Nanomolar oxytocin synergizes with weak electrical afferent stimulation to activate the locomotor CPG of the rat spinal cord in vitro.

Synergizing the effect of afferent fibre stimulation with pharmacological interventions is a desirable goal to trigger spinal locomotor activity, especially after injury. Thus, to better understand the mechanisms to optimize this process, we studied the role of the neuropeptide oxytocin (previously shown to stimulate locomotor networks) on network and motoneuron properties using the isolated neonatal rat spinal cord. On motoneurons oxytocin (1 nM-1 \u3bcM) generated sporadic bursts with superimposed firing and dose-dependent depolarization. No desensitization was observed despite repeated applications. Tetrodotoxin completely blocked the effects of oxytocin, demonstrating the network origin of the responses. Recording motoneuron pool activity from lumbar ventral roots showed oxytocin mediated depolarization with synchronous bursts, and depression of reflex responses in a stimulus and peptide-concentration dependent fashion. Disinhibited bursting caused by strychnine and bicuculline was accelerated by oxytocin whose action was blocked by the oxytocin antagonist atosiban. Fictive locomotion appeared when subthreshold concentrations of NMDA plus 5HT were coapplied with oxytocin, an effect prevented after 24 h incubation with the inhibitor of 5HT synthesis, PCPA. When fictive locomotion was fully manifested, oxytocin did not change periodicity, although cycle amplitude became smaller. A novel protocol of electrical stimulation based on noisy waveforms and applied to one dorsal root evoked stereotypic fictive locomotion. Whenever the stimulus intensity was subthreshold, low doses of oxytocin triggered fictive locomotion although oxytocin per se did not affect primary afferent depolarization evoked by dorsal root pulses. Among the several functional targets for the action of oxytocin at lumbar spinal cord level, the present results highlight how small concentrations of this peptide could bring spinal networks to threshold for fictive locomotion in combination with other protocols, and delineate the use of oxytocin to strengthen the efficiency of electrical stimulation to activate locomotor circuits

Comparative analysis of metazoan chromatin organization

Genome function is dynamically regulated in part by chromatin, which consists of the histones, non-histone proteins and RNA molecules that package DNA. Studies in Caenorhabditis elegans and Drosoph ..

Identification of genetic variants associated with Huntington's disease progression: a genome-wide association study

Background Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate a novel measure of disease progression and to identify genetic markers associated with this progression measure. Methods We generated a progression score on the basis of principal component analysis of prospectively acquired longitudinal changes in motor, cognitive, and imaging measures in the 218 indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008–11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers (data collected 2003–13). We did a genome-wide association analyses in terms of progression for 216 TRACK-HD participants and 1773 REGISTRY participants, then a meta-analysis of these results was undertaken. Findings Longitudinal motor, cognitive, and imaging scores were correlated with each other in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression in TRACK-HD and REGISTRY gave a genome-wide significant signal (p=1·12 × 10−10) on chromosome 5 spanning three genes: MSH3, DHFR, and MTRNR2L2. The genes in this locus were associated with progression in TRACK-HD (MSH3 p=2·94 × 10−8 DHFR p=8·37 × 10−7 MTRNR2L2 p=2·15 × 10−9) and to a lesser extent in REGISTRY (MSH3 p=9·36 × 10−4 DHFR p=8·45 × 10−4 MTRNR2L2 p=1·20 × 10−3). The lead single nucleotide polymorphism (SNP) in TRACK-HD (rs557874766) was genome-wide significant in the meta-analysis (p=1·58 × 10−8), and encodes an aminoacid change (Pro67Ala) in MSH3. In TRACK-HD, each copy of the minor allele at this SNP was associated with a 0·4 units per year (95% CI 0·16–0·66) reduction in the rate of change of the Unified Huntington's Disease Rating Scale (UHDRS) Total Motor Score, and a reduction of 0·12 units per year (95% CI 0·06–0·18) in the rate of change of UHDRS Total Functional Capacity score. These associations remained significant after adjusting for age of onset. Interpretation The multidomain progression measure in TRACK-HD was associated with a functional variant that was genome-wide significant in our meta-analysis. The association in only 216 participants implies that the progression measure is a sensitive reflection of disease burden, that the effect size at this locus is large, or both. Knockout of Msh3 reduces somatic expansion in Huntington's disease mouse models, suggesting this mechanism as an area for future therapeutic investigation

Über die Wirkung von Röntgenstrahlen auf den Zellstoffwechsel : I. Die Beeinflussung des Gasstoffwechsels und der Glykolyse von isoliertem Gewebe durch Röntgenstrahlen

I. X-irradiation of isolated rat diaphragm with 10 to 200 kr produces a change in tissue metabolism which we schematize in two successive phases: 1st phase: Increase of oxygen comsumption, proportional to the dosage; an even greater increase of CO2 production; QCO2/QO2 > 1, that is, aerobic glycolysis; inhibition of anaerobic glycolysis. 2nd phase: Reduction of oxygen consumption, proportional to the dosage (over 65 kr the Qo2 decreases below the control); an even greater decrease of CO2 production: QCO2/QO2 > 1; a greater inhibition of anaerobic glycolysis. With 200 kr or more no increase of respiration appears, but instead from the beginning there is a reduction of the metabolism as described in the second phase. II. A similar effect is found in rat liver and in frog heart tissue. III. When the tissue was incubated in the homologus serum no change in the quality of the described effect was observed. Under our experimental conditions the tissue was X-irradiated within a small quantity of incubation medium and immediately afterwards placed in a fresh medium; this limits the effect of oxidative radicals (arising in the X-irradiated water) upon the tissue. IV. We set forth the experimental hypothesis that all the described changes in the metabolism of the cell after X-irradiation depend upon a primary alteration of electrolyte balance in the cell, especially of the potassium/sodium relationship. The well known decrease of glycolysis after X-irradiation is a consequence of the loss of potassium from the X-irradiated cell

Engineering of a FGM Interlayer to Reduce the Thermal Stresses Inside the PFCs

A substantial contribution of the stresses that arise inside the Plasma-Facing Components (PFCs) when a heat load is applied is caused by the mismatch of the Coefficient of Thermal Expansion (CTE) between the armor, usually made of tungsten (W), and the heat sink. A potential way to reduce such contribution to the secondary stresses is the use of an interlayer made with a Functionally Graded Material (FGM), to be interposed between the two sub-components. By tailoring the W concentration in the volume of the FGM, one can engineer the CTE in such a way that the thermal stresses are reduced inside the PFC. To minimize and, theoretically, reduce to zero the stresses due to the CTE mismatch, the FGM should ensure kinematic continuity between the armor and the heat sink, in a configuration where they deform into exactly the shape they would assume if they were detached from each other. We will show how this condition occurs when the mean thermal strain of each sub-component is the same. This work provides a methodology to determine the thickness and the spatial concentration function of the FGM able to ensure the necessary kinematic continuity between the two sub-components subjected to a generic temperature field monotonously varying in the thickness, while remaining stress-free itself. A method for the stratification of such ideal FGM is also presented. Additionally, it will be shown that the bending of the PFC, if allowed by the kinematic boundary conditions, does not permit, at least generally, the coupling of the expansion of the armor and of the heat sink. As an example of our methodology, a study case of the thermomechanical design of a steel-based PFC with an engineered W/steel FGM interlayer is presented. In such an exercise, we show that our procedure of engineering a FGM interlayer is able to reduce the linearized secondary stress of more than 24% in the most critical section of the heat sink, satisfying all the design criteria

Oxytocin indirectly depolarizes single motoneurons.

<p>A, intracellular recording from a single motoneuron (lL4) shows that, after 5 min, oxytocin (100 nM; see gray bars) depolarises membrane potential and evokes high frequency spiking. Initial resting potential (V_m) is −70 mV. B, lower concentration of oxytocin (1 nM; see bar) determines a slower (8 min) onset of bursts with intense firing activity despite minimal baseline depolarization that persists throughout the long neuropeptide perfusion (40 min). Initial resting potential is −75 mV. Note that the 10 min trace break corresponds to the time spent in generating tests for the cell I/V curve. Different cell from A. C, two consecutive applications of oxytocin (1 μM) induce reproducible responses when timed 20 min apart. Initial resting potential is −69 mV. Different cell from A, B. D, dose response plots of membrane potential depolarization (from baseline; fitted with sigmoidal curve; filled circles) and input resistance (as percentage value with respect to control; gray triangles) for cumulative doses of oxytocin (log scale). Symbols *, § indicate significant difference versus the higher concentrations data (Kruskal-Wallis one way ANOVA on ranks followed by all pairwise multiple comparison with Dunn's method; P<0.001; the number of preparations used to calculate the mean is shown in parentheses; the error bars indicate SD). E, sample trace from a single motoneuron (lL5) demonstrates that oxytocin (100 nM) fails to depolarize the cell when applied (see arrow) in the presence of network block by TTX (250 nM; gray bar).</p

Disinhibited bursting is accelerated by oxytocin, an effect prevented by its selective antagonist.

<p>A, regular disinhibited rhythm induced by 1 μM strychnine and 20 μM bicuculline (top trace in A) is stably sped up (with burst length reduction) by the cumulative addition of oxytocin (5, 100 nM and 1 μM), without any further modifications in the characteristics of single bursts. The cumulative dose response curve in B indicates significant reduction in the average period (expressed as a percentage of the mean variation), starting at concentration of 5 nM (*; one way ANOVA followed by multiple comparison vs strychnine + bicuculline only with Dunnett's method; P = <0.001; the number of preparations used to calculate the mean is shown in parentheses; the error bars indicate SD). C, on a different preparation, a stable disinhibited rhythm (top) remains unchanged by the addition of the OTRs antagonist, atosiban (5 μM, middle), which prevents any acceleration during the following addition of oxytocin (100 nM). The histograms in D, which report the average value of period of disinhibited rhythm in correspondence to the different treatments, show significant rhythm acceleration in the presence of oxytocin (100 nM), an effect reverted to control values after washout (30 min), and prevented by the addition of atosiban (5 nM), which does not <i>per se</i> vary rhythm periodicity (*; Kruskal-Wallis one way ANOVA on ranks followed by multiple comparison vs strychnine + bicuculline only with Dunn's method; P = 0,038; the number of preparations used to calculate the mean is shown in parentheses; the error bars indicate SD).</p

Oxytocin reinstates fictive locomotor oscillations, despite subthreshold concentrations of neurochemicals.

<p>Alternating oscillations of a stable FL, evoked by the addition of 3 μM NMDA and 10 μM 5HT (A), slow down once the concentration of neurochemicals is finely titrated down to 1.7 μM NMDA and 5 μM 5HT (B). A further decrease in NMDA (1.5 μM) + 5HT (4 μM) suppresses locomotor-like discharges, which are finally replaced by a tonic activity (C). By adding oxytocin (1 nM) to subthreshold concentrations of NMDA and 5HT, no FL oscillations reappear (D). By augmenting the neuropeptide to 100 nM, locomotor-like oscillations are restored (E). Further increase in oxytocin (1 μM) does not affect periodicity of the reinstated pattern nor its cycle amplitude (F).</p