Search results for " hippocampus."
showing 10 items of 42 documents
Specific Hippocampal Interneurons Shape Consolidation of Recognition Memory
2020
Summary A complex array of inhibitory interneurons tightly controls hippocampal activity, but how such diversity specifically affects memory processes is not well understood. We find that a small subclass of type 1 cannabinoid receptor (CB1R)-expressing hippocampal interneurons determines episodic-like memory consolidation by linking dopamine D1 receptor (D1R) signaling to GABAergic transmission. Mice lacking CB1Rs in D1-positive cells (D1-CB1-KO) display impairment in long-term, but not short-term, novel object recognition memory (NOR). Re-expression of CB1Rs in hippocampal D1R-positive cells rescues this NOR deficit. Learning induces an enhancement of in vivo hippocampal long-term potenti…
Fractionation of memory in medial temporal lobe amnesia
2006
We report a comprehensive investigation of the anterograde memory functions of two patients with memory impairments (RH and JC). RH had neuroradiological evidence of apparently selective right-sided hippocampal damage and an intact cognitive profile apart from selective memory impairments. JC, had neuroradiological evidence of bilateral hippocampal damage following anoxia due to cardiac arrest. He had anomic and "executive" difficulties in addition to a global amnesia, suggesting atrophy extending beyond hippocampal regions. Their performance is compared with that of a previously reported hippocampal amnesic patient who showed preserved recollection and familiarity for faces in the context …
Inhibition by Anandamide and Synthetic Cannabimimetics of the Release of [3H]d-Aspartate and [3H]GABA from Synaptosomes Isolated from the Rat Hippoca…
2004
Cannabinoids (CB) can act as retrograde synaptic mediators of depolarization-induced suppression of inhibition or excitation in hippocampus. This mechanism may underlie the impairment of some cognitive processes produced by these compounds, including short-term memory formation in the hippocampus. In this study, we investigated several compounds known to interact with CB receptors, evaluating their effects on K +-evoked release of [ 3H]d-aspartate ([ 3H]d-ASP) and [ 3H]GABA from superfused synaptosomes isolated from the rat hippocampus. [ 3H]d-ASP and [ 3H]GABA release were inhibited to different degrees by the synthetic cannabinoids WIN 55,212-2; CP 55,940, and arachidonyl-2′- chloroethyla…
Bruce/apollon promotes hippocampal neuron survival and is downregulated by kainic acid
2005
Prolonged or excess stimulation of excitatory amino acid receptors leads to seizures and the induction of excitotoxic nerve cell injury. Kainic acid acting on glutamate receptors produces degeneration of vulnerable neurons in parts of the hippocampus and amygdala, but the exact mechanisms are not fully understood. We have here investigated whether the anti-apoptotic protein Bruce is involved in kainic acid-induced neurodegeneration. In the rat hippocampus and cortex, Bruce was exclusively expressed by neurons. The levels of Bruce were rapidly downregulated by kainic acid in hippocampal neurons as shown both in vivo and in cell culture. Caspase-3 was activated in neurons exhibiting low level…
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…
Chronic fluoxetine treatment alters the structure, connectivity and plasticity of cortical interneurons
2014
Novel hypotheses suggest that antidepressants, such as the selective serotonin reuptake inhibitor fluoxetine, induce neuronal structural plasticity, resembling that of the juvenile brain, although the underlying mechanisms of this reopening of the critical periods still remain unclear. However, recent studies suggest that inhibitory networks play an important role in this structural plasticity induced by fluoxetine. For this reason we have analysed the effects of a chronic fluoxetine treatment in the hippocampus and medial prefrontal cortex (mPFC) of transgenic mice displaying eGFP labelled interneurons. We have found an increase in the expression of molecules related to critical period pla…
Indicaxanthin from Opuntia ficus-indica Crosses the Blood–Brain Barrier and Modulates Neuronal Bioelectric Activity in Rat Hippocampus at Dietary-Con…
2015
Indicaxanthin is a bioactive and bioavailable betalain pigment from the Opuntia ficus-indica fruits. In this in vivo study, kinetic measurements showed that indicaxanthin is revealed in the rat brain within 1 h from oral administration of 2 μmol/ kg, an amount compatible with a dietary consumption of cactus pear fruits in humans. A peak (20 ± 2.4 ng of indicaxanthin per whole brain) was measured after 2.5 h; thereafter the molecule disappeared with first order kinetics within 4 h. The potential of indicaxanthin to affect neural activities was in vivo investigated by a microiontophoretic approach. Indicaxanthin, administered in a range between 0.085 ng and 0.34 ng per neuron, dose-dependentl…
Selective sparing of face learning in a global amnesic patient
2001
Objective - To test the hypothesis that visual memory for faces can be dissociated from visual memory for topographical material. Method - A patient who developed a global amnesic syndrome after acute carbon monoxide poisoning is described. A neuroradiological examination documented severe bilateral atrophy of the hippocampi. Results - Despite a severe anterograde memory disorder involving verbal information, abstract figures, concrete objects, topographical scenes, and spatial information, the patient was still able to learn previously unknown human faces at a normal (and, in some cases, at a higher) rate. Conclusions - Together with previous neuropsychological evidence documenting selecti…
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 …
Identification of calcium sensing receptor (CaSR) mRNA-expressing cells in normal and injured rat brain
2009
Calcium sensing receptor (CaSR), isolated for the first time from bovine and human parathyroid, is a G-protein-coupled receptors that has been involved in diverse physiological functions. At present a complete in vivo work on the identification of CaSR mRNA-expressing cells in the adult brain lacks and this investigation was undertaken in order to acquire more information on cell type expressing CaSR mRNA in the rat brain and to analyse for the first time its expression in different experimental models of brain injury. The expression of CaSR mRNAs was found mainly in scattered cells throughout almost all the brain regions. A double labeling analysis showed a colocalization of CaSR mRNA expr…