The neurotransmitters at synapses in taste buds are not yet known with confidence. Here we report a new calcium-imaging technique for taste buds that allowed us to test for the presence of glutamate receptors (GluRs) in living isolated tissue preparations. Taste cells of rat foliate papillae were loaded with calcium green dextran (CaGD). Lingual slices containing CaGD-labeled taste cells were i...

l-Glutamate is a major excitatory neurotransmitter that binds ionotropic and metabotropic glutamate receptors. Cerebral endothelial cells from many species have been shown to express several forms of glutamate receptors; however, human cerebral endothelial cells have not been shown to express either the N-methyl-D-aspartate (NMDA) receptor message or protein. This study provides evidence that h...

Two classes of glutamate-activated channels mediate excitation at central synapses: N-methyl-D-aspartic acid (NMDA) receptors and non-NMDA receptors. Despite substantial structural homology, each class generates signals with characteristic kinetics and mediates distinct synaptic functions. In non-NMDA receptors, the strength of intersubunit contacts within ligand-binding domains is inversely co...

NMDA excitotoxicity has been proposed to mediate the death of retinal ganglion cells (RGCs) in glaucoma and ischemia. Here, we reexamine the effects of glutamate and NMDA on rat RGCs in vitro and in situ. We show that highly purified RGCs express NR1 and NR2 receptor subunits by Western blotting and immunostaining, and functional NMDA receptor channels by whole-cell patch-clamp recording. Never...

We have quantified the effects of the N-methyl-d-aspartate (NMDA) receptor antagonist (R)-[(S)-1-(4-bromo-phenyl)-ethylamino]-(2,3-dioxo-1,2,3,4-tetrahydroquinoxalin-5-yl)-methyl]-phosphonic acid (NVP-AAM077) at rat recombinant N-methyl-D-aspartate receptor (NR)1/NR2A and NR1/NR2B NMDA receptors expressed in Xenopus laevis oocytes. We observed no difference in the steady-state levels of inhibit...

Electrophysiological and pharmacological methods were used to examine the role of glutamate in mediating the excitatory and inhibitory responses produced by the N2v rasp phase neurons on postsynaptic cells of the Lymnaea feeding network. The N2v --> B3 motor neuron excitatory synaptic response could be mimicked by focal or bath application of -glutamate at concentrations of >/=10(-3) M. Quisqua...

mammalian CNS, the actions of which are regulated by ionotropic glutamate (iGlu) and metabotropic glutamate receptors (mGlu). mGlu receptors are a family of G-protein-coupled receptors comprising eight members, refered to as mGlu1-8. Group I receptors include mGlu1 and mGlu5, which when expressed are coupled via Gq to phospholipase C. Group II (mGlu2 and mGlu3) and group III (mGlu4,6,7,8) recep...

Small volumes of N-Methyl-D-Aspartate (NMDA) and non-NMDA excitatory amino acid receptor agonists were applied to localized regions of the dendritic trees of lamprey spinal neurons along their medial-lateral axis to obtain a spatial map of glutamate receptor distribution. Voltage clamp and frequency domain methods were used to obtain quantitative kinetic data of the voltage dependent ionic chan...

Glutamate receptors play major roles in excitatory transmission in the vertebrate brain. Among ionotropic glutamate receptors (AMPA, kainate, NMDA), AMPA receptors mediate fast synaptic transmission and require TARP auxiliary subunits. NMDA receptors and kainate receptors play roles in synaptic transmission, but it remains uncertain whether these ionotropic glutamate receptors also have essenti...