bluuebunny/crossref_metadata_2025_split huggingface dataset:
Albumin promotes neuronal survival by increasing the synthesis and release of glutamate
Authors: Tabernero Arantxa , Granda Begoña , Medina Ana , Sánchez‐Abarca Luis Ignacio , Lavado Eva , Medina José M. 
Published: March 2003

AbstractIt is well known that the presence of albumin within the brain and the CSF is developmentally regulated. However, the physiological relevance of this phenomenon is not well established. We have previously shown that albumin specifically increases the flux of glucose and lactate through the pyruvate dehydrogenase reaction in astrocytes. Here we show that, in neurones, albumin also increases the oxidation of glucose and lactate through the pyruvate dehydrogenase‐catalysed reaction, the final purpose of this being the synthesis of glutamate. Thus, in neurones, the presence of albumin strongly increased the synthesis and release of glutamate to the extracellular medium. Our results also suggest that glutamate release caused by albumin is designed to promote neuronal survival. Thus, under culture conditions in which neurones die by apoptosis, the presence of albumin promoted neuronal survival and maintained the differentiation programme of these cells, as judged by the expression of the axonal protein, GAP‐43. The effect of albumin on neuronal survival was counteracted by the presence of DNQX, an antagonist of non‐NMDA‐glutamate receptors, suggesting that the glutamate synthesized and released due to the presence of albumin is responsible for neuronal survival. In addition, the effect of albumin seemed to depend on the activity of the NGF receptor, TrkA, suggesting that the glutamate synthesized and released due to the presence of albumin promotes neuronal survival through the activity of TrkA.
A perforated patch‐clamp study of calcium currents and exocytosis in chromaffin cells of wild‐type and α1A knockout mice
Authors: Aldea Marcos , Jun Kisun , Shin Hee‐Sup , Andrés‐Mateos Eva , Solís‐Garrido Luisa M. , Montiel Carmen , García Antonio G. , Albillos Almudena 
Published: March 2003

AbstractSimultaneous recordings of inward whole‐cell Ca2+ channel currents (ICa) and increments of capacitance as an indication of exocytosis (ΔCm), were performed in voltage‐clamped single adrenal chromaffin cells from wild‐type and α1A subunit deficient mice, using the perforated‐patch configuration of the patch‐clamp technique. Using protocol #1 (one single Ca2+ channel blocker per cell), to dissect the components of ICa, L channels contributed 43%, N channels 35% and P/Q channels 30% to the total ICa of wild‐type cells. Using protocol #2 (cumulative sequential addition of 3 µm nifedipine, 1 µmω‐conotoxin GVIA, and 1 µmω‐agatoxin IVA), L, N and P/Q channels contributed 40%, 34% and 14%, respectively, to ICa; an R component of around 11% remained. In wild‐type mice the changes of ΔCm paralleled those of ICa. In α1A deficient mice the L component of ICa rose to 53% while the P/Q disappeared; the N and R components were similar. In these mice, ΔCm associated to N and R channels did not vary; however, the P/Q component was abolished while the L component increased by 20%. In conclusion, exocytosis was proportional to the relative density of each Ca2+ channel subtype, L, N, P/Q, R. Ablation of the α1A gene led to a loss of P/Q channel current and to a compensatory increase of L channel‐associated secretion; however, this compensation was not sufficient to maintain the overall exocytotic response, that was diminished by 35% in α1A‐deficient mice. This may be due to altered Ca2+ homeostasis in these mice, as compared to wild mouse chromaffin cells.
The C‐terminal C1 cassette of the N‐methyl‐d‐aspartate receptor 1 subunit contains a bi‐partite nuclear localization sequence
Authors: Holmes K. D. , Mattar P. , Marsh D. R. , Jordan V. , Weaver L. C. , Dekaban G. A. 
Published: March 2003

AbstractThe N‐methyl‐d‐aspartate receptor (NMDAR) is a multimeric transmembrane protein composed of at least two subunits. One subunit, NR1, is derived from a single gene and can be subdivided into three regions: the N‐terminal extracellular domain, the transmembrane regions, and the C‐terminal intracellular domain. The N‐terminal domain is responsible for Mg2+ metal ion binding and channel activity, while the transmembrane domains are important for ion channel formation. The intracellular C‐terminal domain is involved in regulating receptor activity and subcellular localization. Our recent experiments indicated that the intracellular C‐terminal domain, when expressed independently, localizes almost exclusively in the nucleus. An examination of the amino acid sequence reveals the presence of a putative nuclear localization sequence (NLS) in the C1 cassette of the NR1 intracellular C‐terminus. Using an expression vector designed to test whether a putative NLS sequence is a valid, functional NLS, we have demonstrated that a bi‐partite NLS does in fact exist within the NR1‐1 C‐terminus. Computer algorithms identified a putative helix–loop–helix motif that spanned the C0C1 cassettes of the C‐terminus. These data suggest that the NR1 subunit may represent another member of a family of transmembrane proteins that undergo intramembrane proteolysis, releasing a cytosolic peptide that is actively translocated to the nucleus leading to alterations in gene regulation.
Oxidation of DOPAC by nitric oxide: effect of superoxide dismutase
Authors: Laranjinha João , Cadenas Enrique 
Published: March 2003

AbstractThis study aimed to characterize the redox interaction between 3,4‐dihydroxyphenylacetic acid (DOPAC) and nitric oxide (·NO), and to assess the reductive and oxidative decay pathways of the DOPAC semiquinone originating from this interaction. The reaction between DOPAC and ·NO led to the formation of the DOPAC semiquinone radical, detected by electron paramagnetic resonance (EPR) and stabilized by Mg2+, and the nitrosyl anion detected as nitrosylmyoglobin. The EPR signal corresponding to the DOPAC semiquinone was modulated as follows: (i) it was suppressed by glutathione and ascorbic acid with the formation of new EPR spectra corresponding to the glutathionyl and ascorbyl radical, respectively; (ii) it was enhanced by Cu,Zn‐superoxide dismutase; the enzyme also accelerated the decay of the semiquinone species to DOPAC quinone. These results are interpreted as a one‐electron oxidation of DOPAC by ·NO; the reductive decay of the semiquinone back to DOPAC was facilitated by reducing agents, such as glutathione and ascorbate, whereas the oxidative decay to DOPAC quinone was facilitated by superoxide dismutase. The latter effect is understood in terms of a reversible conversion of nitrosyl anion to ·NO by the enzyme. The biological relevance of these reactions is also discussed in terms of the reactivity of peroxynitrite towards DOPAC as a model with implications for aerobic conditions.
Activation of the antioxidant response element in primary cortical neuronal cultures derived from transgenic reporter mice
Authors: Johnson D. A. , Andrews G. K. , Xu W. , Johnson J. A. 
Published: March 2003

AbstractMany phase II protective genes contain a cis‐acting enhancer region known as the antioxidant response element (ARE). Increased expression of these genes contributes to the protection of cells from oxidative stress. Transgenic reporter mice were created that carry in their genome the core ARE coupled to the human placental alkaline phosphatase (hPAP) reporter gene. Primary cortical cultures derived from these mice were treated with tBHQ resulting in a dose‐dependent increase in hPAP activity. Histochemical staining for hPAP activity was observed in both glia and neurons from tBHQ‐treated cultures. The tBHQ‐mediated increase in hPAP was not affected by the antioxidant glutathione monoethyl ester (GSHEE), whereas the increase in hPAP following DEM treatment was completely blocked by GSHEE. Pre‐treatment of cultures with the PI3‐kinase inhibitor LY 294002 demonstrated a dose‐dependent decrease in tBHQ‐induced hPAP activity. In addition, the tBHQ‐mediated expression of ARE‐driven genes in primary cortical cultures was blocked by LY 294002. Interestingly, basal expression of Nrf2 was also inhibited by LY 294002. We theorize that increased levels of genes controlled by the ARE are important for cellular protection against oxidative stress. These ARE‐hPAP transgenic mice will be an important in vivo model for testing our hypothesis.
Specificity of resistance to oxidative stress
Authors: Dargusch Richard , Schubert David 
Published: March 2003

AbstractTwo clonal nerve‐like cell lines derived from HT22 and PC12 have been selected for resistance to glutamate toxicity and amyloid toxicity, respectively. In the following experiments it was asked if these cell lines show cross‐resistance toward amyloid beta peptide (Aβ) and glutamate as well as toward a variety of additional neurotoxins. Conversely, it was determined if inhibitors of oxytosis, a well‐defined oxidative stress pathway, also protect cells from the neurotoxins. It is shown that both glutamate and amyloid resistant cells are cross resistant to most of the other toxins or toxic conditions, while inhibitors of oxytosis protect from glutathione and cystine depletion and H2O2 toxicity, but not from the toxic effects of nitric oxide, rotenone, arsenite or cisplatin. It is concluded that while there is a great deal of cross‐resistance to neurotoxins, the components of the cell death pathway which has been defined for oxytosis are not used by many of the neurotoxins.
Dynamics of tyrosine hydroxylase promoter activity during midbrain dopaminergic neuron development
Authors: Matsushita Natsuki , Okada Hideki , Yasoshima Yasunobu , Takahashi Kazuaki , Kiuchi Kazutoshi , Kobayashi Kazuto 
Published: March 2003

AbstractDopamine (DA)‐producing neurons in the ventral midbrain are generated from a specified neuronal lineage and form selective axonal pathways that mediate multiple CNS functions. Expression of the gene encoding tyrosine hydroxylase (TH), which is a key enzyme of catecholamine biosynthesis, is regulated during the development of midbrain DA neurons. In the present study, we report the developmental regulation and cell type specificity of TH gene promoter in the ventral midbrain by using a green fluorescent protein (GFP) reporter system. Transgenic mice were generated that express GFP in the majority of midbrain DA neurons under the control of the 9‐kb upstream region of the rat TH gene. At an early embryonic stage, GFP expression was induced in the developing DA neurons, and the expression was then markedly down‐regulated at later embryonic stages. However, the expression was reactivated and approached the adult levels during early post‐natal development. These developmental changes in GFP expression patterns suggest the presence of multistep regulatory mechanisms for TH gene expression during DA neuron development. The TH promoter appears to possess transcriptional elements at least necessary for the induction of TH expression at the early embryonic stage and its reactivation during the post‐natal development.
Convergent evidence from microdialysis and presynaptic immunolabeling for the regulation of γ‐aminobutyric acid release in the globus pallidus following acute clozapine or haloperidol administration in rats
Authors: See Ronald E. , Berglind William J. , Krentz Lisa , Meshul Charles K. 
Published: March 2003

AbstractAntipsychotic drugs (APDs) have been primarily characterized for their effects on dopaminergic terminal regions in the brain, especially within the corpus striatum. Efferent GABA pathways are the primary outflow of striatal processing via their projections to the substantia nigra and the globus pallidus (GP). In the current study, we analyzed changes in pallidal GABA function following acute APD administration by means of in vivo microdialysis, followed by immunolabeling of presynaptic GABA terminal density in the contralateral hemisphere of the same animals. Acute administration of the atypical APD, clozapine (10 or 30 mg/kg, s.c.), produced a dose‐dependent decrease in extracellular GABA. A corresponding dose‐dependent increase in the density of presynaptic terminal GABA immunolabeling in the GP was found. In contrast, the typical APD, haloperidol (1 or 3 mg/kg, s.c.), had no significant effects on either measure, although a non‐significant increase in extracellular GABA and decrease in the density of GABA terminal immunolabeling was noted. Paw retraction tests conducted during the time of microdialysis showed that haloperidol produced a typical pattern of highly pronounced motor impairment, while clozapine showed an atypical profile of minimal catalepsy. These complementary results obtained from in vivo neurochemistry and presynaptic neurotransmitter labeling suggest that systemic clozapine suppresses neuronal GABA release within the GP. This decrease in released pallidal GABA may play a role in the low motor side‐effect liability of atypical APDs.
Stimulatory effect of vitamin C on autophagy in glial cells
Authors: Martin Antonio , Joseph James A. , Cuervo Ana Maria 
Published: March 2003

AbstractIntracellular accumulation of damaged or abnormal proteins is a common event associated with numerous neurodegenerative diseases and other age‐related pathologies. Increasing the activity of the intracellular proteolytic systems normally responsible for the removal of these abnormal proteins might be beneficial in lessening the severity or development of those pathologies. In this study we have used human astrocyte glial cells to investigate the effect of vitamin C (ascorbate) on the intracellular turnover of proteins. Supplementation of the culture medium with physiological concentrations of vitamin C did not affect protein synthesis, but did increase the rate of protein degradation by lysosomes. Vitamin C accelerated the degradation of intra‐ and extracellular proteins targeted to the lysosomal lumen by autophagic and heterophagic pathways. At the doses analyzed, vitamin C lowered and stabilized the acidic intralysosomal pH at values that result in maximum activation of the lysosomal hydrolases.
The NADH oxidase activity of the plasma membrane of synaptosomes is a major source of superoxide anion and is inhibited by peroxynitrite
Authors: Martín‐Romero Francisco Javier , Gutiérrez‐Martín Yolanda , Henao Fernando , Gutiérrez‐Merino Carlos 
Published: March 2003

AbstractPlasma membrane vesicles from adult rat brain synaptosomes (PMV) have an ascorbate‐dependent NADH oxidase activity of 35–40 nmol/min/(mg protein) at saturation by NADH. NADPH is a much less efficient substrate of this oxidase activity, with a Vmax 10‐fold lower than that measured for NADH. Ascorbate‐dependent NADH oxidase activity accounts for more than 90% of the total NADH oxidase activity of PMV and, in the absence of NADH and in the presence of 1 mm ascorbate, PMV produce ascorbate free radical (AFR) at a rate of 4.0 ± 0.5 nmol AFR/min/(mg protein). NADH‐dependent ·O2− production by PMV occurs with a rate of 35 ± 3 nmol/min/(mg protein), and is a coreaction product of the NADH oxidase activity, because: (i) it is inhibited by more than 90% by addition of ascorbate oxidase, (ii) it is inhibited by 1 µg/mL wheat germ agglutinin (a potent inhibitor of the plasma membrane AFR reductase activity), and (iii) the KM(NADH) of the plasma membrane NADH oxidase activity and of NADH‐dependent ·O2− production are identical. Treatment of PMV with repetitive micromolar ONOO– pulses produced almost complete inhibition of the ascorbate‐dependent NADH oxidase and ·O2− production, and at 50% inhibition addition of coenzyme Q10 almost completely reverts this inhibition. Cytochrome c stimulated 2.5‐fold the plasma membrane NADH oxidase, and pretreatment of PMV with repetitive 10 µm ONOO– pulses lowers the K0.5 for cytochrome c stimulation from 6 ± 1 (control) to 1.5 ± 0.5 µm. Thus, the ascorbate‐dependent plasma membrane NADH oxidase activity can act as a source of neuronal ·O2−, which is up‐regulated by cytosolic cytochrome c and down‐regulated under chronic oxidative stress conditions producing ONOO–.
Adenosine A1 receptor down‐regulation in mothers and fetal brain after caffeine and theophylline treatments to pregnant rats
Authors: León David , Albasanz José Luis , Ruíz María Angeles , Fernández Mercedes , Martín Mairena 
Published: March 2003

AbstractPregnant rats were treated daily with 1 g/L of caffeine or theophylline in their drinking water during pregnancy and the effect of these methylxanthines on adenosine A1 receptor was assayed using binding and reverse transcription polymerase chain reaction (RT–PCR) assays in brains from both mothers and full‐term fetuses. In plasma membranes from pregnant rat brain, caffeine and theophylline caused a significant decrease in total receptor numbers, of the same order in both cases (30%), with no significant changes on receptor affinity. The effect of these adenosine receptor antagonists on plasma membranes from fetal brains was more marked, being detected at approximately 50% of the total receptors detected in control conditions. However, in this tissue, a significant increase in the receptor affinity, of the same order in both cases, was also detected after antagonist administration. No significant variation on the potency of caffeine and theophylline as antagonists was detected after treatments in mothers; however, higher affinities were detected in fetuses. A decrease in the total receptor numbers in fetal brain was associated with an increase in the mRNA coding A1 receptor, as determined by RT–PCR assays, not having detected any mRNA difference in maternal brain. No variation in the levels of mRNA coding A2A receptor was detected in any case. These results suggest that maternal caffeine or theophylline intake modulates adenosine A1 receptor, causing a down‐regulation of adenosine A1 receptor in brain in both mothers and fetuses.
Calpain activates caspase‐3 during UV‐induced neuronal death but only calpain is necessary for death
Authors: McCollum Adrian T. , Nasr Payman , Estus Steven 
Published: March 2003

AbstractWhile caspases have been strongly implicated in delayed neuronal death in a variety of experimental paradigms, other proteases such as calpain can also contribute to neuronal death. To evaluate the relative roles of caspase and calpain, we used a model system wherein UV treatment induced moderate or severe delayed cortical neuronal death, as quantified by propidium iodide and calcein AM. UV treatment led to increases in both caspase and calpain activation. Calpain inhibitor III (MDL‐28170) reduced caspase activation, suggesting that caspase activation was mediated by calpain. Calpain contributed to neuronal death, as indicated by strong neuroprotection provided by calpain inhibitor III, calpeptin, or Ca2+‐free medium. In contrast, caspase inhibitors were not neuroprotective. These results suggest that UV neurotoxicity is mediated by a loss of Ca2+ homeostasis which leads to a calpain‐dependent, caspase‐independent cell death. That calpain, but not caspase, may mediate death in instances involving the activation of both proteases may have relevance to other neuronal death models.
Anesthetic and ethanol effects on spontaneously opening glycine receptor channels
Authors: Beckstead Michael J. , Phelan Rachel , Trudell James R. , Bianchini Michael J. , Mihic S. John 
Published: March 2003

AbstractStrychnine‐sensitive glycine receptors mediate inhibitory neurotransmission occurring in the brain stem and spinal cord. Alcohols, volatile anesthetics and inhaled drugs of abuse are positive allosteric modulators of glycine receptor function, normally enhancing function only in the presence of glycine. A complication in studying allosteric actions on ligand‐gated ion channels is in the dissection of their effects on neurotransmitter binding from their effects on channel opening. Mutation of an aspartate residue at position 97 to arginine in the glycine receptor α1 subunit simulated the effects of glycine binding, producing receptors that exhibited tonic channel opening in the absence of neurotransmitter; i.e. these receptors demonstrated a dissociation of channel opening from neurotransmitter binding. In these receptors, ethanol, enflurane, chloroform, halothane, 1,1,1‐trichloroethane and toluene elicited inward currents in the absence of glycine. We previously identified mutations on ligand‐gated ion channels that eliminate ethanol, anesthetic and inhalant actions (such as S267I on α1 glycine receptors). The double mutant (D97R and S267I) receptors were both constitutively active and resistant to the enhancing effects of ethanol and enflurane. These data demonstrate that ethanol and volatile anesthetics can affect glycine receptor channel opening independently of their effects on enhancing neurotransmitter binding.
Systemic fatty acid responses to transient focal cerebral ischemia: influence of neuroprotectant therapy with human albumin
Authors: Rodriguez de Turco Elena B. , Belayev Ludmila , Liu Yitao , Busto Raul , Parkins Nilda , Bazan Nicolas G. , Ginsberg Myron D. 
Published: March 2003

AbstractHuman albumin therapy is highly neuroprotective in focal cerebral ischemia. Because albumin is the main carrier of free fatty acids (FFA) in plasma, we investigated the content and composition of plasma FFA in jugular vein (JV), femoral artery (FA) and femoral vein (FV) of rats given intravenous human albumin (1.25 g/kg) or saline vehicle (5 mL/kg) 1 h after a 2 h middle cerebral artery occlusion (MCAo) or sham surgery. Arachidonic acid was the only FFA significantly increased by MCAo in all plasma samples prior to albumin administration, remaining at the same level regardless of subsequent treatments. Albumin treatment induced in both MCAo‐ and sham‐groups a 1.7‐fold increase in total plasma FFA (mainly 16:0, 18:1, 18:2n‐6) during 90‐min reperfusion. MCAo selectively stimulated the albumin‐mediated mobilization of n‐3 polyunsaturated fatty acids (PUFA), with an early increase in 22:5n‐3 and 22:6n‐3 in the FA prior to detectable changes in the JV. In the MCAo‐albumin group, the lower level of FFA in JV as compared with FA and FV suggests an albumin‐mediated systemic mobilization and supply of FFA to the brain, which may favor the replenishment of PUFA lost from cellular membranes during ischemia and/or to serve as an alternative source of energy, thus contributing to albumin neuroprotection.
Adrenergic inducibility of AP‐1 binding in the rat pineal gland depends on prior photoperiod
Authors: Guillaumond F. , Becquet D. , Bosler O. , François‐Bellan A. M. 
Published: March 2003

AbstractThe main known function of the pineal gland in mammals is the temporal synchronization of physiological rhythms to seasonal changes of day length (photoperiod). In rat, the transcription factor activating protein‐1 (AP‐1) displays a circadian rhythm in its DNA binding in the pineal gland, which results from the rhythmic expression of Fra‐2. We postulated that, if AP‐1 is an important component of pineal gland functioning, then variations in photoperiodic conditions should lead to an adaptation of the AP‐1 binding rhythm. Here we show that AP‐1 binding patterns adapt to variations in lighting conditions, in the same way as the rhythm of arylalkylamine‐N‐acetyltransferase (AA‐NAT) activity. This adaptation appeared to result from photoperiodic adaptation of the rhythmic fra‐2 gene expression and was reflected byan adapted delay between the onset of night and the acrophase of the nocturnal peak. We further showed that photoperiodic adaptation of both the AP‐1 binding and AA‐NAT activity rhythms resulted from adapted changes in adrenergic inducibility of both variables at night onset. We finally provided evidence that AP‐1 shared with the CREM gene encoding the transcriptional repressor protein inducible cAMP early repressor (ICER) the ability to be hypersensitive or subsensitive to adrenergic stimuli, depending on prior photoperiod.