Neuroscience research
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Neuroscience research · Feb 2008
Thalamic neural activation in the cyclophosphamide-induced visceral pain model in mice.
The afferent nociceptive information from the lower urinary tract terminates in the dorsal horn of the spinal cord, and then projects to the thalamus. In the present study, we examined the effects of visceral nociception from the lower urinary tract on the neural activity of thalamic neurons using cyclophosphamide (CP)-induced cystitis, a model of visceral nociception. The levels of c-fos mRNA as well as protein, a marker of neural activation, were investigated in the thalamus using in situ hybridization histochemistry and immunohistochemistry. ⋯ The induction of c-fos mRNA of CP-treated mice was significantly inhibited by capsaicin pretreatment to deplete C-fibers. Our results indicate that visceral nociception from the lower urinary tract activates thalamic neurons and this activation is mediated in part through the activation of the capsaicin-sensitive C-fiber afferents. The present findings suggest that the levels of c-fos in the paraventricular area of the thalamus may be a useful marker for evaluating the afferent nerve activity from the lower urinary tract.
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Neuroscience research · Jan 2008
Possible involvement of neurons in locus coeruleus in inhibitory effect on glossopharyngeal expiratory activity in a neonatal rat brainstem-spinal cord preparation in vitro.
In this study, we found that a certain motor branch of glossopharyngeal (IX) motor nerves stably exhibits not only inspiratory activity but also expiratory activity with pons removal in neonatal rat brainstem-spinal cord preparations in vitro. Because this finding indicates that IX expiratory activity is masked by an inhibitory mechanism operating in the pons, we sought to determine the candidate neurons that exert an inhibitory effect on IX expiratory activity. ⋯ The local administration of clonidine into the bilateral locus coeruleus (LC) evoked burst discharges during the expiratory phase in the IX motor rootlet. These results suggest that neurons in the LC that possess an alpha2 adrenergic receptor on the membrane surface exert a tonic inhibitory effect on IX expiratory activity in neonatal rat brainstem-spinal cord preparations.
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Neuroscience research · Dec 2007
Edaravone inhibits the expression of vascular endothelial growth factor in human astrocytes exposed to hypoxia.
Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), a free radical scavenger, reduces brain edema in patients with acute ischemic stroke. We have addressed the effect of edaravone on the expression of vascular endothelial growth factor (VEGF), a potential mediator of brain edema, in astrocytes exposed to hypoxia. Normal human astrocytes in culture were treated with edaravone, and the levels of VEGF mRNA and protein were analyzed by reverse transcription-polymerase chain reaction (RT-PCR), real-time quantitative PCR and enzyme-linked immunosorbent assay (ELISA). ⋯ ChIP assay confirmed that edaravone reduced HIF-1alpha binding to VEGF promoter. We conclude that edaravone inhibits VEGF expression in astrocytes exposed to hypoxia, at least partly, through the down-regulation of HIF-1alpha. These findings offer a partial explanation for the protective effect of edaravone on the development of brain edema in patients with acute ischemic stroke.
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Neuroscience research · Dec 2007
Adenosine induces expression of glial cell line-derived neurotrophic factor (GDNF) in primary rat astrocytes.
Adenosine, which accumulates rapidly during ischemia due to the breakdown of ATP, has beneficial effects in many tissues. We examined whether adenosine induces the production of glial cell line-derived neurotrophic factor (GDNF) in cultured astrocytes. We evaluated GDNF mRNA expression and GDNF production in astrocytes cultured with adenosine and the adenosine selective receptor agonists 5-(N-ethylcarboxamido) adenosine (NECA), N(6)-cyclopentyladenosine (CPA) and 2-p-(2-carboxyethyl) phenethylamino-5'-N-ethylcarboxamindo-adenosine hydrochloride (CGS 21680). ⋯ Furthermore, the amounts of GDNF produced were significantly reduced in astrocytes of the adenosine-treated SHRSP compared with those of WKY. These results indicate that adenosine induces the expression of GDNF, and adenosine A(2B) receptors participate in the regulation of GDNF levels in astrocytes. This expression was attenuated in astrocytes of SHRSP compared with those of WKY.
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Neuroscience research · Nov 2007
Immunohistochemical demonstration of the calcium channel alpha2 subunit in the chicken dorsal root ganglion and spinal cord: a special reference to colocalization with calbindin-D28k in dorsal root ganglion neurons.
We used immunohistochemical methods to examine the distribution of the calcium channel alpha2 (CCalpha2) subunit in the chicken spinal cord and dorsal root ganglion (DRG) neurons and determine its relationship with calbindin-D28k (CB) in the DRG neurons. In the spinal cord, CCalpha2 subunit was detected in nerve terminals, which were observed as dot-like structures, and in laminae I, II, III and Lissauer's tract in the dorsal horn. ⋯ This may indicate a close correlation between the CCalpha2 subunit and CB in the nociceptive neurons. Thus, it is postulated that the mode of nociceptive transmission may involve a cellular Ca(2+)-regulating system that consists of both Ca(2+) entry via calcium channels with the alpha2delta subunit and intracellular Ca(2+)-binding activity of CB in the nociceptive neurons of the DRG.