Arthrogryposis in Murrah buffaloes in southern Brazil

Congenital arthrogryposis is described in a Murrah buffalo herd. The disease was characterized by curvature and multiple articular rigidity of the hindlimbs or of all limbs without associated defects except for one case of brachygnatia. Histologically there was reduction of motor neurons from the ventral horns of the spinal cord and hypoplasia of the limb muscles. Analysis of the herd breeding records suggests that the disease is genetically transmitted by an autosomal recessive trait.

Interaction between affordance and handedness recognition: a chronometric study

The visualization of tools and manipulable objects activates motor-related areas in the cortex, facilitating possible actions toward them. This pattern of activity may underlie the phenomenon of object affordance. Some cortical motor neurons are also covertly activated during the recognition of body parts such as hands. One hypothesis is that different subpopulations of motor neurons in the frontal cortex are activated in each motor program; for example, canonical neurons in the premotor cortex are responsible for the affordance of visual objects, while mirror neurons support motor imagery triggered during handedness recognition. However, the question remains whether these subpopulations work independently. This hypothesis can be tested with a manual reaction time (MRT) task with a priming paradigm to evaluate whether the view of a manipulable object interferes with the motor imagery of the subject's hand. The MRT provides a measure of the course of information processing in the brain and allows indirect evaluation of cognitive processes. Our results suggest that canonical and mirror neurons work together to create a motor plan involving hand movements to facilitate successful object manipulation.

Reliability of a new measure of motoneuron excitability

Objectlve:--This study examined the intraclass reliability· of different measures of the excitability of the Hoffmann reflex, derived from stimulus-response curves. The slope of the regression line of the H-reflex stimulus-response curve advocated by Funase et al. (1994) was also compared to the peak of the first derivative of the H-reflex stimulus-response curve (dHIdVmax), a new measure introduced in this investigation. A secondary purpose was to explore the possibility of mood as a covariate when measuring excitability of the H-reflex arc. Methods: The H-reflex amplitude at a stimulus intensity corresponding to 5% of the maximum M-wave (Mmax) is an established measure that was used as an additional basis of comparison. The H-reflex was elicited in the soleus for 24 subjects (12 males and 12 females) on five separate days. Vibration was applied to the Achilles tendon prior to stimulation to test the sensitivity of the measures on test day four. The means of five evoked potentials at each gradually increasing intensity, from below H-reflex threshold to above Mmax, were used to create both the H-reflex and M-wave stimulus response curves for each subject across test days. The mood of the subjects was assessed using the Subjective Exercise Experience Scale (SEES) prior to the stimulation protocol each day. Results: There was a modest decrease in all H-reflex measures from the first to third test day, but it was non-significant (P's>0.05). All measures of the H-reflex exhibited a profound reduction following vibration on test day four, and then returned to baseline levels on test day five (P's<0.05). The intraclass correlation coefficient (ICC) for H-reflex amplitude at 5% of Mmax was 0.85. The ICC for the slope of the regression line was 0.79 while it was 0.89 for dH/dVmax. Maximum M-wave amplitude had an ICC of 0.96 attesting to careful methodological controls. The SEES subscales of fatigue and psychological well-being remained unchanged IV across the five days. The psychological distress subscale (PO.05). Conclusions: The peak of the first derivative of the H-reflex stimulus-response curve (dH/dVmax) was shown to have comparable reliability and sensitivity to other more established measures of excitability. Psychological distress and the amplitude of the H-reflex at 5% Mmax follow similar trends across days, however there was no significant correlation between the two measures. Significance: The proposed method appears to be a more robust measure ofH-reflex excitability than the other methods tested. As such it would be an advantageous method to apply in clinical and investigative settings. Additionally, the results suggest that the relationship between psychological distress and H-reflex amplitude should be investigated further.

Modulation of muscle contraction by a FMRFamide-related peptide

A FMRFamide-like neuropeptide with the sequence "DRNFLRF-NH2" was recently isolated from pericardial organs of crayfish (Mercier et aI., Peptides, 14, 137-143, 1993). This neuropeptide, referred to as "DF2'" has already been shown to elicit cardioexcitation and to enhance synaptic transmission at neuromuscular junctions. Possible effects ofDF2 on muscle were investigated using superficial extensor muscles of the abdomen of the crayfish, Procambarus clar/ai. These muscles are of the tonic type and generate slow contractions that affect posture. DF2, at concentrations of 10-8 M or higher, increased muscle tonus and induced spontaneous, rhythmic contractions. These effects were antagonized by 5 rnM Mn2+ but not by lO-7M tetrodotoxin (TTX). Thus, they represent direct actions on muscle cells (rather than effects on motor neurons) and are likely to involve calcium influx. In contrast, deep abdominal extensor muscles, responsible for rapid swimming movements, and superficial flexor muscles do not generate contractions in response to the peptide. 2 Spontaneous contractions were also induced in the superficial extensor muscles by decreasing the temperature to II-13°C. Such contractions were also TTX-insensitive and they were antagonized by adding calcium channel blockers (Mn2+, Cd2+ or Ni2+) or by removing calcium from the bathing solution. This suggests that the spontaneous contractions depend on an influx of calcium from the extracellular solution. N-type and L-type voltage dependent calcium channel blockers did not reduce the effect of the peptide or the spontaneous contractions suggesting that calcium influx is not through N- or L-type calcium channels.

Identification of novel retinoid receptors and their roles in vertebrate and invertebrate nervous systems

In vertebrates, signaling by retinoic acid (RA) is known to play an important role in embryonic development, as well as organ homeostasis in the adult. In organisms such as adult axolotls and newts, RA is also important for regeneration of the CNS, limb, tail, and many other organ systems. RA mediates many of its effects in development and regeneration through nuclear receptors, known as retinoic acid receptors (RARs) and retinoid X receptors (RXRs). This study provides evidence for an important role of the RA receptor, RAR~2, in ,( '. regeneration ofthe spinal cord and tail of the adult newt. It has previously been proposed that the ability of the nervous system to regenerate might depend on the presence or absence of this RAR~2 isoform. Here, I show for the very first time, that the regenerating spinal cord of the adult newt expresses this ~2 receptor isoform, and inhibition of retinoid signaling through this specific receptor with a selective antagonist inhibits tail and spinal cord regeneration. This provides the first evidence for a role of this receptor in this process. Another species capable of CNS ~~generation in the adult is the invertebrate, " Lymnaea stagnalis. Although RA has been detected in a small number of invertebrates (including Lymnaea), the existence and functional roles of the retinoid receptors in most invertebrate non-chordates, have not been previously studied. It has been widely believed, however, that invertebrate non-chordates only possess the RXR class of retinoid receptors, but not the RARs. In this study, a full-length RXR cDNA has been cloned, which was the first retinoid receptor to be discovered in Lymnaea. I then went on to clone the very first full-length RAR eDNA from any non-chordate, invertebrate species. The functional role of these receptors was examined, and it was shown that normal molluscan development was altered, to varying degrees, by the presence of various RXR and RAR agonists or antagonists. The resulting disruptions in embryogenesis ranged from eye and shell defects, to complete lysis of the early embryo. These studies strongly suggest an important role for both the RXR and RAR in non-chordate development. The molluscan RXR and RAR were also shown to be expressed in the adult, nonregenerating eNS, as well as in individual motor neurons regenerating in culture. More specifically, their expression displayed a non-nuclear distfibution, suggesting a possible non-genomic role for these 'nuclear' receptors. It was shown that immunoreactivity for the RXR was present in almost all regenerating growth cones, and (together with N. Farrar) it was shown that this RXR played a novel, non-genomic role in mediating growth cone turning toward retinoic acid. Immunoreactivity for the novel invertebrate RAR was also found in the regenerating growth cones, but future work will be required to determine its functional role in nerve cell regeneration. Taken together, these data provide evidence for the importance of these novel '. retinoid receptors in development and regeneration, particularly in the adult nervous system, and the conservation of their effects in mediating RA signaling from invertebrates to vertebrates.

Cell-selective modulation of the Drosophila neuromuscular system by a neuropeptide

Neuropeptides can modulate physiological properties of neurons in a cell-specific manner. The present work examines whether a neuropeptide can also modulate muscle tissue in a cell-specific manner, using identified muscle cells in third instar larvae of fruit flies. DPKQDFMRFa, a modulatory peptide in the fruit fly Drosophila melanogaster, has been shown to enhance transmitter release from motor neurons and to elicit contractions by a direct effect on muscle cells. We report that DPKQDFMRFa causes a nifedipine-sensitive drop in input resistance in some muscle cells (6 and 7) but not others (12 and 13). The peptide also increased the amplitude of nerve-evoked contractions and compound excitatory junctional potentials (EJPs) to a greater degree in muscle cells 6 and 7 than 12 and 13. Knocking down FMRFa receptor (FR) expression separately in nerve and muscle indicate that both presynaptic and postsynaptic FR expression contributed to the enhanced contractions, but EJP enhancement was due mainly to presynaptic expression. Muscle-ablation showed that DPKQDFMRFa induced contractions and enhanced nerve-evoked contractions more strongly in muscle cells 6 and 7 than cells 12 and 13. In situ hybridization indicated that FR expression was significantly greater in muscle cells 6 and 7 than 12 and 13. Taken together, these results indicate that DPKQDFMRFa can elicit cell-selective effects on muscle fibres. The ability of neuropeptides to work in a cell-selective manner on neurons and muscle cells may help explain why so many peptides are encoded in invertebrate and vertebrate genomes.

clc is co-expressed with clf or cntfr in developing mouse muscles

Affiliation: Jean-François Gauchat : Département de Pharmacologie, Faculté de médecine, Université de Montréal

Influence de TDP-43 sur la régulation de hnRNP A1 : un impact potentiel sur la sclérose latérale amyotrophique

La SLA est une maladie neurodégénérative fatale se déclenchant tardivement. Elle est caractérisée par la perte des neurones moteurs supérieurs et inférieurs. Jusqu’à présent, aucun traitement ne permet de ralentir ou de guérir la maladie de façon robuste. De récentes découvertes portant sur TDP-43 et hnRNP A1 y ont identifié des mutations reliées à des cas de SLA. Comme les deux possèdent de multiples fonctions dans le métabolisme de l’ARN, l’impact de ces mutations devient difficile à définir. Notre hypothèse est que TDP-43 régule hnRNP A1 et que les mutations causant la SLA dérégulent ce mécanisme, aboutissant ainsi à un impact majeur sur la vulnérabilité des neurones moteurs. Nos résultats démontrent que TDP-43 lie l’ARNm de hnRNP A1, mais n’affecte pas sa stabilité. En revanche, TDP-43 réprime l’expression de hnRNP A1. Ce mécanisme pourrait être appliqué in vivo où le ratio protéique hnRNP A1B/A1 augmente chez les souris âgées et davantage chez les TDP-43A315T dans la région cervicale et lombaire de la moelle épinière. Cette différence n’est pas causée par un défaut de l’épissage alternatif. Aussi, la mutation TDP-43A315T serait davantage responsable de cette différence que la surexpression de TDP-43 (résultats obtenus en culture). L’impact d’une telle augmentation sur la cellule pourrait être la formation d’agrégats puisque la forme hnRNP A1B possède quatre domaines de fibrillation de plus que hnRNP A1. Nos résultats pourraient donc fournir un mécanisme potentiel de la formation d’inclusions cytoplasmiques reconnues comme étant une des caractéristiques pathologiques principales de la SLA.

Uncovering the role of misfolded SOD1 in the pathogenesis of Amyotrophic Lateral Sclerosis

La sclérose latérale amyothrophique (SLA) est une maladie neurodégénérative charactérisée par la perte des neurones moteurs menant à la paralysie et à la mort. Environ 20% des cas familiaux de la SLA sont causés par des mutations de la superoxyde dismutase 1 (SOD1), conduisant vers un mauvais repliement de la protéine SOD1, ce qui a comme conséquence un gain de fonction toxique. Plusieurs anticorps spécifiques pour la forme mal repliée de la protéine ont été générés et utilisés comme agent thérapeutique dans des modèles précliniques. Comment le mauvais repliement de SOD1 provoque la perte sélective des neurones moteurs demeure non résolu. La morphologie, le bilan énergétique et le transport mitochondrial sont tous documentés dans les modèles de la SLA basés sur SOD1, la détérioration des mitochondries joue un rôle clé dans la dégénération des neurones moteurs. De plus, la protéine SOD1 mal repliée s’associe sélectivement sur la surface des mitochondries de la moelle épinière chez les modèles de rongeurs de la SLA. Notre hypothèse est que l’accumulation de la protéine SOD1 mal repliée sur les mitochondries pourrait nuire aux fonctions mitochondriales. À cette fin, nous avons développé un nouvel essai par cytométrie de flux afin d’isoler les mitochondries immunomarquées avec des anticorps spécifiques à la forme malrepliée de SOD1 tout en évaluant des aspects de la fonction mitochondriale. Cette méthode permettra de comparer les mitochondries portant la protéine SOD1 mal repliée à celles qui ne la portent pas. Nous avons utilisé un anticorps à conformation spécifique de SOD1, B8H10, pour démontrer que la protéine mal repliée SOD1 s’associe avec les mitochondries de la moelle épinière des rat SOD1G93A d’une manière dépendante du temps. Les mitochondries avec la protéine mal repliée SOD1 B8H10 associée à leur surface (B8H10+) ont un volume et une production excessive de superoxyde significativement plus grand, mais possèdent un potentiel transmembranaire comparable aux mitochondries B8H10-. En outre, la présence de la protéine mal repliée SOD1 reconnue par B8H10 coïncide avec des niveaux plus élevés de la forme pro-apoptotique de Bcl-2. L’immunofluorescence de sections de moelle épinière du niveau lombaire avec l’anticorps spécifique à la conformation B8H10 et AMF7-63, un autre anticorps conformationnel spécifique de SOD1, démontre des motifs de localisations distincts. B8H10 a été trouvé principalement dans les neurones moteurs et dans plusieurs points lacrymaux dans tout le neuropile. Inversement, AMF7-63 a marqué les neurones moteurs ainsi qu’un réseau fibrillaire distinctif concentré dans la corne antérieure. Au niveau subcellulaire, SOD1 possèdant la conformation reconnu par AMF7-63 est aussi localisée sur la surface des mitochondries de la moelle épinière d’une manière dépendante du temps. Les mitochondries AMF7-63+ ont une augmentation du volume comparé aux mitochondries B8H10+ et à la sous-population non marquée. Cependant, elles produisent une quantité similaire de superoxyde. Ensemble, ces données suggèrent qu’il y a plusieurs types de protéines SOD1 mal repliées qui convergent vers les mitochondries et causent des dommages. De plus, différentes conformations de SOD1 apportent une toxicité variable vers les mitochondries. Les protéines SOD1 mal repliées réagissant à B8H10 et AMF7-63 sont présentes en agrégats dans les fractions mitochondriales, nous ne pouvons donc pas prendre en compte leurs différents effets sur le volume mitochondrial. Les anticorps conformationnels sont des outils précieux pour identifier et caractériser le continuum du mauvais repliement de SOD1 en ce qui concerne les caractéristiques biochimiques et la toxicité. Les informations présentes dans cette thèse seront utilisées pour déterminer le potentiel thérapeutique de ces anticorps.

Altérations synaptiques à la jonction neuromusculaire dans un modèle murin de sclérose latérale amyotrophique

La sclérose latérale amyotrophique est une maladie neurodégénérative fatale caractérisée par la dégénérescence progressive des neurones moteurs centraux et périphériques. L’un des premiers signes de la maladie est la dénervation de la jonction neuromusculaire (JNM). Les diverses unités motrices (UM) ne présentent toutefois pas la même vulnérabilité à la dénervation dans la SLA: les UM rapide fatigables sont en fait les plus vulnérables et les UM lentes sont les plus résistantes. Alors que des études précédentes ont démontré dans plusieurs modèles animaux de la SLA de nombreuses variations synaptiques, les découvertes ont été contradictoires. Par ailleurs, le type d’UM n’a pas été tenu en compte dans ces divers travaux. Nous avons donc émis l’hypothèse que la présence de la mutation SOD1 pourrait affecter différemment la transmission synaptique des UM, en accord avec leur vulnérabilité sélective. En effectuant des enregistrements électrophysiologiques et de l’immunohistochimie, nous avons étudié la transmission synaptique des différents types d’UM du muscle à contraction rapide Extensor Digitorum Longus (EDL; rapide fatigable (FF) MU) et du muscle à contraction lente Soleus (SOL; lente (S) and rapide fatigue-résistante (FR) MU) de la souris SOD1G37R et leur congénères WT. Pour identifier le type d’UM, un marquage par immunohistochimie des chaînes de myosine a été effectué. Un triple marquage de la JNM a également été effectué pour vérifier son intégrité aux différents stades de la maladie. À P160, dans la période asymptomatique de la maladie, alors qu’aucune altération morphologique n’était présente, l’activité évoquée était déjà altérée différemment en fonction des UM. Les JNMs FF mutantes ont démontré une diminution de l’amplitude des potentiels de plaque motrice (PPM) et du contenu quantique, alors que les JNMs lentes démontraient pratiquement le contraire. Les JNMs FR montraient quant à elles une force synaptique semblable au WT. À P380, dans la période présymtomatique, de nombreuses altérations morphologiques ont été observées dans le muscle EDL, incluant la dénervation complète, l’innervation partielle et les extensions du nerf. La transmission synaptique évoquée des UM FF étaient toujours réduites, de même que la fréquence des potentiels de plaque motrice miniatures. À P425, à l’apparition des premiers symptômes, l’activité synaptique des JNMs S était redevenue normale alors que les JNMs FR ont montré à ce moment une diminution du contenu quantique par rapport au contrôle. De manière surprenante, aucun changement du ratio de facilitation n’a été observé malgré les changements flagrants de la force synaptique. Ces résultats révèlent que la fonction de la JNM est modifiée différemment en fonction de la susceptibilité des UM dans l’ALS. Cette étude fournit des pistes pour une meilleure compréhension de la physiologie de la JNM durant la pathologie qui est cruciale au développement d’une thérapie adéquate ciblant la JNM dans la SLA.

Cholinergic receptor subtypes functional regulation in spinal cord injured monoplegic rats

The present study deals with the Cholinergic Receptor subtypes functional regulation in spinal cord injured monoplegic rats: Effect of 5-HT GABA and bone marrow cells.Spinal cord injury causes permanent and irrevocable motor deficits and neurodegeneration. Disruption of the spinal cord leads to diminished transmission of descending control from the brain to motor neurons and ascending sensory information. Behavioural studies showed deficits in motor control and coordination in SCI rats. Cholinergic system plays an important role in SCI, the evaluation of which provides valuable insight on the underlying mechanisms of motor deficit that occur during SCI. The cholinergic transmission was studied by assessing the muscarinic and nicotinic receptors; cholinergic enzymes- ChAT and AChE; second messenger enzyme PLC; transcription factor CREB and second messengers - IP3, cAMP and cGMP. We observed a decrease in the cholinergic transmission in the brain and spinal cord of SCI rats. The disrupted cholinergic system is the indicative of motor deficit and neuronal degeneration in the spinal cord and brain regions. SCI mediated oxidative stress and apoptosis leads to neuronal degeneration in SCI rats. The decreased expression of anti oxidant enzymes – SOD, GPx and neuronal cell survival factors - BDNF, GDNF, IGF-1, Akt and cyclin D2 along with increased expression of apoptotic factors – Bax, caspase-8, TNFa and NF-kB augmented the neuronal degeneration in SCI condition. BMC administration in combination with 5-HT and GABA in SCI rats showed a reversal in the impaired cholinergic neurotransmission and reduced the oxidative stress and apoptosis. It also enhanced the expression of cell survival factors in the spinal cord region. In SCI rats treated with 5-HT and GABA, the transplanted BMC expressed NeuN confirming that 5-HT and GABA induced the differentiation and proliferation of BMC to neurons in the spinal cord. Neurotrophic factors and anti-apoptotic elements in SCI rats treated with 5-HT and GABA along with BMC rendered neuroprotective effects accompanied by improvement in behavioural deficits. This resulted in a significant reversal of altered cholinergic neurotransmission in SCI. The restorative and neuro protective effects of BMC in combination with 5-HT and GABA are of immense therapeutic significance in the clinical management of SCI.

Expression of SOD1 G93A or wild-type SOD1 in primary cultures of astrocytes down-regulates the glutamate transporter GLT-1: lack of involvement of oxidative stress

Glutamate excitotoxicity is implicated in the aetiology of amyotrophic lateral sclerosis (ALS) with impairment of glutamate transport into astrocytes a possible cause of glutamate-induced injury to motor neurons. It is possible that mutations of Cu/Zn superoxide dismutase (SOD1), responsible for about 20% of familial ALS, down-regulates glutamate transporters via oxidative stress. We transfected primary mouse astrocytes to investigate the effect of the FALS-linked mutant hSOD1(G93A) and wild-type SOD1 (hSOD1(wt)) on the glutamate uptake system. Using western blotting, immunocytochemistry and RT-PCR it was shown that expression of either hSOD1(G93A) or hSOD1(wt) in astrocytes produced down-regulation of the levels of a glutamate transporter GLT-1, without alterations in its mRNA level. hSOD1(G93A) or hSOD1(wt) expression caused a decrease of the monomeric form of GLT-1 without increasing oxidative multimers of GLT-1. The effects were selective to GLT-1, since another glutamate transporter GLAST protein and mRNA levels were not altered. Reflecting the decrease in GLT-1 protein, [H-3]D-aspartate uptake was reduced in cultures expressing hSOD1(G93A) or hSOD1(wt). The hSOD1-induced decline in GLT-1 protein and [H-3]D-aspartate uptake was not blocked by the antioxidant Trolox nor potentiated by antioxidant depletion using catalase and glutathione peroxidase inhibitors. Measurement of 2',7'-dichlorofluorescein (DCF)-induced fluorescence revealed that expression of hSOD1(G93A) or hSOD1(wt) in astrocytes does not lead to detectable increase of intracellular reactive oxygen species. This study suggests that levels of GLT-1 protein in astrocytes are reduced rapidly by overexpression of hSOD1, and is due to a property shared between the wild-type and G93A mutant form, but does not involve the production of intracellular oxidative stress.

Generation, description and storage of dendritic morphology data

It is generally assumed that the variability of neuronal morphology has an important effect on both the connectivity and the activity of the nervous system, but this effect has not been thoroughly investigated. Neuroanatomical archives represent a crucial tool to explore structure–function relationships in the brain. We are developing computational tools to describe, generate, store and render large sets of three–dimensional neuronal structures in a format that is compact, quantitative, accurate and readily accessible to the neuroscientist. Single–cell neuroanatomy can be characterized quantitatively at several levels. In computer–aided neuronal tracing files, a dendritic tree is described as a series of cylinders, each represented by diameter, spatial coordinates and the connectivity to other cylinders in the tree. This ‘Cartesian’ description constitutes a completely accurate mapping of dendritic morphology but it bears little intuitive information for the neuroscientist. In contrast, a classical neuroanatomical analysis characterizes neuronal dendrites on the basis of the statistical distributions of morphological parameters, e.g. maximum branching order or bifurcation asymmetry. This description is intuitively more accessible, but it only yields information on the collective anatomy of a group of dendrites, i.e. it is not complete enough to provide a precise ‘blueprint’ of the original data. We are adopting a third, intermediate level of description, which consists of the algorithmic generation of neuronal structures within a certain morphological class based on a set of ‘fundamental’, measured parameters. This description is as intuitive as a classical neuroanatomical analysis (parameters have an intuitive interpretation), and as complete as a Cartesian file (the algorithms generate and display complete neurons). The advantages of the algorithmic description of neuronal structure are immense. If an algorithm can measure the values of a handful of parameters from an experimental database and generate virtual neurons whose anatomy is statistically indistinguishable from that of their real counterparts, a great deal of data compression and amplification can be achieved. Data compression results from the quantitative and complete description of thousands of neurons with a handful of statistical distributions of parameters. Data amplification is possible because, from a set of experimental neurons, many more virtual analogues can be generated. This approach could allow one, in principle, to create and store a neuroanatomical database containing data for an entire human brain in a personal computer. We are using two programs, L–NEURON and ARBORVITAE, to investigate systematically the potential of several different algorithms for the generation of virtual neurons. Using these programs, we have generated anatomically plausible virtual neurons for several morphological classes, including guinea pig cerebellar Purkinje cells and cat spinal cord motor neurons. These virtual neurons are stored in an online electronic archive of dendritic morphology. This process highlights the potential and the limitations of the ‘computational neuroanatomy’ strategy for neuroscience databases.

Expression and function of the bile acid receptor GpBAR1 (TGR5) in the murine enteric nervous system

BACKGROUND: Bile acids (BAs) regulate cells by activating nuclear and membrane-bound receptors. G protein coupled bile acid receptor 1 (GpBAR1) is a membrane-bound G-protein-coupled receptor that can mediate the rapid, transcription-independent actions of BAs. Although BAs have well-known actions on motility and secretion, nothing is known about the localization and function of GpBAR1 in the gastrointestinal tract. METHODS: We generated an antibody to the C-terminus of human GpBAR1, and characterized the antibody by immunofluorescence and Western blotting of HEK293-GpBAR1-GFP cells. We localized GpBAR1 immunoreactivity (IR) and mRNA in the mouse intestine, and determined the mechanism by which BAs activate GpBAR1 to regulate intestinal motility. KEY RESULTS: The GpBAR1 antibody specifically detected GpBAR1-GFP at the plasma membrane of HEK293 cells, and interacted with proteins corresponding in mass to the GpBAR1-GFP fusion protein. GpBAR1-IR and mRNA were detected in enteric ganglia of the mouse stomach and small and large intestine, and in the muscularis externa and mucosa of the small intestine. Within the myenteric plexus of the intestine, GpBAR1-IR was localized to approximately 50% of all neurons and to >80% of inhibitory motor neurons and descending interneurons expressing nitric oxide synthase. Deoxycholic acid, a GpBAR1 agonist, caused a rapid and sustained inhibition of spontaneous phasic activity of isolated segments of ileum and colon by a neurogenic, cholinergic and nitrergic mechanism, and delayed gastrointestinal transit. CONCLUSIONS & INFERENCES: G protein coupled bile acid receptor 1 is unexpectedly expressed in enteric neurons. Bile acids activate GpBAR1 on inhibitory motor neurons to release nitric oxide and suppress motility, revealing a novel mechanism for the actions of BAs on intestinal motility.

Modulation of event-related desynchronization during kinematic and kinetic hand movements

Background Event-related desynchronization/synchronization (ERD/ERS) is a relative power decrease/increase of electroencephalogram (EEG) in a specific frequency band during physical motor execution and mental motor imagery, thus it is widely used for the brain-computer interface (BCI) purpose. However what the ERD really reflects and its frequency band specific role have not been agreed and are under investigation. Understanding the underlying mechanism which causes a significant ERD would be crucial to improve the reliability of the ERD-based BCI. We systematically investigated the relationship between conditions of actual repetitive hand movements and resulting ERD. Methods Eleven healthy young participants were asked to close/open their right hand repetitively at three different speeds (Hold, 1/3 Hz, and 1 Hz) and four distinct motor loads (0, 2, 10, and 15 kgf). In each condition, participants repeated 20 experimental trials, each of which consisted of rest (8–10 s), preparation (1 s) and task (6 s) periods. Under the Hold condition, participants were instructed to keep clenching their hand (i.e., isometric contraction) during the task period. Throughout the experiment, EEG signals were recorded from left and right motor areas for offline data analysis. We obtained time courses of EEG power spectrum to discuss the modulation of mu and beta-ERD/ERS due to the task conditions. Results We confirmed salient mu-ERD (8–13 Hz) and slightly weak beta-ERD (14–30 Hz) on both hemispheres during repetitive hand grasping movements. According to a 3 × 4 ANOVA (speed × motor load), both mu and beta-ERD during the task period were significantly weakened under the Hold condition, whereas no significant difference in the kinetics levels and interaction effect was observed. Conclusions This study investigates the effect of changes in kinematics and kinetics on resulting ERD during repetitive hand grasping movements. The experimental results suggest that the strength of ERD may reflect the time differentiation of hand postures in motor planning process or the variation of proprioception resulting from hand movements, rather than the motor command generated in the down stream, which recruits a group of motor neurons.