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1.
J Phys Condens Matter ; 30(33): 334003, 2018 Aug 22.
Artículo en Inglés | MEDLINE | ID: mdl-29988023

RESUMEN

Water-induced reordering in ultrathin ionic liquid films has been observed using in situ x-ray photoelectron spectroscopy. An ultrathin layer of 1-butyl-3-methylimidazolium tetrafluoroborate ([C4C1Im][BF4]) was deposited on a rutile TiO2 (1 1 0) single crystal and exposed to water vapour at a relative humidity of ~70% in an in situ cell. Water was found to adsorb onto the ionic liquid surface, causing a reordering of the ions at the interface. Water initially remained trapped on the ionic liquid surface as the in situ cell was evacuated. This could have negative implications for supported ionic liquid phase catalysis, where reactants and products move in and out of an ionic liquid containing the catalyst. This insight into the behaviour at the water/ionic liquid interface provides a basis for understanding interfacial behaviour in more complex gas/ionic liquid systems.

2.
Neuroscience ; 177: 1-11, 2011 Mar 17.
Artículo en Inglés | MEDLINE | ID: mdl-21219970

RESUMEN

The aim of this study was to examine the role of metabotropic glutamate receptors (mGluR) in the generation of oscillatory field activity at theta frequency (4-12 Hz) in the medial septal slice prepared from rat brain. Bath application of mGluR agonists and antagonists showed that activation of mGluR1-type receptors produces persistent theta frequency oscillations in a dose-responsive manner. This activity, induced by the group I mGluR agonist (RS)-3,5-dihydroxyphenylglycine (DHPG), was reduced by ionotropic glutamate receptor antagonists and abolished by further addition of a GABAA receptor antagonist. However, addition of a GABAA receptor antagonist on its own converted the DHPG-induced oscillations to intermittent episodes of accentuated theta frequency activity following a burst. In a proportion of slices, DHPG induced large amplitude field population spiking activity (100-300 µV) which is correlated linearly with the field theta oscillations and is sensitive to glutamate receptor antagonists, suggesting a role of this type of spikes in theta generation induced by DHPG. These data demonstrate that DHPG-sensitive neuronal networks within medial septum generate theta rhythmic activity and are differentially modulated by excitatory and inhibitory ionotropic neurotransmissions.


Asunto(s)
Relojes Biológicos/fisiología , Agonistas de Aminoácidos Excitadores/farmacología , Receptores de Glutamato Metabotrópico/agonistas , Núcleos Septales/fisiología , Ritmo Teta/fisiología , Animales , Relojes Biológicos/efectos de los fármacos , Antagonistas de Aminoácidos Excitadores/farmacología , Masculino , Técnicas de Cultivo de Órganos , Ratas , Ratas Wistar , Receptores de Glutamato Metabotrópico/antagonistas & inhibidores , Receptores de Glutamato Metabotrópico/fisiología , Núcleos Septales/efectos de los fármacos , Ritmo Teta/efectos de los fármacos
3.
Neuroscience ; 166(3): 952-69, 2010 Mar 31.
Artículo en Inglés | MEDLINE | ID: mdl-20083165

RESUMEN

The medial septum diagonal band complex (MS/DB) projects via cholinergic and GABAergic pathways to the hippocampus and plays a key role in the hippocampal theta rhythm. In the MS/DB we have previously described a population of fast spiking GABAergic neurons that contain parvalbumin and mediate theta frequency activity in vitro. The Kv3.1 potassium channel is a delayed rectifier channel that plays a major role in fast spiking neurons in the CNS, and has previously been localized in the MS/DB. To determine which cell types in the MS/DB express the Kv3.1b ion channel subunit, transgenic mice in which the expression of GABAergic and glutamate markers are associated with the expression of green fluorescent protein (GFP; GAD67-GFP and VGluT2-GFP mice, respectively) were used for immunofluorescence and axonal tract tracing. Electrophysiological studies were also carried out on rat MS/DB slices to examine the role of the Kv3.1 channel in theta frequency oscillations. The results for the MS/DB were as follows: (1) cholinergic cells did not express GFP in either GAD67-GFP or VGluT2-GFP mice, and there was GAD67 immunoreactivity in GFP-positive neurons in GAD67-GFP mice and in a small proportion (6%) of GFP-positive neurons in VGluT2-GFP mice. (2) Kv3.1b immunofluorescence was associated with the somata of GABAergic neurons, especially those that contained parvalbumin, and with a minority of glutamatergic neurons, but not with cholinergic neurons, and with GABAergic axonal terminal-like processes around certain GABAergic neurons. (3) Both Kv3.1b-positive and -negative GABAergic neurons were septo-hippocampal, and there was a minor projection to hippocampus from VGluT2-GFP neurons. (4) Kainate-induced theta oscillations in the MS/DB slice were potentiated rather than inhibited by the Kv3.1 blocker 4-aminopyridine, and this agent on its own produced theta frequency oscillations in MS/DB slices that were reduced by ionotropic glutamate and GABA receptor antagonists and abolished by low extracellular calcium. These studies confirm the presence of heterogeneous populations of septo-hippocampal neurons in the MS/DB, and suggest that presence of Kv3.1 in the GABAergic neurons does not contribute to theta activity through fast spiking properties, but possibly by the regulation of transmitter release from axonal terminals.


Asunto(s)
Banda Diagonal de Broca/metabolismo , Neuronas/metabolismo , Canales de Potasio Shaw/metabolismo , 4-Aminopiridina/farmacología , Animales , Calcio/metabolismo , Colina O-Acetiltransferasa/metabolismo , Banda Diagonal de Broca/citología , Antagonistas de Aminoácidos Excitadores/farmacología , Espacio Extracelular/metabolismo , Antagonistas del GABA/farmacología , Glutamato Descarboxilasa/biosíntesis , Glutamato Descarboxilasa/genética , Ácido Glutámico/metabolismo , Proteínas Fluorescentes Verdes/biosíntesis , Proteínas Fluorescentes Verdes/genética , Hipocampo/fisiología , Técnicas In Vitro , Masculino , Ratones , Ratones Transgénicos , Proteínas del Tejido Nervioso/antagonistas & inhibidores , Proteínas del Tejido Nervioso/metabolismo , Parvalbúminas/metabolismo , Terminales Presinápticos/metabolismo , Ratas , Ratas Wistar , Canales de Potasio Shaw/antagonistas & inhibidores , Proteínas de Transporte Vesicular de Acetilcolina/metabolismo , Proteína 2 de Transporte Vesicular de Glutamato/biosíntesis , Proteína 2 de Transporte Vesicular de Glutamato/genética , Ácido gamma-Aminobutírico/metabolismo
4.
Neuroscience ; 166(1): 84-93, 2010 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-20004706

RESUMEN

The hippocampus is an area important for learning and memory and exhibits prominent and behaviourally relevant theta (4-12 Hz) and gamma (30-100 Hz) frequency oscillations in vivo. Hippocampal slices produce similar types of oscillatory activity in response to bath-application of neurotransmitter receptor agonists. The medial septum diagonal band area (MS/DB) provides both a cholinergic and GABAergic projection to the hippocampus, and although it plays a major role in the generation and maintenance of the hippocampal theta rhythm in vivo, there is evidence for intrinsic theta generation mechanisms in the hippocampus, especially in area CA3. The aim of this study was to examine the role of the nicotinic receptor (nAChR) in the induction of oscillatory field activity in the in vitro preparation of the rat hippocampus. Bath-application of a low concentration of nicotine (1 muM) to transversely-cut hippocampal slices produced persistent theta-frequency oscillations in area CA3 of the hippocampus. These oscillations were reduced by both GABA(A) receptor antagonists and ionotropic glutamate receptor antagonists, indicating the involvement of local GABAergic and glutamatergic neurons in the production of the rhythmic theta activity. The nicotine-induced theta activity was inhibited by non-selective nAChR antagonists and partially by an alpha7* nAChR antagonist. The induction of theta frequency oscillations in CA3 by nicotine was mimicked alpha7* nAChR agonists but not by non-alpha7* nAChR agonists. In conclusion, theta activity in the hippocampus may be promoted by tonic stimulation of alpha7* nAChRs, possibly via selective stimulation of theta-preferring interneurons in the hippocampus that express post-synaptic alpha7* nAChRs.


Asunto(s)
Relojes Biológicos/efectos de los fármacos , Hipocampo/efectos de los fármacos , Neuronas/efectos de los fármacos , Nicotina/farmacología , Receptores Nicotínicos/efectos de los fármacos , Ritmo Teta/efectos de los fármacos , Potenciales de Acción/efectos de los fármacos , Potenciales de Acción/fisiología , Animales , Relojes Biológicos/fisiología , Región CA3 Hipocampal/efectos de los fármacos , Región CA3 Hipocampal/fisiología , Antagonistas de Aminoácidos Excitadores/farmacología , Antagonistas del GABA/farmacología , Hipocampo/fisiología , Interneuronas/efectos de los fármacos , Interneuronas/metabolismo , Masculino , Neuronas/fisiología , Agonistas Nicotínicos/farmacología , Técnicas de Cultivo de Órganos , Ratas , Ratas Wistar , Receptores de GABA-A/efectos de los fármacos , Receptores de GABA-A/metabolismo , Receptores Nicotínicos/metabolismo , Transmisión Sináptica/efectos de los fármacos , Transmisión Sináptica/fisiología , Receptor Nicotínico de Acetilcolina alfa 7
5.
Neuroscience ; 132(3): 789-800, 2005.
Artículo en Inglés | MEDLINE | ID: mdl-15837139

RESUMEN

GABA(B) receptors are believed to play a role in rhythmic activity in the mammalian brain. The aim of our study was to examine the presynaptic and postsynaptic locations of these receptors in the medial septal diagonal band area (MS/DB), an area known to pace the hippocampus theta rhythm. Whole-cell patch recordings were made from parasagittal MS/DB slices obtained from the 16-25 day rat. Neurons were classified into GABAergic and cholinergic subtypes according to previous electrophysiological criteria. Bath application of the GABA(B) receptor agonist baclofen in the presence of tetrodotoxin, and brief tetanic fiber stimulation in the presence of ionotropic receptor antagonists, provided evidence for the presence of postsynaptic GABA(B) receptor transmission to GABAergic but not cholinergic neurons. Bath application of baclofen, at concentrations too low to elicit postsynaptic activity in MS/DB neurons, significantly reduced the amplitudes of stimulus-evoked ionotropic receptor inhibitory postsynaptic potentials (IPSPs) and excitatory postsynaptic potentials (EPSPs) and the paired pulse depression of these evoked potentials. Baclofen also significantly reduced the frequencies but not the amplitudes of miniature inhibitory postsynaptic currents (IPSCs) and excitatory postsynaptic currents (EPSCs), indicating the presence of presynaptic GABA(B) receptors on GABAergic and glutamatergic terminals in the MS/DB. Baclofen, also at a concentration too low to elicit postsynaptic activity, reduced the frequencies and amplitudes of spontaneous IPSCs and EPSCs recorded in the presence of 200-400 nM kainate. Rhythmic compound IPSCs at theta frequencies were recorded under these conditions in some neurons, and these rhythmic compound IPSCs were disrupted by the activation but not by the inhibition of GABA(B) receptors. These results suggest that GABA(B) receptors modulate rather than generate rhythmic activity in the MS/DB, and that this modulatory effect occurs via receptors located on presynaptic terminals.


Asunto(s)
Neuronas/metabolismo , Receptores de GABA-A/metabolismo , Tabique Pelúcido/citología , 6-Ciano 7-nitroquinoxalina 2,3-diona/farmacología , Animales , Animales Recién Nacidos , Baclofeno/análogos & derivados , Baclofeno/farmacología , Bicuculina/farmacología , Relación Dosis-Respuesta a Droga , Relación Dosis-Respuesta en la Radiación , Interacciones Farmacológicas , Estimulación Eléctrica/métodos , Agonistas de Aminoácidos Excitadores/farmacología , Antagonistas de Aminoácidos Excitadores/farmacología , Potenciales Postsinápticos Excitadores/efectos de los fármacos , Potenciales Postsinápticos Excitadores/efectos de la radiación , Agonistas del GABA/farmacología , Antagonistas del GABA/farmacología , Técnicas In Vitro , Ácido Kaínico/farmacología , Potenciales de la Membrana/efectos de los fármacos , Potenciales de la Membrana/fisiología , Potenciales de la Membrana/efectos de la radiación , Inhibición Neural/efectos de los fármacos , Inhibición Neural/fisiología , Inhibición Neural/efectos de la radiación , Neuronas/efectos de los fármacos , Neuronas/efectos de la radiación , Técnicas de Placa-Clamp/métodos , Ácidos Fosfínicos/farmacología , Propanolaminas/farmacología , Ratas , Ratas Wistar , Tabique Pelúcido/crecimiento & desarrollo , Bloqueadores de los Canales de Sodio/farmacología , Tetrodotoxina/farmacología , Factores de Tiempo , Valina/análogos & derivados , Valina/farmacología
6.
Eur J Neurosci ; 19(10): 2753-68, 2004 May.
Artículo en Inglés | MEDLINE | ID: mdl-15147309

RESUMEN

The medial septal diagonal band complex (MS/DB), made up of cholinergic and GABAergic neurons, plays an important role in the generation of the hippocampal theta rhythm. A GABAergic neuron type in the MS/DB that has fast spiking properties was shown previously to contain parvalbumin immunoreactivity and to form axosomatic connections with unidentified somata. The aim in the current study was to determine the neurochemical identities of these target neurons. In slices and in perfused-fixed brain, staining for parvalbumin immunoreactivity first of all revealed the presence of two types of parvalbumin-positive somata in the MS/DB: medially located neurons with parvalbumin-positive basket-like terminals on them, and more laterally located neurons with fewer parvalbumin-positive contacts on them. In MS/DB slices, the terminals of fast spiking neurons filled with biocytin correspondingly made either numerous contacts that surrounded the parvalbumin-positive cell body in basket-like formation, or 1-5 contacts on a localized patch of the soma. These contacts were shown by electron microscopy to form synaptic junctions. No terminals of biocytin-filled fast spiking neurons were observed on cholinergic neurons, and dual staining in perfused-fixed brain did not reveal the presence of parvalbumin-containing terminals on cholinergic somata. Our results suggest therefore that there are two subtypes of parvalbumin-containing neuron in the MS/DB, and that these are interconnected via axosomatic synapses. The contrasting topographical organization of the two types of parvalbumin-containing neuron suggests that they may receive different types of afferent input, but this will require substantiation in future studies. We propose that generation of rhythmic activity in the MS/DB is controlled by contrasting contributions from two types of parvalbumin-positive neuron, and that the role of the cholinergic neuron is modulatory.


Asunto(s)
Axones/metabolismo , Lisina/análogos & derivados , Proteínas de Transporte de Membrana , Red Nerviosa/metabolismo , Neuronas/metabolismo , Parvalbúminas/metabolismo , Núcleos Septales/citología , Sinapsis/metabolismo , Proteínas de Transporte Vesicular , Potenciales de Acción/fisiología , Animales , Axones/ultraestructura , Proteínas Portadoras/metabolismo , Recuento de Células/métodos , Dendritas/metabolismo , Dendritas/ultraestructura , Electrofisiología/métodos , Inmunohistoquímica/métodos , Técnicas In Vitro , Lisina/metabolismo , Masculino , Microinyecciones/métodos , Microscopía Inmunoelectrónica/métodos , Neuronas/clasificación , Neuronas/citología , Ratas , Ratas Wistar , Sinapsis/ultraestructura , Proteínas de Transporte Vesicular de Acetilcolina
7.
Am J Physiol Heart Circ Physiol ; 283(2): H819-28, 2002 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-12124232

RESUMEN

Desensitization of the cardiac muscarinic K+ channel was studied in cultured neonatal rat atrial cells and in Chinese hamster ovary (CHO) cells transfected with muscarinic receptor (HM(2)), G protein-coupled inward rectifying K+ channels 1 and 4, and G protein-coupled receptor kinase 2. In atrial cells incubated in 10 microM carbachol for 24 h, channel activity in cell-attached patches was substantially reduced as a result of long-term desensitization. The long-term desensitization was also observed in CHO cells transfected with the wild-type receptor and receptor kinase (as well as the channel). However, long-term desensitization was greatly reduced or abolished if the cells were 1) not transfected with the receptor kinase, 2) transfected with a mutant receptor lacking phosphorylation sites (rather than the wild-type receptor), or 3) transfected with a mutant receptor kinase lacking kinase activity (rather than the wild-type receptor kinase). We suggest that long-term desensitization of the cardiac muscarinic receptor-K+ channel system to muscarinic agonist may involve phosphorylation of the receptor by receptor kinase.


Asunto(s)
Miocardio/metabolismo , Canales de Potasio/metabolismo , Proteínas Tirosina Quinasas Receptoras/fisiología , Receptores Muscarínicos/metabolismo , Animales , Células CHO , Células Cultivadas , Cricetinae , Proteínas Quinasas Dependientes de AMP Cíclico/fisiología , Electrofisiología , Quinasa 2 del Receptor Acoplado a Proteína-G , Mutación , Fosforilación , Ratas , Proteínas Tirosina Quinasas Receptoras/genética , Receptor Muscarínico M2 , Receptores Muscarínicos/genética , Factores de Tiempo , Transfección , Quinasas de Receptores Adrenérgicos beta
8.
J Chem Neuroanat ; 24(1): 1-13, 2002 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-12084407

RESUMEN

Axon terminals synapsing on neurones in the nucleus tractus solitarii (NTS) that originate from the central nucleus of the amygdala (CeA) have been shown to contain gamma-aminobutyric acid (GABA) immunoreactivity. Here we investigated whether such terminals also contain somatostatin (SOM), a neuropeptide found in axons distributed throughout the NTS and in somata in the CeA, and known to modulate cardiovascular reflexes when microinjected into the NTS. With fluorescence microscopy, SOM immunoreactivity was seen in the varicosities of some axons throughout the NTS that were anterogradely labelled with biotin dextran amine injected into the CeA. Such varicosities were frequently observed in close proximity to dendrites of NTS neurones that were immunoreactive for the SOM receptor sst(2A) subtype, and in many cases also for catecholamine synthesising enzymes. In the caudal, cardioregulatory zone of NTS, SOM immunoreactivity was localised by electron microscopic pre-embedding gold labelling to boutons containing dense-cored and clear pleomorphic vesicles and forming symmetrical synapses, mostly onto dendrites. Additional post-embedding gold labelling for GABA suggested that a subpopulation (29%) of GABAergic terminals sampled in this area of NTS contained SOM. Almost all boutons anterogradely labelled from the amygdala were GABA-immunoreactive (-IR) and 21% of these were SOM-IR. A similar proportion of these boutons (22%) formed synapses onto dendrites containing immunoreactivity for the SOM receptor sst(2A) subtype. These observations provide evidence that some of the GABAergic projection neurones in the CeA that inhibit baroreceptor reflex responses in the NTS in response to fear or emotional stimuli could release SOM, which might modulate the activity of NTS neurones via an action on sst(2A) receptors.


Asunto(s)
Amígdala del Cerebelo/química , Terminales Presinápticos/química , Receptores de Somatostatina/metabolismo , Núcleo Solitario/química , Somatostatina/metabolismo , Ácido gamma-Aminobutírico/análisis , Amígdala del Cerebelo/metabolismo , Amígdala del Cerebelo/ultraestructura , Animales , Inmunohistoquímica , Masculino , Terminales Presinápticos/metabolismo , Terminales Presinápticos/ultraestructura , Ratas , Receptores de Somatostatina/biosíntesis , Receptores de Somatostatina/ultraestructura , Núcleo Solitario/metabolismo , Núcleo Solitario/ultraestructura , Ácido gamma-Aminobutírico/metabolismo
9.
J Neurochem ; 79(3): 699-712, 2001 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-11701773

RESUMEN

The effects of amyloid beta protein on voltage-gated K(+) channel currents were studied using the whole-cell patch-clamp technique. The 1-40 amino acid form of amyloid beta protein was applied to primary cultures of rat cerebellar granule and cortical neurones for 24 h. Both the unaggregated and aggregated forms of the peptide, which have differing biological activities, were used. In cerebellar granule neurones, 24-h pre-incubation with 1 microM unaggregated amyloid beta protein resulted in a 60% increase in the 'A'-type component of K(+) current. Increased delayed rectifier activity was Cd(2+)-sensitive and was presumed to be secondary to an increase in voltage-gated Ca(2+) channel current activity. Unaggregated amyloid beta protein had no effect on any component of the K(+) channel current in cortical neurones. One micromolar of aggregated amyloid beta protein had no effect on K(+) channel current in either cell type but reduced cell survival within 24 h as measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) assays. The unaggregated form of amyloid beta protein had no neurotoxic effects when applied to either neurone type for up to 72 h. These data indicate that the unaggregated, non-pathological form of amyloid beta protein causes changes in the ion channel function of neurones, possibly reflecting a physiological role for the peptide.


Asunto(s)
Péptidos beta-Amiloides/toxicidad , Activación del Canal Iónico/efectos de los fármacos , Neuronas/fisiología , Fragmentos de Péptidos/toxicidad , Canales de Potasio/fisiología , Enfermedad de Alzheimer/fisiopatología , Péptidos beta-Amiloides/química , Animales , Cloruro de Cadmio/farmacología , Células Cultivadas , Cerebelo/citología , Corteza Cerebral/citología , Potenciales de la Membrana/efectos de los fármacos , Neuronas/efectos de los fármacos , Técnicas de Placa-Clamp , Fragmentos de Péptidos/química , Potasio/metabolismo , Ratas , Solubilidad
10.
Vision Res ; 41(24): 3185-95, 2001 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-11711142

RESUMEN

Human subjects perform poorly at matching different images of unfamiliar faces. When images are taken by different capture devices (cameras), matching is difficult for human perceivers and also for automatic systems. We test an automatic face recognition system based on principal components analysis (PCA) and compare its performance with that of human subjects tested on the same set of images. A number of variants of the PCA system are compared, using different matching metrics and different numbers of components. PCA performance critically depends on the choice of distance metric, with a Mahalanobis metric consistently outperforming a Euclidean metric. Under optimal conditions, the automatic PCA system exceeds human performance on the same images. We hypothesise that unfamiliar face recognition may be mediated by processes corresponding to rather simple functions of the inputs.


Asunto(s)
Cara , Interpretación de Imagen Asistida por Computador/normas , Reconocimiento en Psicología/fisiología , Humanos , Análisis de los Mínimos Cuadrados , Masculino , Sistema Métrico , Fotograbar , Grabación en Video
11.
J Exp Psychol Appl ; 7(3): 207-18, 2001 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-11676099

RESUMEN

People can be inaccurate at matching unfamiliar faces shown in high-quality video images, even when viewpoint and facial expressions are closely matched. However, identification of highly familiar faces appears good, even when video quality is poor. Experiment 1 reported a direct comparison between familiar and unfamiliar faces. Participants who were personally familiar with target items appearing on video were highly accurate at a verification task. Unfamiliar participants doing the same task performed very inaccurately. Familiarity affected discriminability, but not bias. Experiments 2 and 3 showed that brief periods of familiarization have little beneficial effect unless "deep" or "social" processing is encouraged. The results show that video evidence can be used effectively as a probe to identity when the faces shown are highly familiar to observers, but caution should be used where images of unfamiliar people are being compared.


Asunto(s)
Aprendizaje Discriminativo , Cara , Recuerdo Mental , Reconocimiento Visual de Modelos , Televisión , Adulto , Atención , Femenino , Humanos , Masculino , Enmascaramiento Perceptual
12.
J Histochem Cytochem ; 49(10): 1221-34, 2001 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-11561006

RESUMEN

The functionally important effects on the heart of ACh released from vagal nerves are principally mediated by the muscarinic K+ channel. The aim of this study was to determine the abundance and cellular location of the muscarinic K+ channel subunits Kir3.1 and Kir3.4 in different regions of heart. Western blotting showed a very low abundance of Kir3.1 in rat ventricle, although Kir3.1 was undetectable in guinea pig and ferret ventricle. Although immunofluorescence on tissue sections showed no labeling of Kir3.1 in rat, guinea pig, and ferret ventricle and Kir3.4 in rat ventricle, immunofluorescence on single ventricular cells from rat showed labeling in t-tubules of both Kir3.1 and Kir3.4. Kir3.1 was abundant in the atrium of the three species, as shown by Western blotting and immunofluorescence, and Kir3.4 was abundant in the atrium of rat, as shown by immunofluorescence. Immunofluorescence showed Kir3.1 expression in SA node from the three species and Kir3.4 expression in the SA node from rat. The muscarinic K+ channel is activated by ACh via the m2 muscarinic receptor and, in atrium and SA node from ferret, Kir3.1 labeling was co-localized with m2 muscarinic receptor labeling throughout the outer cell membrane.


Asunto(s)
Atrios Cardíacos/metabolismo , Ventrículos Cardíacos/metabolismo , Miocardio/metabolismo , Canales de Potasio de Rectificación Interna , Canales de Potasio/metabolismo , Receptores Muscarínicos/metabolismo , Nodo Sinoatrial/metabolismo , Animales , Western Blotting , Hurones , Técnica del Anticuerpo Fluorescente , Canales de Potasio Rectificados Internamente Asociados a la Proteína G , Cobayas , Microscopía Confocal , Especificidad de Órganos , Ratas , Receptor Muscarínico M2 , Especificidad de la Especie
13.
Brain Res Bull ; 55(2): 257-67, 2001 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-11470325

RESUMEN

Although the neurotoxic actions of aluminium (Al) have been well documented, its contribution to neurodegenerative diseases such as Alzheimer's disease remains controversial. In the present study, we applied histochemical techniques to identify changes induced by intracerebroventricular Al injections (5.4 microg in 5.5 microl, daily over a period of 5 successive days) in the adult rat brain after survival periods of either 1 or 6 weeks. For both Al- and saline-infused controls, no major signs of gross histological changes were evident in cresyl violet-stained sections. Al (as indicated by the fluorescent Morin staining) was concentrated in white matter of the medial striatum, corpus callosum, and cingulate bundle. Immunoreactivity of astrocytes and phagocytic microglia based on glial fibrillary acidic protein and ED1 markers, respectively, revealed a greater inflammatory response in Al-injected animals compared to controls. Damage of the cingulate bundle in Al-treated animals led to a severe anterograde degeneration of cholinergic terminals in cortex and hippocampus, as indicated by acetylcholinesterase labelling. Our data suggest that the enhancement of inflammation and the interference with cholinergic projections may be the modes of action through which Al may cause learning and memory deficits, and contribute to pathological processes in Alzheimer's disease.


Asunto(s)
Aluminio/toxicidad , Enfermedad de Alzheimer/inducido químicamente , Encéfalo/efectos de los fármacos , Neuronas/efectos de los fármacos , Neurotoxinas/toxicidad , Acetilcolina/metabolismo , Acetilcolinesterasa/metabolismo , Aluminio/farmacocinética , Enfermedad de Alzheimer/patología , Enfermedad de Alzheimer/fisiopatología , Animales , Astrocitos/efectos de los fármacos , Astrocitos/metabolismo , Astrocitos/patología , Encéfalo/patología , Encéfalo/fisiopatología , Colina O-Acetiltransferasa/metabolismo , Fibras Colinérgicas/efectos de los fármacos , Fibras Colinérgicas/patología , Relación Dosis-Respuesta a Droga , Flavonoides/farmacocinética , Proteína Ácida Fibrilar de la Glía/metabolismo , Gliosis/inducido químicamente , Gliosis/patología , Gliosis/fisiopatología , Glutamato Descarboxilasa/metabolismo , Inmunohistoquímica , Indicadores y Reactivos/farmacocinética , Masculino , Microglía/efectos de los fármacos , Microglía/metabolismo , Microglía/patología , Neuronas/metabolismo , Neuronas/patología , Neurotoxinas/farmacocinética , Ratas , Ratas Wistar
14.
J Comp Neurol ; 430(3): 410-32, 2001 Feb 12.
Artículo en Inglés | MEDLINE | ID: mdl-11169477

RESUMEN

Neurons in the medial septal/diagonal band complex (MS/DB) in vivo exhibit rhythmic burst-firing activity that is phase-locked with the hippocampal theta rhythm. The aim was to assess the morphology of local axon collaterals of electrophysiologically identified MS/DB neurons using intracellular recording and biocytin injection in vitro. Cells were classified according to previous criteria into slow-firing, fast-spiking, regular-spiking, and burst-firing neurons; previous work has suggested that the slow-firing neurons are cholinergic and that the other types are GABAergic. A novel finding was the existence of two types of burst-firing neuron. Type I burst-firing neurons had significantly longer duration after hyperpolarisation potentials when held at -60 mV, and at -75 mV, type I neurons exhibited a low-threshold spike with more rapid activation and inactivation kinetics than those of type II neurons. We have, also for the first time, described the main features of the local axon collaterals of the five neuron types. All filled neurons possessed a main axon that gave forth 1-12 local primary axon collaterals. All electrophysiological types, except for the type I burst-firing neuron, had a main axon that coursed toward the fornix. Myelination of the main axon was a prominent feature of all but the slow-firing neurons. Branching of the primary axon collaterals of the fast-spiking and type I burst-firing neurons was more extensive than that of the other cell types, with those of the slow-firing neurons exhibiting the least branching. All cell types possessed axon collaterals of the en passant type, and some in addition had twiglike or basketlike axon terminals. All cell types made synapses on distal dendrites; a proportion of the fast-spiking and burst-firing cells in addition had basketlike terminals that made synaptic contacts on proximal dendrites and on somata. Two morphological types of somata were postsynaptic to the basket cells: large (20-30-microm) oval cells with dark cytoplasm, and large oval cells with paler cytoplasm, often with an apical dendrite. The presence of lamellar bodies in the large dark neurons suggests that they may be cholinergic neurons, because previous work has localised these structures in some neurons that stain for choline acetyltransferase. Our work suggests therefore that there may be GABAergic neurons in the MS/DB that form basket synaptic contacts on at least two types of target cell, possibly cholinergic and GABAergic neurons, which means that the basket cells could play a key role in the generation of rhythmic activity in the MS/DB.


Asunto(s)
Potenciales de Acción/fisiología , Axones/fisiología , Axones/ultraestructura , Ratas Wistar/fisiología , Núcleos Septales/citología , Núcleos Septales/fisiología , Animales , Axones/clasificación , Membrana Celular/fisiología , Tamaño de la Célula/fisiología , Dendritas/fisiología , Dendritas/ultraestructura , Estimulación Eléctrica , Lisina/análogos & derivados , Lisina/farmacología , Vías Nerviosas/citología , Vías Nerviosas/fisiología , Técnicas de Cultivo de Órganos , Terminales Presinápticos/clasificación , Terminales Presinápticos/fisiología , Terminales Presinápticos/ultraestructura , Ratas , Ratas Wistar/anatomía & histología , Sinapsis/fisiología , Sinapsis/ultraestructura
15.
Neuroscience ; 99(4): 613-26, 2000.
Artículo en Inglés | MEDLINE | ID: mdl-10974425

RESUMEN

The central nucleus of the amygdala is involved in the modulation of autonomic, somatic and endocrine functions, as well as behavioural responses to stressful stimuli. Anatomical and physiological studies have suggested that this nucleus sends projections to the nucleus of the solitary tract, the primary site of termination of vagal and glossopharyngeal afferent fibres in the brain stem. To determine the neurochemical nature of the amygdaloid input to the nucleus of the solitary tract, anterograde tracing with biotinylated dextran amine was combined with post-embedding immunogold labelling for GABA and glutamate immunoreactivities and with pre-embedding labelling for the vesicular GABA transporter. Following injection of biotin dextran amine into the central nucleus of the amygdala, anterogradely labelled axons and varicosities were found throughout the rostrocaudal extent of the nucleus of the solitary tract, particularly in the medial, ventral and ventrolateral subnuclei. The anterogradely labelled terminals were found to make predominantly symmetrical synaptic contacts with dendrites, and occasionally onto cell bodies and dendritic spines, and to contain immunoreactivity for GABA and for the vesicular GABA transporter. Immunolabelling of serial sections with antibodies to glutamate showed that none of these axon terminals contained high enough densities of gold particle labelling to suggest that they contained other than low metabolic levels of glutamate immunoreactivity. These results provide conclusive evidence for a GABAergic pathway from the central nucleus of the amygdala to the nucleus of the solitary tract. This GABAergic projection may provide a substrate for inhibition of lower brain stem visceral reflexes, including baroreflex inhibition, through which the central nucleus of the amygdala could participate in cardiovascular regulation related to emotional behaviour and the defence reaction.


Asunto(s)
Amígdala del Cerebelo/química , Amígdala del Cerebelo/citología , Biotina/análogos & derivados , Proteínas de Transporte de Membrana , Transportadores de Anión Orgánico , Núcleo Solitario/química , Núcleo Solitario/citología , Ácido gamma-Aminobutírico/fisiología , Acetilcolinesterasa/análisis , Animales , Proteínas Portadoras/análisis , Dextranos , Colorantes Fluorescentes , Proteínas Transportadoras de GABA en la Membrana Plasmática , Ácido Glutámico/análisis , Masculino , Proteínas de la Membrana/análisis , Microscopía Inmunoelectrónica , Vías Nerviosas , Neuronas/química , Neuronas/enzimología , Neuronas/ultraestructura , Terminales Presinápticos/química , Terminales Presinápticos/ultraestructura , Ratas , Ratas Wistar , Ácido gamma-Aminobutírico/análisis
16.
J Pediatr Nurs ; 15(3): 175-82, 2000 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-10897555

RESUMEN

A grounded theory approach was used to explore the influence of peer relationships on adjustment to cystic fibrosis (CF) in 15 adolescents. Discovering the course was the core category that captured the influence of peers on adjustment to CF. Four subcategories were identified: (1) losing ground, (2) being out of the loop, (3) finding a new company of friends, (4) fighting a never-ending battle. The downward progression of CF and increasing social interactions with peers with CF during hospitalization helped them learn CF was a lifelong disease with relentless demands. Interventions should focus on strategies for promoting peer support, a positive attitude, and hope to create a sense of belonging, social competence, and well-being.


Asunto(s)
Adaptación Psicológica , Fibrosis Quística/psicología , Relaciones Interpersonales , Grupo Paritario , Adolescente , Adulto , Fibrosis Quística/enfermería , Progresión de la Enfermedad , Femenino , Humanos , Masculino , Modelos Psicológicos , Sudeste de Estados Unidos
17.
Neuroscience ; 98(4): 661-8, 2000.
Artículo en Inglés | MEDLINE | ID: mdl-10891609

RESUMEN

Nuclei of the medial septum/diagonal band region of the mammalian forebrain contain neurons that give rise to the septohippocampal pathway, which has separate cholinergic and GABAergic components. This pathway is known to influence hippocampal-dependent memory and learning processes, but the precise role of each component is unclear. In this study, we tested the hypothesis that fast-firing, non-bursting medial septum/diagonal band neurons are GABAergic. We used brain slice preparations from young adult guinea-pigs and rats, or from weanling rats, to perform current-clamp recordings from medial septum/diagonal band neurons. Recorded neurons were injected with biocytin for subsequent visualization with fluorescent avidin, and then hybridized with a 35S-labeled riboprobe for glutamate decarboxylase-67 messenger RNA. As a positive control, guinea-pig cerebellar Purkinje cells were labeled and hybridized with the riboprobe. As expected, labeled Purkinje cells were glutamate decarboxylase-67 messenger RNA positive. Slow-firing, cholinergic (choline acetyltransferase-positive) guinea-pig medial septum/diagonal band neurons were glutamate decarboxylase-67 messenger RNA negative. Contrary to our hypothesis, of the guinea-pig neurons, only three of 11 fast-firing neurons were glutamate decarboxylase-67 positive. Of the rat medial septum/diagonal band neurons, three of four were positive for glutamate decarboxylase-67 messenger RNA. These data suggest that fast-firing, non-bursting neurons of the medial septum/diagonal band, as sampled by sharp-electrode intracellular recordings in brain slices, may be a heterogeneous group of neurons, some of which are GABAergic. Together with recent data demonstrating the presence of another GABAergic marker, parvalbumin, in fast-firing septal neurons, we conclude that GABAergic septohippocampal neurons include a population of fast-firing, non-bursting neurons. The influence of these neurons on the hippocampus is likely to occur on a shorter time-scale and over a wider range of firing frequencies as compared to slowly firing cholinergic septohippocampal neurons.


Asunto(s)
Glutamato Descarboxilasa/metabolismo , Neuronas/metabolismo , Núcleos Septales/metabolismo , Ácido gamma-Aminobutírico/metabolismo , Animales , Electrofisiología , Cobayas , Masculino , Neuronas/fisiología , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Núcleos Septales/fisiología , Tabique del Cerebro/metabolismo
18.
J Histochem Cytochem ; 48(6): 769-80, 2000 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-10820151

RESUMEN

The aim of this study was to establish, using immunolabeling, whether the Kv1.5 K(+) channel is present in the pacemaker of the heart, the sinoatrial (SA) node. In the atrial muscle surrounding the SA node and in the SA node itself (from guinea pig and ferret), Western blotting analysis showed a major band of the expected molecular weight, approximately 64 kD. Confocal microscopy and immunofluorescence labeling showed Kv1.5 labeling clustered in atrial muscle but punctate in the SA node. In atrial muscle, Kv1.5 labeling was closely associated with labeling of Cx43 (gap junction protein) and DPI/II (desmosomal protein), whereas in SA node Kv1.5 labeling was closely associated with labeling of DPI/II but not labeling of Cx43 (absent in the SA node) or Cx45 (another gap junction protein present in the SA node). Electron microscopy and immunogold labeling showed that the Kv1.5 labeling in atrial muscle is preferentially associated with desmosomes rather than gap junctions.


Asunto(s)
Canales de Potasio con Entrada de Voltaje , Canales de Potasio/análisis , Nodo Sinoatrial/química , Animales , Western Blotting/métodos , Bovinos , Conexina 43/análisis , Conexinas/análisis , Proteínas del Citoesqueleto/análisis , Desmoplaquinas , Femenino , Hurones , Técnica del Anticuerpo Fluorescente Indirecta , Cobayas , Humanos , Canal de Potasio Kv1.5 , Masculino , Ratones , Fracciones Subcelulares
19.
Eur J Neurosci ; 12(3): 828-38, 2000 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-10762312

RESUMEN

Perineuronal nets, composed of extracellular matrix material, have previously been associated with parvalbumin-immunoreactive neurons in the medial septum/diagonal band (MS/DB) complex of the rat. The aim of this study was to correlate the presence of perineuronal nets with electrophysiological properties and parvalbumin immunoreactivity in MS/DB neurons. Intracellular recordings were made from cells in a brain slice preparation maintained in vitro, and neurons were characterized into four populations: (i) slow-firing neurons, (ii) burst-firing neurons, (iii) fast spiking neurons with narrow action potentials and a small degree of spike frequency adaptation, and (iv) regular spiking neurons with broader action potentials and a high degree of spike frequency adaptation. Following electrophysiological characterization, neurons were filled with biocytin, processed for parvalbumin immunoreactivity and stained for perineuronal nets using Wisteria floribunda lectin. The three substances were viewed with triple fluorescence. Fast spiking, nonadapting neurons, shown previously to contain parvalbumin immunoreactivity, were nearly all ensheathed by perineuronal nets. There was a population of small parvalbumin-immunoreactive neurons which did not possess perineuronal nets, and which were not encountered with the intracellular electrodes. The other three neuron types in the MS/DB did not contain parvalbumin immunoreactivity or perineuronal nets. In keeping with this neurochemical profile for electrophysiologically identified neurons, burst-firing neurons had action potential parameters more similar to those of regular spiking than of fast spiking neurons. We conclude that fast spiking neurons, presumed to be GABAergic septohippocampal projection neurons, are surrounded by supportive structures to enable the high level of neuronal discharge required for producing disinhibition of hippocampal pyramidal neurons.


Asunto(s)
Banda Diagonal de Broca/fisiología , Neuronas/metabolismo , Oligodendroglía/fisiología , Parvalbúminas/metabolismo , Tabique del Cerebro/fisiología , Potenciales de Acción/fisiología , Animales , Banda Diagonal de Broca/citología , Electrofisiología , Femenino , Inmunohistoquímica , Técnicas In Vitro , Lisina/análogos & derivados , Masculino , Potenciales de la Membrana/fisiología , Microscopía Fluorescente , Red Nerviosa/citología , Red Nerviosa/fisiología , Oligodendroglía/metabolismo , Técnicas de Placa-Clamp , Ratas , Ratas Wistar , Tabique del Cerebro/citología
20.
J Biol Chem ; 275(7): 4713-8, 2000 Feb 18.
Artículo en Inglés | MEDLINE | ID: mdl-10671502

RESUMEN

Beta-amyloid protein is thought to underlie the neurodegeneration associated with Alzheimer's disease by inducing Ca(2+)-dependent apoptosis. Elevated neuronal expression of the proinflammatory cytokine interleukin-1beta is an additional feature of neurodegeneration, and in this study we demonstrate that interleukin-1beta modulates the effects of beta-amyloid on Ca(2+) homeostasis in the rat cortex. beta-Amyloid-(1-40) (1 microM) caused a significant increase in (45)Ca(2+) influx into rat cortical synaptosomes via activation of L- and N-type voltage-dependent Ca(2+) channels and also increased the amplitude of N- and P-type Ca(2+) channel currents recorded from cultured cortical neurons. In contrast, interleukin-1beta (5 ng/ml) reduced the (45)Ca(2+) influx into cortical synaptosomes and inhibited Ca(2+) channel activity in cultured cortical neurons. Furthermore, the stimulatory effects of beta-amyloid protein on Ca(2+) influx were blocked following exposure to interleukin-1beta, suggesting that interleukin-1beta may govern neuronal responses to beta-amyloid by regulating Ca(2+) homeostasis.


Asunto(s)
Péptidos beta-Amiloides/fisiología , Canales de Calcio Tipo L/fisiología , Calcio/metabolismo , Interleucina-1/fisiología , Neuronas/metabolismo , Fragmentos de Péptidos/fisiología , Sinaptosomas/metabolismo , Animales , Células Cultivadas , Corteza Cerebral/citología , Corteza Cerebral/metabolismo , Homeostasis , Activación del Canal Iónico , Transporte Iónico , Ratas
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