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Nerve Impulse (nerve + impulse)
Selected AbstractsStrain- and region-specific gene expression profiles in mouse brain in response to chronic nicotine treatmentGENES, BRAIN AND BEHAVIOR, Issue 1 2008J. Wang A pathway-focused complementary DNA microarray and gene ontology analysis were used to investigate gene expression profiles in the amygdala, hippocampus, nucleus accumbens, prefrontal cortex (PFC) and ventral tegmental area of C3H/HeJ and C57BL/6J mice receiving nicotine in drinking water (100 ,g/ml in 2% saccharin for 2 weeks). A balanced experimental design and rigorous statistical analysis have led to the identification of 3.5,22.1% and 4.1,14.3% of the 638 sequence-verified genes as significantly modulated in the aforementioned brain regions of the C3H/HeJ and C57BL/6J strains, respectively. Comparisons of differential expression among brain tissues showed that only a small number of genes were altered in multiple brain regions, suggesting presence of a brain region-specific transcriptional response to nicotine. Subsequent principal component analysis and Expression Analysis Systematic Explorer analysis showed significant enrichment of biological processes both in C3H/HeJ and C57BL/6J mice, i.e. cell cycle/proliferation, organogenesis and transmission of nerve impulse. Finally, we verified the observed changes in expression using real-time reverse transcriptase polymerase chain reaction for six representative genes in the PFC region, providing an independent replication of our microarray results. Together, this report represents the first comprehensive gene expression profiling investigation of the changes caused by nicotine in brain tissues of the two mouse strains known to exhibit differential behavioral and physiological responses to nicotine. [source] Activation of nervous system development genes in bone marrow derived mesenchymal stem cells following spaceflight exposure,JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2010Massimiliano Monticone Abstract Stalled cell division in precursor bone cells and reduced osteoblast function are considered responsible for the microgravity-induced bone loss observed during spaceflight. However, underlying molecular mechanisms remain unraveled. Having overcome technological difficulties associated with flying cells in a space mission, we present the first report on the behavior of the potentially osteogenic murine bone marrow stromal cells (BMSC) in a 3D culture system, flown inside the KUBIK aboard space mission ISS 12S (Soyuz TMA-8,+,Increment 13) from March 30 to April 8, 2006 (experiment "Stroma-2"). Flight 1g control cultures were performed in a centrifuge located within the payload. Ground controls were maintained on Earth in another KUBIK payload and in Petri dishes. Half of the cultures were stimulated with osteo-inductive medium. Differences in total RNA extracted suggested that cell proliferation was inhibited in flight samples. Affymetrix technology revealed that 1,599 genes changed expression after spaceflight exposure. A decreased expression of cell-cycle genes confirmed the inhibition of cell proliferation in space. Unexpectedly, most of the modulated expression was found in genes related to various processes of neural development, neuron morphogenesis, transmission of nerve impulse and synapse, raising the question on the lineage restriction in BMSC. J. Cell. Biochem. 111: 442,452, 2010. © 2010 Wiley-Liss, Inc. [source] After-effects of near-threshold stimulation in single human motor axonsTHE JOURNAL OF PHYSIOLOGY, Issue 3 2005Hugh Bostock Subthreshold electrical stimuli can generate a long-lasting increase in axonal excitability, superficially resembling the phase of superexcitability that follows a conditioning nerve impulse. This phenomenon of ,subthreshold superexcitability' has been investigated in single motor axons in six healthy human subjects, by tracking the excitability changes produced by conditioning stimuli of different amplitudes and waveforms. Near-threshold 1 ms stimuli caused a mean decrease in threshold at 5 ms of 22.1 ± 6.0% (mean ±s.d.) if excitation occurred, or 6.9 ± 2.6% if excitation did not occur. The subthreshold superexcitability was maximal at an interval of about 5 ms, and fell to zero at 30 ms. It appeared to be made up of two components: a passive component linearly related to conditioning stimulus amplitude, and a non-linear active component. The active component appeared when conditioning stimuli exceeded 60% of threshold, and accounted for a maximal threshold decrease of 2.6 ± 1.3%. The passive component was directly proportional to stimulus charge, when conditioning stimulus duration was varied between 0.2 and 2 ms, and could be eliminated by using triphasic stimuli with zero net charge. This change in stimulus waveform had little effect on the active component of subthreshold superexcitability or on the ,suprathreshold superexcitability' that followed excitation. It is concluded that subthreshold superexcitability in human motor axons is mainly due to the passive electrotonic effects of the stimulating current, but this is supplemented by an active component (about 12% of suprathreshold superexcitability), due to a local response of voltage-dependent sodium channels. [source] Rapid cortical reorganisation and improved sensitivity of the hand following cutaneous anaesthesia of the forearmEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2009Anders Björkman Abstract The cortical representation of various body parts constantly changes based on the pattern of afferent nerve impulses. As peripheral nerve injury results in a cortical and subcortical reorganisation this has been suggested as one explanation for the poor clinical outcome seen after peripheral nerve repair in humans. Cutaneous anaesthesia of the forearm in healthy subjects and in patients with nerve injuries results in rapid improvement of hand sensitivity. The mechanism behind the improvement is probably based on a rapid cortical and subcortical reorganisation. The aim of this work was to study cortical changes following temporary cutaneous forearm anaesthesia. Ten healthy volunteers participated in the study. Twenty grams of a local anaesthetic cream (EMLA®) was applied to the volar aspect of the right forearm. Functional magnetic resonance imaging was performed during sensory stimulation of all fingers of the right hand before and during cutaneous forearm anaesthesia. Sensitivity was also clinically assessed before and during forearm anaesthesia. A group analysis of functional magnetic resonance image data showed that, during anaesthesia, the hand area in the contralateral primary somatosensory cortex expanded cranially over the anaesthetised forearm area. Clinically right hand sensitivity in the volunteers improved during forearm anaesthesia. No significant changes were seen in the left hand. The clinically improved hand sensitivity following forearm anaesthesia is probably based on a rapid expansion of the hand area in the primary somatosensory cortex which presumably results in more nerve cells being made available for the hand in the primary somatosensory cortex. [source] Evidence for functional NK1 -tachykinin receptors on motor neurones supplying the circular muscle of guinea-pig small and large intestineNEUROGASTROENTEROLOGY & MOTILITY, Issue 4 2000Bian The guinea-pig intestine was investigated to determine which neurones are excited via NK1 receptors. The specific NK1 receptor agonists [Sar9, Met(O2)11]-SP and septide contracted the circular muscle of all regions via a tetrodotoxin (TTX)-insensitive mechanism. In the proximal colon, they also evoked a TTX-sensitive relaxation; in the distal colon, the contractions were larger when nerve impulses were blocked with TTX, indicating that the agonists excited inhibitory motor neurones. In the duodenum and ileum, TTX reduced agonist-evoked contractions indicating that excitatory motor neurones were activated. In the presence of indomethacin, TTX enhanced contractions of ileal circular muscle evoked by these agonists suggesting that NK1 receptors were on inhibitory motor neurones. Blockade of nitric oxide synthase (NOS) enhanced NK1 receptor agonist evoked contractions of duodenal circular muscle, indicating that the agonists excite inhibitory motor neurones in duodenum. Neurones immunoreactive for NK1 receptors were studied in the duodenum and distal colon. As reported previously for the ileum,1 some neurones were immunoreactive for NOS and had Dogiel type I morphology; features characteristic of inhibitory motor neurones. In conclusion, there are functional NK1 receptors on excitatory and inhibitory motor neurones in the guinea-pig small intestine and on inhibitory motor neurones in the colon. [source] Knockdown resistance to DDT and pyrethroids: from target-site mutations to molecular modellingPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 11 2008TG Emyr Davies Abstract Naturally derived insecticides such as pyrethrum and man-made insecticides such as DDT and the synthetic pyrethroids act on the voltage-gated sodium channel proteins found in insect nerve-cell membranes. The correct functioning of these channels is essential for the normal transmission of nerve impulses, and this process is disrupted by binding of the insecticides, leading to paralysis and eventual death. Some insect pest populations have evolved modifications of the sodium channel protein that inhibit the binding of the insecticide and result in the insect developing resistance. This perspective outlines the current understanding of the molecular processes underlying target-site resistance to these insecticides (termed kdr and super-kdr), and how this knowledge may in future contribute to the design of novel insecticidal compounds. Copyright © 2008 Society of Chemical Industry [source] | ||||||||||