STIMULATION OF PHOSPHOINOSITIDE HYDROLYSIS BY TRANS-(+/-)-ACPD IS GREATLY ENHANCED WHEN ASTROCYTES ARE CULTURED IN A SERUM-FREE DEFINED MEDIUM

Recent studies have demonstrated that astrocytes have much greater abilities to produce and respond to signalling molecules in the CNS than had been previously estimated. We now report a dramatic enhancement in the ability of a glutamate metabotropic receptor agonist, 1-aminocyclopentane-trans-(+/-)-1,3-dicarboxylic acid (trans-(+/-)-ACPD, to stimulate phosphoinositide hydrolysis in astrocytes cultured in a serum-free defined medium compared with astrocytes cultured in conventional serum-containing medium (43.2 +/- 3.6 vs. 3.2 +/- 0.48-fold of basal, respectively). This enhancement was selective to trans-(+/-)-ACPD as little or no difference in the response to carbachol or norepinephrine was seen between the two culture conditions. These results indicate a great potential for the phosphoinositide pathway in astrocyte glutamatergic signal transduction.