title: Baicalin Activates Glycine and γ-Aminobutyric Acid Receptors on Substantia Gelatinosa Neurons of the Trigeminal Subsnucleus Caudalis in Juvenile Mice.
abstract: The substantia gelatinosa (SG) of the trigeminal subnucleus caudalis (Vc) receives nociceptive afferent inputs from thin-myelinated A[Formula: see text] fibers 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[Formula: see text] pipette solution, the baicalin (300[Formula: see text][Formula: see text]M) induced repeatable inward currents ([Formula: see text][Formula: see text]pA, [Formula: see text]) without desensitization on all the SG neurons tested. Further, the inward currents showed a concentration (0.1-3[Formula: see text]mM) dependent pattern. The inward current was sustained in the presence of tetrodotoxin (0.5[Formula: see text][Formula: see text]M), a voltage sensitive Na[Formula: see text] channel blocker. In addition, baicalin-induced inward currents were reduced in the presence of picrotoxin (50[Formula: see text][Formula: see text]M), a GABAA receptor antagonist, flumazenil (100[Formula: see text][Formula: see text]M), a benzodiazepine-sensitive GABAA receptor antagonist, and strychnine (2[Formula: see text][Formula: see text]M), 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 GABAA and/or the glycine receptor. Our results suggest that baicalin may be a potential target for orofacial pain modulation.
authors.affiliation: * Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Chonbuk National University, Jeonju 561-756, Republic of Korea.
authors.forename: Hua
authors.initials: H
authors.lastname: Yin
authors.affiliation: * Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Chonbuk National University, Jeonju 561-756, Republic of Korea.
authors.forename: Janardhan Prasad
authors.initials: JP
authors.lastname: Bhattarai
authors.affiliation: * Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Chonbuk National University, Jeonju 561-756, Republic of Korea.
authors.forename: Sun Mi
authors.initials: SM
authors.lastname: Oh
authors.affiliation: * Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Chonbuk National University, Jeonju 561-756, Republic of Korea.
authors.forename: Soo Joung
authors.initials: SJ
authors.lastname: Park
authors.affiliation: † Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu, South Korea.
authors.forename: Dong Kuk
authors.initials: DK
authors.lastname: Ahn
authors.affiliation: * Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Chonbuk National University, Jeonju 561-756, Republic of Korea.
authors.forename: Seong Kyu
authors.initials: SK
authors.lastname: Han
mesh_terms: D000375:Aging; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005157:Facial Pain / Q000188:drug therapy; D005260:Female; D005419:Flavonoids / Q000302:isolation & purification / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D051379:Mice; D009474:Neurons / Q000378:metabolism*; D018696:Neuroprotective Agents; D008517:Phytotherapy; D018079:Receptors, GABA / Q000378:metabolism*; D018009:Receptors, Glycine / Q000378:metabolism*; D031364:Scutellaria baicalensis / Q000737:chemistry; D013376:Substantia Gelatinosa / Q000166:cytology*; D014275:Trigeminal Caudal Nucleus / Q000166:cytology*
chemical_list: D000893:Anti-Inflammatory Agents; D000972:Antineoplastic Agents, Phytogenic; D005419:Flavonoids; D018696:Neuroprotective Agents; D018079:Receptors, GABA; D018009:Receptors, Glycine; C038044:baicalin
keywords: Baicalin; GABA; Glycine; Patch Clamp; Subatantia Gelatinaosa