The fundamental role of N-methyl-D-aspartate (NMDA) receptors in many cortical functions has been firmly defined, as has its involvement in a number of neurological and psychiatric diseases. However, until recently very little was known about the anatomical localization of NMDA receptors in the cerebral cortex of mammals. The recent application of molecular biological techniques to the study of...

The cholinergic amacrine cells of the rabbit retina may be labeled with 3H-choline, and the activity of the cholinergic population may be monitored by following the release of 3H-ACh. In magnesium-free medium, the glutamate analog NMDA caused massive ACh release, up to 50x the basal efflux. Magnesium blocked the NMDA-evoked release of ACh with an IC50 of 151 microM. The NMDA-evoked release of A...

Neuroprotection can be induced by low doses of NMDA, which activate both synaptic and extrasynaptic NMDA receptors. This is in apparent contradiction with our recent findings that extrasynaptic NMDA receptor signaling exerts a dominant inhibitory effect on prosurvival signaling from synaptic NMDA receptors. Here we report that exposure to low preconditioning doses of NMDA results in preferentia...

N-Methyl D-aspartate (NMDA) receptor activation of extracellular-signal regulated kinase (ERK) was examined in primary cortical cultures. Tetrodotoxin, NMDA receptor antagonists, or reduced extracellular calcium (0.1 mm) greatly decreased basal levels of phospho-ERK2, indicating that activity-dependent activation of NMDA receptors maintained a high level of basal ERK2 activation. This activity-...

NMDA receptors play important roles in synaptic plasticity and neuronal development. The functions of NMDA receptors are modulated by many endogenous substances, such as external pH (pHe), as well as second messenger systems. In the present study, the nerve-muscle cocultures of Xenopus embryos were used to investigate the effects of both external and intracellular pH (pHi) changes on the functi...

We examined the effects of selective agonists of ionotropic excitatory amino acid (EAA) receptor subtypes on induction of the immediate early gene c-fos. We used in situ hybridization to measure c-fos mRNA and fura-2 imaging to measure intracellular calcium (Ca2+i) in individual dentate gyrus neurons maintained in vitro. Activation of either NMDA or non-NMDA receptor subtypes is sufficient to i...

NMDA-induced intrinsic voltage oscillations depend on L-type calcium channels in spinal motoneurons of adult turtles. J. Neurophysiol. 80: 3380-3382, 1998. In a slice preparation from adult turtles, bath-applied N-methyl-D-aspartate (NMDA) induced rhythmic activity in spinal motoneurons. The underlying intrinsic oscillation in membrane potential was revealed in the presence of tetrodotoxin (TTX...

Under standard conditions, cultured ventral spinal neurons cluster AMPA- but not NMDA-type glutamate receptors at excitatory synapses on their dendritic shafts in spite of abundant expression of the ubiquitous NMDA receptor subunit NR1. We demonstrate here that the NMDA receptor subunits NR2A and NR2B are not routinely expressed in cultured spinal neurons and that transfection with NR2A or NR2B...

The development of sensory maps is thought to require an activity-dependent structural rearrangement of afferent terminal arbors within the CNS which recreates the topographic relations of sensory somata present in the periphery. In the frog retinotectal projection, activation of the NMDA receptor plays a role in this structural plasticity. Exposure of the optic tectum of tadpoles to NMDA recep...

The activity-dependent mechanism that refines the topography of the retinotectal projection in frogs is mediated by the NMDA receptor. Earlier studies found that chronic treatment of the optic tectum with the NMDA receptor antagonist DL-2-amino-5-phosphonovaleric acid (DL-AP5) desegregated eye-specific stripes in three-eyed frogs, while chronic treatment with NMDA sharpened stripe borders (Clin...