FUNCTIONAL EVIDENCE FOR A L-AP3-SENSITIVE METABOTROPIC RECEPTOR DIFFERENT FROM GLUTAMATE METABOTROPIC RECEPTOR MESSENGER GLUR1

The efficacy of mGluR agonists quisqualate and IS,3R-aminocyclopentane -1,3-dicarboxylic acid (IS,3R-ACPD) in stimulating the inositol phosph ate (IP) formation in primary cultures of cerebellar granule neurons c orrelated with mGluR1 mRNA expression and was affected by the medium K Cl content. L-2-Amino-3-phosphonopropionic acid (L-AP3) mimicked the s timulatory action of mGluR agonists. Maximal stimulatory doses of mGlu R agonist IS,3R-ACPD and L-AP3 were additive, suggesting the action of L-AP3 on a receptor different from mGluR1. Indeed, in embryonic kidne y 293 cells transfected with mGluR1 cDNA quisqualate and IS,3R-ACPD bu t not L-AP3 stimulated the IP formation.