Brain research. Molecular brain research
-
Brain Res. Mol. Brain Res. · Oct 2003
Comparative StudyGlutamate receptor RNA editing: a molecular analysis of GluR2, GluR5 and GluR6 in human brain tissues and in NT2 cells following in vitro neural differentiation.
The properties of some glutamate receptors are modified by RNA editing. This post-transcriptional mechanism involves the enzymatic deamination of specific adenosines in the pre-mRNA of the glutamate receptors, performed by specific RNA adenosine deaminases (ADARs). This event gives rise to the substitution of a gene-encoded amino acid with a different one that modifies the physiological properties of the ion channel. ⋯ Whereas GluR gene expression increased during NT2 neural differentiation, the expression of ADAR genes may be detected at comparable levels even in undifferentiated NT2 cells, remaining relatively stable during the differentiation process. Furthermore, most of the glutamate receptor editing sites increased their editing levels during NT2 neural differentiation, suggesting that the level of ADAR mRNAs is not closely related to the variable editing levels detected in the GluRs analysed. In human brain tissues, the editing levels appeared finely modulated in the different areas, indicating the possible formation of ion channels with different functional properties, thus generating a complex tissue-specific regulation of receptors and modulation of excitatory stimuli.
-
Brain Res. Mol. Brain Res. · Aug 2003
Comparative StudyExtracellular signaling-regulated kinase-1 and -2 (ERK 1/2) mediate referred hyperalgesia in a murine model of visceral pain.
We have investigated the role of spinal extracellular signaling-regulated kinase-1 and -2 (ERK1/2) in a model of visceral pain and hyperalgesia induced by intracolonic instillation of irritants in adult mice. Instillation of either capsaicin or mustard oil induced a significant activation of lumbosacral spinal ERK1/2, measured by immunoblot, with a peak 2.4-fold increase over control levels between 45 and 90 min post-treatment. Intracolonic saline did not produce significant activation of lumbosacral spinal ERK1/2, and none of the treatments evoked ERK1/2 activation in thoracic or cervical spinal cord. ⋯ Treatment with U0126 did not affect spontaneous pain behavior or colon inflammation. Our data show that ERK activation plays a specific role in maintaining prolonged referred (secondary) hyperalgesia in visceral pain. The time course and subcellular localization of the effects observed suggest that ERK is involved in transcriptional events underlying the maintenance of secondary hyperalgesia.
-
Brain Res. Mol. Brain Res. · Jul 2003
Comparative StudyCaffeic acid phenethyl ester (CAPE) prevents inflammatory stress in organotypic hippocampal slice cultures.
Caffeic acid phenethyl ester (CAPE) is an antioxidant component of propolis, a natural product secreted by honeybee. Recent literature shows that CAPE inhibits nuclear factor kappa B (NFkappaB) activation in cell lines. Since NFkappaB was shown to be a crucial factor in neuroinflammation and to be associated with some neuropathologies, CAPE might reduce these disorders in brain too and have therapeutic applications. ⋯ We compared CAPE effects with those of other drugs: anti-inflammatory as acetyl-salicylate and dexamethasone (glucocorticoid), antioxidant as pyrrolidine dithiocarbamate, or selective permeant inhibitor of NFkappaB as SN 50 peptide. These studies lead us to conclude that CAPE presents an interesting and original neuropharmacological profile compared to these drugs and might be helpful in the prevention of neurotoxic events due to excessive inflammatory reaction in brain. CAPE interferes with several effectors of neuroinflammation that might have complementary and synergic effects and allows a rather durable control since an acute treatment at the time of endotoxin exposure allows to control inflammatory factors for over 48 h.
-
Brain Res. Mol. Brain Res. · Jul 2003
Comparative StudyTemporal changes in the expression of brain-derived neurotrophic factor mRNA in the ventromedial nucleus of the hypothalamus of the developing rat brain.
Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family, which is important for the growth, differentiation, and survival of neurons during development. We have performed a detailed mapping of BDNF mRNA in the neonatal rat brain using a quantitative in situ hybridization technique. At postnatal day (PND) 4, hypothalamic structures showed only modest expression of BDNF mRNA, with the exception of the ventromedial nucleus (VMN), where expression was higher than that detected in the hippocampus. ⋯ In contrast, the low levels of BDNF mRNA observed in the CA3 region of the hippocampus increased to adult levels following PND 10. As the VMN undergoes sexual differentiation, we compared BDNF, NGF, NT-3, and trkB mRNA expression in the VMN in males and females at embryonic day 20 and PND 4, but found no differences between them. These results suggest that localized and high level expression of BDNF mRNA in the neonatal VMN plays an important role in its neural organization and functional development.
-
Brain Res. Mol. Brain Res. · Mar 2003
Exogenous brain-derived neurotrophic factor prevents postischemic downregulation of [3H]muscimol binding to GABA(A) receptors in the cortical penumbra.
We have previously shown that exogenous application of brain-derived neurotrophic factor (BDNF) reduces infarct volume in the cortical ischemic penumbra after experimental focal ischemia [Stroke 31 (2000) 2212-2217]. Since BDNF is known to modulate the expression and function of various neurotransmitter receptors, we addressed the question whether BDNF may act via modification of postischemic ligand binding to excitatory NMDA and AMPA and/or inhibitory GABA(A) receptors, respectively. Transient focal cerebral ischemia was induced in male Wistar rats for 2 h using the suture occlusion technique. ⋯ Transient focal ischemia caused a significant reduction of [(3)H]muscimol binding to GABA(A) receptors within the ischemic cortical penumbra of placebo-treated rats. This was largely prevented by exogenous application of BDNF. [(3)H]MK-801 and [(3)H]AMPA binding values were also reduced in the cortical penumbra and the corresponding area of the contralateral hemisphere. Our data suggest that the neuroprotective effect of BDNF against ischemic damage in the cortical penumbra may be mediated in part by maintained activity of the inhibitory GABAergic system which likely counteracts glutamate induced excitotoxicity.