Characterization of metabotropic glutamate receptor-stimulated phosphoinositide hydrolysis in rat cultured cerebellar granule cells

摘要

1 The pharmacology of excitatory amino acid (EAA)-stimulated phosphoinositide (PI) hydrolysis, monitored via [~3H]-inositol monophosphate accumulation, was investigated in primary cultufes of rat cerebellar granule cells. 2 EAA-stimulated PI hydrolysis peaked after 4-5 days in vitro and subsequently declined. 3 The agonist order of potency was found to be (EC_(50)): L-quisqualic acid (Quis) (2 μM) > > L-glutamate (50 μM) > (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid ((1S,3R)-ACPD) (102 μM). L-Glutamate (E_(max) = 873% of basal activity) elicited the largest stimulation of PI hydrolysis, whereas Quis (E_(max) = 603%) and (1S,3R)-ACPD (E_(max) = 306%) produced somewhat lower stimulations. 4 Several phenylglycine derivatives were found to be active in inhibiting 2 μM Quis-stimulated PI hydrolysis, in order of potency (IC_(50)): (S)-4-carboxy-3-hydroxyphenylglycine (41 μM) ≥ (S)-4-carbox-yphenylglycine (51 μM) > > (+)-α-methyl-4-carboxyphenylglycine (243 μM). 5 Cultured cerebellar granule cells of the rat appear to have Group I mGluR pharmacology similar to that reported for cloned mGluR1 and provide an ideal system for investigating novel mGluR1 ligands in a native environment.