bluuebunny/crossref_metadata_2025_split huggingface dataset:
Histamine H2‐like receptors in chick cerebral cortex: effects on cyclic AMP synthesis and characterization by [3H]tiotidine binding
Authors: Zawilska Jolanta B. , Woldan‐Tambor Agata , Nowak Jerzy Z. 
Published: March 2003

AbstractIn this study, histamine (HA) receptors in chick cerebral cortex were characterized using two approaches: (1) analysis of the effects of HA‐ergic drugs on the cAMP‐generating system, and (2) radioreceptor binding of [3H]tiotidine, a selective H2antagonist. HA was a weak activator of adenylyl cyclase in a crude membrane preparation of chick cerebrum. On the other hand, HA (0.1–1000 μm) potently and concentration dependently stimulated cAMP production in [3H]adenine pre‐labelled slices of chick cerebral cortex, displaying an EC50value (concentration that produces 50% of maximum response) of 2.65 μm. The effect of HA was mimicked by agonists of HA receptors with the following rank order of potency: HA ≥  4‐methylHA (H2) ≥ Nα,Nα‐dimethylHA (H3 ≫ H2 = H1) ≫  2‐methylHA (H1) ≫ 2‐thiazolylethylamine (H1) ≥ Rα‐methylHA (H3) ≫ amthamine, dimaprit (H2), immepip (H3, H4). The HA‐evoked increase in cAMP production in chick cerebral cortex was antagonized by selective H2receptor blockers (aminopotentidine ≥ tiotidine > ranitidine ≫ zolantidine), and not significantly affected by mepyramine and thioperamide, selective H1and H3/H4receptor blockers, respectively. A detailed analysis of the antagonistic action of aminopotentidine (vs. HA) revealed a non‐competitive mode of action. The binding of [3H]tiotidine to chick cortical membranes was rapid, stable and reversible. Saturation analysis resulted in a linear Scatchard plot, suggesting binding to a single class of receptor binding site with high affinity [equilibrium dissociation constant (Kd) = 4.42 nm] and high capacity [maximum number of binding sites (Bmax) = 362 fmol/mg protein]. The relative rank order of HA‐ergic drugs to inhibit [3H]tiotidine binding to chick cerebrum was: antagonists – tiotidine ≫ aminopotentidine = ranitidine ≥ zolantadine ≫ thioperamide ≈ triprolidine; agonists – HA ≥ 4‐methylHA ≫ 2‐methylHA ≥Rα‐methylHA ≈ dimaprit. In conclusion, chick cerebral cortex contains H2‐like HA receptors that are linked to the cAMP‐generating system and are labelled with [3H]tiotidine. The pharmacological profile of these receptors is different from that described for their mammalian counterpart. It is suggested that the studied receptors represent either an avian‐specific H2‐like HA receptors or a novel subtype of HA receptors.
Chronic nicotine treatment reduces β‐amyloidosis in the brain of a mouse model of Alzheimer's disease (APPsw)
Authors: Nordberg Agneta , Hellström‐Lindahl Ewa , Lee Mandy , Johnson Mary , Mousavi Malahat , Hall Ros , Perry Elaine , Bednar Ivan , Court Jennifer 
Published: March 2003

AbstractAlzheimer's disease neuropathology is characterised by β‐amyloid plaques and neurofibrillary tangles. Inhibition of β‐amyloid accumulation may be essential for effective therapy in Alzheimer's disease. In this study we have treated transgenic mice carrying the Swedish mutation of human amyloid precursor protein [Tg(Hu.APP695.K670N‐M671L)2576], which develop brain β‐amyloid deposits, with nicotine in drinking fluid (200 µg/mL) from 9–14.5 months of age (5.5 months). A significant reduction in amyloid β peptide 1–42 positive plaques by more than 80% (p < 0.03) was observed in the brains of nicotine treated compared to sucrose treated transgenic mice. In addition, there was a selective reduction in extractable amyloid β peptides in nicotine treated mice; cortical insoluble 1–40 and 1–42 peptide levels were lower by 48 and 60%, respectively (p < 0.005), whilst there was no significant change in soluble 1–40 or 1–42 levels. The expression of glial fibrillary acidic protein was not affected by nicotine treatment. These results indicate that nicotine may effectively reduce amyloid β peptide aggregation in brain and that nicotinic drug treatment may be a novel protective therapy in Alzheimer's disease.
Transglutaminase overexpression sensitizes neuronal cell lines to apoptosis by increasing mitochondrial membrane potential and cellular oxidative stress
Authors:   Mauro Piacentini,, Grazia Farrace Maria , Piredda Lucia , Matarrese Paola , Ciccosanti Fabiola , Falasca Laura , Rodolfo Carlo , Giammarioli Anna Maria , Verderio Elisabetta , Griffin Martin , Malorni Walter 
Published: March 2003

Abstract‘Tissue’ transglutaminase (tTG) selectively accumulates in cells undergoing apoptosis both in vivo and in vitro. Considering the central role played by mitochondria in apoptosis, we investigated the relationships existing amongst tTG expression, apoptosis and mitochondrial function. To this aim we studied the mechanisms of apoptosis in a neuronal cell line (SK‐N‐BE (2)) in which the tTG‐expression was driven by a constitutive promoter. Furthermore, a tet‐off inducible promoter was also used in 3T3 fibroblastic cells used as control. Both cell lines, when expressing tTG, appeared ‘sensitized’ to apoptosis. Strikingly, we found major differences in the morphological features of mitochondria among cell lines in the absence of apoptotic stimuli. In addition, these ultrastructural characteristics were associated with specific functional features: (i) constitutively hyperpolarized mitochondria and (ii) increased reactive oxygen intermediates production. Importantly, after mitochondrial‐mediated apoptosis by stauro‐ sporine, a rapid loss of mitochondrial membrane potential was found in tTG cells only. Taken together, these results seem to suggest that, via hyperpolarization, tTG might act as a ‘sensitizer’ towards apoptotic stimuli specifically targeted to mitochondria. These results could also be of pathogenetic relevance for those diseases that are characterized by increased tTG and apoptotic rate together with impaired mitochondrial function, e.g. in some neurodegenerative disease.
Progressive decrease of amyloid precursor protein carboxy terminal fragments (APP‐CTFs), associated with tau pathology stages, in Alzheimer's disease
Authors: Sergeant Nicolas , David Jean‐Philippe , Champain Danie , Ghestem Antoine , Wattez Annick , Delacourte André 
Published: March 2003

AbstractAmyloid precursor protein (APP) dysfunction is a key aetiologic agent in Alzheimer's disease (AD). The processing of this transmembrane protein generates carboxy terminal fragments (CTFs) upstream of β‐amyloid peptide (Aβ) production. The physiologic significance of APP‐CTFs is still poorly understood, as well as the relationship that could link APP dysfunction and tau pathology in familial and non‐familial AD (non‐FAD). In the present study, we have investigated the quantitative and qualitative changes of APP‐CTFs in different brain areas of non‐demented and demented patients from a prospective and multidisciplinary study. A significant decrease of the five APP‐CTFs was observed, which correlated well with the progression of tau pathology, in most cases with infraclinical AD and AD, either familial or non‐FAD. Furthermore, solubility properties and the ratio between the five bands were also modified, both in the Triton‐soluble and/or ‐insoluble fractions. Together, we show here for the first time a modification directly observed on APP‐CTFs upstream of Aβ products and its relationship with tau pathology, which could reflect the basic aetiological mechanisms of AD.
Myelin‐associated glycoprotein modulates expression and phosphorylation of neuronal cytoskeletal elements and their associated kinases
Authors: Dashiell Suzanne M. , Tanner Sandra L. , Pant Harish C. , Quarles Richard H. 
Published: March 2003

AbstractDecreased phosphorylation of neurofilaments in mice lacking myelin‐associated glycoprotein (MAG) was shown to be associated with decreased activities of extracellular‐signal regulated kinases (ERK1/2) and cyclin‐dependent kinase‐5 (cdk5). These in vivo changes could be caused directly by the absence of a MAG‐mediated signaling pathway or secondary to a general disruption of the Schwann cell–axon junction that prevents signaling by other molecules. Therefore, in vitro experimental paradigms of MAG interaction with neurons were used to determine if MAG directly influences expression and phosphorylation of cytoskeletal proteins and their associated kinases. COS‐7 cells stably transfected with MAG or with empty vector were co‐cultured with primary dorsal root ganglion (DRG) neurons. Total amounts of the middle molecular weight neurofilament subunit (NF‐M), microtubule‐associated protein 1B (MAP1B), MAP2, and tau were up‐regulated significantly in DRG neurons in the presence of MAG. There was also increased expression of phosphorylated high molecular weight neurofilament subunit (NF‐H), NF‐M, and MAP1B. Additionally, in similar in vitro paradigms, total and phosphorylated NF‐M were increased significantly in PC12 neurons co‐cultured with MAG‐expressing COS cells or treated with a soluble MAG Fc‐chimera. The increased expression of phosphorylated cytoskeletal proteins in the presence of MAG in vitro was associated with increased activities of ERK 1/2 and cdk5. We propose that interaction of MAG with an axonal receptor(s) induces a signal transduction cascade that regulates expression of cytoskeletal proteins and their phosphorylation by these proline‐directed protein kinases.
Protective action of the peroxisome proliferator‐activated receptor‐γ agonist pioglitazone in a mouse model of Parkinson's disease
Authors: Breidert T. , Callebert J. , Heneka M. T. , Landreth G. , Launay J. M. , Hirsch E. C. 
Published: March 2003

AbstractWe examined the effect of pioglitazone, a peroxisome proliferator‐activated receptor‐γ (PPARγ)agonistofthethiazolidinedione class, on dopaminergic nerve cell death and glial activation in the 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) mouse model of Parkinson's disease. The acute intoxication of C57BL/6 mice with MPTP led to nigrostriatal injury, as determined by tyrosine hydroxylase (TH) immunocytochemistry, and HPLC detection of striatal dopamine and metabolites. Damage to the nigrostriatal dopamine system was accompanied by a transient activation of microglia, as determined by macrophage antigen‐1 (Mac‐1) and inducible nitric oxide synthase (iNOS) immunoreactivity, and a prolonged astrocytic response. Orally administered pioglitazone (∼ 20 mg/kg/day) attenuated the MPTP‐inducedglialactivation and prevented the dopaminergic cell loss in the substantia nigra pars compacta (SNpc). In contrast, there was little reduction of MPTP‐induced dopamine depletion, with no detectable effect on loss of TH immunoreactivity and glial response in the striatum of pioglitazone‐treated animals. Low levels of PPARγ expression were detected in the ventral mesencephalon and striatum, and were unaffected by MPTP or pioglitazone treatment. Since pioglitazone affects primarily the SNpc in our model, different PPARγ‐independent mechanisms may regulate glial activation in the dopaminergic terminals compared with the dopaminergic cell bodies after acute MPTP intoxication.
The neuronal choline transporter CHT1 is regulated by immunosuppressor‐sensitive pathways
Authors: Guermonprez Lydie , O'Regan Seana , Meunier François‐Marie , Morot‐Gaudry‐Talarmain Yvette 
Published: March 2003

AbstractThe immunosuppressor cyclosporin A inhibits the peptidyl‐prolyl‐cis/trans‐isomerase activity of cyclophilins and the resulting complex inhibits the phosphatase activity of calcineurin. Both enzymes were detected in peripheral nerve endings isolated from the electric organ of Torpedo and shown to be affected by 10 µm cyclosporin A. Among the cholinergic properties studied, choline uptake was specifically inhibited by cyclosporin A to a maximum of 40%. Cyclosporin A decreased the rate of choline transport but not the binding of the non‐transportable choline analogue hemicholinium‐3, indicating that the number of membrane transporters was not affected. Through the use of two other immunosuppressors, FK506, which also inhibits calcineurin, and rapamycin, which does not, two different mechanisms of choline uptake inhibition were uncovered. FK506 inhibited the rate of choline transport, whereas rapamycin diminished the affinity for choline. The Torpedo homologue of the high affinity choline transporter CHT1 was cloned and its activity was reconstituted in Xenopus oocytes. Choline uptake by oocytes expressing tCHT1 was inhibited by all three immunosuppressors and also by microinjection of the specific calcineurin autoinhibitory domain A457−481, indicating that the phosphatase calcineurin regulates CHT1 activity and could be the common target of cyclosporin and FK506. Rapamycin, which changed the affinity of the transporter, may have acted through an immunophilin on the isomerization of critical prolines that are found in the tCHT1 sequence.
Feasibility of ex vivo gene therapy for neurological disorders using the new retroviral vector GCDNsap packaged in the vesicular stomatitis virus G protein
Authors: Suzuki A. , Obi K. , Urabe T. , Hayakawa H. , Yamada M. , Kaneko S. , Onodera M. , Mizuno Y. , Mochizuki H. 
Published: March 2003

AbstractNeuronal progenitor cells (NPC) are particularly suited as the target population for genetic and cellular therapy of neurological disorders such as Parkinson's disease or stroke. However, genetic modification of these cells using retroviral vectors remains a great challenge because of the low transduction rate and the need for fetal calf serum (FCS) during the transduction process that induces the cell differentiation to mature neurons. To overcome these problems, we developed a new retrovirus production system in which the simplified retroviral vector GCDNsap engineered to be resistant to denovo methylation was packaged in the vesicular stomatitis virus G protein (VSV‐G), concentrated by centrifugation, and resuspended in serum‐free medium (StemPro‐34 SFM). In transduction experiments using enhanced green fluorescent protein (EGFP) as a marker, the concentrated FCS‐free virus supernatant infected NPC at a high rate, while maintaining the ability of these cells to self‐renew and differentiate in vitro. When such cells were grafted into mouse brains, EGFP‐expressing NPC were detected in the region around the injection site at 8 weeks post transplantation. These findings suggest that the gene transfer system described here may provide a useful tool to genetically modify NPC for treatments of neurological disorders.
Cytochrome c release precedes mitochondrial membrane potential loss in cerebellar granule neuron apoptosis: lack of mitochondrial swelling
Authors: Wigdal Susan S. , Kirkland Rebecca A. , Franklin James L. , Haak‐Frendscho Mary 
Published: March 2003

AbstractIt has been suggested that release of cytochrome c (Cyt c) from mitochondria during apoptotic death is through opening of the mitochondrial permeability transition pore followed by swelling‐induced rupture of the mitochondrial outer membrane. However, this remains controversial and may vary with cell type and model system. We determined that in mouse cerebellar granule neurons, Cyt c redistribution preceded the loss of mitochondrial membrane potential during the apoptotic process, suggesting that the pore did not open prior to release. Furthermore, when mitochondria were morphologically assessed by electron microscopy, they were not obviously swollen during the period of Cyt c release. This indicates that the pore mechanism of action, if any, is not through mitochondrial outer membrane rupture. While bongkrekic acid, an inhibitor of pore opening, modestly delayed apoptotic death, it also caused a significant (p < 0.05) suppression of protein synthesis. An equivalent suppression of protein synthesis by cycloheximide had a similar delaying effect, suggesting that bongkrekic acid was acting non‐specifically. These findings suggest that mitochondrial permeability transition pore is not involved in Cyt c release from mitochondria during the apoptotic death of cerebellar granule neurons.
Putative histamine‐gated chloride channel subunits of the insect visual system and thoracic ganglion
Authors: Witte Ines , Kreienkamp Hans‐Juergen , Gewecke Michael , Roeder Thomas 
Published: March 2003

AbstractHistamine‐gated chloride channels, members of the ligand‐gated ion channel superfamily, are thought to be peculiar for arthropods. Their cognate ligand, histamine, is the transmitter of all arthropod photoreceptors and of thoracic mechanoreceptors. To identify putative histamine‐gated chloride channel subunits we scanned the Drosophila genome for putative ligand‐gated chloride channel subunits and found 12 candidate genes. We found four groups of transcripts based on their expression pattern. Only members of the last group show an expression pattern that is consistent with our knowledge about histamine‐gated chloride channels in insects. In the brain these transcripts (Dm HA‐Cl I and II) are exclusively present in interneurones postsynaptic to photoreceptors. Within the lamina (the first visual ganglion) only the L1–L3 neurones are labelled. The lack of non‐photoreceptor dependent staining in the brain indicates that mechanosensory transmission differs between the head and the thorax/abdomen, and that the receptors responding to brain‐intrinsic histaminergic cells use different signalling pathways. The putative histamine‐gated chloride channels show the greatest homology mammalian glycine receptors. These ion‐channels are the first specific molecular markers for postsynaptic cells in the insect visual system, thus representing ideal tools to study its physiology and development.
Analysis on the promoter region of exon IV brain‐derived neurotrophic factor in NG108‐15 cells
Authors: Takeuchi Yusuke , Miyamoto Eishichi , Fukunaga Kohji 
Published: March 2003

AbstractWe have reported that the nuclear isoforms of Ca2+/calmodulin‐dependent protein kinase II (CaM KII) are involved in the expression of the exon IV‐containing brain‐derived neurotrophic factor (BDNF) mRNA. We document here the cis‐elements and transcription factors responsive to CaM KII inthe activation of the promoter upstream of the exon IV (exon IV‐BDNF promoter). Effects of constitutively active mutants of CaM KIV, MAPK kinase kinase (MEKK) and protein kinase A (PKA) on the exon IV‐BDNF promoter activity were also evaluated by transfection and luciferase assay. The exon IV‐BDNF promoter activity was increased by transfection with CaM KII, MEKK and PKA, but not by CaM KIV. Deletion and mutational analysis of the promoter revealed that the region between nucleotides −56 and −27 was responsive to CaM KII, which contained a CCAAT‐box in the region between nucleotides −56 and −43. Expression of C/EBPβ increased the promoter activity and potentiated the effects of CaM KII. The region between nucleotides −79 and −56 was responsive to MEKK, in which both a GA‐rich sequence and a GC‐box were included. Expression of Sp1 increased the promoter activity, which was further enhanced by transfection with MEKK. The region between nucleotides −43 and −27 was responsive to both PKA and CaM KII, but the transcription factors involved in the region remained unclear. These results suggest that the promoter of the exon IV‐BDNF is at least regulated by CaM KII, MEKK and PKA, and that C/EBP/β and Sp1 are potential transcription factors activated by CaM KII and MEKK, respectively.
The 5′‐flanking region of the rat GABAA receptor α2‐subunit gene (Gabra2)
Authors: Fuchs Karoline , Celepirovic Nevenka 
Published: March 2003

AbstractThe GABAA receptor α2‐subunit gene (Gabra2) has a specific spatial and temporal pattern of expression in rat brain. As a first step towards understanding the molecular mechanism underlying this regulation, we have investigated the structural properties of the 5′‐ flanking region of the rat Gabra2 gene. We identified six α2 transcript isoforms, each of which differs only in the 5′‐untranslated region (UTR). Alignment of cDNA and genomic DNA sequences revealed that six 5′‐UTRs are generated from three alternative first exons by alternative splicing using internal and terminal 5′‐splice donor sites present in these exons. Promoter regions containing multiple transcription initiation sites were identified in the 5′ proximity of each first exon. Two of these promoters lack TATA and CCAAT sequences. Finally, we have shown that differential activation of alternative promoters is used for the expression of the α2 mRNA isoforms during brain development, and that the diversity at the 5′‐end of these transcripts affects GABAA receptor expression. Taken together, these results suggest that the expression of the Gabra2 gene can be influenced at both the transcriptional and post‐transcriptional levels.
Pyroglutamate‐modified amyloid β‐peptides – AβN3(pE) – strongly affect cultured neuron and astrocyte survival
Authors: Russo Claudio , Violani Elisabetta , Salis Serena , Venezia Valentina , Dolcini Virginia , Damonte Gianluca , Benatti Umberto , D'Arrigo Cristina , Patrone Eligio , Carlo Pia , Schettini Gennaro 
Published: March 2003

AbstractN‐terminally truncated amyloid‐β (Aβ) peptides are present in early and diffuse plaques of individuals with Alzheimer's disease (AD), are overproduced in early onset familial AD and their amount seems to be directly correlated to the severity and the progression of the disease in AD and Down's syndrome (DS). The pyroglutamate‐containing isoforms at position 3 [AβN3(pE)−40/42] represent the prominent form among the N‐truncated species, and may account for more than 50% of Aβ accumulated in plaques. In this study, we compared the toxic properties, fibrillogenic capabilities, and in vitro degradation profile of Aβ1–40, Aβ1–42, AβN3(pE)−40 and AβN3(pE)−42. Our data show that fibre morphology of Aβ peptides is greatly influenced by the C‐terminus while toxicity, interaction with cell membranes and degradation are influenced by the N‐terminus. AβN3(pE)−40 induced significantly more cell loss than the other species both in neuronal and glial cell cultures. Aggregated AβN3(pE) peptides were heavily distributed on plasma membrane and within the cytoplasm of treated cells. AβN3(pE)−40/42 peptides showed a significant resistance to degradation by cultured astrocytes, while full‐length peptides resulted partially degraded. These findings suggest that formation of N‐terminally modified peptides may enhance β‐amyloid aggregation and toxicity, likely worsening the onset and progression of the disease.