bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chronic ethanol consumption impairs the circadian rhythm of pro‐opiomelanocortin and period genes mRNA expression in the hypothalamus of the male rat
Authors: Chen Cui Ping , Kuhn Peter , Advis Juan P. , Sarkar Dipak K. 
Published: July 2010

AbstractCertain psychiatric disorders are known to alter the body's biological rhythms. However, currently, very little information is known about the effect of chronic ethanol administration on the circadian clock or the rhythm of β‐endorphin‐containing neurons that participate in the control of the reward and reinforcement of alcohol drinking. Here, we report that administration of ethanol, via a liquid diet paradigm for a period of 2 weeks, abolishes the circadian rhythm of pro‐opiomelanocortin mRNA expression of β‐endorphin neurons in the arcuate nucleus of the hypothalamus. The circadian expression of the clock governing rat period genes (rPeriod1mRNA andrPeriod2mRNA) in the arcuate nucleus was significantly altered, suggesting that ethanol administration disrupted the internal clock. Moreover, ethanol consumption altered the circadian rhythms ofrPeriod2andrPeriod3mRNA levels in the suprachiasmatic nucleus, suggesting that ethanol also affected the function of the central pacemaker. Our findings identified the vulnerability of the body's clock machinery and its opioidergic system to chronic alcohol drinking.
Differentiation‐induced alterations in cyclic AMP signaling in the Cath.a differentiated (CAD) neuronal cell line
Authors: Johnston Christopher A. , Beazely Michael A. , Bilodeau Matthew L. , Andrisani Ourania , Watts Val J. 
Published: July 2010

AbstractRegulation of intracellular cyclic AMP is critical to the modulation of many cellular activities, including cellular differentiation. Moreover, morphological differentiation has been linked to subsequent alterations in the cAMP signaling pathway in various cellular models. The current study was designed to explore the mechanism for the previously reported enhancement of adenylate cyclase activity in Cath.a differentiated cells following differentiation. Differentiation of Cath.a differentiated cells stably expressing the D2Ldopamine receptor markedly potentiated both forskolin‐ and A2‐adenosine receptor‐stimulated cAMP accumulation. This enhancement was accompanied by a twofold increase in adenylate cyclase 6 (AC6) expression and a dramatic loss in the expression of AC9. The ability of Ca2+to inhibit drug‐stimulated cAMP accumulation was enhanced following differentiation, as was D2Ldopamine receptor‐mediated inhibition of Gαs‐stimulated cAMP accumulation. Differentiation altered basal and drug‐stimulated phosphorylation of the cAMP‐response element‐binding protein, which was independent of changes in protein kinase A expression. The current data suggest that differentiation of the neuronal cell model, Cath.a differentiated cells induces significant alterations in the expression and function of both the proximal and distal portions of the cAMP signaling pathway and may impact cellular operations dependent upon this pathway.
Colloquium 15: Role of the Protease‐Activated Receptors in Neural Development, Degeneration and Trauma. Expression and regulation of PARs in brain and spinal cord
Authors: Citron B. A. , Suo Z. , Ameenuddin S. , Davis J. T. , Festoff B. W. 
Published: July 2010

Signalling through protease activated receptors (PARs) is important during neural development and reappears during certain CNS disorders resulting in loss of neurons. These heptohelical G‐protein coupled receptors (GPCRs) are activated by specific proteolysis of N‐terminal fragments. How they are regulated at transcriptional and post‐transcriptional levels is of paramount importance in developing neuroprotective strategies. We and others showed in vitro that serine protease signalled apoptosis involves activation of PAR‐1 and a pathway involving coupled Gs, intracellular calcium elevation, activation of caspases, and apoptotic cell death. In vivo, after spinal cord injury in rats and during motor neuron degeneration in wobbler mice, PAR‐1 is up‐regulated in the regions most affected even prior to the onset of phenotypic motor loss in the homozygous recessive wobbler mouse. Information is beginning to appear on transcriptional regulation of PAR expression and involves several transcription factors (TFs) such as AP‐1, SP‐1, NFκB and, more recently, JAK/STAT. The regulation of PARs in the nervous system will be reviewed with an emphasis on those PARs unregulated during neurodegeneration and in response to CNS injury. In summary, immunohistochemistry, quantitative mRNA, gene array analyses of the receptor sequences present and their modulation by exogenous factors indicate that they are potential targets for therapeutic intervention to help preserve neuronal health.Acknowledgements:  Supported by the Dept. of Veterans Affairs, Christopher Reeve Paralysis Foundation, ALS Association, Lied Endowment, KUMCRI and Midwest Biomedical Research Foundation.
Protease‐activated receptors (PARs), microglial reactivity and neurodegeneration
Authors: Suo Z. , Citron B. A. , Ameenuddin S. , Andrade‐Gordon P. , Festoff B. W. 
Published: July 2010

Microglial activity accompanies many types of neurodegeneration and neurotrauma. Thrombin is an early arriving modulator at sites of CNS damage. How it affects cascades leading to neurodegeneration is an area of important study. To investigate the roles of PARs in thrombin‐induced microglial activation, primary microglial cultures from wild type and PAR1 deficient (PAR1 −/−) mice, along with N9 microglial cell line, were treated with thrombin, PAR1 (SFLLRN) and PAR4 (GYPGQV) agonist peptides (AP). Changes in [Ca2+]i, phosphorylation states of mitogen‐activated protein kinases (MAPKs), p38, p44/42, cell proliferation and tumor necrosis factor‐α (TNFα) secretion were examined by calcium imaging, Western blots, MTS assay and ELISA. We found that activation of microglial PAR1 or PAR4 induces a rapid cytosolic free [Ca2+]i increase and transient activation of both p38 and p44/42 MAPKs. Moreover, activation of either PAR1 or PAR4 directly contributes to thrombin‐induced microglial proliferation. In addition, activation of PAR4, but not PAR1, alone mimics the direct effect of thrombin on TNF‐α induction. Nonetheless, activation of PAR1 by PAR1AP potentiates PAR4AP‐induced TNF‐α production. We conclude that activation of PAR1 and PAR4 alone each contributes to different aspects of microglial activation by thrombin. In addition, PAR1 and PAR4 function in concert to mediate thrombin's overall effect on microglia.Acknowledgements:  Supported by V.A. Medical Research, Missouri Alzheimer's Research Fund, Univ. of Kansas medical Center Research Institute, ALS Association, Chrsitorpher reeve Paralysis Foundation, Lied Endowment and Midwest Biomedical Research Foundation.
Developmental expression of NMDA receptors in primary cortical cell culture: relationship to function and excitotoxicity
Authors: Christmann B. , Uliasz T. F. , Hewett S. J. 
Published: July 2010

Over‐activation of the N‐methyl‐d‐aspartate (NMDA) receptor results in a Ca2+‐dependent neurotoxicity termed excitotoxicity. Primary neuronal cell cultures are often used to study the mechanisms of excitotoxicity. While the expression of the NMDA receptor (NR) subunits and their relationship to Ca2+ entry/accumulation and excitotoxicity has been studied extensively, all three parameters have not been examined concurrently. To determine unequivocally whether developmental expression of NR protein and function do indeed coincide with the appearance of excitotoxicity, we examined the temporal relationship between NR subunit expression, NMDA‐induced Ca2+ accumulation, and NMDA‐mediated excitotoxicity simultaneously using sister plates derived from the same mixed cortical cell culture preparations. Western Blot analysis of total protein isolated from cells cultured for 1, 4, 7, 10 and 14 days revealed a time‐dependent increase in NR1, NR2A and NR2B subunit expression, which surprisingly did not correlate with NMDA receptor function, as assessed by measurement of NMDA‐induced 45Ca2+ accumulation. However, when only NR subunit surface expression was quantified, a correlation between expression and 45Ca2+ accumulation did indeed exist. To our surprise, the emergence of excitotoxicity did not show a direct relationship to 45Ca2+ accumulation as has been reported previously. Thus, it appears that other factors besides total Ca2+ accumulation must contribute to the emergence of excitotoxicity in mixed murine cortical cell cultures.Acknowledgements: Supported by a grant from The Patrick and Catherine Weldon Donaghue Medical Foundation.
NAAG and NAALADase influence NMDA receptor activation and axon‐to‐glia signalling in crayfish medial giant nerve fibers
Authors: Urazaev, A. K. , Gafurov B. S. , Grossfeld R. M. , Lieberman E. M. 
Published: July 2010

Action potential generation in crayfish giant nerve fibers causes a transient depolarization followed by a prolonged hyperpolarization in their associated glial cells. The glial potential changes, involving a nicotinic acetylcholine receptor (nAChR)‐induced decrease in Cl– permeability, are caused by axonal release of N‐acetylaspartylglutamate (NAAG) acting specifically on glial group II metabotropic glutamate (mGLURII). In addition, GLU formed by NAAG hydrolysis by NAALADase acts on NMDARs as well as mGLURs. Application of NMDA or l‐aspartate also produces glial cell hyperpolarization that can be inhibited by antagonists of NMDA receptors (MK801) but not by antagonists of AMPA/kainate (AP4) or mGLURs (EGLU). Reducing extracellular Ca2+ depresses the NMDA effect while Na+ depletion, block of voltage‐dependent Ca2+ channels (verapamil) or the nAChR (d‐tubocurarin) completely prevent the response to NMDA. The hyperpolarization caused by high frequency stimulation of the nerve fiber is only partially reduced by NMDAR blockade suggesting these receptors are not solely responsible for initiating the glial hyperpolarization under physiological conditions. These results also indicate that the transient depolarization, induced by physiological activation of glial NMDARs, opens voltage‐sensitive Ca2+ channels leading to Ca2+ influx. An increase in [Ca2+]i by this mechanism potentiates the ACh release due to mGLURII activation and the subsequent hyperpolarization mediated by the nAChR.Acknowledgements: Supported by NIH grant NS34799 and Guilford Pharmaceuticals, Baltimore, MD, USA.
An essential role for P38 MAP kinase signalling in oligodendrocyte differentiation
Authors: Bhat N. R. , Fan F. , Pawate S. 
Published: July 2010

Proliferating oligodendrocyte progenitors (OLPs) cease to divide and undergo differentiation to express myelin‐specific markers and genes upon growth factor withdrawal. We report here that signalling via p38 mitogen‐activated protein kinase (p38 MAPK) pathway plays an essential role in this process. SB203580, a specific inhibitor of p38 MAPK, interferes with the characteristic morphological transformation (i.e. from a simple bi‐/tri‐polar shape to a complex multipolar structure) of OLPs and the expression of oligodendrocyte differentiation‐specific antigenic markers, i.e. O4, O1 and myelin basic protein (MBP). RT–PCR analysis reveals a reduced level of mRNA for MBP and myelin associated glycoprotein (MAG) in the inhibitor‐treated cultures. Switching of OLPs from a growth medium to a mitogen‐free differentiation medium leads to an increased phosphorylation of CREB, a transcription factor implicated in myelin gene expression, in a p38 MAPK‐dependent manner. Kinase assays indicate a differential regulation of the p38 MAPK isoforms i.e. a decline, with time in culture, in the activity of the α isoform from an initial high level present in OLPs, in contrast to increased activity levels of the β isoform in differentiating cells. Enforced activation of p38 MAPK by transfection with activated forms of its upstream kinases i.e. MAPK kinase 6 [MKK6b(E)] and [MKK3b(E)], results in a precocious induction of MBP and MAG mRNAs and a marked stimulation of the activity of an MBP promoter‐reporter which can be blocked by the p38 MAPK inhibitor. The results presented strongly support a prominent role for p38 MAPK pathway in oligodendrocyte differentiation and myelin‐specific gene expression.Acknowledgements: Supported in part by NINDS grant # NS41035‐01.
Anti‐inflammatory actions of transforming growth factor‐β1 on rat microglia
Authors: Krady J. K. , Basu A. , Enterline J. R. , Levison S. W. 
Published: July 2010

Microglia rapidly respond to CNS injury yet the mechanisms leading to their activation and inactivation remain poorly defined. In particular, few studies have established how interactions among inflammatory mediators affect the innate immune response of microglia. To begin to understand the hierarchy of cytokine signaling we examined the effects of interleukin‐1β (IL‐1β), interleukin‐6 (IL‐6), tumor necrosis factor‐α (TNF‐α), interferon‐γ (IFN‐γ) and transforming growth factor‐β1 (TGF‐β1) on both newborn and bulk isolated adult microglia. To assess the functional state of the cells we assayed the expression of cyclooxygenase‐2 (Cox‐2); interleukin‐6 and tumor necrosis factor‐α, and two protein tyrosine kinases implicated in microglial responses to activational stimuli, Hck and Fak. These studies demonstrated that IL‐1β, TNF‐α, IL‐6, but not IFN‐γ increase the expression of Cox‐2, whereas they all increase the expression of hck and fak. TGF‐β1 had either no effect, or it decreased basal levels of these proteins. Significantly, TGFβ1 blocked the activational effects of IL‐1β when given prior to or simultaneously with IL‐1β. TGF‐β1 blocked the induction of the tyrosine kinases, Cox‐2, and the induction of IL‐6 and TNF‐α mRNAs. Thus we conclude that TGF‐β1 exerts a stronger effect on the microglial state than IL‐1β. However, TGF‐β1 was ineffective in antagonizing the induction of Cox‐2 by IL‐6. Therefore, we conclude that the TGF‐β receptor signalling cascades intersect with IL‐1, but they may not interact with IL‐6 signalling. Consequently, IL‐6 exerts stronger effects on the microglial state than either IL‐1 or TGF‐β.Acknowledgements:  Supported by NMSS award #RG3837.
Involvement of P38MAP kinase in the induction of nitric oxide synthase in human astrocytes
Authors: Anderson J. A. , Jana M. , Dasgupta S. , Liu X. , Pahan K. 
Published: July 2010

The present study underlines the importance of p38 mitogen‐activated protein kinase (p38MAPK) in regulating the expression of iNOS in human astroglia. The combination of IL‐1β and IFN‐γ activated p38MAPK and induced the production of NO and the expression of iNOS in human U373MG astroglial cells. SB203580, a specific inhibitor of p38MAPK, and Dp38, a dominant‐negative mutant of p38MAPK, markedly inhibited cytokine‐induced production of NO and expression of iNOS. Next we investigated the role of NF‐κB in the expression of iNOS. Inhibition of cytokine‐induced NF‐κB activation and iNOS expression by SN50, a specific inhibitor of p50 NF‐κB, but not by SN50M, a nonfunctional peptide mutant, does suggest that activation of NF‐κB is necessary for the expression of iNOS. However, SB203580 and Dp38 had no effect on the activation of NF‐κB suggesting that SB203580 and Dp38 inhibit the expression of iNOS without inhibiting the activation of NF‐κB. Next we examined the role of C/EBP‐b in the expression of iNOS. In contrast to the effect of SB203580 and Dp38 on the activation of NF‐κB, both SB203580 and Dp38 markedly inhibited the activation of C/EBP‐b in cytokine‐stimulated cells. Similar to U373MG astrocytoma cells, Dp38 also inhibited cytokine‐induced expression of iNOS and activation of C/EBP‐b but not that of NF‐κB in human primary astroglia. Taken together, these studies suggest that p38MAPK regulates the expression of iNOS in human astroglia by regulating the activation of C/EBP‐b but not that of NF‐κB.Acknowledgements:  This study was supported by NIH grants (NS39940 and AG19487).
MPTP‐treated senescence accelerated mice as a novel experimental model for Parkinson's disease
Authors: Boldyrev A. A. , Sorokina E. , Kasey V. , Bastrikiva N. , Fedorova T. , Stvolinsky S. 
Published: July 2010

Known experimental models of Parkinson's Disease (PD) are limited by nonsimultaneous expression of physiological and biochemical features. We described a novel PD model consisting of N‐methyl,4‐phenyl‐tetrahydropyridine (MPTP) treatment of Senescence Accelerated Mice (SAM) characteristic of increased level of reactive oxygen species aggravated by deficiency of antioxidant defense system. MPTP treatment was found to suppress locomotion and enhance the nonmotivated behavior (grooming); short‐term tremor and apparent rigidity were also noted. MPTP effect was accompanied with increased level of protein carbonyls and lipid hydroperoxides indicating numerous disorders in antioxidant defense system. The brain of MPTP treated animals demonstrated higher MAO B activity and low level of SOD. Brain of control animals treated with MPTP was demonstrated by unchanged MAO B and two times decreased SOD activity; behavioral alterations in these mice being less manifested than that of SAM animals. The data presented showed that MPTP treated SAM animals are perspective model for Parkinson's disease study.Acknowledgements:  The work is supported by RFBR (## 99‐04‐49420; 00‐04‐48767).
Expression of retrograde transport proteins during oligodendrocyte
Authors: Gould R. M. , Bukher T. , Barbarese E. 
Published: July 2010

Using a combination of subcellular fractionation and suppression subtractive hybridization, we found that a high molecular weight dynein light intermediate chain‐2 mRNA copurifies with myelin basic protein mRNA in rat brain myelin. We used a combination of subtraction efficiency and Northern blot analysis to show that other dynein (dynein heavy chain, dynein intermediate chains 1 and 2 and dynein light intermediate chain‐1) and dynactin (arp‐1, p150glued, dynamitin, CLIP‐170 and capB1) mRNAs do not copurify with these mRNAs in rat brain myelin. We used immunofluorescence and Western blotting to show that all of these proteins are expressed by cultured oligodendrocytes. These results suggest that of all the dynein/dynactin proteins synthesized in oligodendrocytes, only one, dynein light intermediate chain‐2, is synthesized in the cell's processes (near sties of myelin sheath assembly). Consequently, the addition of dynein light intermediate chain‐2 molecules to other dynein/dynactin proteins at sites of myelin sheath assembly may influence retrograde transport initiated at these distal sites.Acknowledgements:  Supported by grant RG2944A5/1 from the National Multiple Sclerosis Society.
Activation of PKC isoforms by ATP/UTP and PMA in murine astrocytes
Authors: Sun G. Y. , Xu J. , Liao Z. , Lo S‐C. , Weisman G. A. 
Published: July 2010

Protein kinase C (PKC) isoforms are known to play an important role in regulating activities of a number of receptor signalling pathways. Our earlier studies have demonstrated that in murine astrocytes, PKC and mitogen‐activated protein kinases (MAPK) are involved in the stimulation of cytosolic phospholipase A2 and arachidonic acid (AA) release by extracellular nucleotides (ATP or UTP) and phorbol myristate acetate (PMA). These studies showed that PKC inhibitors or PKC down‐regulation induced by prolonged exposure to PMA had variable effects on AA release induced by ATP/UTP or PMA. PKC down‐regulation reduced PMA‐ but not ATP/UTP‐mediated AA release. In this study, we examined responses of PKC isoforms to stimulation by ATP/UTP and PMA in primary astrocytes isolated from mouse brain. These astrocytes showed 4 major PKC isoforms, namely, PKCα, ε, ι, and λ. Prolonged treatment of astrocytes with PMA resulted in down‐regulation of PKCα and ε, but not PKCι and λ. Separation of membrane and cytosol fractions revealed that PKCα was largely localized to the cytosol, PKCε in the membrane, whereas PKCι and λ were present in both membrane and cytosol fractions. Rapid translocation of PKCα from the cytosol to cell membrane could be observed in astrocytes treated with PMA, but not ATP or UTP. Neither PMA nor ATP altered cytosol and membrane distribution of PKCε, ι and λ. The lack of an effect of ATP and UTP on PKCα translocation suggests that nucleotide‐mediated AA release occurs by a PKCα‐independent mechanism.Acknowledgements:  Supported by P01 AG 18357 from NIA.
Analysis of glycosphingolipid composition of a neural progenitor cell line
Authors: Suetake K. , Liour S. S. , Tencomnao T. , Kraemer Stacy , Yu Robert K. 
Published: July 2010

Continuous neurogenesis from neural stem cells in adult brain suggests the possibility that these newly generated neural tissue may be capable of repair of the neurodegeneration associated with genetic disorders, trauma, and aging. Glycosphingolipids (GSLs) play important roles in cellular growth, differentiation and cell signalling; however, little is known about the GSL composition in neural progenitor and/or stem cells. In order to characterize the GSL composition in neural stem cells, we studied the multipotential C17.2 cell line that was generated after myc‐transformation of isolated from neonatal mouse cerebellar neural progenitor cells. The developmental potential of C17.2 cells is similar to the endogenous neural stem cells, i.e. they are capable of self‐renewal and differentiation into neurons and glia (Snyder et al. Cell68, 33–51, 1992). HPTLC analysis of the total lipid fractions isolated undifferentiated C17.2 cells revealed that the major GSL expressed in these cells were glucosylceramide, GM3, GM2, GM1, and GD1a. Histochemical staining for GM1 using cholera toxin B subunit revealed punctate staining on the plasma membrane, suggesting GM1 at the plasma membrane, maybe clustered into microdomain‐like structures. Our results indicate that the undifferentiated C17.2 neural stem cell line is unique in expression of a‐series gangliosides. These gangliosides may prove to be useful markers for these cells.Acknowledgements: Supported by an NIH grant NS11853 and a grant from the Children's Medical Research Foundation.
c‐Fos activates phospholipid metabolism in events associated to growth and differentiation
Authors: Caputto B. L. , Gil G. A. , Portal M. M. , Borioli G. A. , Renner M. L. , Guido M. E. 
Published: July 2010

32P phospholipid labelling increases in quiescent fibroblasts stimulated with serum to re‐enter growth. This stimulation of phospholipid synthesis shows two waves that depend on the transcription and translation of the immediate early gene c‐fos. The time‐course pattern of c‐Fos protein expression resembles the activation pattern of phospholipid synthesis (The FASEB J, January 52001, 10.1096/fj.00‐0446fje). NGF‐treatment of PC12 cells promotes a strong increase in the expression of c‐Fos and enhances phospholipid synthesis in a c‐Fos‐concentration‐dependent way. Specifically blocking Fos expression with a c‐Fos mRNA antisense oligonucleotide impairs activation of phospholipid synthesis and also greatly inhibits cell differentiation. By contrast, inhibition of Fos degradation in NGF‐treated cells significantly increases c‐Fos content, phospholipid synthesis and neurite elongation. Blocking nuclear import of c‐Fos (AP‐1) at the initiation of NGF treatment completely blocks neurite formation. However, if c‐Fos nuclear import is blocked 16 h after addition of NGF to the cell cultures, neurite elongation continues almost normally. These results indicate that c‐Fos has a dual function in developing cells: it first releases the nuclear program for differentiation and then sustains growth by activating key components required for membrane genesis, in the cytoplasm. The mechanisms underlying this novel regulatory activity of c‐Fos on phospholipid synthesis, that is independent of its transcription factor activity, are being studied.Acknowledgements:  Financed by Beca Carrillo‐Oñativia, FONCyT, Agencia Córdoba. Ciencia (CONICOR), SeCyT‐UNC, and CONICET.