Neuroscience letters
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Neuroscience letters · Jul 2006
Isoflurane disrupts anterio-posterior phase synchronization of flash-induced field potentials in the rat.
Consciousness presumes a set of integrated functions such as sensory processing, attention, and interpretation, and may depend upon both local and long-range phase synchronization of neuronal activity in cerebral cortex. Here we investigated whether volatile anesthetic isoflurane at concentrations that produce loss of consciousness (LOC) disrupts long-range anterio-posterior and local anterior synchronization of neuronal activity in the rat. In six rats, deep electrodes were chronically implanted in the primary visual cortex (V1) and in two areas of the motor cortex (M1 and M2) for recording of intracortical event-related potentials (ERP). ⋯ Neuronal synchronization was estimated using wavelet coherence computed from the ERP data band-pass filtered at 5-50 Hz. We found that (1) in the waking state, long-range anterio-posterior coherence in 5-25 Hz and 25-50 Hz frequency bands was significantly higher than local anterior coherence; (2) anterio-posterior coherence in both 5-25 Hz and 26-50 Hz bands was significantly reduced by isoflurane in a concentration-dependent manner; (3) local anterior coherence was not affected by isoflurane at any of the concentrations studied. These findings suggest that a disruption of long-range anterio-posterior rather than local anterior synchronization of neuronal activity precedes the anesthetic-induced loss of consciousness.
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Neuroscience letters · Jul 2006
Comparative StudyExaggeration of tissue trauma induces signs and symptoms of acute CRPS I, however displays distinct differences to experimental CRPS II.
As CRPS I frequently develops after tissue trauma, we proposed that an exaggerated inflammatory response to tissue trauma may underlie CRPS I. Therefore, we studied the vascular inflammatory, nociceptive and apoptotic sequelae of (i) soft tissue trauma and (ii) exaggerated soft tissue trauma in comparison to those of (iii) sciatic nerve chronic constriction injury, modeling CRPS II. Standardized soft tissue trauma (TR) was induced by means of a controlled impact injury technique in the hind limb of pentobarbital-anesthetized rats. ⋯ Collectively, these data indicate that exaggeration of trauma response induces signs and symptoms of acute CRPS I. Pain perception displays differences to that in CRPS II. Apoptosis turns out to be a distinctive marker for CRPS, warranting further evaluation in clinical studies.
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Neuroscience letters · Jul 2006
Comparative StudyEnhanced ERK dependent CREB activation reduces apoptosis in staurosporine-treated human neuroblastoma SK-N-BE(2)C cells.
Activation of cAMP response element binding protein (CREB) is implicated in neuronal survival. The mitogen-activated protein kinase/extracellular signal regulated kinase (MAPK/ERK) activates a transcription factor CREB. Previously, we reported that N-acetyl-O-methyldopamine (NAMDA) protects neurons from ischemia via enhancing ERK dependent CREB phosphorylation. ⋯ Cleavage of caspase-3 and poly-(ADP-ribose)-polymerase was additively reduced in cultures treated with NAMDA and forskolin simultaneously, but not in the presence of U0126. The data showed that NAMDA enhances forskolin-induced ERK-CREB activation and potentiates forskolin-induced resistance to apoptosis. The study indicates that enhancing endogenous survival pathways by NAMDA combined with other neuroprotective measure(s) might be a useful strategy to reduce apoptosis.
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Neuroscience letters · Jul 2006
Comparative StudyTransplantation of Schwann cells to subarachnoid space induces repair in contused rat spinal cord.
Schwann cell transplantation is well known to induce repair in the injured spinal cord which disables millions of injured patients throughout the world. An ideal route of delivering the grafted Schwann cells to the spinal cord should neither cause more injury nor reinitiate inflammatory events and also provide a favorable milieu to the grafted cells. In this study, we have utilized subarachnoid route to transplant Schwann cells and evaluated their effects in a contusive model of spinal cord injury. ⋯ Similarly, the axon density at the site of injury was significantly higher. The results indicate the efficacy of subarachnoid route for the transplantation of Schwann cells in inducing repair of the contused spinal cord. We conclude that this route can be useful for the transplantation of Schwann cells and offers a hope for the patients suffering from spinal cord injury.
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Neuroscience letters · Jul 2006
Comparative StudyElectrical stimulation of locus coeruleus strengthens the surround inhibition in layer V barrel cortex in rat.
It is believed that locus coeruleus (LC) influences the sensory information processing. However, its role in cortical surround inhibitory mechanism is not well established. In this experiment, using controlled mechanical displacement of whiskers; we investigated the effect of electrical stimulation of LC on response of layer V barrel cortical neurons in anesthetized rat. ⋯ The response latency of neurons was decreased when LC was stimulated 400 ms before principal whisker deflection but LC stimulation did not affect the neuronal response latency to adjacent whisker displacement. Inhibitory effect of adjacent whisker deflection on neuronal response magnitude was increased by LC stimulation, tested in combined whisker displacement. These findings suggest that LC, by modulating the neuronal responses, enhances the neuronal responsiveness to sensory stimuli and increases their surround inhibition in cortex.