bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glucocorticoids Regulate the Synthesis of Glial Fibrillary Acidic Protein in Intact and Adrenalectomized Rats but Do Not Affect Its Expression Following Brain Injury
Authors: O'Callaghan James P. , Brinton Roberta E. , McEwen Bruce S. 
Published: October 2006

AbstractShort (5 days)‐to long‐term (4 months) corticosterone (CORT) administration by injection, pellet implantation, or in the drinking water decreased glial fibrillary acidic protein (GFAP) by 20–40% in hippocampus and cortex of intact rats. In contrast to CORT, adrenalectomy (ADX) caused elevations (50–125%) in hippocampus and cortex GFAP within 12 days of surgery that persisted for at least 4 months. CORT replacement of ADX rats decreased GFAP amount in hippocampus and cortex. The effects of long‐term CORT and ADX on GFAP in hippocampus and cortex were also seen in striatum, midbrain, and cerebellum, findings suggestive of brain‐wide adrenal steroid regulation of this astrocyte protein. The changes in GFAP amount due to CORT and ADX were paralleled by changes in GFAP mRNA, indicating a possible transcriptional or at least genomic effect of adrenal steroids. Glucocorticoid regulation of GFAP was relatively specific; it could not be generalized to other astrocyte proteins or other major structural proteins of neurons. The negative regulation of GFAP and GFAP mRNA by adrenal steroids suggested that increases in GFAP that result from brain injury may be attenuated by glucocorticoids. However, chronic CORT treatment of intact rats did not reverse or reduce the large increases in GFAP caused by trauma‐or toxicant‐induced brain damage. Thus, glucocorticoids and injury appear to regulate the expression of GFAP through different mechanisms. In contrast to the lack of effects of CORT on brain damage‐induced increases in GFAP, CORT treatment begun in 2‐week ADX rats, after an increase in GFAP had time to occur, did reverse the ADX‐induced increase in GFAP. These results suggest that the increase in GFAP resulting from ADX is not mediated through an injury‐linked mechanism.
Pre‐and Postnatal Developmental Changes of Adrenoceptor Subtypes in Rat Brain
Authors: Erdtsieck‐Ernste B. H. W. , Feenstra M. G. P. , Boer G. J. 
Published: October 2006

Abstractβ‐Adrenergic receptor subtypes, β1 and β2, were studied during pre‐and postnatal development in the rat brain. [125I]Iodocyanopindolol (6–300 pmol/L) binding assays in the presence of 5‐hydroxytryptamine (0.6–6 μmol/L) were used to measure exclusively β‐adrenergic receptors. In forebrain tissue, saturable and stereoselective binding was detected on gestational day 13. The amount of β‐adrenergic binding increased until postnatal day 23, when adult values were reached. The dissociation constants of [125I]iodocyanopindolol binding remained the same throughout development, as did the affinity of several β‐adrenergic and non‐β‐adrenergic compounds. The proportion of the β2‐adrenergic receptors was determined using the β1‐selective antagonist ICI‐89406 (7–150 nmol/L) and was found to change from 65% in prenatal forebrain tissue to 28% in adulthood. In cerebellum/medulla pons tissue, however, the proportion of β2‐receptor binding (80%) remained unchanged during the whole developmental period.
Neuropeptide Y: An Endogenous Inhibitor of Norepinephrine‐Stimulated Melatonin Secretion in the Rat Pineal Gland
Authors: Olcese James 
Published: October 2006

AbstractThe biosynthesis of the hormone melatonin (MEL) by the mammalian pineal gland has been thought to be regulated strictly by stimulatory factors, most predominantly norepinephrine (NE), released from the sympathetic nerve fibers which heavily innervate the gland. Evidence from many investigators suggests that sympathetic fibers may colocalize other neuroactive factors in addition to NE. One of these factors is neuropeptide Y (NPY), which has been found in the nerve fibers of the pineal gland. The present study sought to explore potential interactions between NE and NPY in the regulation of pineal MEL secretion. Specific, saturable, and reversible binding of 125I‐NPY to intact cultured pine‐ alocytes was measured with an affinity constant of 1 nM and an NPY binding site density of 0.04 pmol/mg of protein. In addition, cell culture studies revealed that NPY represents a potent (IC50 of 0.4 nM) endogenous inhibitor of NE‐stimulated MEL secretion. However, this inhibition is accompanied by only a modest reduction (35%) of cyclic AMP accumulation. These findings reinforce the view that the mammalian pineal gland, which appears to integrate both inhibitory as well as stimulatory signals, is an important model of autonomic function, particularly in the context of biological rhythmicity.
K‐252b Is a Selective and Nontoxic Inhibitor of Nerve Growth Factor Action on Cultured Brain Neurons
Authors: Knüsel Beat , Hefti Franz 
Published: October 2006

AbstractK‐252b is a kinase inhibitor structurally related to K‐252a, which is known to abolish selectively the effects of nerve growth factor (NGF) on PC12 cells and PNS neurons. We tested whether K‐252b, K‐252a, and staurosporine, another related compound, are effective and selective inhibitors of NGF actions on CNS neurons. All three compounds, at appropriate concentrations, completely and selectively prevented the NGF‐mediated activity increase of the cholinergic marker enzyme choline acetyltransferase in cultures of rat basal forebrain cells. The stimulatory effects of basic fibroblast growth factor and insulin on choline acetyltransferase in these cultures and on dopamine uptake in cultures of dissociated ventral mesencephalon were not affected. No signs of toxicity were observed in cultures treated with K‐252b. In contrast, K‐252a and staurosporine, at concentrations required to block the NGF actions on cholinergic cells, were cytotoxic and produced cell loss. In addition, K‐252a, at higher concentrations and in the absence of growth factors, increased cell numbers. Our study suggests that K‐252b is a selective and nontoxic inhibitor of NGF actions in the brain and may become a useful tool to study these actions in vivo.
Effects of Intranigral Substance P and Neurokinin A Injections on Extracellular Dopamine Levels Measured with Microdialysis in the Striatum and Frontoparietal Cortex of Rats
Authors: Reid Malcolm S. , Herrera‐Marschitz Mario , Ungerstedt Urban 
Published: October 2006

AbstractExtracellular levels of dopamine (DA) and its metabolite, 3,4‐dihydroxyphenylacetic acid (DOPAC), in the striatum and frontoparietal (sensorimotor) cortex in halo‐ thane‐anesthetized rats were analyzed simultaneously using in vivo microdialysis. Basal DA levels, measured from the microdialysis perfusate, were 6.4 ± 0.8 nM (n = 15) in the striatum and 0.9 ± 0.1 nM (n = 15) in the frontoparietal cortex. Subcutaneous injections of d‐amphetamine (2 mg/kg) increased DA levels 10‐fold in the striatum and fivefold in the cortex. Injections of substance P (0.07 nmol/0.2 μl) into the substantia nigra pars reticulata (SNR) increased DA and DOPAC levels ∼30% in the ipsilateral striatum and 50% in the ipsilateral frontoparietal cortex. Injections of neurokinin A (0.09 nmol/0.2 μl) into the SNR increased DA and DOPAC levels ∼30% in the ipsilateral striatum but did not significantly affect DA levels in the ipsilateral frontoparietal cortex, although DOPAC levels were increased by ∼50%. It is suggested that striatal and cortical DA release is regulated differently by nigral substance P and neurokinin A terminals.
Effects of Hypoxia on the Activity of the Dopaminergic Neuron System in the Rat Striatum as Studied by In Vivo Brain Microdialysis
Authors: Akiyama Yoshinori , Koshimura Kunio , Ohue Tetsuya , Lee Ken , Miwa Soichi , Yamagata Sen , Kikuchi Haruhiko 
Published: October 2006

AbstractThe purpose of the present study is to clarify the effects of hypoxia on the activity of the dopaminergic neurons in the brain and its mechanism of action. For this purpose, the effects of hypoxia on the extracellular levels of 3,4‐dihy‐droxyphenylethylamine (dopamine) were examined in the rat Striatum using in vivo brain microdialysis in the presence or absence of pretreatment with either tetrodotoxin (a blocker of voltage‐dependent sodium channels) or nomifensine (a blocker of dopamine reuptake). Exposure to various degrees of hypoxia (15, 10, and 8% O2 in N2) increased dopamine levels in striatal dialysates to 200, 400, and 1,100%, respectively, of the control value. On reoxygenation, dopamine levels in the dialysates rapidly returned to the control level. Reexposure to hypoxia increased the dopamine levels to the same extent as during the first exposure. After addition of tetrodotoxin (40 mUM) to the perfusion fluid or pretreatment with nomifensine (100 mg/kg, i.p.), exposure to hypoxia no longer increased the dopamine levels. These results suggest that although hypoxia induces an increase in the extracellular dopamine levels (hence, an apparent increase in the activity of the dopaminergic neurons), this increase is not the result of an increase in dopamine release itself, but rather the result of inhibition of the dopamine reuptake mechanism.
Physicochemical Characterization of Recombinant Human Nerve Growth Factor Produced in Insect Cells with a Baculovirus Vector
Authors: Barnett Jim , Chow Joan , Nguyen Binh , Eggers Daryl , Osen Eric , Jarnagin Kurt , Saldou Natalie , Straub Ken , Gu Leo , Erdos Lisa , Chaing Hi‐Shi , Fausnaugh Jodi , Townsend R. Reid , Lile Jack , Collins Frank , Chan Hardy 
Published: October 2006

AbstractRecombinant human nerve growth factor (rhNGF) secreted by insect cells was purified by ion‐exchange and reversed‐phase chromatography to near homogeneity. The Nterminus of the secreted molecule was analogous to that of mouse salivary gland NGF. In its native conformation, the insect cell produced rhNGF molecules were homodimers consisting of 120 amino acid polypeptide chains. Mature rhNGF was found not to be significantly glycosylated (<0.08 mol of N‐acetylglucosamine/mol of protein). The rhNGF was homogeneous with regard to molecular weight and amino acid sequence. Isoelectric focusing resolved the rhNGF into one major and one minor component. Because rhNGF frominsect cells can be obtained in large quantities, purified to near homogeneity, and is similar to natural NGF with regard to physicochemical properties and biological activity, it is suitable for further evaluation in animal models as a therapeutic molecule for neurodegenerative diseases such as Alzheimer's disease.
Urinary but Not Brain Isatin Levels Are Reduced in Germ‐Free Rats
Authors: Sandier M. , Przyborowska Anna , Halket J. , Watkins P. , Glover Vivette , Coates Marie E. 
Published: October 2006

AbstractGerm‐free rats excreted considerably smaller amounts of the monoamine oxidase‐inhibiting compound isatin than the substantially larger output by conventional animals of the same strain, although concentrations in brain and other tissues were similar in the two groups. Thus, isatin is likely to be elaborated both endogenously in rat tissues and “exogenously” by flora inhabiting the lumen of the alimentary tract.
Distribution of Na+, K+‐ATPase α‐Subunit Isoforms in Rat Pituitary
Authors: Rowe Paul M. , Link William T. , Osborn Charlene P. , Gainer Harold , Albers R. Wayne 
Published: October 2006

AbstractThe distributions of a‐subunit isoforms of the Na+, K+‐ ATPase in rat pituitary were determined by immunoblotting and immunohistochemistry. Immunoreactivity for all three forms is present in the neural lobe, whereas the anterior lobe contains only α1 and α2. Most areas of the intermediate lobe exhibit faint immunoreactivity for only α1. but thin strands of cells which stain strongly for all three isoforms are also present in this lobe. The previously reported ouabain inhibitable Na+, K−‐ATPase activity in the neural lobe is consistent with the presence of both α2 and α3 subunits.
A Monoclonal Antibody That Reacts Immunohistochemically with Amyloid Deposits in the Brain Tissue of Alzheimer Patients Binds to an Epitope Present on Complement Factor 4
Authors: McDonald B. , Esiri M. M. , McIlhinney R. A. J. 
Published: October 2006

AbstractThe mouse monoclonal antibody SMP has previously been demonstrated to react immunohistochemically with neurofibrillary tangles, argyrophilic plaques, and lep‐tomeningeal vascular amyloid deposits in the brain tissue of individuals dying from pathologically diagnosed Alzheimer's disease. In preliminary studies the antibody was shown, by size exclusion chromatography, to bind to a protein with an apparent molecular mass of 260 kDa present in the CSF and serum of demented individuals. Chromatographic separation of a 40% ammonium sulphate precipitate of CSF and serum yielded immunoreactive fractions that were subjected to 9% sodium dodecyl sulphate‐polyacrylamide gel electrophoresis followed by western blotting. Probing the nitrocellulose blot with the antibody revealed that the antibody selectively binds to a protein chain with an apparent molecular mass of 100 kDa. By using a combination of affinity chromatography and sodium dodecyl sulphate‐polyacrylamide gel electrophoresis, coupled with western blotting, the serum component with which the antibody reacts has been identified as complement factor 4. In addition, the antibody has been shown to react specifically with an epitope on the α‐chain of this protein.
Effect of Tetrahydrobiopterin on Serotonin Synthesis, Release, and Metabolism in Superfused Hippocampal Slices
Authors: Wolf William A. , Ziaja Ellen , Arthur Robert A. , Anastasiadis Panagiotis Z. , Levine Robert A. , Kuhn Donald M. 
Published: October 2006

AbstractThe effects of 6R‐5, 6, 7, 8‐tetrahydro‐L‐biopterin (6R‐BH4), the in vivo cofactor for tryptophan hydroxylase, on the synthesis, release, and metabolism of serotonin were studied in superfused slices from rat hippocampus. 6R‐BH4did not alter the spontaneous release of [3H]serotonin but it did significantly increase release when slices were depolarized with 30 mM KC1. Under the same incubation conditions, 6R‐BH4 altered neither the synthesis (basal or tryptophan‐stimulated) nor the metabolism of serotonin in hippocampal slices. The synthetic pteridine 6‐methyl‐5, 6, 7, 8‐tetrahydropterin also augmented release under depolarizing conditions whereas biopterin, the oxidized form of 6R‐BH4, did not. The 6S isotner of BH4, which is relatively inactive as a cofactor for tryptophan hydroxylase, was equipotent with 6R‐ BH4 in stimulating serotonin release. 6R‐BH4 did not inhibit serotonin uptake nor did it function as a serotonin autoreceptor antagonist to increase release. A direct serotonin releasing effect of 6R‐BH4, like that produced by p‐chloroamphetamine, could also be ruled out. At suboptimal concentrations of extracellular calcium, the KC1‐induced release of 3H was significantly reduced, yet the increase in release caused by BH4 remained the same in magnitude. It is concluded that 6R‐BH4 increases the depolarization‐induced release of serotonin through an interaction with the release mechanism itself, possibly by enhancing calcium influx or by increasing the sensitivity of the release mechanism to calcium. The effects of 6R‐BH4 on serotonin release are independent from its function as the cofactor for tryptophan hydroxylase.
Ca2+‐Independent, Ca2+‐Dependent, and Carbachol‐ Mediated Arachidonic Acid Release from Rat Brain Cortex Membrane
Authors: Strosznajder Joanna , Samochocki Marek 
Published: October 2006

AbstractSynaptoneurosomes obtained from the cortex of rat brain prelabeled with [14C] arachidonic acid ([14C]AA) were used as a source of substrate and enzyme in studies on the regulation of AA release. A significant amount of AA is liberated in the presence of 2 mM EGTA, independently of Ca2+, primarily from phosphatidic acid and polyphosphoinositides (poly‐PI). Quinacrine, an inhibitor of phospholipase A2 (PLA2), suppressed AA release by about 60% and neomycin, a putative inhibitor of phospholipase C(PLC), reduced AA release by about 30%. An additive effect was exhibited when both inhibitors were given together. Ca2+ activated AA release. The level of Ca2+ present in the synaptoneurosomal preparation (endogenous level) and 5 μM CaC12 enhance AA liberation by approximately 25%, whereas 2 mM CaC12 resulted in a 50% increase in AA release relative to EGTA. The source for Ca2+‐dependent AA release is predominantly phosphatidylinositol (PI); however, a small pool may also be liberated from neutral lipids. Carbachol, an agonist of the cholinergic receptor, stimulated Ca2+‐dependent AA release by about 17%. Bradykinin enhanced the effect of carbachol by about 10–15%. This agonist‐mediated AA release occurs specifically from phosphoinositides (PI + poly‐PI). Quinacrine almost completely suppresses calcium‐ and carbachol‐mediated AA release. Neomycin inhibits this process by about 30% and totally suppresses the effect of bradykinin. Our results indicate that both phospholipases PLA2 and PLC with subsequent action of DAG lipase are responsible for Ca2+‐ independent AA release. Ca2+‐dependent and carbachol‐mediated AA liberation occurs mainly as the result of PLA2action. A small pool of AA is probably also released by PLC, which seems to be exclusively responsible for the effect of bradykinin.
Exogenous Gangliosides GD1b and GD1b‐Lactone, Stably Associated to Rat Brain P2 Subcellular Fraction, Modulate Differently the Process of Protein Phosphorylation
Authors: Bassi Rosaria , Chigorao Vanna , Fiorilli Amelia , Sonnino Sandro , Tettamanti Guido 
Published: October 2006

AbstractGD1b and GD1b‐lactone (GD1b‐L) gangliosides bind to the same extent to a P2 crude membrane preparation from rat brain. After 30 min of incubation with 10−4, 105, and 10−6 Absolutions of ganglioside, 1,800, 450, and 100 pmol of ganglioside/mg of protein, respectively, were found to be stably associated to the P2 fraction. This association modifies the phosphorylation process of the P2 membrane proteins in a dose‐dependent manner, the maximal effect being reached at a ganglioside association of 1.85 nmol/mg of protein and in large part at 450 pmol/mg of protein. The effects of GD1b and GD1b‐L on the phosphorylation of five proteins, showing apparent molecular masses of 17, 20, 36, 41, and 44 kDa, were different after 0.5 min of phosphorylation reaction as well as after 15 min. After 0.5 min of reaction, in the presence of stably associated GD1b, the phosphorylation of the 36‐, 41‐, and 44‐kDa proteins was increased with reference to the control, whereas the phosphorylation of the 17‐ and 20‐kDa proteins was decreased. GD1b‐L exerted qualitatively similar effects only on the 44‐, 41‐, and 36‐kDa proteins and to a strongly reduced degree. After 15 min of reaction, only the phosphorylation of the 36‐kDa protein was stimulated by GD1b; GD1b‐L exerted a similar effect, but to a low degree.
Astroglial‐Induced In Vitro Angiogenesis: Requirements for RNA and Protein Synthesis
Authors: Laterra John , Goldstein Gary W. 
Published: October 2006

AbstractAstrocytes are believed to affect microvascular endothelial cell differentiation in brain and retina. Bovine retinal microvessel endothelial cells formed capillary‐like structures when cocultured with C6 astroglial cells or in the absence of C6 cells in response to the reconstituted basement membrane protein Matrigel. Using quantitative computer‐assisted image analysis, the requirements for RNA and protein synthesis in these two complementary models of in vitro microvessel morphogenesis were examined. Astroglial‐dependent capillary‐like structure formation was inhibited by up to 87% in a dose‐dependent fashion by cycloheximide (0.01–0.1 μg/ml), puromycin (0.1–0.25 μg/ml), and actinomycin D (0.01– 0.025 μg/ml). In contrast, the astroglial‐independent process in response to Matrigel was not affected by these metabolic inhibitors. These findings suggest that capillary‐like structures form in response to astroglial cells in two distinct sequential stages. The first consists of inductive astroglial‐endothelial interactions requiring both RNA and protein synthesis. This initiates endogenous endothelial morphogenic events that do not appear to require RNA or protein synthesis, consistent with posttranslational regulatory mechanisms. The first astroglial‐dependent step is relevant to the regulation of microvessel formation in brain and retina, whereas the second may represent a morphogenic pathway common to micro‐vessel formation in many tissues.
Glutamate Neurotoxicity Is Independent of Calpain I Inhibition in Primary Cultures of Cerebellar Granule Cells
Authors: Manev Hari , Favaron Marco , Siman Robert , Guidotti Alessandro , Costa Erminio 
Published: October 2006

AbstractGlutamate‐induced neurotoxicity and calpain activity were studied in primary cultures of rat cerebellar granule neurons and glial cells. Calpain activation, as monitored by quantitative immunoblotting of spectrin, required micromolar concentrations of Ca2+ in neuronal homogenates (calpain I) and millimolar Ca2+ concentrations in glial homogenates (calpain II). Glutamate‐induced toxicity and calpain activation were observed in neuronal, but not in glial, cultures. In neurons, calpain I activation by glutamate was dose‐dependent and persisted after withdrawal of neurotoxic doses of glutamate. Natural (GM1) and semisynthetic (LIGA4) gangliosides or the glutamate receptor blocker MK‐801 prevented calpain I activation and delayed neuronal death elicited by glutamate. GM1 and LIGA4 had no effect on calpain I activity in neuronal homogenates, however. Furthermore, two calpain I inhibitors (leupeptin and N‐acetyl‐Leu‐Leu‐ norleucinal) prevented glutamate‐induced spectrin degradation, but failed to affect glutamate neurotoxicity. These results thus suggest that glutamate‐induced neurotoxicity is independent of calpain I activation.
Characterization and Localization of a Long‐Chain Isoprenyltransferase Activity in Porcine Brain: Proposed Role in the Biosynthesis of Dolichyl Phosphate
Authors: Crick Dean C. , Rush Jeffrey S. , Waechter Charles J. 
Published: October 2006

AbstractPig brain microsomes catalyzed the enzymatic transfer of radiolabeled isoprenyl groups from [1‐14C] isopentenyl pyrophosphate ([1‐MC] I‐P‐P) into long‐chain polyisoprenyl pyrophosphates (Poly‐P‐P) and unidentified neutral lipids. The brain isoprenyltransferase activity synthesizing the Poly‐P‐P (1) required 5 mM Mg2+ and 10 mM vanadate ions for maximal activity; (2) exhibited an apparent Km of 8 μM I‐P‐P; (3) utilized exogenous farnesyl pyrophosphate and two stereoisomers of geranylgeranyl pyrophosphate as substrates; (4) was optimal at pH 8.5; and (S) was stimulated by dithiothreitol. The major products were identified as C90and Q95 allyhic Poly‐P‐P on the basis of the following chemical and chromatographic properties: (1) the intact product cochromatographed with authentic Poly‐P‐P on silica‐gel‐impregnated paper, (2) the major product was converted to a compound chromatographically identical to polyisoprenyl monophosphate (Poly‐P) by alkaline hydrolysis; (3) treatment of the labeled Poly‐P with wheat germ acid phosphatase or mild acid yielded neutral labeled products; (4) the KOH hydrolyzed product coeluted with authentic Poly‐P from lipophilic Sephadex LH‐20; and (5) the labeled lipids produced by enzymatic dephosphorylation had mobilities identical to fully unsaturated polyisoprenols containing 18 (C90) and 19 (Q95) isoprene units when analyzed by reverse‐phase chromatography. When subcellular fractions from rat brain gray matter were compared, the highest specific activity was found in the heavy microsomes. These results demonstrate that brain contains an isoprenyltransferase activity, associated with the rough endoplasmic reticulum, capable of synthesizing long‐chain Poly‐P‐P. The enzymatic reactions by which the Poly‐P‐P intermediate is converted to dolichyl phosphate remain to be elucidated.