therefore, maintaining a certain low 17‑β‑estradiol level may aid in the control of catamenial epilepsy.

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