Search results for "NMDA"
showing 10 items of 147 documents
Platelet-activating factor contributes to the induction of long-term potentiation in the rat somatosensory cortex in vitro
2007
The contribution of platelet-activating factor (PAF) to the induction of neocortical LTP was examined in rat brain slices containing the primary somatosensory cortex (SI). Field potentials evoked by single pulse stimulation in cortical layer IV were recorded from layer II/III. In control experiments, tetanic high frequency stimulation (HFS) resulted in input-specific, NMDA receptor-dependent LTP (21.1+/-3.2%; mean+/-SEM; n=15; P0.001). BN-52021 (5 microM), an antagonist at the extracellular PAF receptor, weakened the HFS-induced LTP to 12.4+/-2.7% (n=11; P0.05). In contrast, HFS-induced LTP was significantly enhanced to 29.4+/-2.3% (n=11; P0.05) when brain slices were superfused with ACSF c…
Effects of excitatory amino acids and neuropeptide Y on the discharge activity of suprachiasmatic neurons in rat brain slices
1997
Effects of L-glutamate, AMPA, NMDA and NPY on the discharge activity of neurons located in the ventral subdivision of the suprachiasmatic nucleus were examined in submerged coronal slices of the rat hypothalamus. All substances were bath applied. Application of L-glutamate (14 neurons examined) induced an excitatory response in 8 suprachiasmatic neurons (+248.9 +/- 122.24%, mean +/- S.E.M.; P0.001). A biphasic response, i.e. an initial transient excitation (+54.3 +/- 8.21%; P0.001) succeeded by an inhibition (-66.2 +/- 9.31%; P0.001), was observed in 6 neurons. Application of AMPA (36 neurons examined) resulted in an excitation of 31 neurons (+209.2 +/- 58.58%; P0.0001). Application of NMDA…
Hippocampal dopamine receptors modulate cFos expression in the rat nucleus accumbens evoked by chemical stimulation of the ventral hippocampus
2005
Recently, we have shown that D1 and D2 receptors in the ventral hippocampus (VH) modulate both the locomotor activation and the increase in dopamine (DA) levels in the rat nucleus accumbens (NAc) induced by NMDA stimulation of the VH. In the present study we analyze the possible role of VH D1 and D2 receptors in the modulation of the cFos expression in NAc (core and shell subregions) and in dorsal striatum. This was assessed by immunohistochemical analysis of cFos expression in the rat brains after retro-dialysis application of NMDA (50mM, 10 min) into VH, in absence and in presence of either the D1/D5 receptor antagonist SCH 23390 (100 and 250 microM, 60 min) or the D2 receptor antagonist …
Dose-dependent effect of S(+) ketamine on post-ischemic endogenous neurogenesis in rats.
2009
Background: Ketamine is a non-competitive antagonist at N-methyl-d-aspartate (NMDA) receptors and reduces neuronal injury after cerebral ischemia by blocking the excitotoxic effects of glutamate. However, cerebral regeneration by means of endogenous neurogenesis may be impaired with blockade of NMDA receptors. The effects of S(+) ketamine on post-ischemic neurogenesis are unknown and investigated in this study. Methods: Thirty-two male Sprague–Dawley rats were randomly assigned to the following treatment groups with intravenous S(+) ketamine anesthesia: S(+) ketamine 0.75 mg/kg/min with or without cerebral ischemia and S(+) ketamine 1.0 mg/kg/min with or without cerebral ischemia. Eight non…
Acute ammonia intoxication induces an NMDA receptor-mediated increase in poly(ADP-ribose) polymerase level and NAD+ metabolism in nuclei of rat brain…
2004
Acute ammonia toxicity is mediated by excessive activation of NMDA receptors. Activation of NMDA receptors leads to activation of poly(ADP-ribose) polymerase (PARP) which mediates NMDA excitotoxicity. PARP is activated following DNA damage and may lead to cell death via NAD+ and ATP depletion. The aim of the present work was to assess whether acute ammonia intoxication in vivo leads to increased PARP in brain cells nuclei and to altered NAD+ and superoxide metabolism and the contribution of NMDA receptors to these alterations. Acute ammonia intoxication increases PARP content twofold in brain cells nuclei.NAD+ content decreased by 55% in rats injected with ammonia. This was not due to decre…
Different postischemic protein expression of the GABA_{A} receptor α2 subunit and the plasticity-associated protein MAP1B after treatment with BDNF v…
2009
Purpose Recent data indicate that both brain-derived neurotrophic factor (BDNF) and granulocyte-colony stimulating factor (G-CSF) exert substantial neuroregenerative effects and improve functional outcome after ischemic stroke. In the present study, we checked for potential differences in the postischemic modulation of various excitatory and inhibitory neurotransmitter receptors as well as various marker molecules for structural plasticity by BDNF versus G-CSF. Methods Adult male Wistar rats were subjected to photothrombotic ischemia and subsequently treated with NaCl, BDNF or G-CSF, respectively. After 6 weeks, postischemic protein expression of the NR1, GluR1 and alpha2 subunit of the NMD…
Molecular and functional interactions between tumor necrosis factor-alpha receptors and the glutamatergic system in the mouse hippocampus: Implicatio…
2009
Tumor necrosis factor (TNF)-alpha is a proinflammatory cytokine acting on two distinct receptor subtypes, namely p55 and p75 receptors. TNF-alpha p55 and p75 receptor knockout mice were previously shown to display a decreased or enhanced susceptibility to seizures, respectively, suggesting intrinsic modifications in neuronal excitability. We investigated whether alterations in glutamate system function occur in these naive knockout mice with perturbed cytokine signaling that could explain their different propensity to develop seizures. Using Western blot analysis of hippocampal homogenates, we found that p55(-/-) mice have decreased levels of membrane GluR3 and NR1 glutamate receptor subuni…
Transient oligemia is associated with long-term changes in binding densities of cortical inhibitory GABAA receptors in the rat brain
2009
Recently, we could demonstrate in rats that a short transient oligemic period of only 20-minute duration, induced by systemic hypotension, resulted in a transient decline of spatial memory capacities without any histological damage over a subsequent period of 6 months. In our present study, we checked for more subtle alterations within the highly vulnerable hippocampal CA1 subfield using quantification of neuronal cell density and semi-quantitative analysis of the ischemia-sensitive protein MAP2. Since hippocampal excitatory and inhibitory neurotransmitter receptors are crucially involved in spatial memory processes, quantitative in vitro receptor autoradiography was performed using [(3)H]M…
Evidence for an involvement of NMDA and non-NMDA receptors in synaptic excitation of phrenic motoneurons in the rabbit
1991
Abstract The action of endogenous excitatory amino acids on phrenic motoneurons was studied in anesthetized, vagotomized, paralyzed and artificially ventilated rabbits. The NMDA receptor antagonists APV and ketamine, as well as the non-NMDA receptor antagonists GAMS and DNQX were administered by microinjection into the ventral horn of the spinal segments C3-C5. Injection of each antagonist resulted in a reversible reduction of the phrenic nerve activity. Results suggest an important function of endogenous excitatory amino acids in the excitation of phrenic motneurons. NMDA as well as non-NMDA receptors are involved. The functional role of both receptor types in bulbospinal neurotransmission…
Variations of acidic functions at position 2 and substituents at positions 4, 5 and 6 of the indole moiety and their effect on NMDA-glycine site affi…
2003
The synthetic procedures to obtain indole derivatives with different acidic functions at position 2 of the indole are reported. The synthesised and tested derivatives comprise 5-tetrazolyl, 1,3,4-oxadiazol-5-yl-2-one, and indole-2-carboxylic acid amides with 5-aminotetrazole, methanesulphonamide and trifluoromethanesulphonamide moieties. The binding affinity was evaluated using [3H]MDL 105,519 and pig cortical brain membranes. In general, compounds with acidic functions different from a carboxylic acid moiety are less potent than indole-2-carboxylic acid derivatives. Also, the 4,6-dichloro substitution pattern was compared to 5-tert-butyl derivatives and compounds not substituted in the ben…