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This Article Full Text Full Text (PDF) All Versions of this Article: 100/2/698    most recent 00657.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Kilb, W. Articles by Luhmann, H. J. PubMed PubMed Citation Articles by Kilb, W. Articles by Luhmann, H. J.

Glycine Receptors Mediate Excitation of Subplate Neurons in Neonatal Rat Cerebral Cortex

¹Institute of Physiology and Pathophysiology, Johannes Gutenberg University, Mainz, Germany; ²Department of Physiology, Hamamatsu University School of Medicine, Shizuoka; ³Department of Physiology, Division of Physiome, Hyogo College of Medicine, Hyogo; and ⁴Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences at Kagawa Campus, Tokushima Bunri University, Kagawa, Japan

Submitted 14 June 2007; accepted in final form 12 June 2008

The development of the cerebral cortex depends on genetic factors and early electrical activity patterns that form immature neuronal networks. Subplate neurons (SPn) are involved in the construction of thalamocortical innervation, generation of oscillatory network activity, and in the proper formation of the cortical columnar architecture. Because glycine receptors play an important role during early corticogenesis, we analyzed the functional consequences of glycine receptor activation in visually identified SPn in neocortical slices from postnatal day 0 (P0) to P4 rats using whole cell and perforated patch-clamp recordings. In all SPn the glycinergic agonists glycine, β-alanine, and taurine induced dose-dependent inward currents with the affinity for glycine being higher than that for β-alanine and taurine. Glycine-induced responses were blocked by the glycinergic antagonist strychnine, but were unaffected by either the GABAergic antagonist gabazine, the N-methyl-D-aspartate–receptor antagonist D-2-amino-5-phosphonopentanoic acid, or picrotoxin and cyanotriphenylborate, antagonists of -homomeric and ₁-subunit–containing glycine receptors, respectively. Under perforated-patch conditions, glycine induced membrane depolarizations that were sufficient to trigger action potentials (APs) in most cells. Furthermore, glycine and taurine decreased the injection currents as well as the synaptic stimulation strength required to elicit APs, indicating that glycine receptors have a consistent excitatory effect on SPn. Inhibition of taurine transport and application of hypoosmolar solutions induced strychnine-sensitive inward currents, suggesting that taurine can act as a possible endogenous agonist on SPn. In summary, these results demonstrate that SPn express glycine receptors that mediate robust excitatory membrane responses during early postnatal development.