Developmental changes in glutamate receptor stimulated inositol phospholipid metabolism and 45Ca(2+)-accumulation in...

In chicken forebrain the two phases of synapse development, formation and maturation, are temporally well separated. We have used this model system to determine the developmental profile of glutaminergic activation of phosphoinositidase C. Stimulation of [3H]inositol-loaded forebrain prisms by quisqualic acid (QA; 30 microM), or the metabotropic agonist 1-aminocyclopentane-trans-1,3-dicarboxylic acid (trans-ACPD; 30 microM), significantly increased [3H]inositol phosphate production. This response progressively decreased with developmental age, with the largest (approximately 3-fold) decrease occurring between 21 days and adult (> 10 weeks). In contrast, QA (30 microM) stimulated a quite distinct developmental profile for 45Ca2+ accumulation, with the response being maximal between 7 and 14 days before declining sharply to adult levels by 21-25 days. These results demonstrate that there is a major decrease in metabotropic glutamate receptor activation of phosphoinositidase C during the maturation phase of synapse development.