TY - JOUR
T1 - Inhibitory effects of clonidine on GABA-activated currents in rat DRG neurons
AU - Wang, Qin Wen
AU - Li, Qin
AU - Li, Zhi Wang
PY - 1998/4/14
Y1 - 1998/4/14
N2 - 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.
AB - 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.
KW - Clonidine
KW - Dorsal root ganglion
KW - Inhibition
KW - Whole-cell patch-clamp recording
KW - α- adrenoceptor
KW - γ-aminobutyric acid
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M3 - Article
C2 - 11324513
AN - SCOPUS:0031915543
SN - 0371-0874
VL - 50
SP - 19
EP - 27
JO - Sheng li xue bao : [Acta physiologica Sinica]
JF - Sheng li xue bao : [Acta physiologica Sinica]
IS - 1
ER -