title: Functional GABA(B) receptors expressed in cultured calvarial osteoblasts.
abstract: In immature and mature primary cultured rat calvarial osteoblasts, both mRNA and corresponding proteins were constitutively expressed for 2 splice variants of GABA(B) receptor (GABA(B)R) subunits but not for any known GABA(A) and GABA(C) receptor subunits. The agonist for GABA(B)R baclofen significantly inhibited cAMP formation induced by forskolin in a manner sensitive to the antagonist 2-hydroxysaclofen. Similar expression was seen with mRNA for GABA(B)R-1a and -1b splice variants in the murine calvarial osteoblast cell line MC3TC-E1 cells cultured for 7-21 days in vitro (DIV). In these MC3T3-E1 cells, baclofen not only inhibited the activity of alkaline phosphatase, but also exacerbated Ca2+ accumulation, throughout the culture period up to 28 DIV. These results suggest that GABA may play an unidentified role in mechanisms associated with cellular proliferation, differentiation, and/or development through functional GABA(B)R constitutively expressed in cultured osteoblasts.
authors.affiliation: Department of Molecular Pharmacology, Faculty of Pharmaceutical Sciences, Kanazawa University, 13-1 Takara-machi, Kanazawa, Ishikawa 920-0934, Japan.
authors.forename: Sayumi
authors.initials: S
authors.lastname: Fujimori
authors.forename: Eiichi
authors.initials: E
authors.lastname: Hinoi
authors.forename: Yukio
authors.initials: Y
authors.lastname: Yoneda
mesh_terms: D016475:3T3 Cells; D000469:Alkaline Phosphatase / Q000378:metabolism; D017398:Alternative Splicing; D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D018755:GABA Agonists / Q000494:pharmacology; D015151:Immunoblotting; D051379:Mice; D010006:Osteoblasts / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D051381:Rats; D017208:Rats, Wistar; D018080:Receptors, GABA-B / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012886:Skull / Q000166:cytology*; D013997:Time Factors; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D018755:GABA Agonists; D018080:Receptors, GABA-B; D005680:gamma-Aminobutyric Acid; D000242:Cyclic AMP; D000469:Alkaline Phosphatase; D001418:Baclofen; D002118:Calcium