NONSYNAPTIC GLYCINE RECEPTOR ACTIVATION DURING EARLY NEOCORTICAL DEVELOPMENT

Glycine receptors (GlyRs) contribute to fast inhibitory synaptic trans mission in the brain stem and spinal cord. GlyR subunits are expressed in the developing neocortex, but a neurotransmitter system involving cortical GlyRs has yet to be demonstrated. Here, we show that GlyRs in immature neocortex are excitatory and activated by a nonsynaptically released endogenous ligand. Of the potential ligands for cortical GlyR s, taurine is by far the most abundant in the developing neocortex. We found that taurine is stored in immature cortical neurons and that ma nipulations known to elevate extracellular taurine cause GlyR activati on. These data indicate that nonsynaptically released taurine activate s GlyRs during neocortical development. As fetal taurine deprivation c an cause cortical dysgenesis, it is possible that taurine influences n eocortical development by activating GlyRs.