Experimental neurology
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Experimental neurology · Sep 2013
The interaction between the dopaminergic forebrain projections and the medial prefrontal cortex is critical for memory of objects: implications for Parkinson's disease.
Neuropsychological and neuroimaging studies have implicated the dopaminergic nigrostriatal pathway and the prefrontal cortex in learning and memory deficits in patients with Parkinson's disease. However, little is known about how these two brain regions interact in the processing of learning and memory. We employed a disconnection procedure to test whether interaction of these regions contributes to performance in various memory tasks. ⋯ No differences between groups were found in the spatial working memory test. Our data indicate that locomotor, emotional and sensorimotor factors are not likely to confound the results of the memory tests. Thus, the interaction between the dopaminergic forebrain projections, particularly the nigrostriatal dopamine, and the medial prefrontal cortex is critical for object recognition memory but not for spatial working memory in rats.
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Experimental neurology · Sep 2013
Reticulospinal plasticity after cervical spinal cord injury in the rat involves withdrawal of projections below the injury.
Restoring voluntary fine motor control of the arm and hand is one of the main goals following cervical spinal cord injury (SCI). Although the functional improvement achievable with rehabilitative training in rat models is frequently accompanied by corticospinal tract (CST) plasticity, CST rewiring alone seems insufficient to account for the observed recovery. Recent investigations in animal models of SCI have suggested that the reticulospinal tract (RtST) might contribute to mediating improved motor performance of the forelimb. ⋯ However, all analyses directly below the injured spinal level consistently point to a significant decrease of RtST projections. The mechanism and the functional relevance behind this new finding warrant further study. Our results also suggest that mechanisms other than anatomical plasticity, such as plastic changes on a cellular level, might be responsible for the observed spontaneous recovery.
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Experimental neurology · Sep 2013
Endoplasmic reticulum stress contributes to prediabetic peripheral neuropathy.
Growing evidence suggests that prediabetes and metabolic syndrome are associated with increased risk for the development of microvascular complications including retinopathy, nephropathy, and, most commonly, peripheral painful neuropathy and/or autonomic neuropathy. The etiology of these disabling neuropathies is unclear, and several clinical and experimental studies implicated obesity, impaired fasting glycemia/impaired glucose tolerance, elevated triglyceride and non-esterified fatty acids, as well as oxidative-nitrative stress. Endoplasmic reticulum stress resulting from abnormal folding of newly synthesized proteins and leading to the impairment of metabolism, transcriptional regulation, and gene expression, is emerging as a key mechanism of metabolic diseases including obesity and diabetes. ⋯ A chemical chaperone, trimethylamine oxide, blunted endoplasmic reticulum stress and alleviated sensory nerve conduction velocity deficit, thermal and mechanical hypoalgesia, and tactile allodynia. A selective inhibitor of eukaryotic initiation factor-2α dephosphorylation, salubrinal, improved glucose intolerance and alleviated peripheral nerve dysfunction in high-fat diet fed mice. Our findings suggest an important role of endoplasmic reticulum stress in the neurobiology of prediabetic peripheral neuropathy, and identify a new therapeutic target.
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Experimental neurology · Sep 2013
ReviewOpioid administration following spinal cord injury: implications for pain and locomotor recovery.
Approximately one-third of people with a spinal cord injury (SCI) will experience persistent neuropathic pain following injury. This pain negatively affects quality of life and is difficult to treat. Opioids are among the most effective drug treatments, and are commonly prescribed, but experimental evidence suggests that opioid treatment in the acute phase of injury can attenuate recovery of locomotor function. ⋯ A review of the literature, described here, suggests that caution is warranted when administering opioids after SCI. Opioid administration may synergistically contribute to the pathology of SCI to increase the development of pain, decrease locomotor recovery, and leave individuals at risk for infection. Considering these negative implications, it is important that guidelines are established for the use of opioids following spinal cord and other central nervous system injuries.
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Experimental neurology · Sep 2013
Environmental enrichment promotes robust functional and histological benefits in female rats after controlled cortical impact injury.
Environmental enrichment (EE) consistently induces marked benefits in male rats after traumatic brain injury (TBI), but whether similar efficacy extends to females is not well established. Hence, the aim of this study was to reassess the effect of EE on functional and histological outcome in female rats after brain trauma. Twenty-four normal cycling adult female rats underwent verification of estrous stage prior to controlled cortical impact (CCI) or sham injury and then were assigned to EE or standard (STD) housing. ⋯ EE also provided significant histological protection as confirmed by increased CA(1/3) cell survival and decreased cortical lesion size vs. STD. These data demonstrate that EE confers robust benefits in female rats after CCI injury, which parallels numerous studies in males and lends further credence for EE as a preclinical model of neurorehabilitation.