Functional evidence for a l-AP3-sensitive metabotropic receptor different from glutamate metabotropic receptor mGluR1

Abstract The efficacy of mGluR agonists quisqualate and 1 S ,3 R -aminocyclopentane-1,3-dicarboxylic acid (1 S ,3 R -ACPD) in stimulating the inositol phosphate (IP) formation in primary cultures of cerebellar granule neurons correlated with mGluR1 mRNA expression and was affected by the medium KCl content. l -2-Amino-3-phosphonopropionic acid ( l -AP3) mimicked the stimulatory action of mGluR agonists. Maximal stimulatory doses of mGluR agonist 1 S ,3 R -ACPD and l -AP3 were additive, suggesting the action of l -AP3 on a receptor different from mGluR1. Indeed, in embryonic kidney 293 cells transfected with mGluR1 cDNA quisqualate and 1 S ,3 R -ACPD but not l -AP3 stimulated the IP formation.