Group III metabotropic glutamate receptors in rat cultured calvarial osteoblasts

Reverse transcription polymerase chain reaction revealed expression of mRNA s for particular receptors for the central neurotransmitter L-glutamic acid (Glu) in primary cultures of rat calvarial osteoblastic cells under premat ure to mature states according to the duration of days in vitro, These incl uded metabotropic Glu receptors (mGluR) such as mGluR4 and mGluR8, in addit ion to several ionotropic Glu receptor subunits including NR1 and NR2D. Exp ression of mRNAs was not detected with other mGluR and NR2A-C subunits irre spective of the maturity of cultured cells. The agonist for group III mGluR L-(+)-2-amino-4-phosphonobutyric acid significantly inhibited the forskoli n-induced accumulation of cAMP in premature osteoblasts, which occurred in a manner sensitive to prevention by the group III mGluR antagonist (RS)alph a -cyclopropyl-4-phosphonophenylglycine. These results suggest that Glu may at least in part play a role in mechanisms associated with cellular prolif eration and/or differentiation through group III mGluR functionally express ed in rat calvarial osteoblastic cells. (C) 2001 Academic Press.