bluuebunny/crossref_metadata_2025_split huggingface dataset:
A novel function of Goα: mediation of extracellular signal‐regulated kinase activation by opioid receptors in neural cells
Authors: Zhang Wen‐Bo , Zhang Zhe , Ni Yan‐Xiang , Wu Ya‐Lan , Pei Gang 
Published: July 2010

AbstractGo is the most abundant G protein expressed in brain but its function is less known. Here we show a novel function of Goα as a mediator of opioid receptor‐induced extracellular signal‐regulated kinase activation in neural cells. The current study found that, in neuroblastoma × glioma NG108‐15 hybrid cells, activation of extracellular signal‐regulated kinase through delta opioid receptors was mediated by pertussis toxin‐sensitive G protein and independent of Gβγ subunits, PI3 kinase and receptor internalization. Overexpression of a dominant negative form of Goα1, but not Giα2, completely blocked delta opioid receptor‐induced extracellular signal‐regulated kinase activity. Decreasing Goα expression by RNA interference greatly reduced delta opioid receptor‐induced extracellular signal‐regulated kinase activity and extracellular signal‐regulated kinase‐dependent gene expression, while knocking down Giα2did not. By taking advantage of differences between human and mouse Goα gene sequences, we simultaneously knocked down endogenous Goα expression and expressed exogenous human Goα subunits. We found that both human Goα1and Goα2could mediate delta opioid receptor‐induced extracellular signal‐regulated kinase activation. This study suggests that one of the functions of Goα in the brain is to mediate extracellular signal‐regulated kinase activation by G protein‐coupled receptors.
Both apoptosis and necrosis occur early after intracerebral grafting of ventral mesencephalic tissue: a role for protease activation
Authors: Emgård M. , Hallin U. , Karlsson J. , Bahr B. A. , Brundin P. , Blomgren K. 
Published: July 2010

AbstractNeural transplantation is an experimental treatment for Parkinson's disease. Widespread clinical application of the grafting technique is hampered by a relatively poor survival (around 10%) of implanted embryonic dopamine neurones. Earlier animal studies have indicated that a large proportion of the grafted cells die during graft tissue preparation and within the first few days after intracerebral implantation. The present study was designed to reveal the prevalence of cell death in rat intrastriatal grafts at 90 min, 1, 3, 6 and 42 days after implantation. We examined apoptotic cell death using semi‐thin and paraffin sections stained with methylene blue and an antibody against activated caspase 3, respectively. We identified abundant apoptotic cell death up to 3 days after transplantation. In addition, we studied calpain activation using an antibody specific for calpain‐cleaved fodrin. We report a peak in calpain activity 90 min after grafting. Surprisingly, we did not observe any significant difference in the number of dopaminergic neurones over time. The present results imply that grafted cells may be victims of either an early necrotic or a later apoptotic cell death and that there is substantial cell death as early as 90 min after implantation.
Hydrogen peroxide induces loss of dopamine transporter activity: a calcium‐dependent oxidative mechanism
Authors: Huang Chuen‐Lin , Huang Nai‐Kuei , Shyue Song‐Kun , Chern Yijuang 
Published: July 2010

AbstractH2O2dose dependently inhibited dopamine uptake in PC12 cells and in striatal synaptosomes. Treatment with H2O2resulted in a reversible reduction inVmax, with no effect on itsKmvalue. This suppressive effect of H2O2could be relieved by reducing agents (dithiothreitol and cysteine). Furthermore, an oxidizer (dithiodipyridine) also markedly suppressed the dopamine transporter (DAT). Oxidative stress therefore might contribute to the action of H2O2. H2O2appeared to modify DAT at both extracellular and intracellular sites because cumene‐H2O2(a radical generator mostly restricted to plasma membranes) at high concentrations also slightly suppressed DAT activity and the intracellular overexpression of catalase ameliorated the inhibitory effect of H2O2. Internalization was unlikely to be involved because concanavalin A, which blocked endocytosis, did not prevent the H2O2‐evoked inhibition of DAT activity. Interestingly, H2O2treatment evoked a Ca2+influx in PC12 cells. Moreover, removal of external calcium by EGTA or reduction in the intracellular calcium level using BAPTA‐AM reversed the inhibitory effect of H2O2. Conversely, depletion of intracellular calcium stores using thapsigargin did not affect the reduction in DAT activity by H2O2. Collectively, our results indicate that the DAT, one of the most important proteins controlling the dopaminergic system, is also a redox sensor. In addition, H2O2might suppress the DAT by a Ca2+‐dependent oxidative pathway.
UDP‐N‐acetylglucosaminyl transferase (OGT) in brain tissue: temperature sensitivity and subcellular distribution of cytosolic and nuclear enzyme
Authors: Okuyama Ryo , Marshall Stephen 
Published: July 2010

AbstractIn brain tissue, UDP‐N‐acetylglucosaminyl transferase (OGT) is known to catalyze the addition of a single N‐acetylglucosamine moiety (GlcNAc) onto two proteins linked to the etiology of neurodegenerative disease –β‐amyloid associated protein and tau. Hyperphosphorylation of tau appears to cause neurofibrillary tangles and cell death, and a functional relationship appears to exist between phosphorylation and glycosylation. Since a greater understanding of brain OGT may provide new insights into the pathogenesis of Alzheimer's disease, we examined the characteristics and subcellular distribution of OGT protein and OGT activity and its relationship to O‐linked glycosylation. We found that cytosolic OGT activity is 10 times more abundant in brain tissue compared with muscle, adipose, heart, and liver tissue. Temperature studies demonstrated that cytosolic OGT activity was stable at 24°C but was rapidly inactivated at 37°C (T1/2 = 20 min). Proteases were probably not involved because OGT immunopurified from cytosol retained temperature sensitivity. Subcellular distribution studies showed abundant OGT protein in the nucleus that was enzymatically active. Nuclear OGT activity exhibited a high affinity for UDP‐GlcNAc and a salt sensitivity that was similar to cytosolic OGT; however, nuclear OGT was not inactivated at 37°C, as was the cytosolic enzyme. Two methods were used to measure O‐linked glycoproteins in brain cytosol and nucleosol –[3H]galactose labeling and western blotting using antibodies against O‐linked glycoproteins. Both methods revealed a greater abundance of O‐linked glycoproteins in the nucleus compared to cytosol.
Comparison of circadian expression of tryptophan hydroxylase isoform mRNAs in the rat pineal gland using real‐time PCR
Authors: Sugden David 
Published: July 2010

AbstractA second gene encoding a functional tryptophan hydroxylase activity has recently been described (TPH2), which is expressed abundantly in brainstem, the primary site of serotonergic neurons in the CNS. As serotonin (5‐HT) has an important role as a precursor of the nocturnal synthesis of the pineal gland hormone, melatonin, it was of interest to determine the relative expression of TPH1 and 2 mRNA in the rat pineal during the light:dark (L:D) cycle using sensitive real‐time RT‐PCR assays which were developed for each TPH isoform. TPH1 mRNA expression was 105‐fold more abundant in rat pineal than TPH2, and showed a significant ∼4‐fold nocturnal increase in expression which may contribute to the previously described nocturnal increase in pineal tryptophan hydroxylase activity. TPH2 expression within the gland showed no significant variation with time of day and was very low (∼300 copies/gland) indicating expression in the small proportion of ‘non‐pinealocyte’ cells in the gland.
Differential profile of CRF receptor distribution in the rat stomach and duodenum assessed by newly developed CRF receptor antibodies
Authors: Chatzaki Ekaterini , Murphy Brian J. , Wang Lixin , Million Mulugeta , Ohning Gordon V. , Crowe Paul D. , Petroski Robert , Taché Yvette , Grigoriadis Dimitri E. 
Published: July 2010

AbstractPeripheral corticotropin‐releasing factor (CRF) receptor ligands inhibit gastric acid secretion and emptying while stimulating gastric mucosal blood flow in rats. Endogenous CRF ligands are expressed in the upper gastrointestinal (GI) tissues pointing to local expression of CRF receptors. We mapped the distribution of CRF receptor type 1 (CRF1) and 2 (CRF2) in the rat upper GI. Polyclonal antisera directed against the C‐terminus of the CRF receptor protein were generated in rabbits and characterized by western blotting and immunofluorescence using CRF1‐ and CRF2‐transfected cell lines and in primary cultured neurons from rat brain cortex. A selective anti‐CRF1antiserum (4467a‐CRF1) was identified and used in parallel with another antiserum recognizing both CRF1and CRF2(4392a‐CRF1&2) to immunostain gastric tissue sections. Antiserum 4467a‐CRF1demonstrated specific immunostaining in a narrow zone in the upper oxyntic gland within the stomach corpus. Conversely, 4392a‐CRF1&2labeled cells throughout the oxyntic gland and submucosal blood vessels. Pre‐absorption with the specific antigen peptide blocked immunostaining in all experiments. Doublestaining showed co‐localization of 4392a‐CRF1&2but not 4467a‐CRF1immunoreactivity with H/K‐ATPase and somatostatin immunostaining in parietal and endocrine cells of the oxyntic gland. No specific staining was observed in the antrum with either antisera, whereas only antiserum 4392a‐CRF1&2showed modest immunoreactivity in the duodenal mucosa. Finally, co‐localization of CRF2and urocortin immunoreactivity was found in the gastric glands. These results indicate that both CRF receptor subtypes are expressed in the rat upper GI tissues with a distinct pattern and regional differences suggesting differential function.
4‐Hydroxytamoxifen attenuates methamphetamine‐induced nigrostriatal dopaminergic toxicity in intact and gonadetomized mice
Authors: Kuo Yu‐Min , Chen Hsiang‐Hua , Shieh Chih‐Chang , Chuang Kuo‐Pin , Cherng Chianfang G. , Yu Lung 
Published: July 2010

AbstractThe present study was undertaken to assess the ability of 4‐hydroxytamoxifen (4‐OHT) to alter methamphetamine‐induced nigrostriatal dopaminergic toxicity. Three daily doses of 4‐OHT (6 µg/day) effectively attenuated methamphetamine‐induced nigrostriatal dopamine depletions in both sexes of intact and gonadectomized C57BL/6 J mice. 4‐OHT alone did not alter the dopamine content levels in the striatum. Both male and female mice exhibited similar Cu, Zn‐superoxide dismutase protein levels in the striata whether after gonadectomy or 4‐OHT treatment. Furthermore, basal body temperature and methamphetamine‐induced hyperthermia were not affected by 4‐OHT treatment in either sex of mice. Using a lucigenen‐derived chemiluminescence assay, we found that 4‐OHT by itself can serve as a potent superoxide anion radical scavengerin vitro. The protective effects of 4‐OHT against methamphetamine‐induced nigrostriatal dopamine depletion can be, in part, due to its antioxidative characteristics. The free radical‐scavenging ability of 4‐OHT calls for further investigations for its uses in clinical practice.
Effect of methylphenidate on dopamine/DARPP signalling in adult, but not young, mice
Authors: Fukui Ryuichi , Svenningsson Per , Matsuishi Toyojiro , Higashi Hideho , Nairn Angus C. , Greengard Paul , Nishi Akinori 
Published: July 2010

AbstractMethylphenidate (MPH), a dopamine uptake inhibitor, is the most commonly prescribed drug for the treatment of attention‐deficit/hyperactivity disorder (ADHD) in children. We examined the effect of MPH on dopamine‐ and cAMP‐regulated phosphoprotein,Mr32 kDa (DARPP‐32) phosphorylation at Thr34 (PKA‐site) and Thr75 (Cdk5‐site) using neostriatal slices from young (14–15‐ and 21–22‐day‐old) and adult (6–8‐week‐old) mice. MPH increased DARPP‐32 Thr34 phosphorylation and decreased Thr75 phosphorylation in slices from adult mice. The effect of MPH was blocked by a dopamine D1 antagonist, SCH23390. In slices from young mice, MPH did not affect DARPP‐32 phosphorylation. As with MPH, cocaine stimulated DARPP‐32 Thr34 phosphorylation in slices from adult, but not from young mice. In contrast, a dopamine D1 agonist, SKF81297, regulated DARPP‐32 phosphorylation comparably in slices from young and adult mice, as did methamphetamine, a dopamine releaser. The results suggest that dopamine synthesis and the dopamine transporter are functional at dopaminergic terminals in young mice. In contrast, the lack of effect of MPH in young mice is likely attributable to immature development of the machinery that regulates vesicular dopamine release.
Enhancement of ischemia‐induced tyrosine phosphorylation of Kv1.2 by vascular endothelial growth factor via activation of phosphatidylinositol 3‐kinase
Authors: Qiu Mei‐Hong , Zhang Rong , Sun Feng‐Yan 
Published: July 2010

AbstractOur studies observed that, consistent with the literature, ischemic/hypoxic insults increased the expression of voltage‐gated potassium channel (Kv) 1.2 potassium channel as well as elevating the endogenous level of vascular endothelial growth factor (VEGF) in neurons of adult rat brain following middle cerebral artery occlusion and in SH‐SY5Y cells after hypoxia and glucose deprivation. Concomitantly, we also observed that ischemic injury increased the tyrosine phosphorylation of Kv 1.2 inin vivoandin vitro; the introduction of exogenous VEGF could attenuate cell death inin vitromodels. Furthermore, we found that the protective effect of VEGF is mediated through its up‐regulative actions on the tyrosine phosphorylation of Kv 1.2, which in turn has a direct influence on cell viability after ischemic insult. In substantiation of this result, we used anti‐sense methodology to suppress the expression of endogenous VEGF, which significantly inhibited the tyrosine phosphorylation of Kv 1.2 and increased cell death elicited by ischemic/hypoxic injury. Finally, the enhancement of the tyrosine phosphorylation of the channel by VEGF in neuronal cells was significantly attenuated in the presence of wortmannin, an inhibitor of phosphatidylinositol 3‐kinase (PI3‐K), or genestin, an inhibitor of tyrosine kinase, thus suggesting that the phosphorylation of Kv 1.2 induced by VEGF is mechanistically linked to the PI3‐K pathway.
Selective prion protein binding to synaptic components is modulated by oxidative and nitrosative changes induced by copper(II) and peroxynitrite in cholinergic synaptosomes, unveiling a role for calcineurin B and thioredoxin
Authors: Morot‐Gaudry‐Talarmain Y. , Rezaei H. , Guermonprez L. , Treguer E. , Grosclaude J. 
Published: July 2010

AbstractCholine acetyltransferase (ChAT) and choline transport are decreased after nitrosative stress. ChAT activity is altered in scrapie‐infected neurons, where oxidative stress develops. Cellular prion protein (PrPc) may play a neuroprotective function in participating in the redox control of neuronal environment and regulation of copper metabolism, a role impaired when PrPcis transformed into PrPScin prion pathologies. The complex cross‐talk between PrPcand cholinergic neurons was analyzedin vitrousing peroxynitrite and Cu2+treatments on nerve endings isolated fromTorpedo marmorata, a model of the motoneuron pre‐synaptic element. Specific interactions between solubilized synaptic components and recombinant ovine prion protein (PrPrec) could be demonstrated by Biacore technology. Peroxynitrite abolished this interaction in a concentration‐dependent way and induced significant alterations of neuronal targets. Interaction was restored by prior addition of peroxynitrite trapping agents. Cu2+(in the form of CuSO4) treatment of synaptosomes triggered a milder oxidative effect leading to a bell‐shaped increase of PrPrec binding to synaptosomal components, counteracted by the natural thiol agents, glutathione and thioredoxin. Copper(II)‐induced modifications of thiols in several neuronal proteins. A positive correlation was observed between PrPrec binding and immunoreactive changes for calcineurin B and its partners, suggesting a synergy between calcineurin complex and PrP for copper regulation.
Rapid accumulation of Akt in mitochondria following phosphatidylinositol 3‐kinase activation
Authors: Bijur Gautam N. , Jope Richard S. 
Published: July 2010

AbstractWe describe here a new component of the phosphatidylinositol 3‐kinase/Akt signaling pathway that directly impacts mitochondria. Akt (protein kinase B) was shown for the first time to be localized in mitochondria, where it was found to reside in the matrix and the inner and outer membranes, and the level of mitochondrial Akt was very dynamically regulated. Stimulation of a variety of cell types with insulin‐like growth factor‐1, insulin, or stress (induced by heat shock), induced translocation of Akt to the mitochondria within only several minutes of stimulation, causing increases of nearly eight‐ to 12‐fold, and the mitochondrial Akt was in its phosphorylated, active state. Two mitochondrial proteins were identified to be phosphorylated following stimulation of mitochondrial Akt, the β‐subunit of ATP synthase and glycogen synthase kinase‐3β. The finding that mitochondrial glycogen synthase kinase‐3β was rapidly and substantially modified by Ser9 phosphorylation, which inhibits its activity, following translocation of Akt to the mitochondria is the first evidence for a regulatory mechanism affecting mitochondrial glycogen synthase kinase‐3β. These results demonstrate that signals emanating from plasma membrane receptors or generated by stress rapidly modulate Akt and glycogen synthase kinase‐3β in mitochondria.
Repeated cocaine administration changes the function and subcellular distribution of adenosine A1receptor in the rat nucleus accumbens
Authors: Toda Shigenobu , Alguacil Luis F. , Kalivas Peter W. 
Published: July 2010

AbstractAdenosine A1receptor (A1) protein and mRNA is increased in the nucleus accumbens following repeated cocaine treatment. In spite of this protein up‐regulation, A1agonist‐stimulated [35S]GTPγS binding was attenuated in accumbens homogenates of rats withdrawn for 3 weeks from 1 week of daily cocaine injections. Cellular subfractionation revealed that the discrepancy between total A1protein and G protein coupling resulted from a smaller proportion of receptors in the plasma membrane. The decrease in functional receptor in the plasma membrane was further indicated by diminished formation of heteromeric receptor complex consisting of A1and dopamine D1Areceptors. To explore the functional significance of the altered distribution of A1receptors, at 3 weeks after discontinuing repeated cocaine or saline, animals were injected with cocaine and 45 min later the subcellular distribution of A1receptors quantified. Whereas a cocaine challenge in repeated saline‐treated animals induced a marked increase in membrane localization of the A1receptor, the relative distribution of receptors in repeated cocaine rats was not affected by acute cocaine. These data suggest that the sorting and recycling of A1receptors is dysregulated in the nucleus accumbens as the consequence of repeated cocaine administration.
The mGlu2/3 receptor agonist, LY354740, blocks immobilization‐induced increases in noradrenaline and dopamine release in the rat medial prefrontal cortex
Authors: Swanson Chad J. , Perry Kenneth W. , Schoepp Darryle D. 
Published: July 2010

AbstractThe metabotropic glutamate (mGlu2/3) receptor agonist, LY354740, exhibits anxiolytic‐like properties in a number of rodent models. The present study utilizedin vivomicrodialysis to examine the effects of LY354740 on extracellular monoamine levels in the medial prefrontal cortex (mPFC) of animals subjected to 30 min immobilization stress. Immobilization stress significantly elevated extracellular levels of noradrenaline (NA) and dopamine (DA) in the mPFC, while systemic administration of LY354740 (30 mg/kg, s.c.) significantly attenuated immobilization‐induced increases in both NA and DA. Reverse‐dialysis of LY354740 (30 µm) into the mPFC significantly attenuated immobilization‐induced increases in NA, but not DA without affecting basal levels of either amine. In separate studies in the presence of citalopram (1 µm; reverse dialysis into the mPFC), systemic administration of LY354740 attenuated immobilization‐induced increases in NA and DA, but had no effect on serotonin (5‐HT) levels. Co‐administration of the selective mGlu2/3 receptor antagonist, LY341495, partially or fully reversed the attenuation in NA and DA levels produced by LY354740, respectively. Taken together, these data suggest that LY354740 may produce anti‐stress actions, in part, by blocking stress‐related increases in catecholamines in the mPFC via mGlu2/3 receptor stimulation.
Transcriptional regulation of human excitatory amino acid transporter 1 (EAAT1): cloning of theEAAT1promoter and characterization of its basal and inducible activity in human astrocytes
Authors: Kim Seon‐Young , Choi So‐Young , Chao Wei , Volsky David J. 
Published: July 2010

AbstractExcitatory amino acid transporter 1 (EAAT1) is one of the two glial glutamate transporters that clear the extracellular glutamate generated during neuronal signal transmission. Here, we cloned and characterized a 2.1‐kb promoter region of human EAAT1 and investigated its function in the transcriptional regulation of theEAAT1gene in human primary astrocytes. The full‐length promoter region lacked TATA and CCAAT boxes and an initiator element, it contained several potential transcription factor‐binding sites and it exhibited promoter activity in primary astrocytes and in several types of transformed cells. Consecutive 5′‐deletion analysis of theEAAT1promoter indicated the presence of negative and positive regulatory regions and a putative core promoter between −57 bp and +20 bp relative to the transcription start site (TSS). The core promoter contained a single GC‐box in position −52/−39 and one E‐box near the TSS and the GC‐box site that was responsible for 90% of the basal promoter activity as determined by mutational analysis. Electrophoretic mobility shift, supershift and competition assays demonstrated binding of stimulating proteins (Sp) 1 and 3 to the GC‐box and upstream stimulating factor (USF) 1 to the E‐box. Treatment of primary human astrocytes with cellular modulators 8‐bromo cyclic AMP and epidermal growth factor increasedEAAT1promoter activity in transient transfection assays and increased cellularEAAT1mRNA expression and glutamate uptake by astrocytes. Conversely, tumor necrosis factor‐α reduced bothEAATpromoter activity and cellularEAAT1mRNA expression. These results enable studies of transcriptional regulation ofEAAT1gene at the promoter level.