title: Verification of γ-Amino-Butyric Acid (GABA) Signaling System Components in Periodontal Ligament Cells In Vivo and In Vitro.
abstract: CNS key neurotransmitter γ-amino-butyric acid (GABA) and its signaling components are likewise detectable in non-neuronal tissues displaying inter alia immunomodulatory functions. This study aimed at identifying potential glutamate decarboxylase (GAD)65 and GABA receptor expression in periodontal ligament (PDL) cells in vivo and in vitro, with particular regard to inflammation and mechanical loading. Gene expression was analyzed in human PDL cells at rest or in response to IL-1ß (5 ng/ml) or TNFα (5 ng/ml) challenge via qRT-PCR. Western blot determined constitutive receptor expression, and confocal laser scanning fluorescence microscopy visualized expression changes induced by inflammation. ELISA quantified GAD65 release. Immunocytochemistry was performed for GABA component detection in vitro on mechanically loaded PDL cells, and in vivo on rat upper jaw biopsies with mechanically induced root resorptions. Statistical significance was set at p < 0.05. GABAB1, GABAB2, GABAA1, and GABAA3were ubiquitously expressed both on gene and protein level. GABAA2and GAD65 were undetectable in resting cells, but induced by inflammation. GABAB1exhibited the highest basal gene expression (6.97 % ± 0.16). IL-1ß markedly increased GABAB2on a transcriptional (57.28-fold ± 12.40) and protein level seen via fluorescence microscopy. TNFα-stimulated PDL cells released GAD65 (3.68 pg/ml ± 0.17 after 24 h, 5.77 pg/ml ± 0.65 after 48 h). Immunocytochemistry revealed GAD65 expression in mechanically loaded PDL cells. In vivo, GABA components were varyingly expressed in an inflammatory periodontal environment. PDL cells differentially express GABA signaling components and secrete GAD65. Inflammation and mechanical loading regulate these neurotransmitter molecules, which are also detectable in vivo and are potentially involved in periodontal pathophysiology.
authors: Department of Orthodontics, Medical Faculty, University of Bonn, Welschnonnenstr. 17, 53111, Bonn, Germany. anna.konermann@gmx.de.
authors: Anna
authors: A
authors: Konermann
authors: Forsyth Institute, 245 First St, Cambridge, MA, 02142, USA.
authors: Alpdogan
authors: A
authors: Kantarci
authors: Forsyth Institute, 245 First St, Cambridge, MA, 02142, USA.
authors: Steven
authors: S
authors: Wilbert
authors: Forsyth Institute, 245 First St, Cambridge, MA, 02142, USA.
authors: Thomas
authors: T
authors: Van Dyke
authors: Department of Orthodontics, Medical Faculty, University of Bonn, Welschnonnenstr. 17, 53111, Bonn, Germany.
authors: Andreas
authors: A
authors: Jäger
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D015870:Gene Expression; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D010513:Periodontal Ligament / Q000378:metabolism*; D010518:Periodontitis / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D018079:Receptors, GABA / Q000235:genetics; D018080:Receptors, GABA-B / Q000378:metabolism; D015398:Signal Transduction; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D018079:Receptors, GABA; D018080:Receptors, GABA-B; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase
keywords: Inflammation; L-Glutamic acid decarboxylase (GAD)65; Neurotransmitter; Periodontal ligament cells; Periodontal pathophysiology; γ-Amino-butyric acid (GABA)