Neuroscience letters
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Neuroscience letters · Sep 2008
A surgical ankle sprain pain model in the rat: effects of morphine and indomethacin.
Ankle sprain is a frequent injury in humans that results in pain, swelling and difficulty in walking on the affected side. Currently a suitable animal model resembling human ankle sprain is lacking. ⋯ Analgesic compounds, morphine and indomethacin, significantly reversed the reduced weight bearing, thus indicating that reduction of weight bearing is partially due to pain. The ALI model is a new ankle sprain model that may be useful for the study of ankle sprain pain mechanisms and treatments, as well as for the screening of new analgesic drugs.
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Neuroscience letters · Aug 2008
GABAA receptor-mediated tonic currents in substantia gelatinosa neurons of rat spinal trigeminal nucleus pars caudalis.
In the present study, we describe GABAA receptor-mediated tonic inhibitory currents in the substantia gelatinosa (SG) region of rat spinal trigeminal nucleus pars caudalis (Vc). The GABA(A) receptor-mediated tonic currents were identified by bath-application of the GABAA receptor antagonists, picrotoxin (1mM), SR95531 (100microM) and bicuculline (100microM). All three antagonists completely blocked outward spontaneous (phasic) inhibitory postsynaptic currents, but only picrotoxin and bicuculline induced a significant (>5pA) inward shift of holding currents at a holding potential (Vh) of 0mV in 60-70% of SG neurons, revealing the existence of tonic outward currents. ⋯ An acute bath-application of THDOC (0.1microM), the stress-related neurosteroid, did enhance tonic currents, but only in a small population of SG neurons. In addition, slices incubated with THDOC for 30min increased the probability of neurons with significant tonic currents. The GABAergic tonic inhibition demonstrated in this study may play a significant role in the sensory processing system of the Vc.
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Neuroscience letters · Aug 2008
5-HT(3A) receptor subunit is expressed in a subpopulation of GABAergic and enkephalinergic neurons in the mouse dorsal spinal cord.
5-Hydroxytryptamine (5-HT)(3) receptors have been proposed to modulate nociception and pain responses at the spinal level. To gain insight into the cellular mechanism of 5-HT(3) receptors, we examined their expression in GABAergic and enkephalinergic (ENKergic) neurons in the spinal dorsal horn (SDH) using single-cell reverse transcription-polymerase chain reaction (RT-PCR). The glutamic acid decarboxylase (GAD)(67)-green fluorescent protein (GFP) knock-in mouse was used in which all GABAergic neurons were fluorescent. ⋯ Of the neurons that co-express GAD(67) mRNA and PPE mRNA, about 22% expressed 5-HT(3A) mRNA. These observations indicate that 5-HT(3A) receptor co-localizes with GABA and ENK in the SDH, suggesting that serotonin may activate GABAergic and ENKergic neurons via 5-HT(3A) receptor subunit and therefore affect the release of GABA and ENK. The different cellular localization of 5-HT(3A) receptor subunit suggest the complex participation of this receptor in the inhibitory neuronal circuits of the SDH neurons.
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Neuroscience letters · Aug 2008
Case ReportsDiffusion tensor imaging of two unrelated Chinese men with hereditary spastic paraplegia associated with thin corpus callosum.
Hereditary spastic paraplegia (HSP) associated with thin corpus callosum is a rare autosomal recessive neurodegenerative disorder characterized by an abnormally thin corpus callosum, normal motor development, slowly progressive spastic paraparesis and cognitive deterioration. To investigate and localize abnormalities in the brains of two Chinese patients with HSP-TCC, with mutations in the spatacsin gene. Diffusion tensor imaging (DTI) was used to determine the mean diffusion (MD) and fractional anisotropy (FA) in the brains of the patients in comparison to 20 healthy subjects. ⋯ Neither increase in FA nor reduction in MD was detected in the brain. Our study provides clear in vivo MR imaging evidence of a more widespread brain involvement of HSP-TCC. MD is more sensitive than FA in detecting lesions in thalamus and subcortical white matter, suggesting that MD may be a better marker of the disease progression.
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Neuroscience letters · Aug 2008
Roles of opioid receptor subtypes on the antinociceptive effect of intrathecal sildenafil in the formalin test of rats.
Recently, it has been known that the antinociception of sildenafil, a phosphodiesterase 5 inhibitor, is mediated through the opioid receptors. There are common three types of opioid receptors mu, delta, and kappa. We characterized the role of subtypes of opioid receptor for the antinociception of sildenafil at the spinal level. ⋯ These results suggest that sildenafil is effective to acute pain and the facilitated pain state at the spinal level. Both mu and delta opioid receptors are involved. However, it seems that kappa opioid receptors play in the effect of sildenafil.