Inhibitory effects of clonidine on GABA-activated currents in rat DRG neurons

Qin Wen Wang, Qin Li, Zhi Wang Li

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Abstract

Whole-cell patch-clamp recordings were performed on neurons from freshly isolated rat dorsal root ganglion (DRG) to investigate modulatory effects of clonidine, an α2-adrenoceptor agonist, on GABA-activated currents. In the majority of the neurons examined (72/75), GABA (10-6 ~ 10-3 mol/L) induced a concentration-dependent inward current, which could be blocked by bicuculine (10-4 ~ 10-5 mol/L). In 51 out of 72 cells, pretreatment with different dosages of clonidine (10-8 ~ 10-4 mol/L) decreased the GABA (10-4 mol/L)-activated current by 8.5%, 19.0%, 33.4%, 44.4% and 40.3%, respectively, while clonidine itself only induced a slight inward current in a few cells (12/72). The inhibitory action of clonidine blockable by yohimbine (10-4 mol/L) was voltage-independent and did not change the membrane conductance during the activation of GABA(A) receptor. Unlike NA, (- )-isoproterenol (10-4 ~ 10-5 mol/L) exerted no effect on GABA-activated currents. Intracellular application of H-7 (10-4 mol/L) via micropipette resulted in a significant blockade of clonidine inhibition (19/20) except one cell showing only a slight inhibition (11.2%). The results suggest that the inhibitory effect of clonidine on GABA-activated currents in DRG neurons might involve phosphorylation of GABA(A) receptor following activation of α2-adrenoceptor through a mechanism of intracellular transduction.

Original languageEnglish (US)
Pages (from-to)19-27
Number of pages9
JournalActa Physiologica Sinica
Volume50
Issue number1
StatePublished - Apr 14 1998

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Keywords

  • Clonidine
  • Dorsal root ganglion
  • Inhibition
  • Whole-cell patch-clamp recording
  • α- adrenoceptor
  • γ-aminobutyric acid

ASJC Scopus subject areas

  • Medicine(all)

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