Search results for "LONG-TERM POTENTIATION"
showing 10 items of 101 documents
Pregnenolone sulphate enhances spatial orientation and object discrimination in adult male rats: Evidence from a behavioural and electrophysiological…
2013
Abstract Neurosteroids can alter neuronal excitability interacting with specific neurotransmitter receptors, thus affecting several functions such as cognition and emotionality. In this study we investigated, in adult male rats, the effects of the acute administration of pregnenolone-sulfate (PREGS) (10 mg/kg, s.c.) on cognitive processes using the Can test, a non aversive spatial/visual task which allows the assessment of both spatial orientation–acquisition and object discrimination in a simple and in a complex version of the visual task. Electrophysiological recordings were also performed in vivo , after acute PREGS systemic administration in order to investigate on the neuronal activati…
D1/D5 modulation of synaptic NMDA receptor currents.
2009
Converging evidence suggests that salience-associated modulation of behavior is mediated by the release of monoamines and that monoaminergic activation of D1/D5receptors is required for normal hippocampal-dependent learning and memory. However, it is not understood how D1/D5modulation of hippocampal circuits can affect salience-associated learning and memory. We have observed in CA1 pyramidal neurons that D1/D5receptor activation elicits a bidirectional long-term plasticity of NMDA receptor-mediated synaptic currents with the polarity of plasticity determined by NMDA receptor, NR2A/B subunit composition. This plasticity results in a decrease in the NR2A/NR2B ratio of subunit composition. Sy…
Gene Expression Profiling of Facilitated L-LTP in VP16-CREB Mice Reveals that BDNF Is Critical for the Maintenance of LTP and Its Synaptic Capture
2011
Expression of VP16-CREB, a constitutively active form of CREB, in hippocampal neurons of the CA1 region lowers the threshold for eliciting the late, persistent phase of long-term potentiation (L-LTP) in the Schaffer collateral pathway. This VP16-CREB-mediated L-LTP differs from the conventional late phase of LTP in not being dependent on new transcription. This finding suggests that in the transgenic mice the mRNA transcript(s) encoding the protein(s) necessary for this form of L-LTP might already be present in CA1 neurons in the basal condition. We used high-density oligonucleotide arrays to identify the mRNAs differentially expressed in the hippocampus of transgenic and wild-type mice. We…
Exogenous t-PA Administration Increases Hippocampal Mature BDNF Levels. Plasmin- or NMDA-Dependent Mechanism?
2014
International audience; Brain-derived neurotrophic factor (BDNF) through TrkB activation is central for brain functioning. Since the demonstration that plasmin is able to process pro-BDNF to mature BDNF and that these two forms have opposite effects on neuronal survival and plasticity, a particular attention has been paid to the link between tissue plasminogen activator (tPA)/plasmin system and BDNF metabolism. However, t-PA via its action on different N-methyl-D-aspartate (NMDA) receptor subunits is also considered as a neuromodulator of glutamatergic transmission. In this context, the aim of our study was to investigate the effect of recombinant (r)t-PA administration on brain BDNF metabo…
The role of pregnenolone sulphate in spatial orientation-acquisition and retention: An interplay between cognitive potentiation and mood regulation
2013
Abstract Neurosteroids can alter neuronal excitability interacting with specific neurotransmitter receptors, thus affecting several functions such as cognition and emotionality. In this study, we investigated, in adult male rats, the effects of the acute administration of pregnenolone-sulfate (PREGS) (10 mg/Kg, s. c.) on cognitive processes using the Can test, a non aversive spatial/visual task which allows the assessment of spatial information-acquisition during the baseline training, and of memory retention in the longitudinal study. Furthermore, on the basis of PREGS pharmacological profile, the modulation of depressive-like behaviour was also evaluated in the forced swim test (FST). Our…
Oligodendrocyte precursor cells modulate the neuronal network by activity-dependent ectodomain cleavage of glial NG2.
2014
The role of glia in modulating neuronal network activity is an important question. Oligodendrocyte precursor cells (OPC) characteristically express the transmembrane proteoglycan nerve-glia antigen 2 (NG2) and are unique glial cells receiving synaptic input from neurons. The development of NG2+ OPC into myelinating oligodendrocytes has been well studied, yet the retention of a large population of synapse-bearing OPC in the adult brain poses the question as to additional functional roles of OPC in the neuronal network. Here we report that activity-dependent processing of NG2 by OPC-expressed secretases functionally regulates the neuronal network. NG2 cleavage by the α-secretase ADAM10 yields…
Chronic Moderate Hyperammonemia Impairs Active and Passive Avoidance Behavior and Conditional Discrimination Learning in Rats
2000
Abstract The cerebral dysfunction associated with hepatic encephalopathy is generally considered to have hyperammonemia as one of its main causes. Hyperammonemia impairs the neuronal glutamate–nitric oxide–cyclic GMP pathway and the induction of NMDA receptor-dependent long-term potentiation in the hippocampus. We studied the performance of pre/neonatally and postnatally exposed rats to hyperammonemia on active avoidance, passive avoidance, and conditional discrimination tasks. Pre/neonatal hyperammonemia slowed learning of active avoidance behaviors and impaired memory for the passive avoidance task while postnatal hyperammonemia impaired learning on the conditional discrimination task. Hy…
Behavioural parameters in aged rats are related to LTP and gene expression of ChAT and NMDA-NR2 subunits in the striatum.
2004
Striatal parameters were assessed for their relevance to age-related behavioural decline. Forty aged rats (28-30 months) were tested in the water maze and open field. Of these, seven superior and seven inferior learners were compared with each other in terms of levels of in vitro short- and long-term potentiation (STP and LTP), and gene expression of choline acetyltransferase (ChAT) as well as of the NMDA-NR2A-C subunits assessed by quantitative RT-PCR. Results revealed that the superior as compared with the inferior learners had higher levels of ChAT mRNA in the striatum. For the superior group, ChAT mRNA was correlated with escape on to the cued platform in the water maze, whereas level o…
Short-term ischemia usually used for ischemic preconditioning causes loss of dendritic integrity after long-term survival in the gerbil hippocampus
2006
Ischemic preconditioning has been established as a powerful experimental neuroprotective strategy, both after global and focal cerebral ischemia. Little is known, however, about the structural and functional long-term outcome. Therefore, our present study was designed to check for potential subtle alterations in the hippocampus after long-term survival. Gerbils were subjected either to short-term ischemia of 2.5 min duration usually used for ischemic preconditioning (n=8) or to sham operation (n=6) and allowed to survive for 6 weeks. Hippocampi with neuronal densities comparable to those of sham-operated control animals were analyzed for dendritic marker proteins MAP2, MAP1B and synaptopodi…
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…