Neuroscience
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Previous studies have shown that glial cell line-derived neurotrophic factor (GDNF) exerts significant neuroprotective effects on substantia nigra (SN) neurons in the rat 6-hydroxydopamine (6-OHDA) model of Parkinson's disease (PD). In this study we used enzyme-linked immunosorbent assay (ELISA) to determine GDNF brain levels and distribution to target regions (i.e. striatum and SN) following intranasal administration of GDNF at different time points after administration. Brain levels increased significantly within 1h following a single 50-μg dose of GDNF in a liposomal formulation, returning to baseline by 24h. ⋯ In a third study, autoradiography was performed on brain sections taken 1h after intranasal (125)I-labeled GDNF. Radioactivity was detected throughout the brain along the rostral-to-caudal axis, indicating that nasally administered GDNF can reach target areas. Collectively, these results demonstrate that intranasal administration of GDNF in liposomes or PBS achieves significant increases in GDNF in target brain areas, supporting use of intranasal administration as a non-invasive means of delivering GDNF to the brain to protect dopamine neurons and arrest disease progression in PD.
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Exposure to loud, prolonged sounds (acoustic trauma, AT) leads to the death of both inner and outer hair cells (IHCs and OHCs), death of neurons of the spiral ganglion and degeneration of the auditory nerve. The auditory nerve (8cn) projects to the three subdivisions of the cochlear nuclei (CN), the dorsal cochlear nucleus (DC) and the anterior (VCA) and posterior (VCP) subdivisions of the ventral cochlear nucleus (VCN). There is both anatomical and physiological evidence for plastic reorganization in the denervated CN after AT. ⋯ There was close geographic overlap between the degenerating fibers and activated microglia, consistent with a scavenger role for activated microglia. At the longest survival time, there were still silver-stained fibers but very little staining of activated microglia in overlapping regions. There were, however, activated microglia in the surrounding brainstem and cerebellar white matter.
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Accumulated evidence suggests that enhanced neurogenesis stimulated by ischemic injury contributes to stroke outcome. However, it is unclear whether hyperglycemia, which is frequently tested positive in patients with acute ischemic stroke, influences stroke-induced neurogenesis. The aim of the present study is to examine the effect of hyperglycemia on stroke-induced neurogenesis in a rat model of transient focal cerebral ischemia. ⋯ The severe hyperglycemic rats also showed dramatically decreased proliferation of neural stem/progenitor cells (NSPCs) (P<0.05) and down-regulation of the phosphorylation of cyclic-AMP response element-binding protein (pCREB) (P<0.05)and brain-derived neurotrophic factor (BDNF) (P<0.05) in ipsilateral SVZ. But the above-mentioned detrimental effects were not observed in rats that were rendered with mild hyperglycemia (9.43 ± 1.39-10.13 ± 1.24 mM). Our findings indicate that severe instead of mild hyperglycemia exacerbates ischemic injury and inhibits stroke-induced SVZ neurogenesis by a mechanism involving suppression of CREB and BDNF signaling.
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It has been shown that chronic pain is able to induce depressive disorders in humans, in part, due to peripheral inflammation that reaches the central nervous system. However, the mechanisms involved remain to be established. The purpose of this study was to investigate whether sciatic nerve crush could produce depression-like behaviors, in addition to pain-related behaviors, in mice. Once confirmed, this model was used to investigate tumor necrosis factor-α (TNF-α) as a key mediator involved in the pathophysiology of both pain and depression. ⋯ The sciatic nerve crush model represents a good model to study to mechanisms underlying both pain and depressive-like behaviors. Furthermore, inhibitors of TNF-α synthesis, like thalidomide, have a potential to treat depressive disorders associated with neuropathic pain.
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The incidence of asthma is more common in boys than in girls during the childhood, and more common in premenopausal female than age-matched males. Our previous study demonstrated a gender difference in histamine-mediated neuroexcitability in nodose ganglia neurons (NGNs), highlighting a possibility of histamine-mediated gender difference in asthma via visceral afferent function. In the present study, we aimed to explore the gender difference in expression profiles of histamine receptors (HRs) in nodose ganglia (NG) and individual identified NGNs to provide deeper insights into the mechanisms involved in sexual dimorphism of asthma. ⋯ H2R was widely and highly expressed in low-threshold and sex-specific subpopulation of myelinated Ah-types compared with myelinated A- and unmyelinated C-type NGNs. Unexpectedly, weak expression of H1R was detected in both myelinated and unmyelinated NGNs by immunofluorescence, which was further confirmed by single-cell RT-PCR. Our results suggest that the sexual dimorphism in the expression of H2R and H3R in vagal afferents very likely contributes, at least partially, to the gender difference in prevalence and severity of asthma.