TY - JOUR
T1 - Baicalin Activates Glycine and γ -Aminobutyric Acid Receptors on Substantia Gelatinosa Neurons of the Trigeminal Subsnucleus Caudalis in Juvenile Mice
AU - Yin, Hua
AU - Bhattarai, Janardhan Prasad
AU - Oh, Sun Mi
AU - Park, Soo Joung
AU - Ahn, Dong Kuk
AU - Han, Seong Kyu
N1 - Publisher Copyright:
© 2016 World Scientific Publishing Company.
PY - 2016/4/1
Y1 - 2016/4/1
N2 - The substantia gelatinosa (SG) of the trigeminal subnucleus caudalis (Vc) receives nociceptive afferent inputs from thin-myelinated Afibers and unmyelinated C fibers and has been shown to be involved in the processing of orofacial nociceptive information. Scutellaria baicalensis Georgi (Huang-Qin, SbG), one of the 50 fundamental herbs of Chinese herbology, has been used historically as anti-inflammatory and antineoplastic medicine. Baicalin, one of the major compounds of SbG, has been reported to have neuroprotective, anti-inflammatory and analgesic effects. However, the receptor type activated by baicalin and its precise action mechanism on the SG neurons of Vc have not yet been studied. The whole-cell patch clamp technique was performed to examine the ion channels activated by baicalin on the SG neurons of Vc. In high Cl-pipette solution, the baicalin (300μM) induced repeatable inward currents (-24.8±3.57pA, n=19) without desensitization on all the SG neurons tested. Further, the inward currents showed a concentration (0.1-3mM) dependent pattern. The inward current was sustained in the presence of tetrodotoxin (0.5μM), a voltage sensitive Na+ channel blocker. In addition, baicalin-induced inward currents were reduced in the presence of picrotoxin (50μM), a GABAA receptor antagonist, flumazenil (100μM), a benzodiazepine-sensitive GABA A receptor antagonist, and strychnine (2μM), a glycine receptor antagonist, respectively. These results indicate that baicalin has inhibitory effects on the SG neurons of the Vc, which are due to the activation of GABA A and/or the glycine receptor. Our results suggest that baicalin may be a potential target for orofacial pain modulation.
AB - The substantia gelatinosa (SG) of the trigeminal subnucleus caudalis (Vc) receives nociceptive afferent inputs from thin-myelinated Afibers and unmyelinated C fibers and has been shown to be involved in the processing of orofacial nociceptive information. Scutellaria baicalensis Georgi (Huang-Qin, SbG), one of the 50 fundamental herbs of Chinese herbology, has been used historically as anti-inflammatory and antineoplastic medicine. Baicalin, one of the major compounds of SbG, has been reported to have neuroprotective, anti-inflammatory and analgesic effects. However, the receptor type activated by baicalin and its precise action mechanism on the SG neurons of Vc have not yet been studied. The whole-cell patch clamp technique was performed to examine the ion channels activated by baicalin on the SG neurons of Vc. In high Cl-pipette solution, the baicalin (300μM) induced repeatable inward currents (-24.8±3.57pA, n=19) without desensitization on all the SG neurons tested. Further, the inward currents showed a concentration (0.1-3mM) dependent pattern. The inward current was sustained in the presence of tetrodotoxin (0.5μM), a voltage sensitive Na+ channel blocker. In addition, baicalin-induced inward currents were reduced in the presence of picrotoxin (50μM), a GABAA receptor antagonist, flumazenil (100μM), a benzodiazepine-sensitive GABA A receptor antagonist, and strychnine (2μM), a glycine receptor antagonist, respectively. These results indicate that baicalin has inhibitory effects on the SG neurons of the Vc, which are due to the activation of GABA A and/or the glycine receptor. Our results suggest that baicalin may be a potential target for orofacial pain modulation.
KW - Baicalin
KW - GABA
KW - Glycine
KW - Patch Clamp
KW - Subatantia Gelatinaosa
UR - http://www.scopus.com/inward/record.url?scp=84964216462&partnerID=8YFLogxK
U2 - 10.1142/S0192415X16500221
DO - 10.1142/S0192415X16500221
M3 - Article
C2 - 27080947
AN - SCOPUS:84964216462
SN - 0192-415X
VL - 44
SP - 389
EP - 400
JO - American Journal of Chinese Medicine
JF - American Journal of Chinese Medicine
IS - 2
ER -