Experimental neurology
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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.
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Experimental neurology · Sep 2013
Functional consequences of ethidium bromide demyelination of the mouse ventral spinal cord.
Ethidium bromide (EB) has been extensively used in the rat as a model of spinal cord demyelination. However, this lesion has not been addressed in the adult mouse, a model with unlimited genetic potential. Here we characterize behavioral function, inflammation, myelin status and axonal viability following bilateral injection of 0.20 mg/mL ethidium bromide or saline into the ventral white matter (VWM) of female C57Bl/6 mice. ⋯ As these data suggest that EB-injection in the mouse spinal cord is a non-remyelinating lesion, we sought to ask whether wheel running could promote recovery by enhancing plasticity of local lumbar circuitry independent of remyelination. This did not occur as BMS and Treadscan assessment revealed no significant effect of wheel running on recovery. However, this study defines the importance of descending ventral motor pathways to locomotor function in the mouse as VWM loss results in a chronic hindlimb deficit.
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Experimental neurology · Sep 2013
Loss of GABAergic neurons in the hippocampus and cerebral cortex of Engrailed-2 null mutant mice: implications for autism spectrum disorders.
The homeobox-containing transcription factor Engrailed-2 (En2) is involved in patterning and neuronal differentiation of the midbrain/hindbrain region, where it is prominently expressed. En2 mRNA is also expressed in the adult mouse hippocampus and cerebral cortex, indicating that it might also function in these brain areas. Genome-wide association studies revealed that En2 is a candidate gene for autism spectrum disorders (ASD), and mice devoid of its expression (En2(-/-) mice) display anatomical, behavioral and clinical "autistic-like" features. ⋯ Here we show that the Engrailed proteins are present in postnatal GABAergic neurons of the mouse hippocampus and cerebral cortex, and adult En2(-/-) mice show reduced expression of GABAergic marker mRNAs in these areas. In addition, reduction in parvalbumin (PV), somatostatin (SOM) and neuropeptide Y (NPY) expressing interneurons is detected in the hippocampus and cerebral cortex of adult En2(-/-) mice. Our results raise the possibility of a link between altered function of En2, anatomical deficits of GABAergic forebrain neurons and the pathogenesis of ASD.
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Experimental neurology · Sep 2013
A novel reproducible model of neonatal stroke in mice: comparison with a hypoxia-ischemia model.
Neonatal stroke occurs in 1/4000 live births and leaves life-long neurological impairments, such as cerebral palsy and epilepsy. Currently, the rodent models of neonatal stroke that are available exhibit significant inter-animal variability, which makes it difficult to accurately assess the mechanisms of brain injury and the efficacy of candidate treatments. We aimed to introduce a novel, highly reproducible model of stroke, middle cerebral artery occlusion (MCAO), in immature mice, and to evaluate the reproducibility of this model compared with a conventional hypoxia-ischemia (HI) model. ⋯ Mice with MCAO exhibited significant neurofunctional deficits in the rotarod and open-field tests. Preclinical studies for neonatal stroke could become more reliable using this model, with even a potential reduction in the number of pups required for statistical significance. The contrasting variability between the two models may provide insights into the factors that contribute to inter-animal variability in brain injury.
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Experimental neurology · Sep 2013
Interleukin-10 down-regulates voltage gated sodium channels in rat dorsal root ganglion neurons.
The over-expression of voltage-gated sodium channels (VGSCs) in dorsal root ganglion (DRG) neurons following peripheral nerve injury contributes to neuropathic pain by generation of the ectopic discharges of action potentials. However, mechanisms underlying the change in VGSCs' expression are poorly understood. Our previous work has demonstrated that the pro-inflammatory cytokine TNF-α up-regulates VGSCs. ⋯ Consistent with the electrophysiological results, real-time PCR and western blot revealed that IL-10 (200 pg/ml) down-regulated VGSCs in both mRNA and protein levels and reversed the up-regulation of VGSCs by TNF-α. Moreover, repetitive intrathecal administration of rrIL-10 for 3 days (4 times per day) attenuated mechanical allodynia in L5 spinal nerve ligation model and profoundly inhibited the excitability of DRG neurons. These results suggested that the down-regulation of the sodium channels in DRG neurons might contribute to the therapeutic effect of IL-10 on neuropathic pain.