Proteomics: in pursuit of effective traumatic brain injury therapeutics

Effective traumatic brain injury (TBI) therapeutics remain stubbornly elusive. Efforts in the field have been challenged by the heterogeneity of clinical TBI, with greater complexity among underlying molecular phenotypes than initially conceived. Future research must confront the multitude of factors comprising this heterogeneity, representing a big data challenge befitting the coming informatics age. Proteomics is poised to serve a central role in prescriptive therapeutic development, as it offers an efficient endpoint within which to assess post-TBI biochemistry. We examine rationale for multifactor TBI proteomic studies and the particular importance of temporal profiling in defining biochemical sequences and guiding therapeutic development. Lastly, we offer perspective on repurposing biofluid proteomics to develop theragnostic assays with which to prescribe, monitor and assess pharmaceutics for improved translation and outcome for TBI patients

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

LEDs and Solid-State Lighting: the potential health issues

International audienc

Modeling the vivid white color of the beetle Calothyrza margaritifera

The elytra of the longhorn Calothyrza margaritifera exhibit bright white zones which appear, under SEM, to be composed of structures looking like long white hairs: flat cone-shaped rods of 100-200 μm in length and a base of 10-20 μm. Each hair is composed of an envelope of chitin or chitin and associated proteins, filled with small agglomerated spheres of the same material, of mean diameter 550 nm. The optical properties of this multiscale structure have been characterized: hemispherical reflectance spectra, bidirectional reflectance spectra, spatial scattering maps. A multiscale optical model, taking into account this complex structure has been developed for predicting the optical properties. Starting from the SEM image, the representative basic scattering structure is extracted, from the scale of the nanometer to the millimeter. By using the Mie theory and solving the Radiative Transfer Equation, the local optical properties of this structure are calculated. Thanks to a 3D modeler the basic structural element is then duplicated with small deviations in its shape, position and orientation for reproducing the overall SEM image. A photon-mapping is then implemented on this 3D structure with a spectral evaluation of illumination maps based on Monte-Carlo ray shooting. The first predictions of this multiscale model are in qualitative and almost quantitative agreement with the white color measured on the elytron of this insect and of its spatial dispersion. The brightness of the visual effect is explained by considerations about the human vision

Activation of 5-HT2A receptors upregulates the function of the neuronal K-Cl cotransporter KCC2

International audienceIn healthy adults, activation of γ-aminobutyric acid (GABA) A and glycine receptors inhibits neurons as a result of low intracellular chloride concentration ([Cl-] i), which is maintained by the potassium chloride cotransporter KCC2. A reduction of KCC2 expression or function is implicated in the pathogenesis of several neurological disorders, including spasticity and chronic pain following spinal cord injury (SCI). Given the critical role of KCC2 in regulating the strength and robustness of inhibition, identifying tools that may increase KCC2 function and, hence, restore endogenous inhibition in pathological conditions is of particular importance. We show that activation of 5-hydroxytryptamine (5-HT) type 2A receptors to se-rotonin hyperpolarizes the reversal potential of inhibitory postsyn-aptic potentials (IPSPs), E IPSP , in spinal motoneurons, increases the cell membrane expression of KCC2 and both restores endogenous inhibition and reduces spasticity after SCI in rats. Up-regulation of KCC2 function by targeting 5-HT 2A receptors, therefore, has therapeutic potential in the treatment of neurological disorders involving altered chloride homeostasis. However, these receptors have been implicated in several psychiatric disorders, and their effects on pain processing are controversial, highlighting the need to further investigate the potential systemic effects of specific 5-HT 2A R ago-nists, such as (4-bromo-3,6-dimethoxybenzocyclobuten-1-yl)methyl-amine hydrobromide (TCB-2). T he neuron-specific K +-Cl-cotransporter KCC2 (encoded by the solute carrier family 12 member 5, Slc12a5) extrudes Cl-and is responsible for the low [Cl-] i in mature neurons (1-3), a prerequisite for hyperpolarizing inhibition mediated by GABA A receptors (GABA A Rs) and glycine receptors (GlyRs). The expression or the function of KCC2 is reduced in several neurological disorders (2, 4), and the resulting slight increase in [Cl-] i (depola-rizing shift of the chloride equilibrium potential, E Cl) dramatically compromises the inhibitory control of firing rate and excitatory inputs (5-7). Given the role of KCC2 in regulating the strength of inhibitory synaptic transmission, identifying tools that may increase KCC2 function and, hence, restore endogenous inhibition in pathological conditions is of particular importance. Spasticity is a disabling complication affecting individuals with spinal cord injury (SCI) and is characterized by a velocity-dependent increase in muscle tone resulting from hyperexcitable stretch reflexes, spasms, and hypersensitivity to normally innocuous sensory stimulations (8, 9). Down-regulation of KCC2 after SCI in rats is implicated in the development of spasticity (10) and chronic pain (11, 12). Notably, the expression of KCC2 in the motoneuron membrane is reduced, and, concomitantly, the density of cyto-plasmic clusters is higher, suggesting that the surface stability of the transporter is reduced in these pathological conditions (10). Mounting evidence indicates that phosphorylation of KCC2 in the C-terminal intracellular domain dynamically regulates its activity and surface expression (1). In particular, phosphorylation by protein kinase (PK)C, enhances KCC2 activity and reduces endo-cytosis (13). Interestingly, activation of 5-hydroxytryptamine type 2 receptors (5-HT 2 Rs) to serotonin stimulates PKC and strengthens the left-right alternation of motor bursts observed during loco-motion (14-16), which rely on reciprocal inhibition (17, 18). We hypothesized that 5-HT 2 R activity modulates KCC2 function and/ or expression. Our results indicate that the activation of the 5-HT 2A R subtype hyperpolarizes E IPSP via a PKC-dependent mechanism , increases KCC2 expression in the plasma membrane of motoneurons, and reduces SCI-induced spasticity. Results Negative Shift of E IPSP and Up-Regulation of KCC2. We first examined the effect of the 5-HT 2A/2B/2C R agonist (±)-2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI) (10 μM; Table S1) on E IPSP in control neonatal rats [postnatal day (P)5-P7]. DOI-hyperpolarized E IPSP within 10-20 min (Fig. 1 A and B). This effect was long-lasting (at least 2 h; Fig. 1B). E IPSP was significantly more hyperpolarized when motoneurons were recorded in the presence of DOI compared with control (8 mV; Fig. 1C, Left). There was a concomitant trend toward a depolarization of the resting membrane potential (V rest) by DOI (+2 mV; P > 0.05). As a result, the amplitude of hyperpolarizing IPSPs recorded at V rest increased significantly (Fig. 1C, Right). The next series of experiments was performed on animals that underwent a neonatal SCI. E IPSP was significantly more depolar-ized in those animals tested at P5-P7, compared with controls of the same age, as shown previously (19) (compare Fig. 1 C and D). Because of the increased sensitivity of neurons to 5-HT in those animals (15), DOI was tested at a lower concentration (1-1.5 μM) than in controls. DOI induced an ∼8-mV hyperpolarization of E IPSP (Fig. 1D, Left). As a result, E IPSP shifted from above to below V rest (Fig. 1D, Right). Another set of animals was treated chronically with DOI from P4 to P6-P7 [0.15 mg/kg, i.p. (15, 20) twice a day]. E IPSP was more hyperpolarized in those DOI-treated animals than in untreated transected animals (Fig. 1E). Values were similar to those measured in control animals. We performed subcellular fractionation of proteins from the lumbosacral spinal cord, followed by immunoblotting with a specific antibody against KCC2. The amount of KCC2 in the membrane fraction (KCC2Mb) was significantly increased after chronic DOI treatment, compared with NaCl-treated pups (Fig. 1F). There was a trend toward an increase in the amount of KCC2 in the cytosolic fraction. As a result, the ratio KCC2Mb/KCC2 cy-toplasm was nonsignificantly increased. We then analyzed the expression of KCC2 by immunohistochemistry. All of the analyses were performed on a homogeneous population of retrogradely labeled lumbar motoneurons [triceps surae (TS) muscles (ankle extensors); Fig. 1G]. GlyRs are colocalized with the anchoring protein gephyrin and can, therefore, be used to label the plasma Author contributions: R.B. an

The role of mesolimbic dopaminergic and retrohippocampal afferents to the nucleus accumbens in latent inhibition: implications for schizophrenia.

Latent inhibition (LI) consists in a retardation of conditioning seen when the to-be-conditioned stimulus is first presented a number of times without other consequence. Disruption of LI has been proposed as a possible model of the cognitive abnormality that underlies the positive psychotic symptoms of acute schizophrenia. We review here evidence in support of the model, including experiments tending to show that: (1) disruption of LI is characteristic of acute, positively-symptomatic schizophrenia; (2) LI depends upon dopaminergic activity; (3) LI depends specifically upon dopamine release in n. accumbens; (4) LI depends upon the integrity of the hippocampal formation and the retrohippocampal region reciprocally connected to the hippocampal formation; (5) the roles of n. accumbens and the hippocampal system in LI are interconnected

Étude de l'influence du travail posté et du stress au travail sur les lipides plasmatiques

SCOPUS: cp.jinfo:eu-repo/semantics/publishe