bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stimulation of 5‐hydroxytryptamine (5‐HT2C) receptors in the ventrotegmental area inhibits stress‐induced but not basal dopamine release in the rat prefrontal cortex
Authors: Pozzi Laura , Acconcia Sabrina , Ceglia Ilaria , Invernizzi Roberto W. , Samanin Rosario 
Published: March 2003

AbstractThe present study investigated whether 5‐HT2C receptors in the ventrotegmental area and prefrontal cortex regulate basal and stimulus‐evoked dopamine release in the prefrontal cortex. Using the in vivo microdialysis technique in conscious rats, we studied the effect of a selective 5‐HT2C receptor agonist, Ro60–0175, on basal and immobilization stress‐induced dopamine release in the prefrontal cortex. Ro60–0175 intraperitoneally (2.5 mg/kg) and into the ventrotegmental area (10 µg/0.5 µL) completely antagonized the effect of stress on extracellular dopamine without altering basal levels. Infusion of 10 µm Ro60–0175 through the cortical probe had no significant effect on basal and stress‐induced dopamine release. SB242084 (10 mg/kg), a selective antagonist of 5‐HT2C receptors, significantly increased basal extracellular dopamine and completely prevented the effect of intraperitoneal and intraventrotegmental Ro60–0175 on the stress‐induced rise of extracellular dopamine, but had no effect itself in stressed rats. The results show that Ro60–0175 suppresses cortical dopamine release induced by immobilization stress through the stimulation of 5‐HT2C receptors in the ventrotegmental area. While confirming that endogenous 5‐HT acting on 5‐HT2C receptors tonically inhibit basal dopamine release in the prefrontal cortex, the present findings suggest that the stimulation of 5‐HT2C receptors with an exogenous agonist preferentially inhibit stimulated release.
Generation of reactive oxygen species and activation of NF‐κB by non‐Aβ component of Alzheimer's disease amyloid
Authors: Tanaka Seigo , Takehashi Masanori , Matoh Naomi , Iida Shinya , Suzuki Tomoki , Futaki Shiroh , Hamada Hirofumi , Masliah Eliezer , Sugiura Yukio , Ueda Kunihiro 
Published: March 2003

AbstractNon‐amyloid beta (Aβ) component of Alzheimer's disease (AD) amyloid (NAC) coexists with Aβ protein in senile plaques. After exposure to NAC fibrils, cortical neurons of rat brain primary culture became apoptotic, while astrocytes were activated with extension of their processes. NAC fibrils decreased the activity of reducing 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) in cortical neurons more markedly (IC50 = 5.6 µm) than in astrocytes (IC50≈ 50 µm). The neuron‐specific toxicity of NAC fibrils was indicated also by an increased release of lactate dehydrogenase from the cells. Neuronal apoptosis was suppressed by pre‐treatment with the antioxidants, propyl gallate (PG) and N‐t‐butyl‐phenylnitrone (BPN), or overexpression of human Bcl‐2. Exposure to NAC fibrils enhanced generation of reactive oxygen species (ROS) in neurons and less efficiently in astrocytes, as demonstrated by oxidation of 2′,7′‐dichlorofluorescin. The site of ROS generation was shown to be mitochondria by oxidation of chloromethyl‐tetramethyl rosamine. Exposure to NAC fibrils increased also the nuclear translocation of nuclear factor kappa B (NF‐κB) and enhanced its DNA‐binding activity, which was inhibited by PG and BPN more efficiently in neurons than in astrocytes. These results suggest that NAC fibrils increase mitochondrial ROS generation and activate NF‐κB, thereby causing a differential change in gene expression between neurons and astrocytes in the AD brain.
Inhibition of oxidative stress produced by plasma membrane NADH oxidase delays low‐potassium‐induced apoptosis of cerebellar granule cells
Authors: Martín‐Romero Francisco Javier , García‐Martín Elena , Gutiérrez‐Merino Carlos 
Published: March 2003

AbstractFrom 1 to 3 h after the onset of cerebellar granule cells (CGC) apoptosis in a low‐K+(5 mm KCl) medium there was a large decay of NADH and a 2.5‐fold increase of the rate of reactive oxygen species (ROS) production (measured using CGC loaded with dichlorodihydrofluorescein). During the same time period, the ascorbate‐dependent NADH oxidase activity, which accounted for more than 90% of both total NADH oxidase activity and NADH‐dependent ·O2– production of CGC lysates, increased 2.5‐ to threefold. The stimulation of the ascorbate‐dependent NADH oxidase activity by oxidized cytochrome c, 2.5‐fold at saturation with a K0.5 of 4–5 µm cytochrome c, can at least partially explain this activation. The plasma membrane ascorbate‐dependent NADH oxidase activity accounted for more than 70% of the total activity (both in terms of NADH oxidase and ·O2– release) of CGC lysates. 4‐Hydroxyquinazoline (4‐HQ), which was found to block this apoptotic process, prevented the increase of ROS production. 4‐HQ protection against cell viability loss and DNA fragmentation correlated with the inhibition by 4‐HQ of the ascorbate‐dependent NADH oxidase activity of CGC lysates, showing the same K0.5‐value (4–5 mm 4‐HQ). The efficient blockade of CGC apoptosis by addition of superoxide dismutase to the medium further supports the neurotoxic role of ·O2– overproduction by the plasma membrane ascorbate‐dependent NADH oxidase.
Matrix metalloproteinase‐1 activates a pertussis toxin‐sensitive signaling pathway that stimulates the release of matrix metalloproteinase‐9
Authors: Conant Katherine , Haughey Norman , Nath Avindra , Hillaire Coryse St. , Gary Devin S. , Pardo Carlos A. , Wahl Larry M. , Bilak Masako , Milward Elizabeth , Mattson Mark P. 
Published: March 2003

AbstractThe matrix metalloproteinases (MMPs) are a family of structurally related metalloendopeptidases so named due to their propensity to target extracellular matrix (ECM) proteins. Accumulating evidence, however, suggests that these proteases cleave numerous non‐ECM substrates including enzymes and cell surface receptors. MMPs may also bind to cell surface receptors, though such binding has typically been thought to mediate internalization and degradation of the bound protease. More recently, it has been shown that MMP‐1 coimmunoprecipitates with the α2β1integrin, a receptor for collagen. This association may serve to localize the enzymatic activity of MMP‐1 so that collagen is cleaved and cell migration is facilitated. In other studies, however, it has been shown that integrin engagement may be linked to the activation of signaling cascades including those mediated by Giα containing heterotrimers. As an example, α2β1can form a complex with CD47 that may associate with Giα. In the present study we have therefore investigated the possibility that MMP‐1 may affect intracellular changes that are linked to the activation of a Gi protein‐coupled receptor. We show that treatment of neural cells with MMP‐1 is followed by a rapid reduction in cytosolic levels of cAMP. Moreover, MMP‐1 potentiates proteinase activated receptor‐1 (PAR‐1) agonist‐linked increases in intracellular calcium, an effect which is often observed when an agonist of a Gi protein‐coupled receptor is administered in association with an agonist of a Gq coupled receptor. In addition, MMP‐1 stimulates pertussis toxin sensitive release ofMMP‐9 both from cultured neural cells and monocyte/macrophages. Together, these results suggest that MMP‐1 signals through a pertussis toxin‐sensitive G protein‐coupled receptor.
Membrane‐bound histamine N‐methyltransferase in mouse brain: possible role in the synaptic inactivation of neuronal histamine
Authors: Barnes William G. , Hough Lindsay B. 
Published: March 2003

AbstractIn the CNS, histamine is a neurotransmitter that is inactivated by histamine N‐methyltransferase (HNMT), a soluble enzyme localized to the cytosol of neurons and endothelial cells. However, it has not been established how extracellular histamine, a charged molecule at physiological pH, reaches intracellular HNMT. Present studies investigated two potential routes of histamine inactivation in mouse brain nerve terminal fractions (synaptosomes): (i) histamine uptake and (ii) histamine metabolism by HNMT. Intact synaptosomes demonstrated a weak temperature‐dependent histamine uptake (0.098 pmol/min‐mg protein), but contained a much greater capacity to metabolize histamine by HNMT (1.4 pmol/min‐mg protein). Determination of the distribution of HNMT within synaptosomes revealed that synaptosomal membranes (devoid of soluble HNMT) contribute HNMT activity equivalent to intact synaptosomes (14.3 ± 2.2 and 18.2 ± 4.3 pmol/min‐tube, respectively) and suggested that histamine‐methylating activity is associated with the membrane fraction. Additional experimental findings that support this hypothesis include: (i) the histamine metabolite tele‐methylhistamine (tMH) was found exclusively in the supernatant fraction following an HNMT assay with intact synaptosomes; (ii) the membrane‐bound HNMT activity was shown to increase 6.5‐fold upon the solubilization of the membranes with 0.1% Triton X‐100; and (iii) HNMT activity from the S2 fraction, ruptured synaptosomes, and synaptosomal membranes displayed different stability profiles when stored over 23 days at − 20°C. Taken together, these studies demonstrate functional evidence for the existence of membrane‐bound HNMT. Although molecular studies have not yet identified the nature of this activity, the present work suggests that levels of biologically active histamine may be controlled by an extracellular process.
Prostaglandin H2 (PGH2) accelerates formation of amyloid β1−42 oligomers
Authors: Boutaud Olivier , Ou Joyce J. , Chaurand Pierre , Caprioli Richard M. , Montine Thomas J. , Oates John A. 
Published: March 2003

AbstractEpidemiologic evidence implicates cyclooxygenase activity in the pathogenesis of Alzheimer's disease, in which amyloid plaques have been found to contain increased levels of dimers and higher multimers of the amyloid β peptide. The product of the oxygenation of arachidonic acid by the cyclooxygenases, prostaglandin H2 (PGH2), rearranges non‐enzymatically to several prostaglandins, including the highly reactive γ‐keto aldehydes, levuglandins E2 and D2. We demonstrate that PGH2 markedly accelerates the formation of dimers and higher oligomers of amyloid β1−42. This is associated with the formation of levuglandin adducts of the peptide. These findings provide the molecular basis for a hypothesis linking cyclooxygenase activity to the formation of oligomers of amyloid β.
Repeated cocaine administration alters the expression of genes in corticolimbic circuitry after a 3‐week withdrawal: a DNA macroarray study
Authors: Toda Shigenobu , McGinty Jacqueline F. , Kalivas Peter W. 
Published: March 2003

AbstractAddiction to psychostimulants elicits behavioral and biochemical changes that are assumed to be mediated by alterations of gene expression in the brain. The changes in gene expression after 3 weeks of withdrawal from chronic cocaine treatment were evaluated in the nucleus accumbens core and shell, dorsal prefrontal cortex and caudate using a complementary DNA (cDNA) array. The level of mRNA encoded by several genes was identified as being up‐ or down‐regulated in repeated cocaine versus saline subjects. The results from the cDNA array were subsequently confirmed at the protein level with immunoblotting. Of particular interest, parallel up‐regulation in protein and mRNA was found for the adenosine A1 receptor in the accumbens core, neuroglycan C in the accumbens shell, and the GluR5 glutamate receptor subtype in dorsal prefrontal cortex. However, there was an increase in TrkB protein in the nucleus accumbens core of cocaine‐treated rats without a corresponding alteration in mRNA. These changes of gene expression in corticolimbic circuitry may contribute to the psychostimulant‐induced behavioral changes associated with addiction.
Structural role of zinc ions bound to postsynaptic densities
Authors: Jan Huei‐Hsuan , Chen I‐Tong , Tsai Yu‐Yi , Chang Yen‐Chung 
Published: March 2003

AbstractPostsynaptic densities (PSDs) isolated from porcine cerebral cortices are large aggregates consisting of more than 30 different proteins. Inductively coupled plasma–mass spectrometric analyses revealed that isolated PSDs contained zinc at a concentration of 4.1 nmol per mg protein. Treatment with 8 murea lead to dissociation of the PSDs into small components and, concomitantly, depletion of most of their bound zinc. After removal of the urea by dialysis, urea‐dissociated PSD proteins did not reassemble into aggregates by themselves. Adding ZnCl2to urea‐treated PSD samples resulted in the assembly of urea‐dissociated proteins into large aggregates with morphology and protein composition closely resembling those of the original PSDs. Mg2+, Ca2+, Co2+, Cd2+, Cu2+, Mn2+, Fe3+, K+and Na+ions at higher concentrations also induced the aggregation of urea‐dissociated PSD protein. The structures of the K+‐, Na+‐, Mg2+‐ and Ca2+‐induced aggregates were distinct from that of the original PSDs. Our results indicate that the structure of the PSD could be disassembled and reassembled underin vitroconditions. They further suggest that Zn2+ions, by binding to certain zinc‐binding proteins, play an important role in the formation and maintenance of the structure of the PSD.
Mapping sites responsible for interactions of agrin with neurons
Authors: Burgess Robert W. , Dickman Dion K. , Nunez Lorna , Glass David J. , Sanes Joshua R. 
Published: March 2003

AbstractThe multidomain proteoglycan agrin is a critical organizer of postsynaptic differentiation at the skeletal neuromuscular junction. Agrin is also abundant in the brain, but its roles there are unknown. As a step toward understanding these roles, we mapped sites responsible for interactions of neurons with agrin. First, we used a series of recombinant agrin fragments to show that at least four sites on agrin interact with chick ciliary neurons. Use of blocking antibodies and peptides indicated that neurons adhere to a site in the second of three G domains by means of αVβ1 integrin, and to a site in the last of four epidermal growth factor (EGF) repeats via a distinct β1 integrin. A third, integrin‐independent adhesion site is near to but distinct from the site that induces postsynaptic differentiation in muscles. These domains are insufficient, however, to account for neurite outgrowth‐inhibiting properties of full‐length agrin, which are mediated by the N‐terminal half of the molecule. We then used a second set of agrin mutants to demonstrate and map a transmembrane domain in the amino‐terminus of the SN‐isoform of agrin. The extracellular matrix‐bound form of agrin, called LN, bears an amino‐terminus required for secretion and binding to laminin. The SN form, which is selectively expressed by neurons, bears a variant amino terminus that converts agrin from a secreted, matrix‐associated protein to a type‐II transmembrane protein, providing a mechanism for presenting agrin in central, as opposed to neuromuscular, synaptic clefts. The SN‐amino terminus can mediate externalization and membrane anchoring of heterologous proteins, but is insufficient to target them to the synapse. Together, these studies define sites that contribute to the subcellular localization of and signaling by neuronal agrin.
SEL‐10 interacts with presenilin 1, facilitates its ubiquitination, and alters A‐beta peptide production
Authors: Li Jinhe , Pauley Adele M. , Myers Rick L. , Shuang Rongqing , Brashler John R. , Yan Riqiang , Buhl Allen E. , Ruble Cara , Gurney Mark E. 
Published: March 2003

AbstractMutations in the human presenilin genes (PS1 or PS2) have been linked to autosomal dominant, early onset Alzheimer's disease (AD). Presenilins, probably as an essential part of gamma‐secretase, modulate gamma‐cleavage of the amyloid protein precursor (APP) to the amyloid β‐peptide (Aβ). Mutations in sel‐12, a Caenorhabditis elegans presenilin homologue, cause a defect in egg laying that can be suppressed by loss of function mutations in a second gene, SEL‐10. SEL‐10 protein is a homologue of yeast Cdc4, a member of the SCF (Skp1‐Cdc53/CUL1‐F‐box protein) E2‐E3 ubiquitin ligase family. In this study, we show that human SEL‐10 interacts with PS1 and enhances PS1 ubiquitination, thus altering cellular levels of unprocessed PS1 and its N‐ and C‐terminal fragments. Co‐transfection of sel‐10 and APP cDNAs in HEK293 cells leads to an alteration in the metabolism of APP and to an increase in the production of amyloid β‐peptide, the principal component of amyloid plaque in Alzheimer's disease.
Inhibition of lipopolysaccharide‐induced cyclooxygenase‐2, tumor necrosis factor‐α and [Ca2+]i responses in human microglia by the peripheral benzodiazepine receptor ligand PK11195
Authors: Choi Hyan B. , Khoo C. , Ryu Jae K. , Van Breemen Edo , Kim Seung U. , McLarnon James G. 
Published: March 2003

AbstractThe anti‐inflammatory actions of the mitochondrial peripheral benzodiazepine receptor (PBR) agonist PK11195 [1‐(2‐chloro‐ phenyl)‐N‐methyl‐N‐(1‐methylpropyl)‐3‐isoquinoline‐carboxamide] were investigated in human microglia. Application of the microglial inflammatory stimulus lipopolysaccharide (LPS, at 100 ng/mL for 3 h), induced enhancement of the expressions of the inducible enzyme, cyclooxygenase‐2 (COX‐2) and the pro‐inflammatory cytokine, tumor necrosis factor‐α (TNF‐α). PK11195 (at 50 µm) significantly inhibited the LPS‐induced up‐regulation of both inflammatory factors; at a lower concentration of PK11195 (2 µm) expression of TNF‐α, but not COX‐2, was reduced. Production of both factors, using immunocytochemistry for COX‐2 and ELISA for TNF‐α, was markedly reduced with 50 µm of PK11195 added to LPS solution. Acute application of LPS induced a transient increase in intracellular Ca2+[Ca2+]i exhibiting both a slow development and recovery in kinetic behavior. This increase in [Ca2+]i consisted primarily of a Ca2+ influx component accompanied by a smaller mobilization from intracellular Ca2+ stores. In the presence of PK11195, the amplitude of the [Ca2+]i response induced by LPS was reduced by 54%. Another mitochondrial agent cyclosporin A (CsA), which also acts at the permeability transition pore (PTP) of mitochondrial membrane but at a site different from the PBR, was ineffective in reducing either the LPS‐induced expression of COX‐2 and TNF‐α or the endotoxin increase in [Ca2+]i. These results indicate that the mitochondrial effector PK11195 is a specific and effective agent for inhibiting LPS‐induced microglial expressions of COX‐2 and TNF‐α and that modulation of Ca2+‐mediated signaling pathways could be involved in the anti‐inflammatory actions.
Galanin inhibits tyrosine hydroxylase expression in midbrain dopaminergic neurons
Authors: Counts Scott E. , McGuire Susan O. , Sortwell Caryl E. , Crawley Jacqueline N. , Collier Timothy J. , Mufson Elliott J. 
Published: March 2003

AbstractGalanin (GAL) inhibits midbrain dopamine (DA) activity in several experimental paradigms, yet the mechanism underlying this inhibition is unclear. We examined the effects of GAL on the expression of tyrosine hydroxylase (TH) in primary cultures of rat embryonic (E14) ventral mesencephalon (VM). One micromolar GAL had no effect on the number of TH‐immunoreactive (ir) neurons in VM cultures. However, 1 µm GAL reduced an approximately 100% increase in TH‐ir neurons in 1 mm dibutyryl cAMP (dbcAMP)‐treated cultures by ∼50%. TH‐ir neuron number in dbcAMP‐treated VM cultures was dose‐responsive to GAL and the GAL receptor antagonist M40 blocked GAL effects. Semi‐quantitative RT‐PCR and quantitative immunoblotting experiments revealed that GAL had no effect on TH mRNA levels in VM cultures but reduced TH protein. VM cultures expressed GALR1, GALR2, and GALR3 receptor mRNA. However, dbcAMP treatment resulted in a specific ∼200% increase in GALR1 mRNA. GALR1 activity is linked to a pertussis toxin (PTX)‐sensitive opening of G protein‐gated K+ channels (GIRKs). GAL reduction of TH‐ir neuron number in dbcAMP + GAL‐treated cultures was sensitive to both PTX and tertiapin, a GIRK inhibitor. GAL inhibition of midbrain DA activity may involve a GALR1‐ mediated reduction of TH in midbrain dopaminergic neurons.
Analysis of the PC12 cell transcriptome after differentiation with pituitary adenylate cyclase‐activating polypeptide (PACAP)
Authors: Vaudry David , Chen Yun , Ravni Aurélia , Hamelink Carol , Elkahloun Abdel G. , Eiden Lee E. 
Published: March 2003

AbstractPituitary adenylate cyclase‐activating polypeptide (PACAP) promotes neurite outgrowth and inhibits proliferation of rat pheochromocytoma (PC12) cells. Characterizing the PACAP‐differentiated PC12 cell transcriptome should provide genetic insight into how these processes occur in these cells, and in neuronal precursors in vivo. For this purpose, RNA samples were collected from PC12 cells before or after a 6‐h treatment with PACAP, from which a labeled cDNA was hybridized to a high‐density cDNA array containing 15 365 genes. The genomic response to PACAP involves at least 73 genes. Among the genes differentially expressed in the presence of PACAP, 71% were up regulated, and 29% down regulated, 2‐fold or more. Sixty‐six percent of the messages affected by PACAP code for functionally categorized proteins, most not previously known to be regulated during PC12 cell differentiation. PACAP has been shown to induce PC12 cell neurite outgrowth through the mitogen‐activated protein kinase kinase (MEK) pathway independently of protein kinase A (PKA). Therefore treatments were conducted in the absence or presence of the PKA inhibitor H89, or the MEK inhibitor U0126 in order to identify subsets of genes involved in specific aspects of PC12 cell differentiation. Co‐treatment of PC12 cells with PACAP plus H89 revealed a cluster of five genes specifically regulated through the PKA pathway and co‐treatment of the cells with PACAP and U0126 revealed a cluster of 13 messages specifically activated through the MEK pathway. Many of the known genes regulated by PACAP have been associated with neuritogenesis (i.e. villin 2 or annexin A2) or cell growth (i.e. growth arrest specific 1 or cyclin B2). Thus, some of the expressed sequence tags (ESTs) that exhibit the same regulation pattern (i.e. AU016391 or AW552690) may also be involved in the neuritogenic and anti‐mitogenic effects of PACAP in PC12 cells. Among the 73 PACAP regulated genes, 10 are disqualified on pharmacological grounds as actors in PACAP‐mediated neurite outgrowth or growth arrest, leaving 63 new PACAP‐regulated genes implicated in neuronal differentiation. Thirteen of these are candidates for mediating ERK‐dependent neurite outgrowth, and 47 are possibly involved in the ERK‐independent growth arrest induced by PACAP.
Arachidonic acid and anandamide have opposite modulatory actions at the glycine transporter, GLYT1a
Authors: Pearlman Rhonda Jo , Aubrey Karin R. , Vandenberg Robert J. 
Published: March 2003

AbstractThe GLYT1 subtypes of glycine transporter are expressed in glia surrounding excitatory synapses in the mammalian CNS and may regulate synaptic glycine concentrations required for activation of the NMDA subtypes of glutamate receptor. In this report we demonstrate that the rate of glycine transport by GLYT1 is inhibited by arachidonic acid. The cyclo‐oxygenase and lipoxygenase inhibitors indomethacin and nordihydroguaiaretic acid, and the protein kinase C inhibitor staurosporine, had no effect on the extent of arachidonic acid inhibition of transport, which suggests that the inhibitory effects of arachidonic acid result from a direct interaction with the transporter. In contrast to arachidonic acid, its amide derivative, anandamide, and the more stable analogue R1‐methanandamide stimulate glycine transport. This stimulation is unlikely to be a secondary effect of cannabinoid receptor stimulation because the cannabinoid receptor agonist WIN 55 212–2 had no effect on transport. We suggest that the stimulatory effects of anandamide on GLYT1 are due to a direct interaction with the transporter.