1
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Sparling K, Butler DC. Oral Corticosteroids for Skin Disease in the Older Population: Minimizing Potential Adverse Effects. Drugs Aging 2024; 41:795-808. [PMID: 39285122 DOI: 10.1007/s40266-024-01143-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2024] [Indexed: 10/16/2024]
Abstract
Corticosteroids play a crucial role as anti-inflammatory and immunomodulatory agents in dermatology and other medical specialties; however, their therapeutic benefits are accompanied by significant risks, especially in older adults. This review examines the broad spectrum of adverse effects (AEs) associated with oral corticosteroid therapy and offers strategies to prevent, monitor, and manage these issues effectively in older adults. AEs associated with systemic corticosteroids include immune suppression, gastrointestinal problems, hyperglycemia, insulin resistance, weight gain, cardiovascular complications, ocular issues, osteoporosis, osteonecrosis, muscle weakness, collagen impairment, psychiatric symptoms, and adrenal suppression. To minimize these AEs, tailored dosing and duration, frequent monitoring, and additional preventative measures can be employed to optimize corticosteroid treatment. By customizing management plans to the specific needs and risk factors associated with each patient, clinicians can promote the safe and effective use of oral corticosteroids, ultimately improving outcomes and quality of life in patients with inflammatory dermatologic disorders.
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Affiliation(s)
- Kennedy Sparling
- University of Arizona, College of Medicine - Phoenix, 475 N 5th St, Phoenix, AZ, 85004, USA.
| | - Daniel C Butler
- University of Arizona, College of Medicine - Tucson, Tucson, AZ, USA
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2
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Wei C, Benzow K, Koob MD, Gomez CM, Du X. The Transcription Factor, α1ACT, Acts Through a MicroRNA Network to Regulate Neurogenesis and Cell Death During Neonatal Cerebellar Development. CEREBELLUM (LONDON, ENGLAND) 2023; 22:651-662. [PMID: 35729466 PMCID: PMC10307715 DOI: 10.1007/s12311-022-01431-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/09/2022] [Indexed: 11/29/2022]
Abstract
MicroRNAs, a class of small RNA regulators, function throughout neurodevelopment, from neural stem cell neurogenesis to neuronal maturation, synaptic formation, and plasticity. α1ACT, a transcription factor (TF), plays a critical role in neonatal cerebellar development by regulating an ensemble of genes. Of these, ChIP-seq analysis matched near 50% genes directly regulated by α1ACT. Yet, more than half the regulated transcripts lacked direct interaction with α1ACT. To investigate whether α1ACT acts through a microRNA network, we studied α1ACT-associated simultaneous miRNA:mRNA transcriptome profiles, using miRNA-seq paired with RNA-seq. Thirty-one differentially expressed miRNAs (DEMs) associated with α1ACT-regulated differentially expressed genes (DEGs) were profiled in α1ACT-overexpressing PC12 cells and were further validated in neonatal transgenic mouse cerebellum overexpressing α1ACT in a context-dependent manner. Here, we also demonstrated that α1ACT facilitates neurogenesis and development of dendritic synapses and is partially a result of the downregulation of the miR-99 cluster, miR-143, miR-23, miR-146, miR-363, and miR-484. On the other hand, the miR-181, miR-125, and miR-708 clusters were upregulated by α1ACT, which inhibit MAPK signaling and cell death pathways by targeting Ask1, Odc1, Atf4, and Nuf2 for decreased expression. MiR-181a-5p was verified as the most abundant DEM in neonatal cerebellum, which was further induced by α1ACT. Overall, under α1ACT modulation, up-/downregulated miRNA clusters with their paired target genes may form a regulatory network controlling the balance between the neuronal proliferation, differentiation, and cell death in the cerebellum to promote neonatal development. Our findings concerning the α1ACT-related miRNA/mRNA expression profiles in neonatal cerebellum may inform future investigations for cerebellar development.
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Affiliation(s)
- Cenfu Wei
- Department of Neurology, University of Chicago, Chicago, IL, 60637, USA
| | - Kellie Benzow
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Michael D Koob
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, 55455, USA
| | | | - Xiaofei Du
- Department of Neurology, University of Chicago, Chicago, IL, 60637, USA.
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3
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Li A, Zhang S, Loconte V, Liu Y, Ekman A, Thompson GJ, Sali A, Stevens RC, White K, Singla J, Sun L. An intensity-based post-processing tool for 3D instance segmentation of organelles in soft X-ray tomograms. PLoS One 2022; 17:e0269887. [PMID: 36048824 PMCID: PMC9436087 DOI: 10.1371/journal.pone.0269887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 05/29/2022] [Indexed: 11/29/2022] Open
Abstract
Investigating the 3D structures and rearrangements of organelles within a single cell is critical for better characterizing cellular function. Imaging approaches such as soft X-ray tomography have been widely applied to reveal a complex subcellular organization involving multiple inter-organelle interactions. However, 3D segmentation of organelle instances has been challenging despite its importance in organelle characterization. Here we propose an intensity-based post-processing tool to identify and separate organelle instances. Our tool separates sphere-like (insulin vesicle) and columnar-shaped organelle instances (mitochondrion) based on the intensity of raw tomograms, semantic segmentation masks, and organelle morphology. We validate our tool using synthetic tomograms of organelles and experimental tomograms of pancreatic β-cells to separate insulin vesicle and mitochondria instances. As compared to the commonly used connected regions labeling, watershed, and watershed + Gaussian filter methods, our tool results in improved accuracy in identifying organelles in the synthetic tomograms and an improved description of organelle structures in β-cell tomograms. In addition, under different experimental treatment conditions, significant changes in volumes and intensities of both insulin vesicle and mitochondrion are observed in our instance results, revealing their potential roles in maintaining normal β-cell function. Our tool is expected to be applicable for improving the instance segmentation of other images obtained from different cell types using multiple imaging modalities.
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Affiliation(s)
- Angdi Li
- iHuman Institute, ShanghaiTech University, Shanghai, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Shuning Zhang
- iHuman Institute, ShanghaiTech University, Shanghai, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Valentina Loconte
- iHuman Institute, ShanghaiTech University, Shanghai, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Yan Liu
- iHuman Institute, ShanghaiTech University, Shanghai, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Axel Ekman
- Department of Anatomy, University of California San Francisco, San Francisco, CA, United States of America
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States of America
| | | | - Andrej Sali
- California Institute for Quantitative Biosciences, Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, United States of America
| | - Raymond C. Stevens
- iHuman Institute, ShanghaiTech University, Shanghai, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- Department of Biological Sciences, Bridge Institute, University of Southern California, Los Angeles, CA, United States of America
- Department of Chemistry, Bridge Institute, University of Southern California, Los Angeles, CA, United States of America
| | - Kate White
- Department of Chemistry, Bridge Institute, University of Southern California, Los Angeles, CA, United States of America
- * E-mail: (KW); (JS); (LS)
| | - Jitin Singla
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
- * E-mail: (KW); (JS); (LS)
| | - Liping Sun
- iHuman Institute, ShanghaiTech University, Shanghai, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- * E-mail: (KW); (JS); (LS)
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4
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Lü XY, Meng C, An S, Zhao YF, Wang ZG. Study on influence of external factors on the electrical excitability of PC12 quasi-neuronal networks through Voltage Threshold Measurement Method. PLoS One 2022; 17:e0265078. [PMID: 35263381 PMCID: PMC8906582 DOI: 10.1371/journal.pone.0265078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 02/22/2022] [Indexed: 11/18/2022] Open
Abstract
The aim of this paper was to investigate the influence of four different external factors (acetylcholine, ethanol, temperature and lidocaine hydrochloride) on PC12 quasi-neuronal networks by multielectrode-array-based Voltage Threshold Measurement Method (VTMM). At first, VTMM was employed to measure the lowest amplitude of the voltage stimulating pulses that could just trigger the action potential from PC12 quasi-neuronal networks under normal conditions, and the amplitude was defined as the normal voltage threshold (VTh). Then the changes of the VTh of PC12 quasi-neuronal networks treated by the four external factors were tested respectively. The results showed the normal VTh of PC12 quasi-neuronal networks was 36 mV. The VTh has negative correlation with the concentration of acetylcholine and has positive correlation with the concentration of ethanol. The curves of the correlation of the VTh with temperature and the concentration of lidocaine hydrochloride were U-shaped and Λ-shaped respectively. Comparing with our earlier studies on hippocampal neuronal networks and hippocampal slices, PC12 quasi-neuronal networks not only had the same typical voltage threshold characteristic, but also had similar changes on electrical excitability when treated by the four external factors mentioned above. Therefore, the rapid-formed PC12 quasi-neuronal networks could replace neuronal networks in proper conditions, and VTMM could be used to analyze the influence of external factors on the electrical excitability of PC12 quasi-neuronal networks.
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Affiliation(s)
- Xiao-Ying Lü
- State Key Laboratory of Bioelectronics, Southeast University, Nanjing, Jiangsu Province, China
- Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
- * E-mail: (XYL); (ZGW)
| | - Chen Meng
- State Key Laboratory of Bioelectronics, Southeast University, Nanjing, Jiangsu Province, China
| | - Shuai An
- State Key Laboratory of Bioelectronics, Southeast University, Nanjing, Jiangsu Province, China
| | - Yong-Fang Zhao
- State Key Laboratory of Bioelectronics, Southeast University, Nanjing, Jiangsu Province, China
| | - Zhi-Gong Wang
- Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
- Institute of RF- & OE-ICs, Southeast University, Nanjing, Jiangsu Province, China
- * E-mail: (XYL); (ZGW)
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5
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Hu L, Savy A, Grimaud L, Guille-Collignon M, Lemaître F, Amatore C, Delacotte J. Electroactive fluorescent false neurotransmitter FFN102 partially replaces dopamine in PC12 cell vesicles. Biophys Chem 2019; 245:1-5. [DOI: 10.1016/j.bpc.2018.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 10/30/2018] [Accepted: 11/04/2018] [Indexed: 01/09/2023]
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6
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Barbosa DJ, Capela JP, de Lourdes Bastos M, Carvalho F. In vitro models for neurotoxicology research. Toxicol Res (Camb) 2015; 4:801-842. [DOI: 10.1039/c4tx00043a] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023] Open
Abstract
The nervous system has a highly complex organization, including many cell types with multiple functions, with an intricate anatomy and unique structural and functional characteristics; the study of its (dys)functionality following exposure to xenobiotics, neurotoxicology, constitutes an important issue in neurosciences.
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Affiliation(s)
- Daniel José Barbosa
- REQUIMTE (Rede de Química e Tecnologia)
- Laboratório de Toxicologia
- Departamento de Ciências Biológicas
- Faculdade de Farmácia
- Universidade do Porto
| | - João Paulo Capela
- REQUIMTE (Rede de Química e Tecnologia)
- Laboratório de Toxicologia
- Departamento de Ciências Biológicas
- Faculdade de Farmácia
- Universidade do Porto
| | - Maria de Lourdes Bastos
- REQUIMTE (Rede de Química e Tecnologia)
- Laboratório de Toxicologia
- Departamento de Ciências Biológicas
- Faculdade de Farmácia
- Universidade do Porto
| | - Félix Carvalho
- REQUIMTE (Rede de Química e Tecnologia)
- Laboratório de Toxicologia
- Departamento de Ciências Biológicas
- Faculdade de Farmácia
- Universidade do Porto
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7
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Yakushenko A, Schnitker J, Wolfrum B. Printed Carbon Microelectrodes for Electrochemical Detection of Single Vesicle Release from PC12 Cells. Anal Chem 2012; 84:4613-7. [DOI: 10.1021/ac300460s] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Alexey Yakushenko
- Peter Grünberg Institute (PGI-8/ICS-8), Forschungszentrum Jülich,
52425 Jülich,
Germany
- JARA- Fundamentals
of Future
Information Technology, Forschungszentrum Jülich, 52425 Jülich,
Germany
| | - Jan Schnitker
- Peter Grünberg Institute (PGI-8/ICS-8), Forschungszentrum Jülich,
52425 Jülich,
Germany
- JARA- Fundamentals
of Future
Information Technology, Forschungszentrum Jülich, 52425 Jülich,
Germany
| | - Bernhard Wolfrum
- Peter Grünberg Institute (PGI-8/ICS-8), Forschungszentrum Jülich,
52425 Jülich,
Germany
- JARA- Fundamentals
of Future
Information Technology, Forschungszentrum Jülich, 52425 Jülich,
Germany
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8
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Mielke JG, Wang YT. Insulin, synaptic function, and opportunities for neuroprotection. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2011; 98:133-86. [PMID: 21199772 DOI: 10.1016/b978-0-12-385506-0.00004-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A steadily growing number of studies have begun to establish that the brain and insulin, while traditionally viewed as separate, do indeed have a relationship. The uptake of pancreatic insulin, along with neuronal biosynthesis, provides neural tissue with the hormone. As well, insulin acts upon a neuronal receptor that, although a close reflection of its peripheral counterpart, is characterized by unique structural and functional properties. One distinction is that the neural variant plays only a limited part in neuronal glucose transport. However, a number of other roles for neural insulin are gradually emerging; most significant among these is the modulation of ligand-gated ion channel (LGIC) trafficking. Notably, insulin has been shown to affect the tone of synaptic transmission by regulating cell-surface expression of inhibitory and excitatory receptors. The manner in which insulin regulates receptor movement may provide a cellular mechanism for insulin-mediated neuroprotection in the absence of hypoglycemia and stimulate the exploration of new therapeutic opportunities.
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Affiliation(s)
- John G Mielke
- Faculty of Applied Health Sciences, Department of Health Studies and Gerontology, University of Waterloo, Waterloo, Ontario, Canada
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9
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Abstract
This review attempts to touch on the history and application of amperometry at PC12 cells for fundamental investigation into the exocytosis process. PC12 cells have been widely used as a model for neural differentiation and as such they have been used to examine the effects of differentiation on exocytotic release and specifically release at varicosities. In addition, dexamethasone-differentiated cells have been shown to have an increased number of releasable vesicles with increased quantal size, thereby allowing for an even broader range of applications including neuropharmacological and neurotoxicological studies. PC12 cells exhibiting large numbers of events have two distinct pools of vesicles, one about twice the quantal size of the other and each about half the total releasable vesicles. As will be outlined in this review, these cells have served as an extremely useful model of exocytosis in the study of the latency of stimulation-release coupling, the role of exocytotic proteins in regulation of release, effect of drugs on quantal size, autoreceptors, fusion pore biophysics, environmental factors, health and disease. As PC12 cells have some advantages over other models for neurosecretion, including chromaffin cells, it is more than likely that in the following decade PC12 cells will continue to serve as a model to study exocytosis.
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Affiliation(s)
- R H S Westerink
- Cellular and Molecular Toxicology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands.
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10
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Lynch KL, Martin TFJ. Synaptotagmins I and IX function redundantly in regulated exocytosis but not endocytosis in PC12 cells. J Cell Sci 2007; 120:617-27. [PMID: 17264148 DOI: 10.1242/jcs.03375] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Synaptotagmin I is considered to be a Ca2+ sensor for fast vesicle exocytosis. Because Ca2+-dependent vesicle exocytosis persists in synaptotagmin I mutants, there must be additional Ca2+ sensors. Multiple synaptotagmin isoforms co-reside on vesicles, which suggests that other isoforms complement synaptotagmin I function. We found that full downregulation of synaptotagmins I and IX, which co-reside on vesicles in PC12 cells, completely abolished Ca2+-dependent vesicle exocytosis. By contrast, Ca2+-dependent exocytosis persisted in cells expressing only synaptotagmin I or only synaptotagmin IX, which indicated a redundancy in function for these isoforms. Although either isoform was sufficient to confer Ca2+ regulation on vesicle exocytosis, synaptotagmins I and IX conferred faster and slower release rates, respectively, indicating that individual isoforms impart distinct kinetic properties to vesicle exocytosis. The downregulation of synaptotagmin I but not synaptotagmin IX impaired compensatory vesicle endocytosis, which revealed a lack of isoform redundancy and functional specialization of synaptotagmin I for endocytic retrieval.
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Affiliation(s)
- Kara L Lynch
- Department of Biochemistry, 433 Babcock Drive, University of Wisconsin, Madison, WI 53706, USA
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11
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Jameson RR, Seidler FJ, Qiao D, Slotkin TA. Adverse neurodevelopmental effects of dexamethasone modeled in PC12 cells: identifying the critical stages and concentration thresholds for the targeting of cell acquisition, differentiation and viability. Neuropsychopharmacology 2006; 31:1647-58. [PMID: 16319912 DOI: 10.1038/sj.npp.1300967] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The use of dexamethasone (DEX) to prevent respiratory distress in preterm infants is suspected to produce neurobehavioral deficits. We used PC12 cells to model the effects of DEX on different stages of neuronal development, utilizing exposures from 24 h up to 11 days and concentrations from 0.01 to 10 microM, simulating subtherapeutic, therapeutic, and high-dose regimens. In undifferentiated cells, even at the lowest concentration, DEX inhibited DNA synthesis and produced a progressive deficit in the number of cells as evaluated by DNA content, whereas cell growth (evaluated by the total protein to DNA ratio) and cell viability (Trypan blue exclusion) were promoted. When cell differentiation was initiated with nerve growth factor, the simultaneous inclusion of DEX still produced a progressive deficit in cell numbers and promoted cell growth and viability while retarding the development of neuritic projections as monitored by the membrane/total protein ratio. Again, even 0.01 microM DEX was effective. We next assessed effects at mid-differentiation by introducing nerve growth factor for 4 days followed by coexposure to DEX. Although effects on cell number, growth, and neurite extension were still detectable, the outcomes were generally less notable. DEX also shifted the fate of PC12 cells away from the cholinergic phenotype and toward the adrenergic phenotype, with the maximum effect achieved at the outset of differentiation. Our results indicate that DEX directly disrupts neuronal cell replication, differentiation, and phenotype at concentrations below those required for the therapy of preterm infants, providing a mechanistic link between glucocorticoid use and neurodevelopmental sequelae.
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Affiliation(s)
- Ruth R Jameson
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
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12
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Gartlon J, Kinsner A, Bal-Price A, Coecke S, Clothier RH. Evaluation of a proposed in vitro test strategy using neuronal and non-neuronal cell systems for detecting neurotoxicity. Toxicol In Vitro 2006; 20:1569-81. [PMID: 16959468 DOI: 10.1016/j.tiv.2006.07.009] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2006] [Revised: 07/23/2006] [Accepted: 07/24/2006] [Indexed: 11/25/2022]
Abstract
The European Commission White Paper, "Strategy for a future chemicals policy" (EC, 2001) is estimated to require the testing of approximately 30,000 "existing" chemicals by 2012. Recommended in vitro tests require validation. As the White Paper (EC, 2001) requires neurotoxic data, this study evaluated an in vitro testing strategy for predicting in vivo neurotoxicity. The sensitivities of differentiated PC12 cells and primary cerebellum granule cells (CGC) were compared to undifferentiated PC12 cells which can indicate basal cytotoxicity. Cytotoxicants and neurotoxicants selected for testing covered a range of mechanisms and potencies. Neurotoxicants were not distinguished from cytotoxicants despite significantly different cell system responses using all endpoints; cell viability/activity, ATP depletion, MMP depolarisation, ROS production and cytoskeleton modifications. For all chemicals tested, neuronal-like cell systems were generally less sensitive than undifferentiated PC12 cells. Acute oral rodent LD(50) values correlated with cytotoxicity IC(50) values for the respective chemicals tested in each cell system. This study concluded that although simple non-specific assays are required to distinguish basal cytotoxicity from specific neurotoxicity by using different cell systems with different states of neuronal differentiation, further work is required to determine suitable combinations of cell systems and endpoints capable of distinguishing neurotoxicants from cytotoxicants.
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Affiliation(s)
- J Gartlon
- ECVAM, European Commission Joint Research Centre, Via E. Fermi 1, Ispra 21020, Italy.
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13
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Germain D, Maysinger D, Glavinovic MI. Vesicular roundness and compound release in PC-12 cells. J Neurosci Methods 2006; 153:27-42. [PMID: 16290198 DOI: 10.1016/j.jneumeth.2005.10.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Revised: 09/22/2005] [Accepted: 10/03/2005] [Indexed: 11/18/2022]
Abstract
The principal goals of this study were to establish a quantitative morphological analysis of spatial and regional properties of dense core vesicles, and to use this analysis to assess whether homotypic fusion is prominent in chronically treated PC-12 cells at elevated release levels. Simple computerized image processing of electron-micrographs provided the binary images of vesicular dense cores, whilst the artificial intelligence methods were needed to determine the vesicular membranes. As in the past, the presence of large, highly irregular vesicles, provided the morphological evidence of fused vesicles, but the irregularity of vesicular shape was assessed quantitatively-from its roundness. Free space of each vesicle was determined from the distance to its nearest-neighbor, or from the size of its Voronoi polygon. Within a Voronoi polygon, each point is closer to that vesicle than to any other vesicle. Large vesicles were not less round and did not have larger free space, as expected if they result from fusion of several smaller vesicles. In conclusion, we present a novel and rigorous morphological analysis of spatial and regional properties of dense core vesicles. The results demonstrate that the homotypic fusion is not prominent in PC-12 cells, before or following a chronic treatment that enhances release.
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Affiliation(s)
- D Germain
- Department of Computer Engineering, McGill University, Montreal, Canada
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14
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Schmidt M, Weidler C, Naumann H, Anders S, Schölmerich J, Straub RH. Reduced capacity for the reactivation of glucocorticoids in rheumatoid arthritis synovial cells: possible role of the sympathetic nervous system? ACTA ACUST UNITED AC 2005; 52:1711-20. [PMID: 15934114 DOI: 10.1002/art.21091] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
OBJECTIVE Cortisol, the biologically active glucocorticoid, is a major endogenous antiinflammatory factor in rheumatoid arthritis (RA). The aim of this study was to examine the local conversion of cortisol to biologically inactive cortisone and vice versa (the cortisol-cortisone shuttle) in RA and osteoarthritis (OA) patients. METHODS Thin-layer chromatography and phosphorimaging were used to examine the cortisol-cortisone shuttle in mixed synovial cells. Double immunohistochemistry was used to assess the key enzymes 11beta-hydroxysteroid dehydrogenase 1 (11beta-HSD1) and 11beta-HSD2 and their possible cellular locations. RESULTS Double immunohistochemistry demonstrated 11beta-HSD1/2+ macrophages in the sublining area. The ratio of 11beta-HSD2+ cells to 11beta-HSD1+ cells was significantly higher in RA than in OA patients. Cortisol was converted to inactive cortisone in mixed synovial cells from RA and OA patients, which was largely inhibited by carbenoxolone (11beta-HSD1 and 11beta-HSD2 inhibitor). Using metyrapone to inhibit the 11beta-HSD1 reducing reaction (cortisone --> cortisol), we demonstrated that the capacity for reactivation of cortisone to cortisol was significantly higher in OA than in RA patients. Although the capacity for the cortisone-cortisol shuttle was higher in synovial cells from less-inflamed OA tissue compared with inflamed RA tissue, it was obvious that synovial inflammation in RA, but not OA, was related positively to the reactivation of cortisone. This indicates that in RA, a cause other than typical inflammatory factors inhibits the reactivation of cortisone. Since isoproterenol and adenosine inhibited the cortisol-cortisone shuttle, the loss of sympathetic nerve fibers (loss of beta-adrenergic agonist and adenosine) may be the missing link that accounts for the increased cortisol-cortisone shuttle in RA. CONCLUSION This study demonstrates a reduced capacity for local reactivation of cortisone in RA synovial cells. Since synthetic glucocorticoids also use this reactivation shuttle, the results also apply to therapeutic glucocorticoids. This defective reactivation of cortisone may be an important unrecognized pathophysiologic factor in RA.
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Affiliation(s)
- Martin Schmidt
- Hospital of the Friedrich-Schiller-University, Jena, Germany
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15
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Batbayar B, Zelles T, Vér A, Fehér E. Plasticity of the different neuropeptide-containing nerve fibres in the tongue of the diabetic rat. J Peripher Nerv Syst 2004; 9:215-23. [PMID: 15574134 DOI: 10.1111/j.1085-9489.2004.09402.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Common oral complications of diabetes mellitus are xerostomia, impairment of taste, atrophic lesions of the tongue, leukoplakia, lichen oris planus, and tumours, which might be the consequence of chronic inflammation and changes in innervation. In this work, we examined the density of different neuropeptide-containing nerve fibres immunohisto- and immunocytochemically in the root of the control and diabetic rat's tongue. Quantitative analysis showed that the number of immunoreactive (IR) nerve fibres was decreased after 1 week of the streptozotocin treatment, which was prevented by immediate insulin treatment. However, after 4 weeks duration of diabetes, the number of all investigated IR nerve fibres increased significantly (p<0.05), which was further enhanced by the delayed insulin treatment. The numbers of substance P (SP) and vasoactive intestinal polypeptide IR perikarya were also increased by insulin treatment. The electron-microscopic investigations showed that some of the nerve terminals from diabetic animals were found in degeneration. After 4 weeks duration of diabetes, the number of inflammatory cells as well as the mast cell/nerve fibre contacts was also increased. The immunocells also showed IR for SP and neuropeptide Y in the diabetic rats. The insulin treatment decreased both the number and the immunoreactivity of these cells. The increased synthesis and/or regeneration of neuropeptide-containing nerves might indicate the plasticity of nerve fibres in diabetes mellitus, which might happen as a consequence of the changes in the level of neurotrophic factors released by increased number of inflammatory cells or as an effect of insulin.
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16
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Sombers LA, Hanchar HJ, Colliver TL, Wittenberg N, Cans A, Arbault S, Amatore C, Ewing AG. The effects of vesicular volume on secretion through the fusion pore in exocytotic release from PC12 cells. J Neurosci 2004; 24:303-9. [PMID: 14724228 PMCID: PMC6729980 DOI: 10.1523/jneurosci.1119-03.2004] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Many spikes in amperometric records of exocytosis events initially exhibit a prespike feature, or foot, which represents a steady-state flux of neurotransmitter through a stable fusion pore spanning both the vesicle and plasma membranes and connecting the vesicle lumen to the extracellular fluid. Here, we present the first evidence indicating that vesicular volume before secretion is strongly correlated with the characteristics of amperometric foot events. L-3,4-dihydroxyphenylalanine and reserpine have been used to increase and decrease, respectively, the volume of single pheochromocytoma cell vesicles. Amperometry and transmission electron microscopy have been used to determine that as vesicle size is decreased the frequency with which foot events are observed increases, the amount and duration of neurotransmitter released in the foot portion of the event decreases, and vesicles release a greater percentage of their total contents in the foot portion of the event. This previously unidentified correlation provides new insight into how vesicle volume can modulate the activity of the exocytotic fusion pore.
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Affiliation(s)
- L A Sombers
- Department of Chemistry, 152 Davey Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
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17
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Rutenberg AD, Richardson AJ, Montgomery CJ. Diffusion of asymmetric swimmers. PHYSICAL REVIEW LETTERS 2003; 91:080601. [PMID: 14525230 DOI: 10.1103/physrevlett.91.080601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2003] [Indexed: 05/24/2023]
Abstract
Particles moving along curved trajectories will diffuse if the curvature fluctuates sufficiently in either magnitude or orientation. We consider particles moving at a constant speed with either a fixed or a Gaussian distributed magnitude of curvature. At small speeds the diffusivity is independent of the speed. At larger particle speeds, the diffusivity depends on the speed through a novel exponent. We apply our results to intracellular transport of vesicles. In sharp contrast to thermal diffusion, the effective diffusivity increases with vesicle size and so may provide an effective means of intracellular transport.
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Affiliation(s)
- Andrew D Rutenberg
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada B3H 3J5
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18
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Ng YK, Lu X, Gulacsi A, Han W, Saxton MJ, Levitan ES. Unexpected mobility variation among individual secretory vesicles produces an apparent refractory neuropeptide pool. Biophys J 2003; 84:4127-34. [PMID: 12770915 PMCID: PMC1302991 DOI: 10.1016/s0006-3495(03)75137-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Most stored neuropeptide cannot be released from nerve terminals suggesting the existence of a refractory pool of dense core vesicles (DCVs). Past fluorescence photobleaching recovery, single particle tracking and release experiments suggested that the refractory neuropeptide pool corresponds to a distinct immobile fraction of cytoplasmic DCVs. However, tracking of hundreds of individual green fluorescent protein-labeled neuropeptidergic vesicles by wide-field or evanescent-wave microscopy shows that a separate immobile fraction is not evident. Instead, the DCV diffusion coefficient (D) distribution is unusually broad and asymmetric. Furthermore, the distribution shifts with a release facilitator. This unexpected variation, which could reflect heterogeneity among vesicles or in their medium, is shown to generate the appearance of a regulated refractory neuropeptide pool.
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Affiliation(s)
- Yuen-Keng Ng
- Department of Pharmacology, E1351 Biomedical Science Tower, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
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19
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Straub RH, Günzler C, Miller LE, Cutolo M, Schölmerich J, Schill S. Anti-inflammatory cooperativity of corticosteroids and norepinephrine in rheumatoid arthritis synovial tissue in vivo and in vitro. FASEB J 2002; 16:993-1000. [PMID: 12087060 DOI: 10.1096/fj.02-0085com] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Corticosteroids (CS) and norepinephrine (NE) support each other's biological effects. Thus, deficiency of cortisol and reduced synovial sympathetic innervation (SSI) may be proinflammatory in rheumatoid arthritis (RA). This study tested the anti-inflammatory cooperativity of CS and NE in human RA synovial tissue. In an in vivo study, 32 patients with RA (with prior CS therapy/without SSI: n=7; without prior CS therapy/with SSI: 6; with prior CS therapy/with SSI: 19) were investigated for synovial inflammation. In an in vitro study with synoviocytes from RA and OA patients, the separate and combined effects of cortisol and NE were studied. In the in vivo study, patients with prior CS therapy/with SSI showed lower secretion of synovial IL-8 than the other groups, lower synovial density of T cells and macrophages, and lower overall inflammation. In the in vitro study, a cooperative suppressive effect of NE (10(-6) M to 10(-8) M) and cortisol (10(-6) M and 10(-7) M) on secretion of IL-8 and TNF from primary early culture mixed RA synoviocytes was observed. This cooperative effect was not observed in OA synoviocytes. In the same RA and OA patients, the cooperative effect was lost in 3rd passage synovial fibroblasts. This study demonstrates the cooperativity of cortisol and NE for inhibition of proinflammatory mediators produced in the synovial tissue of RA patients. These results underscore that coupling of an efficient secretion of systemic cortisol together with local production of NE is important in order to lower synovial inflammation.
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Affiliation(s)
- Rainer H Straub
- Division of Rheumatology, Department of Internal Medicine I, University Hospital, Regensburg, Germany.
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20
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Berghorn KA, Le WW, Sherman TG, Hoffman GE. Suckling stimulus suppresses messenger RNA for tyrosine hydroxylase in arcuate neurons during lactation. J Comp Neurol 2001; 438:423-32. [PMID: 11559898 DOI: 10.1002/cne.1325] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Tyrosine hydroxylase (TH) mRNA in tuberoinfundibular dopamine (TIDA) neurons is suppressed during lactation but rebounds upon pup removal. A time course of TH mRNA changes after pup removal revealed three phases: (1) a nuclear phase (evident 1.5 hours after pup removal, maximal at 3 hours) with TH mRNA appearing in 1 or 2 nuclear loci with little or no change in cytoplasmic mRNA; (2) a cytoplasmic phase (noted 6 hours after pup removal, peaked 12-24 hours) with a significant increase in total TH mRNA levels mainly in the cytoplasm; and (3) a stabilization phase (24-48 hours after pup removal) when nuclear signals were low and cytoplasmic RNA showed a slight decline with extension of RNA clusters into the cell dendrites. In rats whose pups could suckle only on one side, TH was up-regulated only on the side contralateral to nipple blockade. These data indicate that after suckling terminates, TH up-regulation is evident at 1.5 hours, but 6 hours is needed before the cells transport sufficient mRNA into the cytoplasm. The rapid signaling of TH up-regulation stems from the fact that the TIDA neurons respond to neural signals from termination of suckling.
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Affiliation(s)
- K A Berghorn
- Laboratory for Pregnancy and Newborn Research, Department of Physiology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA
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21
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Straub RH, Cutolo M, Zietz B, Schölmerich J. The process of aging changes the interplay of the immune, endocrine and nervous systems. Mech Ageing Dev 2001; 122:1591-611. [PMID: 11511399 DOI: 10.1016/s0047-6374(01)00289-5] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The immune, endocrine and nervous systems interact with each other by means of cytokines, hormones and neurotransmitters. Interaction is dependent on specific receptors and respective signaling pathways in target cells. During aging, changes occur on many levels of these global systems which depend on oxidative damage, non-enzymatic glycosylation, mitochondrial mutations, defects in cell cycle control, mitotic dysregulation, genome instability, telomere shortening and other chromosomal pathologies. An alteration of the numerical value of a parameter of one system can lead to changes of the numerical value of a variable of another system. In a non-linear dynamic process these changes can contribute to the aging phenotype. Although it is extremely difficult to dissect linear interrelations of three global systems during aging, this review attempts to identify some simple linear pathways. Furthermore, it is demonstrated that chronic inflammatory diseases may accelerate the aging process. This review also reveals that new statistical and computational methods are necessary to unravel the complexity of the aging process.
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Affiliation(s)
- R H Straub
- Laboratory of Neuroendocrinoimmunology, Department of Internal Medicine I, University Hospital Regensburg, 93042, Regensburg, Germany.
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22
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Straub RH, Cutolo M. Involvement of the hypothalamic--pituitary--adrenal/gonadal axis and the peripheral nervous system in rheumatoid arthritis: viewpoint based on a systemic pathogenetic role. ARTHRITIS AND RHEUMATISM 2001; 44:493-507. [PMID: 11263762 DOI: 10.1002/1529-0131(200103)44:3<493::aid-anr95>3.0.co;2-u] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
From the compendium presented above, the following statements become evident: 1) Inappropriately low secretion of cortisol in relation to inflammation is a typical feature of the inflammatory disease in patients with RA. 2) The secretion of adrenal androgens is significantly reduced, which is a problem in postmenopausal women and elderly men due to a lack of downstream sex hormones. 3) Serum levels of testosterone are markedly reduced in RA. 4) Sympathetic nerve fibers are markedly reduced in the synovial tissue of patients with RA, whereas proinflammatory sensory fibers (substance P) are present. 5) Substance P serves to continuously sense painful stimuli in the periphery, and the nociceptive input from the inflamed joint shows a large amplification in the spinal cord. This leads to continuous pain with stabilization of the afferent sensory input and continuous release of proinflammatory substance P into the lumen of the joint. From these facts it is obvious that alterations of the systemic antiinflammatory feedback systems contribute significantly to the pathogenesis of RA. Disease therapy directed at these alterations must provide a mechanism to replace the adrenal glands (glucocorticoids), the gonadal glands (androgens), and the sympathetic nervous system (adenosine increase by low-dose MTX, sulfasalazine, and salicylates) in order to integrate their immunosuppressive effects at the local site of synovial inflammation. Although local processes of the adaptive immune system are important in pathogenesis in the acute phase of RA, these mechanisms may be less important during the chronic phase of the disease in the absence of a specific trigger. We believe that a defect of systemic antiinflammatory feedback systems is an important factor in the perpetuation of RA. This review reinforces the belief that combined therapeutic approaches on a neuroendocrine immune basis are of crucial importance in a pathogenetically oriented therapy of RA.
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Affiliation(s)
- R H Straub
- Department of Internal Medicine I, University Hospital, Regensburg, Germany
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23
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Abstract
It has been well established that the volume of secretory vesicles can be modulated. However, we present the first data demonstrating that the amount of transmitter in a vesicle can regulate its volume. Amperometry and transmission electron microscopy have been used to determine that l-3,4-dihydroxyphenylalanine and reserpine increase and decrease, respectively, the volume of single pheochromocytoma cell vesicles as well as their catecholamine content. Because changes in vesicular catecholamine content are tracked by changes in vesicle volume, our results indicate that when quantal size is altered via the vesicular monoamine transporter the concentration of catecholamines within the vesicles remains relatively constant. This previously unidentified cellular response provides new insight into how catecholamines can be packaged in and released from secretory vesicles.
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24
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Enhancement of the dense-core vesicle secretory cycle by glucocorticoid differentiation of PC12 cells: characteristics of rapid exocytosis and endocytosis. J Neurosci 2000. [PMID: 10729329 DOI: 10.1523/jneurosci.20-07-02495.2000] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The secretory cycle of dense-core vesicles (DCVs) in physiologically stimulated patch-clamped PC12 cells was analyzed using both amperometry and capacitance measurements. Untreated cells had low or undetectable Ca currents and sparse secretory responses to short depolarizations. Dexamethasone (5 microM) treatment for 5-7 d tripled Ca current magnitude and dramatically increased quantal secretion in response to depolarization with action potentials. Such cells expressed L-, N-, and P-type Ca channels, and depolarization evoked rapid catecholamine secretion recorded as amperometric spikes; the average latency was approximately 50 msec. These spikes were much smaller and shorter than those of primary adrenal chromaffin cells, reflecting the smaller size of DCVs in PC12 cells. Depolarizing pulse trains also elicited a rapid increase in membrane capacitance corresponding to exocytosis in differentiated but not in naïve cells. On termination of stimulation, membrane capacitance declined within 20 sec to baseline indicative of rapid endocytosis (RE). RE did not take place when secretion was stimulated in the presence of Ba or Sr, indicating that RE is Ca-specific. RE was blocked when either anti-dynamin antibodies or the pleckstrin homology domain of dynamin-1 was loaded into the cell via the patch pipette. These studies indicate that neuroendocrine differentiation of PC12 cells with glucocorticoids enhances the development of the excitable membrane and increases the coupling between Ca channels and vesicle release sites, leading to rapid exocytosis and endocytosis. Slow catecholamine secretion in undifferentiated cells may be caused in part by a lack of localized secretory machinery rather than being an intrinsic property of dense-core vesicles.
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25
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Westerink RH, de Groot A, Vijverberg HP. Heterogeneity of catecholamine-containing vesicles in PC12 cells. Biochem Biophys Res Commun 2000; 270:625-30. [PMID: 10753674 DOI: 10.1006/bbrc.2000.2470] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Vesicular catecholamine release has been measured amperometrically from undifferentiated rat PC12 cells using carbon fiber microelectrodes. During superfusion with high K(+) saline, vesicular release was detected from approximately 50% of 200 cells investigated. On repeated stimulation the releasable pool of vesicles is rapidly depleted, while vesicle contents remains constant. Vesicular catecholamine release is not restored within 1 h after depletion of the releasable pool. Although the distribution of the cube root of vesicle contents of many cells is apparently Gaussian, maximum likelihood analysis of single cell data demonstrates double Gaussian distributions with median vesicle contents of 141 and 293 zeptomole. It is concluded that the releasable pool of vesicles in PC12 cells is heterogeneous. In the presence of l-DOPA mean vesicle contents increases, but cessation of release cannot be prevented, indicating that the number of releasable vesicles in PC12 cells is limited by a slow rate of vesicle cycling.
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Affiliation(s)
- R H Westerink
- Research Institute of Toxicology, Utrecht University, Utrecht, NL-3508 TD, The Netherlands
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26
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Anderson BB, Chen G, Gutman DA, Ewing AG. Demonstration of two distributions of vesicle radius in the dopamine neuron of Planorbis corneus from electrochemical data. J Neurosci Methods 1999; 88:153-61. [PMID: 10389661 DOI: 10.1016/s0165-0270(99)00024-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
An electrochemical model to calculate the relative size and neurotransmitter concentration of individual nerve cell vesicles is presented to examine potentially different types of vesicles in Planorbis corneus. Amperometric current transients resulting from individual exocytosis events detected from single cells contain the information necessary to quantify vesicular neurotransmitter amount and to estimate other important cellular properties such as vesicular neurotransmitter concentration and vesicle radius. Use of a simplifying assumption that the cross-sectional area of the contents of each release event is the apparent electroactive area of the electrode and that the shape of the decreasing phase of each current transient follows Cottrell-like behavior, the Cottrell equation and Faraday's law can be combined to yield expressions for relative vesicle radius and neurotransmitter concentration. This analysis has been applied to data obtained from the cell body of the giant dopamine neuron of the pond snail P. corneus. The histogram of vesicular dopamine concentration reveals a single wide distribution and the histogram of vesicle radius reveals a bimodal radius distribution. These data strongly suggest two distinct classes of vesicle radius in the P. corneus neuron lead to the bimodal distribution of amount released reported earlier.
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Affiliation(s)
- B B Anderson
- Penn State University, Department of Chemistry, University Park 16802, USA
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27
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Anderson BB, Zerby SE, Ewing AG. Calculation of transmitter concentration in individual PC12 cell vesicles with electrochemical data and a distribution of vesicle size obtained by electron microscopy. J Neurosci Methods 1999; 88:163-70. [PMID: 10389662 DOI: 10.1016/s0165-0270(99)00023-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A mathematical model is described to accurately calculate vesicle size and neurotransmitter concentration distributions from electrochemical data. This model uses parameters from electrochemical exocytosis data obtained from PC12 cells in culture to calculate a size distribution that is then correlated to the size of vesicles obtained by electron microscopy. The relative standard deviation of the size distribution calculated from electrochemical data is 25% which matches the relative standard deviation of the vesicle size distribution measured by electron microscopy. The distribution calculated from electrochemical data is normalized to the vesicle size distribution of PC12 cell vesicles obtained from electron microscopy. Calculation of a vesicular catecholamine concentration histogram from the normalized size data and electrochemical parameters is then possible for individual exocytosis events. The average vesicular catecholamine concentration for PC12 cells as calculated by this method is 148+/-7 mM. More importantly, there is a distribution of concentration rather than a constant value. Additionally, the model permits evaluation of the concentration of transmitter in each individual vesicle and vesicle size for each vesicle from electrochemical data when the overall vesicle size distribution is known.
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Affiliation(s)
- B B Anderson
- Department of Chemistry, Penn State University, University Park 16802, USA
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28
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Brown JW, Fishman LM, Carballeira A. Studies of the neuronal transdifferentiation process in cultured human pheochromocytoma cells: effects of steroids with differing functional groups on catecholamine content and cell morphology. Steroids 1998; 63:587-94. [PMID: 9830685 DOI: 10.1016/s0039-128x(98)00068-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The neuronal differentiation of adrenal pheochromocytoma cells from human subjects was studied in vitro for periods of up to 65 days. Changes with time in culture were observed in both intracellular catecholamine content (progressive decreases in epinephrine, norepinephrine, and dopamine, except for a possible transient early increase in the latter) and in morphology (increases in neurite outgrowth) of cells cultured in control medium; supplementation of cultures with nerve growth factor resulted in a substantial increase in neurite formation. The effects on these changes of the presence in the culture medium of various steroids were examined. The addition of 11-oxygenated steroids (aldosterone, corticosterone, cortisol, or dexamethasone) at 10(-5) M concentrations caused at least 2.5-fold increases in mean intracellular dopamine and norepinephrine levels; with dexamethasone, 9-10-fold increases were observed. Intracellular epinephrine content was also enhanced by 11,17-oxygenated steroids (dexamethasone and cortisol), but not by the other 11-oxygenated compounds studied. These two 11,17-oxygenated glucocorticoids also inhibited the morphologic changes seen with extended periods in culture, decreasing the outgrowth of neurite projections and causing cells to attain a vacuolated and granular appearance; the presence of dexamethasone strongly inhibited the morphologic changes induced by nerve growth factor. 11-Deoxy steroid intermediates (pregnenolone, 11-deoxycorticosterone, and 11-deoxycortisol) had little or no effect on catecholamine content or on morphology. Preliminary observations suggest that C-18 and C-19 sex steroid hormones (17 beta-estradiol and testosterone) may have morphologic effects opposite to those of the 11-oxygenated compounds, showing a slight stimulatory influence on the formation of neurite projections, but no significant effect on catecholamine content.
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Affiliation(s)
- J W Brown
- Department of Medicine, University of Miami School of Medicine, Florida, USA
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29
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Abstract
D2-like dopamine autoreceptors regulate dopamine release and are implicated in important actions of antipsychotic drugs and rewarding behaviors. To directly observe the effects of D2 autoreceptors on exocytic neurotransmitter release, we measured quantal release of dopamine from pheochromocytoma PC12 cells that express D2 and D4 autoreceptors. High potassium-evoked secretion in PC12 cells produced a unimodal population of quantal sizes. We found that exposures to the D2-like agonist quinpirole that inhibited tyrosine hydroxylase activity by approximately 50% also reduced quantal size by approximately 50%. The reduced quantal size was blocked by the D2 antagonist sulpiride and reversed by L-DOPA. Quinpirole also decreased the frequency of stimulation-evoked quantal release. Together, these findings indicate effects on quantal neurotransmission by D2-like dopamine autoreceptors previously distinguished as synthesis-modulating autoreceptors that regulate tyrosine hydroxylase activity versus impulse-regulating autoreceptors that modulate membrane potential. The results also provide an initial demonstration of a receptor-mediated mechanism that alters quantal size.
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30
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Clark RA, Ewing AG. Quantitative measurements of released amines from individual exocytosis events. Mol Neurobiol 1997; 15:1-16. [PMID: 9396001 DOI: 10.1007/bf02740612] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Chemical analysis of single cells is an area of great interest in the biological sciences. Single-cell systems are being utilized as a model to understand in vivo processes better. One method that is moving to the forefront in cellular analysis is electrochemistry. Owing to their rapid response time and small dimensions, voltammetric microelectrode techniques, such as amperometry and fast-scan voltammetry, have made it possible to monitor minute amounts of biological compounds and transiently occurring chemical events in cellular systems. The application of these methods to the quantitation of individual vesicular release events from single cells is overviewed here. The application of electrochemical monitoring to several types of cultured cells, including bovine adrenal chromaffin cells, rat pheochromocytoma (PC12) cells, beige mouse mast cells, superior cervical ganglion neurons, and human pancreatic beta-cells, as well as to the invertebrate systems, the leech Hirudo medicinalis, and pond snail Planorbis corneus has provided a wealth of new information concerning exocytosis. Results obtained from the studies highlight the potential of electrochemical techniques in cellular analysis to contribute to our understanding of molecular and pharmacological effects on exocytosis. This article overviews work done on all the above cell types with an emphasis on PC12 cells.
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Affiliation(s)
- R A Clark
- Department of Chemistry, Pennsylvania State University, University Park 16802, USA
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31
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Berse B, Blusztajn JK. Modulation of cholinergic locus expression by glucocorticoids and retinoic acid is cell-type specific. FEBS Lett 1997; 410:175-9. [PMID: 9237624 DOI: 10.1016/s0014-5793(97)00568-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Modulation of mRNA expression of choline acetyltransferase (ChAT) and the vesicular acetylcholine transporter (VAChT) by the glucocorticoid dexamethasone and by retinoic acid was examined in two neuronal cell lines: basal forebrain-derived SN56 and pheochromocytoma PC12. Dexamethasone up-regulated ChAT and VAChT in SN56 cells, while it had inhibitory effects on these genes in PC12 cells. Retinoic acid stimulated the cholinergic markers in both cell types, but in SN56 cells its effect was partially additive with that of dexamethasone, whereas it was much smaller and abrogated by dexamethasone in PC12 cells. Acetylcholine content correlated with these mRNA changes. The presence of a glucocorticoid response element consensus sequence in the VAChT/ChAT gene locus suggests direct transcriptional regulation by glucocorticoids.
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Affiliation(s)
- B Berse
- Department of Pathology, Boston University School of Medicine, MA 02118, USA
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32
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Schroeter S, Levey AI, Blakely RD. Polarized expression of the antidepressant-sensitive serotonin transporter in epinephrine-synthesizing chromaffin cells of the rat adrenal gland. Mol Cell Neurosci 1997; 9:170-84. [PMID: 9245500 DOI: 10.1006/mcne.1997.0619] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Antidepressant-sensitive serotonin (5-hydroxytryptamine, 5HT) transporters (SERTs) clear the amine from extracellular spaces in the CNS and periphery as a mechanism for transmitter inactivation and recycling. Although it is known that SERTs are preferentially expressed on basolateral domains in transfected epithelial cells, details of the transporter's membrane localization in vivo are lacking. 5HT and 5HT receptors have been identified in the rodent adrenal gland. Using SERT antagonist autoradiography, we establish the presence of antidepressant-sensitive transport sites in the rat adrenal medulla. Immunofluorescence experiments using antibodies specific for the SERT COOH and NH2 termini, for 5HT, or for catecholamine biosynthetic enzymes suggest that SERT mediates intra-cellular 5HT accumulation by epinephrine-secreting chromaffin cells. Using confocal microscopy, we establish that SERT expression is nonuniformly distributed along the plasma membrane of chromaffin cells. Notably, SERT immunoreactivity is largely absent from plasma membranes bordering smooth muscle that surrounds vascular sinusoids. Rather, SERT is highly expressed in membranes adjoining other chromaffin cells, consistent with a role for 5HT and SERT in autocrine or paracrine control of chromaffin cell physiology. SNAP-25, a t-SNARE protein implicated in neurotransmitter release, was found to colocalize with SERT. In contrast, Na,K ATPase and NCAM are uniformly distributed along the entire perimeter of chromaffin cell membranes. These findings underscore a role for 5HT and SERT in adrenal physiology, reveal unrecognized polarity of chromaffin cell plasma membranes, and warrant a consideration of common targeting mechanisms localizing amine transporters near release sites.
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Affiliation(s)
- S Schroeter
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-6600, USA
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33
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Abstract
Glutamate kills neuronal cells by either a receptor-mediated pathway or the inhibition of cystine uptake, the "oxidative pathway." Antioxidants can block cell death initiated by either pathway, suggesting that toxicity is dependent on the production of free radicals. We provide evidence that in a neuronal cell line, glutamate toxicity via the oxidative pathway requires monoamine metabolism as a source of free radicals. Glutamate toxicity is inhibited by monoamine oxidase (MAO) type-A-specific inhibitors, but only at concentrations much higher than those required to inhibit classical type-A MAO. Toxicity is not inhibited by MAO type-B-specific inhibitors at any concentration. Furthermore, treatment of cells with agents that block monoamine uptake inhibits glutamate toxicity. These results suggest that an enzyme distinct from MAO is involved in monoamine metabolism and demonstrate a relationship between glutamate toxicity and monoamine metabolism. These data also have implications for the understanding and treatment of neurodegenerative disorders in which glutamate toxicity is thought to be involved.
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Capasso A, Di Giannuario A, Loizzo A, Pieretti S, Sorrentino L. Actinomycin D blocks the reducing effect of dexamethasone on amphetamine and cocaine hypermotility in mice. GENERAL PHARMACOLOGY 1996; 27:707-12. [PMID: 8853309 DOI: 10.1016/0306-3623(95)02077-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
1. The present study examined a time-course effect of dexamethasone (DEX) on amphetamine and cocaine-induced hypermotility in mice and the influence of actinomycin D (dactinomycin), a protein synthesis inhibitor, on DEX effects. 2. Amphetamine (5 mg/kg IP) and cocaine (10 mg/kg IP) increased markedly the locomotor activity of mice, whereas DEX alone (0.1-1.0-10 mg/kg IP) did not modify the activity of control mice. 3. DEX pretreatment 0, 15, 30, 60 and 120 min before amphetamine or cocaine strongly decreased both amphetamine and cocaine effects, but no dose-related effect was observed. 4. The time-course study performed with DEX revealed differences in its reducing effect on cocaine and amphetamine hypermotility when the groups of animals treated with the steroid immediately before the cocaine (or amphetamine) injection were compared to those treated with the steroid later (15, 30, 60 and 120 min). 5. Furthermore, actinomycin D was able to block the reducing effect of DEX on both amphetamine and cocaine hypermotility. 6. Therefore, considering that the administration time of the steroid seems to be an important factor for reducing both cocaine and amphetamine hypermotility, and actinomycin D was able to block the reducing effect of the steroid, our study suggests that DEX exerts its reducing effect through a genomic activation.
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Affiliation(s)
- A Capasso
- School of Pharmacy, University of Salerno, Italy
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Belai A, Calcutt NA, Carrington AL, Diemel LT, Tomlinson DR, Burnstock G. Enteric neuropeptides in streptozotocin-diabetic rats; effects of insulin and aldose reductase inhibition. JOURNAL OF THE AUTONOMIC NERVOUS SYSTEM 1996; 58:163-9. [PMID: 8738309 DOI: 10.1016/0165-1838(95)00129-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The aim of the present study was to determine whether diabetes-induced changes in the distribution of enteric neuropeptides, could be prevented in 12-week streptozotocin-diabetic rats, by rigorous control of glycaemia, using daily adminstration of insulin, or an aldose reductase inhibitor (ponalrestat). The pattern of distribution of nerve fibres and cell bodies, containing immunoreactive vasoactive intestinal polypeptide (VIP), galanin (GAL), calcitonin gene-related peptide (CGRP) and substance P was examined in the myenteric plexus of ileum from control, untreated diabetic, insulin-treated diabetic and aldose reductase inhibitor-treated diabetic rats. The increase in VIP- and GAL-like immunoreactivity, seen in the myenteric plexus of untreated diabetic rat ileum, was not present in the myenteric plexus of ileum from insulin- and aldose reductase inhibitor-treated diabetic rats. With CGRP-like immunoreactive fibres, there was a clear decrease in the ileum of untreated diabetic rats. This was prevented by insulin treatment, but aldose reductase inhibitor treatment had no effect. No alterations in substance P-like immunoreactivity were seen in the myenteric plexus of ileum from any of the groups investigated. Generally, the similarity of effect of ponalrestat and insulin on VIP and galanin expression in this study supports a primary effect of insulin via glycaemic control. The dissimilarity of the effect of the two treatments on CGRP expression may imply a neurotrophic effect of insulin, although there are certainly consequences of hyperglycaemia other than exaggerated flux through the polyol pathway.
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Affiliation(s)
- A Belai
- Department of Anatomy and Developmental Biology, University College London, UK
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36
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Capasso A, Di Giannuario A, Loizzo A, Pieretti S, Sorrentino L. Dexamethasone pretreatment reduces the psychomotor stimulant effects induced by cocaine and amphetamine in mice. Prog Neuropsychopharmacol Biol Psychiatry 1995; 19:1063-79. [PMID: 8584683 DOI: 10.1016/0278-5846(95)00197-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
1. The present study examined a comparison of the effect of DEX on psychomotor stimulant effects of cocaine and amphetamine in mice by using the locomotor activity test. 2. Cocaine (10 mg/kg/i.p.) and amphetamine (5 mg/kg/i.p.) increased markedly locomotor activity of mice whereas DEX per se (0.1-1.0-10 mg/kg/i.p.) did not modify the activity of control mice. 3. DEX pretreatment decreased the stimulating effects induced both by cocaine and amphetamine but no consistent dose-related effects were observed. 4. The results suggest that DEX may play an important role on the stimulating effects of cocaine and amphetamine and that it may be of some utility in the clinical management of psychostimulants abuse.
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Affiliation(s)
- A Capasso
- School of Pharmacy, University of Salerno, Italy
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37
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38
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Gyévai AT, Bartha E. Early and late hormonal modulation of cholinergic maturation in culture of embryonic mesencephali. BIOTHERAPY (DORDRECHT, NETHERLANDS) 1992; 5:205-14. [PMID: 1419468 DOI: 10.1007/bf02171053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Dissociated cells from 13- and 17-day-old embryonic rat mesencephali have grown in primary cultures in order to compare the early and late influences of different agents--insulin, dexamethasone and nerve growth factor (NGF)--on the expression of cholinergic maturation process. We have studied cholin acetyltransferase (ChAT) activity, which is regarded as a specific marker for cholinergic function of the brain, and a widely used differentiation marker, the acetyl-cholinesterase (AchE) enzyme. Biochemical maturation of increasing specific activity of ChAT in both younger and older cells was taken into consideration. During cultivation the AchE activity was slightly increased in younger cells, but a dramatic decrease could be noted in older ones. Insulin in concentration from 10 to 27 micrograms mL-1 causes a significant inhibition in ChAT activity in comparison with the enzyme activity measured in control cultures (insulin ranging from 1 to 100 ng), independently of embryos age. This polypeptide hormone is able to enhance AchE activity in the cultured cells, especially in older ones. With continuous treatment of the culture with dexamethasone, a synthetic glucocorticoid, the ChAT activity in younger cells reaches a maximum curve by day 9 (nine). At this time the AchE activity shows a slighter, no significant increase than at any other time during cultivation. In cell cultures taken from 17-day-old embryos however dexamethasone treatment evoked a significant decrease in ChAT activity with a concomitant increase of AchE activity which was compared to insulin treatment. In spite of the fact that the NGF is able to enhance the ChAT activity, no significant alteration in AchE activity can be measured in younger cell cultures. These results suggest an uneven expression of the enzymes in embryonic rat mesencephali in the presence of above agents depending on the age of cells.
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Affiliation(s)
- A T Gyévai
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest
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Shipley JE, Schteingart DE, Tandon R, Pande AC, Grunhaus L, Haskett RF, Starkman MN. EEG sleep in Cushing's disease and Cushing's syndrome: comparison with patients with major depressive disorder. Biol Psychiatry 1992; 32:146-55. [PMID: 1330006 DOI: 10.1016/0006-3223(92)90017-t] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Because patients with Cushing' syndrome (CS) and Major depressive disorder (MDD) share features of hypercortisolism and the depressive syndrome, we compared electro-encephalographic (EEG) sleep in patients with pituitary-ACTH-dependent Cushing's syndrome (Cushing's disease, CD), patients with ACTH-independent Cushing's syndrome (AICS), patients with major depressive disorder (MDD), and normal subjects. There were substantial similarities in the abnormal polysomnography profiles of patients with CD, AICS, and MDD. All three patient groups demonstrated poorer sleep continuity, shortened rapid eye movement (REM) latency, and increased first REM period density compared with normal subjects. In addition, AICS patients and MDD patients had elevated REM activity and density. These findings are discussed in terms of models of pathophysiology that relate abnormalities in sleep, mood, and hypothalamic-pituitary-adrenal function.
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Affiliation(s)
- J E Shipley
- Sleep Program, University of Michigan School of Medicine, Ann Arbor
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40
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Kimura H, Schubert D. Schwannoma-derived growth factor promotes the neuronal differentiation and survival of PC12 cells. J Biophys Biochem Cytol 1992; 116:777-83. [PMID: 1530950 PMCID: PMC2289303 DOI: 10.1083/jcb.116.3.777] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Schwannoma-derived growth factor (SDGF) was initially isolated from schwannoma cells as a mitogen for glial cells and fibroblasts. The present data show that SDGF causes the morphological and molecular differentiation of rat PC12 cells in a manner similar to, but distinguishable from nerve growth factor (NGF). It also promotes PC12 survival in serum-free conditions. SDGF induced changes include neurite outgrowth and the induction of the mRNAs for GAP-43 and transin, proteins which are highly expressed in axons. In addition, both SDGF and NGF induce the transcription factor, NGFI-A. The time course of the response to SDGF is similar to that for NGF. Gap-43 mRNA induction by both SDGF and NGF is inhibited by dexamethasone, but dexamethasone has no effect on NGFI-A mRNA synthesis. These observations show that SDGF has a differentiation and survival promoting effect on PC12 cells in addition to its mitogenic activity on glial cells and fibroblasts.
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Affiliation(s)
- H Kimura
- Salk Institute, San Diego, California 92186-5800
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41
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Tsao H, Aletta J, Greene L. Nerve growth factor and fibroblast growth factor selectively activate a protein kinase that phosphorylates high molecular weight microtubule-associated proteins. Detection, partial purification, and characterization in PC12 cells. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)55420-x] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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42
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Rausch DM, Lewis DL, Barker JL, Eiden LE. Functional expression of dihydropyridine-insensitive calcium channels during PC12 cell differentiation by nerve growth factor (NGF), oncogenic ras, or src tyrosine kinase. Cell Mol Neurobiol 1990; 10:237-55. [PMID: 2163753 DOI: 10.1007/bf00734577] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
1. Recombinant retroviruses were used to introduce a temperature-sensitive v-src gene and oncogenic c-Ha-ras into PC12 cells, and stable cell lines expressing these genes were established. 2. As previously reported, expression of v-src (Alema et al., 1985) or c-Ha-ras (Noda et al., 1985) in PC12 cells results in neurite outgrowth resembling that induced by NGF. We report here that v-src but not oncogenic c-Ha-ras induces a stable morphologic neuronal differentiation similar to treatment with NGF. Oncogenic c-Ha-ras-induced neurite outgrowth is not stable with long-term culture, rather the cells revert to an undifferentiated morphology with altered cell cycle kinetics. 3. The stable neuronal phenotype induced by v-src and NGF is characterized by the functional expression of dihydropyridine-insensitive calcium currents.
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Affiliation(s)
- D M Rausch
- Unit on Molecular and Cellular Neurobiology, National Institute of Mental Health, NIH, Bethesda, Maryland 20892
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43
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Gizang-Ginsberg E, Ziff EB. Nerve growth factor regulates tyrosine hydroxylase gene transcription through a nucleoprotein complex that contains c-Fos. Genes Dev 1990; 4:477-91. [PMID: 1972929 DOI: 10.1101/gad.4.4.477] [Citation(s) in RCA: 205] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We have studied nerve growth factor (NGF) regulation of the expression of the tyrosine hydroxylase (TH) gene in PC12 cells. The TH gene encodes the initial and rate-limiting enzyme of the catecholamine biosynthetic pathway. We show that the TH gene is transiently transcriptionally induced by a mechanism reliant on new protein synthesis during 1-2 hr of NGF stimulation, a time following the induction of the c-fos gene at 15 min post-NGF treatment. A potential regulatory sequence located within the TH gene promoter, the TH-FSE, shares homology to a known regulatory element, the fat-specific element (FSE), which is found upstream from genes activated during adipocyte differentiation and binds the Fos-Jun transcription factor complex. We show that the TH-FSE DNA sequence elevates the basal level of transcription from the rat TH promoter and is required for NGF inducibility. This DNA element binds authentic Fos-Jun products produced abundance during NGF stimulation and by in vitro translation. We demonstrate further that the TH-FSE can bind proteins present in PC12 nuclear extracts in a sequence-specific manner. The DNA/nucleoprotein complex that forms increases in abundance during NGF stimulation and reaches a maximum level at 4 hr of treatment. Antibody inhibition studies utilizing an anti-Fos antibody indicate that Fos and/or Fos-related antigen(s) associate with the TH-FSE and suggest that the Fos protein family contributes to the regulation of TH in vivo. These results support a model in which NGF-induced immediate early genes, including c-Fos, contribute to the regulation of delayed early genes such as TH and thereby control neuronal differentiation.
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Affiliation(s)
- E Gizang-Ginsberg
- Department of Biochemistry, New York University Medical Center, New York 10016
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44
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Abstract
Voltage-gated sodium currents and acetylcholine-elicited currents in clonal rat pheochromocytoma cells (PC12) were studied using the whole-cell patch-clamp technique. After treatment of cultures with nerve growth factor (NGF, 2-4 nM) for 5 or more days, both Na currents and ACh responses increased by 5-7-fold. We tested the ability of a number of treatments reported to induce physiological differentiation in neuroblastoma or neuroblastoma-glioma hybrid cells. We found that no treatment was as effective as NGF, and mitotic inhibitors and 8-bromocyclic AMP reduced the efficacy of NGF at increasing both sodium currents and ACh responses. Some treatments were able to selectively reduce or enhance the ability of NGF to induce ACh responses or sodium currents. Dexamethasone, in particular, completely blocked the NGF-induced increase in ACh response, while leaving Na currents unaffected. Furthermore, in individual cells the Na current density and ACh current density are uncorrelated. These observations indicate that physiological differentiation in PC12 cells is regulated differently than in neuroblastoma cells and, further, in PC12 cells sodium currents and ACh responses are independently regulated.
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Affiliation(s)
- C K Ifune
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110
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45
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Jhanwar-Uniyal M, Renner KJ, Bailo MT, Luine VN, Leibowitz SF. Corticosterone-dependent alterations in utilization of catecholamines in discrete areas of rat brain. Brain Res 1989; 500:247-55. [PMID: 2605494 DOI: 10.1016/0006-8993(89)90320-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
This study investigated the impact of chronic adrenalectomy (ADX), and subsequent corticosterone (CORT) replacement to ADX rats, on brain levels of norepinephrine (NE) and dopamine (DA) and their extent of depletion after alpha-methyl-p-tyrosine (alpha-MpT) administration. Seven discrete hypothalamic areas, namely, the paraventricular nucleus (PVN), medial preoptic nucleus (POM), dorsomedial nucleus (DMN), ventromedial hypothalamus (VMH), perifornical lateral hypothalamus (PLH), supraoptic nucleus (SON), and arcuate nucleus/median eminence (ARC-ME), were examined. The steady-state content of NE and DA in all areas remained essentially unaltered 7 days after ablation of the adrenal glands, as well as after subsequent CORT replacement therapy in ADX rats. However, ADX, which reduced circulating CORT levels to 0.3 microgram % as compared to greater than 3.0 micrograms % in sham rats, caused a significant increase in the depletion of NE following alpha-MpT treatment, in 4 out of the 7 brain sites examined (PVN, PLH, DMN and ARC-ME). In these brain sites, the NE turnover rate (K, pg/microgram protein/h) and rate constant (K, h-1) increased following ADX. The chronic subcutaneous CORT implant (200 mg), which raised circulating CORT levels of ADX rats to 11 micrograms %, prevented this enhancement of NE turnover in the PVN, PLH and ARC-ME, but not the DMN. Unlike NE, DA utilization in the 7 discrete hypothalamic areas of alpha-MpT-treated rats remained unaltered after ablation of the adrenal glands, as well as after the CORT replacement therapy in ADX rats.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M Jhanwar-Uniyal
- Laboratory of Neuroendocrinology, Rockefeller University, New York, NY 10021
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46
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Rausch DM, Dickens G, Doll S, Fujita K, Koizumi S, Rudkin BB, Tocco M, Eiden LE, Guroff G. Differentiation of PC12 cells with v-src: comparison with nerve growth factor. J Neurosci Res 1989; 24:49-58. [PMID: 2810396 DOI: 10.1002/jnr.490240108] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The PC12 rat pheochromocytoma cell line is used extensively as a model to study neuronal differentiation. These cells resemble adrenal chromaffin cells, differentiating both morphologically and biochemically when cultured in the presence of dexamethasone, but develop a sympathetic neuron-like phenotype when cultured in the presence of nerve growth factor. Expression of the protein product of the v-src oncogene in PC12 cells also induces neurite outgrowth similar to that resulting from nerve growth factor treatment (Alema et al: Nature 316:557-559, 1985). It is thus possible that c-src or a src-like tyrosine kinase participates in the signal transduction pathway by which nerve growth factor acts on PC12 cells. In this study a temperature-sensitive v-src gene has been introduced into PC12 cells. When cultures of these src-transformed cells are switched from the nonpermissive (40 degrees C) to the permissive (37 degrees C) temperature they elaborate neurites. The differentiation induced by src has been compared with that induced by nerve growth factor by determining whether src-transformed PC12 cells at 37 degrees C exhibit the same biochemical alterations as those induced in PC12 cells treated with nerve growth factor. Neurite extension at 37 degrees C in v-src-transformed cells, like NGF-induced differentiation, is accompanied by an increase in the nerve growth factor-inducible large external (NILE) protein. However, neurite extension in v-src-transformed cells is not blocked by the protein kinase inhibitor K-252a, which completely blocks NGF-induced neurite extension. Likewise, EGF receptor down-regulation and the development of saxitoxin and tetanus toxin binding sites are either much reduced or completely absent in src-differentiated compared with NGF-differentiated PC12 cells.
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Affiliation(s)
- D M Rausch
- Unit on Molecular and Cellular Neurobiology, National Institute of Mental Health, Bethesda, MD 20892
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47
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Aletta JM, Shelanski ML, Greene LA. Phosphorylation of the peripherin 58-kDa neuronal intermediate filament protein. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)83788-7] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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48
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Tocco MD, Contreras ML, Koizumi S, Dickens G, Guroff G. Decreased levels of nerve growth factor receptor on dexamethasone-treated PC12 cells. J Neurosci Res 1988; 20:411-9. [PMID: 2846859 DOI: 10.1002/jnr.490200403] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Treatment of PC12 cells with dexamethasone leads, in a period of days, to a 60% decrease in the binding of (125I)nerve growth factor. The decrease was maximal after 3 days of treatment with 1 microM dexamethasone, but some decrease was seen after 6 hr and at concentrations as low as 10 nM. The effect was specific for the glucocorticosteroids. Scatchard plots confirmed the overall loss of nerve growth factor binding, and studies with trypsin digestion and Triton X-100 extraction indicated that the decrease in binding was largely due to a decrease in the number of low-affinity receptors. Nerve growth factor-induced changes, such as the induction of ornithine decarboxylase and the generation of neurites, were inhibited, but only minimally, in dexamethasone-treated cells.
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Affiliation(s)
- M D Tocco
- Section on Growth Factors, National Institute of Child Health and Human Development, Bethesda, Maryland 20892
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49
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Holsboer F. Implications of altered limbic-hypothalamic-pituitary-adrenocortical (LHPA)-function for neurobiology of depression. Acta Psychiatr Scand Suppl 1988; 341:72-111. [PMID: 2844059 DOI: 10.1111/j.1600-0447.1988.tb08556.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The current article suggests that the neuroendocrine system constitutes a bidirectional link between the brain and humoral homeostasis in the periphery. Any change of neuronal activity in the brain--regardless whether induced by external stimuli or endogenous errors of metabolism--may result in altered composition of gene products. Among these are peptides which directly or indirectly alter endocrine activity and may concomitantly induce a variety of behavioral effects. This has been experimentally demonstrated by neuropeptidergic manipulation of sleep-electroencephalographic (EEG) measures and behavioral studies in animals. An integral part of the neuroendocrine communication are effects of peripheral hormones upon brain structures and their interactions with the immune system. Within this framework all hormones of the limbic-hypothalamic- pituitary-adrenocortical (LHPA)-axis play a dominant role, because: (1) corticotropin-releasing hormone (CRH) was shown to integrate centrally behavioral and metabolic responses to stress; and (2) corticosteroids exert a host of neurochemical changes within the CNS which by far exceed their primary endocrine feedback action. As a corollary, hyperexposure to corticosteroids induces widespread changes of neuronal cell biology which are of clinical significance for depression research (e.g. neuronal cell loss in the hippocampus, down-regulation of glucocorticoid receptors within monoaminergic neurons). Clinical neuroendocrine research over the past years focussed upon evaluation of pathophysiology underlying dexamethasone resistant cortisol levels or hypercortisolism linked to depression and utilized advanced methods for multihormonal analysis and newly synthesized neuropeptides (e.g. CRH) for challenge studies in combination with neurophysiological assessments.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- F Holsboer
- Department of Psychiatry, University of Freiburg, West Germany
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50
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Saadat S, Thoenen H. Regulation of tyrosine hydroxylase mRNA levels in rat pheochromocytoma PC12 cells by cell-cell contact. Exp Cell Res 1988; 176:187-93. [PMID: 2897311 DOI: 10.1016/0014-4827(88)90133-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
It has previously been shown that cell density increases the specific enzyme activity of tyrosine hydroxylase (TH) in cultures of PC12 cells. The difference in TH activity was shown to be due to cell-cell contact rather than to diffusible factors released by the PC12 cells (C. Lucas, D. Edgar, and H. Thoenen (1979) Exp. Cell Res. 121, 79-86). We have extended these studies and demonstrated that TH is regulated at the transcriptional level. Cells were harvested from confluent high-density cultures and replated at either low (2 x 10(4) cells/cm2) or high density (5 x 10(5) cells/cm2). At low density, the mRNATH and TH enzyme activity decreased to low levels within several hours. The decrease in TH activity resulting from the loss of cell-cell contact appears to be an active process, as it occurs much more rapidly than would be expected from the turnover rate of the protein in cells cultured continuously at high density. In contrast to low-density cultures the mRNATH and TH activity levels in replated high-density cultures decreased only slightly and then increased four fold at the mRNATH and five fold at the TH activity levels as compared to low-density cultures 2 days after replating. The increase in mRNATH preceded the increase in TH activity by 1 day. Since alpha-amanitin inhibited the increase in TH levels, we conclude that cell-cell contact regulates TH in PC12 cells at the transcriptional level.
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Affiliation(s)
- S Saadat
- Max-Planck-Institute for Psychiatry, Department of Neurochemistry, Planegg-Martinsried, Federal Republic of Germany
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