Tetramethylpyrazine Reduces Epileptogenesis Progression in Electrical Kindling Models by Modulating Hippocampal Excitatory Neurotransmission

Yan Jin, Song Cai, Yuepeng Jiang, Kai Zhong, Chengping Wen, Yeping Ruan, Lindsey A. Chew, Rajesh Khanna, Zhenghao Xu, Jie Yu

Research output: Contribution to journalArticle

Abstract

Antiepileptic drugs (AEDs) are the primary agents prescribed for clinical management of limbic epilepsy. However, high incidence of pharmacoresistance and a limited armory of drugs for inhibiting the pathological progression of epilepsy pose major obstacles to managing epilepsy. Here, we investigated the effect of tetramethylpyrazine (TMP), the main bioactive alkaloid isolated from the oriental medicine Ligusticum chuanxiong Hort., against the epileptogenesis progression of acute hippocampal and corneal (6 Hz) electrical kindling models of TLE. TMP dose-dependently limited the progression of seizures and reduced the after-discharge duration (ADDs) in a hippocampal mouse kindling model. Mice treated with TMP (20, 50 mg/kg, i.p.) remained in stage 1 of epileptic progression for a protracted period, requiring additional stimulation to induce stages 2-5 epileptic phenotypes. TMP (50 mg/kg) also inhibited 6 Hz corneal kindling progression. In contrast, TMP did not reverse the phenotypes induced in a generalized seizures (GS) model, or the maximal electroshock (MES) or pentylenetetrazole (PTZ)-induced models of epilepsy. Furthermore, patch clamp recordings revealed no effect of TMP (10 μM) on CA1 hippocampal neurons' intrinsic properties but suppressed the (i) frequency of spontaneous excitatory post synaptic currents (sEPSCs), (ii) paired pulse ratio (PPR), and (iii) long-term potentiation (LTP) induction in the Schaffer collateral-CA1 pathway. TMP suppressed the activity of calcium, but not sodium, channels. Taken together, these results suggest that TMP has an antiepileptogenic effect, likely through suppression of excitatory synaptic transmission by its effects on inhibition of calcium channels; these traits distinguish TMP from currently available AEDs. As mice administered TMP did not show any neurologic impairment in the object recognition and open field tests, the data support further development of TMP as a promising treatment for epilepsy.

Original languageEnglish (US)
Pages (from-to)4854-4863
Number of pages10
JournalACS Chemical Neuroscience
Volume10
Issue number12
DOIs
StatePublished - Oct 23 2019
Externally publishedYes

Keywords

  • Tetramethylpyrazine
  • antiepileptic drugs
  • calcium channels
  • epileptogenesis
  • limbic epilepsy
  • long-term potentiation

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Cognitive Neuroscience
  • Cell Biology

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