Neuroscience letters
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Neuroscience letters · Oct 2012
Nerve injury induces the expression of syndecan-1 heparan sulfate proteoglycan in peripheral motor neurons.
Heparan sulfate proteoglycans play important roles in embryogenesis, including the development of the central nervous system. However, their function in nerve regeneration is not yet understood. We previously reported that nerve injury induces the expression of heparan sulfate glycosaminoglycans and syndecan-1, a heparan sulfate proteoglycan, in injured hypoglossal motor neurons. ⋯ However, sciatic nerve axotomy induced very little syndecan-1 expression in injured spinal motor neurons. These results suggest that syndecan-1 may have a crucial role in the survival of injured motor neurons and in nerve regeneration after injury. Our observations also reveal the diversity of peripheral motor neurons.
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Neuroscience letters · Sep 2012
Dissecting the effects of endogenous brain IL-2 and normal versus autoreactive T lymphocytes on microglial responsiveness and T cell trafficking in response to axonal injury.
IL-2 is essential for T-helper regulatory (Treg) cell function and self-tolerance, and dysregulation of both endogenous brain and peripheral IL-2 gene expression may have important implications for neuronal injury and repair. We used an experimental approach combining mouse congenic breeding and immune reconstitution to test the hypothesis that the response of motoneurons to injury is modulated by the combined effects of IL2-mediated processes in the brain that modulate its endogenous neuroimmunological milieu, and IL2-mediated processes in the peripheral immune system that regulate T cell function (i.e., normal versus autoreactive Treg-deficient T cells). ⋯ Changes in activated MHC2(+) microglial in the injured FMN were associated with loss of endogenous brain IL-2 and/or peripheral IL-2. This model may provide greater understanding of the mechanisms involved in determining if T cells entering the injured central nervous system (CNS) have damaging or proregenerative effects.
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Neuroscience letters · Sep 2012
The electrically evoked long latency reflex of the biceps brachii muscle: the impact of train stimuli, preceding stimuli, and voluntary muscle contraction.
Long latency reflex (LLR) responses were examined over the biceps brachii (BB) at different contraction levels after electrical single or train stimuli over the ipsilateral superficial radial nerve with an inter-stimulus interval of 3ms. Two constant motor waves were present, LLR2 with a peak latency value of 53±4ms and LLR3 with 85±10ms. ⋯ In the present study, 3 factors exerted an influence on LLR, namely temporal summation of synaptic potentials (by train stimuli), facilitation (with higher stimulus repetition rates), and volition (resulting in muscle contraction). The augmentation behaviour of LLR may be useful for the investigation of central nervous system diseases such as e.g. movement disorders.
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Neuroscience letters · Sep 2012
Dynamic, but not static, pain sensitivity predicts exercise-induced muscle pain: covariation of temporal sensory summation and pain intensity.
Cross-section studies suggest that measures of pain sensitivity, derived from quantitative sensory testing (QST), are elevated in persons with chronic pain conditions. However, little is known about whether development of chronic pain is preceded by elevated pain sensitivity or pain sensitivity increases as a result of prolonged experience of pain. Here we used QST to test static (single suprathreshold stimuli) and dynamic (temporal sensory summation) pain processing of thermal stimuli. ⋯ Multi-level modeling approaches determined the daily covariation among static and dynamic QST measures and pain intensity. Variation in responses to static pain sensitivity was not associated with pain intensity from DOMS while, in contrast, variation in dynamic pain sensitivity was positively associated with variation in pain intensity from DOMS. This finding supports the use of TSS as a marker of the central pain state and potentially as an appropriate measure for treatment monitoring.
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Neuroscience letters · Sep 2012
Streptozotocin-induced diabetic hyperalgesia in rats is associated with upregulation of Toll-like receptor 4 expression.
Neuropathic pain is one of the common complications of diabetes mellitus, and current treatments often do not meet medical needs. Toll-like receptor 4 (TLR4) has been implicated as a potential therapeutic target in neuropathic and other pain models. In this study, we investigated whether TLR4 expression in spinal cord would be altered in streptozotocin-induced diabetic rat model, which had persistent mechanical and thermal hypersensitivity. ⋯ The protein levels of TNF-α and IL-1β, two downstream proinflammatory cytokines of TLR4 signaling pathway, were also significantly raised and correlated with mechanical/thermal hypersensitivity in diabetic rats. Together, these data have demonstrated that TLR4 and its signaling pathway are associated with neuropathic pain in a diabetic model. It may imply that TLR4 could be a novel target for treating diabetic neuropathy.