GABA and glutamate receptors are expressed in immature "silent" CA1 pyramidal neurons prior to synapse formation, but their function is unknown. We now report the presence of tonic, spontaneous, and evoked currents in embryonic and neonatal CA1 neurons mediated primarily by the activation of GABA(A) receptors. These currents are mediated by a nonconventional release of transmitters, as they per...

Glutamate transporters play important roles in the termination of excitatory neurotransmission and in providing cells with glutamate for metabolic purposes. In the kidney, glutamate transporters are involved in reabsorption of filtered acidic amino acids, regulation of ammonia and bicarbonate production, and protection of cells against osmotic stress.

In vivo microdialysis was used to study the effects of morphine on glutamate release from the ventral tegmentum area (VTA) in freely moving rats. Intraperitoneal (i.p.) injection of acute and repeated morphine at increasing doses significantly enhanced glutamate release. Only a minor tolerance developed to this dosage of morphine. AP-S (2-amino-5-phosphonovaleric acid, 0.5 mg/kg i.p.), a N...

At excitatory synapses on CA1 pyramidal cells of the hippocampus, a larger quantal content is sensed by N-methyl-D-aspartic acid receptors (NMDARs) than by alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs). A novel explanation for this discrepancy is that glutamate released from terminals presynaptic to one cell can diffuse to and activate NMDARs, but not AMPARs, on a ...

Refinement of mammalian neural circuits involves substantial experience-dependent synapse elimination. Using in vivo two-photon imaging, we found that experience-dependent elimination of postsynaptic dendritic spines in the cortex was accelerated in ephrin-A2 knockout (KO) mice, resulting in fewer adolescent spines integrated into adult circuits. Such increased spine removal in ephrin-A2 KOs de...

Glutamate transporters (GluTs) maintain a low ambient level of glutamate in the central nervous system (CNS) and shape the activation of glutamate receptors at synapses. Nevertheless, the mechanisms that regulate the trafficking and localization of transporters near sites of glutamate release are poorly understood. Here, we examined the subcellular distribution and dynamic remodeling of the pre...

Fast excitatory synaptic transmission in the mammalian central nervous system is mediated by glutamate-activated α-amino-5-methyl-3-hydroxy-4-isoxazole propionate (AMPA) receptors. Glutamate binding to AMPA receptors leads rapid activation and desensitization. Synaptically released Zn2+ works as a neuromodulator many brain regions. Here, we show that inhibits GluA2(Q) homomeric an activity- vol...

Ammonia is considered the main pathogenic toxin in hepatic encephalopathy (HE). However, molecular mechanisms involved have been disputed. As altered glutamatergic and GABAergic neurotransmission has reported HE, we investigated whether four members of solute carrier 38 (Slc38) family amino acid transporters-involved replenishment glutamate GABA-contribute to ammonia neurotoxicity HE. We show t...

The interaction between astrocytes and neurons is examined from the standpoint of glutamate neurotoxicity. The review details 1) the distribution of glutamate transporters on astrocytes and neurons, provoking a reformulation of the interdependence between these two cell types in removing extracellular glutamate and preventing excitotoxic injury; 2) the potential involvement of aberrant glutamat...

The extracellular levels of excitatory amino acids are kept low by the action of the glutamate transporters. Glutamate/aspartate transporter (GLAST) and glutamate transporter-1 (GLT-1) are the most abundant subtypes and are essential for the functioning of the mammalian CNS, but the contribution of the EAAC1 subtype in the clearance of synaptic glutamate has remained controversial, because the ...