Characterization of the Inhibitory Effect of Gastrodigenin and Gastrodin on M-type K+ Currents in Pituitary Cells and Hippocampal Neurons.

Chih-Sheng Yang,Sheng-Nan Wu,Ming-Chi Lai,Ping-Yen Liu,Yi-Ching Lo,Chin-Wei Huang

doi:10.3390/ijms21010117

Abstract

Gastrodigenin (HBA) and gastrodin (GAS) are phenolic ingredients found in Gastrodia elata Blume (GEB), a traditional Chinese herbal medicine. These compounds have been previously used to treat cognitive dysfunction, convulsion, and dizziness. However, at present, there is no available information regarding their potential ionic effects in electrically excitable cells. In the current study, the possible effects of HBA and GAS on different ionic currents in pituitary GH3 cells and hippocampal mHippoE-14 neurons were investigated using the patch-clamp technique. The addition of HBA or GAS resulted in the differential inhibition of the M-type K+ current (IK(M)) density in a concentration-dependent manner in GH3 cells. HBA resulted in a slowing of the activation time course of IK(M), while GAS elevated it. HBA also mildly suppressed the density of erg-mediated or the delayed-rectifier K+ current in GH3 cells. Neither GAS nor HBA (10 µM) modified the voltage-gated Na+ current density, although they suppressed the L-type Ca2+ current density at the same concentration. In hippocampal mHippoE-14 neurons, HBA was effective at inhibiting IK(M) density as well as slowing the activation time course. Taken together, the present study provided the first evidence that HBA or GAS could act on cellular mechanisms, and could therefore potentially have a functional influence in various neurologic disorders.

Highlights

Gastrodigenin (p-hydroxybenzyl alcohol, HBA) is a phenolic compound found in traditional Chinese herbal medicine Gastrodia elata Blume (GEB), which is commonly known as Tian Ma in Chinese or Chunma in Korean [1,2]
In the initial set of experiments, the presence of IK(M) in the pituitary GH3 cells was examined to investigate whether HBA could exert any effects on the M-type K+ current
Our present study provides the first electrophysiological evidence to indicate that HBA or GAS, the bioactive ingredients from GEB, exerted inhibitory actions on the M-type K+ current density in a concentration-dependent manner in pituitary GH3 cells

Summary

Introduction

Gastrodigenin (p-hydroxybenzyl alcohol, HBA) is a phenolic compound found in traditional Chinese herbal medicine Gastrodia elata Blume (GEB), which is commonly known as Tian Ma in Chinese or Chunma in Korean [1,2]. Gastrodin (GAS), the glucoside of HBA, is the major bioactive ingredient that can be isolated from GEB. After entering the central nervous system, GAS is metabolized to HBA [8]. HBA is an aglycone derivative of gastrodin. Some previous studies have addressed the potential promoting effects of HBA on cell proliferation and neuroblast differentiation in the dentate gyrus of mice [9]. Despite strong evidence of their beneficial effects on various neurological disorders, HBA and GAS have so far been limited with respect to their effects on membrane ion currents in neurons and neuroendocrine cells

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