Neuroscience letters
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Neuroscience letters · Jun 2015
Effects of α2-adorenoceptor agonist dexmedetomidine on respiratory rhythm generation of newborn rats.
Dexmedetomidine, an α2-adrenoceptor agonist which has a slight side effect on breathing, is clinically used as an analgesic and sedative agent. Previous studies have shown depressing or modest effects of α2-adorenoceptor agonists on respiratory rhythm generation in newborn rat preparation in vitro. In contrast, it was recently reported that dexmedetomidine induced long-lasting activation of respiratory rhythm in brainstem-spinal cord preparation isolated from neonatal mice. ⋯ Spinal cord reflex responses were depressed by the application of dexmedetomidine at the range of 0.1-1nM, a lower concentration than that affecting respiratory rhythm. The inhibitory effect was also reversed by atipamezole. Our findings provide neuronal mechanisms that support the clinical use of dexmedetomidine, which shows sedative and antinociceptive effects with minimal side effects on breathing.
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Neuroscience letters · Jun 2015
Neuroprotective effects of MK-801 against traumatic brain injury in immature rats.
Traumatic brain injury (TBI) is a major health problem in pediatric ages and also has major social, economic, and emotional outcomes, with diverse sequelae in many spheres of everyday life. We aimed to investigate the effect of MK-801, a competitive NMDA receptor antagonist, on hippocampal damage and behavioral deficits on 10-day-old rat pups subjected to contusion injury. The aims of the present study were to determine: (i) the short term effects of MK-801 on hippocampal BDNF, NGF and NMDA receptor immunoreactivity and neuron density in hippocampus (ii) long term effects of MK-801 on cognitive dysfunction following TBI in the immature rats. ⋯ Histopathological and immunohistochemical evaluations showed that treatment with a single dose of 1mg/kg MK-801 (i.p.) significantly ameliorated the trauma induced hippocampal neuron loss and decreased BDNF, NGF and NMDAR expressions in CA1, CA3 and DG hippocampal brain regions. Additionally, treatment with MK-801 ameliorated anxiety and hippocampus dependent memory of animals subjected to trauma. These results show that acute treatment of MK-801 has a neuroprotective role against trauma induced hippocampal neuron loss and associated cognitive impairment in immature rats.
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Neuroscience letters · Jun 2015
Nrf2-signaling and BDNF: A new target for the antidepressant-like activity of chronic fluoxetine treatment in a mouse model of anxiety/depression.
Several studies have shown that Nrf2, a major redox-sensitive transcription factor involved in the cellular defense against oxidative stress, increases susceptibility to depressive-like behavior. However, little is known about the influence of antidepressant drugs on Nrf2 signaling and expression of its target genes (GCLC, NQO1, HO-1) in the brain. ⋯ Furthermore, we found that chronic fluoxetine also increased brain derived neurotrophic factor (BDNF) protein levels in cortex and hippocampus of CORT-treated Nrf2 knockout mice (KO, Nrf2(-/-)). Taken together, these data suggest that Nrf2 signaling contributes to fluoxetine-induced neuroprotection via an unexpected mechanism involving 5-HT transporter SERT blockade, and not through enhancement of BDNF expression.
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Neuroscience letters · Jun 2015
ReviewDemyelinating CMT--what's known, what's new and what's in store?
Inherited neuropathies known collectively as Charcot-Marie-Tooth disease are one of the most common inherited neurological conditions affecting ∼1 in 2500 people. A heterogenous disorder, CMT is divided into subtypes based on the pattern of inheritance and also by neurophysiological studies. ⋯ Understanding the pathogenesis of these disorders requires an intimate knowledge of normal myelin development and homeostasis. Improvements in genetic testing techniques over the last 20 years have contributed majorly to the identification of specific genes, proteins, and molecular pathways that are providing the basis for understanding the disease processes and developing rational approaches to therapy.
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Peripheral neuropathy can lead to neuropathic pain in a subset of patients. Painful peripheral neuropathy is a debilitating disorder, reflected by a reduced quality of life. Therapeutic strategies are limited and often disappointing, as in most cases targeted treatment is not available. ⋯ Functional analyses have shown that these mutations produce a spectrum of pro-excitatory changes in channel biophysics, with the shared outcome at the cellular level of dorsal root ganglion hyperexcitability. Reduced neurite outgrowth may be another consequence of sodium channel mutations, and possible therapeutic strategies include blockade of sodium channels or block of reverse operation of the sodium-calcium exchanger. Increased understanding of the pathophysiology of painful peripheral neuropathy offers new targets that may provide a basis for more effective treatment.