| 1. |
- Dong, Y., et al.
(författare)
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Pituitary Adenylate Cyclase Activating Polypeptide Modulates Catecholamine Storage and Exocytosis in PC12 Cells
- 2014
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 9:3
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Tidskriftsartikel (refereegranskat)abstract
- A number of efforts have been made to understand how pituitary adenylate cyclase activating polypeptide (PACAP) functions as a neurotrophic and neuroprotective factor in Parkinson's disease (PD). Recently its effects on neurotransmission and underlying mechanisms have generated interest. In the present study, we investigate the effects of PACAP on catecholamine storage and secretion in PC12 cells with amperometry and transmission electron microscopy (TEM). PACAP increases quantal release induced by high K+ without significantly regulating the frequency of vesicle fusion events. TEM data indicate that the increased volume of the vesicle is mainly the result of enlargement of the fluidic space around the dense core. Moreover, the number of docked vesicles isn't modulated by PACAP. When cells are acutely treated with L-DOPA, the vesicular volume and quantal release both increase dramatically. It is likely that the characteristics of amperometric spikes from L-DOPA treated cells are associated with increased volume of individual vesicles rather than a direct effect on the mechanics of exocytosis. Treatment with PACAP versus L-DOPA results in different profiles of the dynamics of exocytosis. Release via the fusion pore prior to full exocytosis was observed with the same frequency following treatment with PACAP and L-DOPA. However, release events have a shorter duration and higher average current after PACAP treatment compared to L-DOPA. Furthermore, PACAP reduced the proportion of spikes having rapid decay time and shortened the decay time of both fast and slow spikes. In contrast, the distributions of the amperometric spike decay for both fast and slow spikes were shifted to longer time following L-DOPA treatment. Compared to L-DOPA, PACAP may produce multiple favorable effects on dopaminergic neurons, including protecting dopaminergic neurons against neurodegeneration and potentially regulating dopamine storage and release, making it a promising therapeutic agent for the treatment of PD.
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| 2. |
- Adams, Kelly L., et al.
(författare)
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Steady-State Electrochemical Determination of Lipidic Nanotube Diameter Utilizing an Artificial Cell Model
- 2010
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 1520-6882 .- 0003-2700. ; 82:3, s. 1020-1026
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Tidskriftsartikel (refereegranskat)abstract
- By exploiting the capabilities of steady-state electrochemical measurements, we have measured the inner diameter of a lipid nanotube using Fick’s first law of diffusion in conjunction with an imposed linear concentration gradient of electroactive molecules over the length of the nanotube. Fick’s law has been used in this way to provide a direct relationship between the nanotube diameter and the measurable experimental parameters Δi (change in current) and nanotube length. Catechol was used to determine the Δi attributed to its flux out of the nanotube. Comparing the nanotube diameter as a function of nanotube length revealed that membrane elastic energy was playing an important role in determining the size of the nanotube and was different when the tube was connected to either end of two vesicles or to a vesicle on one end and a pipet tip on the other. We assume that repulsive interaction between neck regions can be used to explain the trends observed. This theoretical approach based on elastic energy considerations provides a qualitative description consistent with experimental data.
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| 3. |
- Berglund, E Carina, et al.
(författare)
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Oral administration of methylphenidate blocks the effect of cocaine on uptake at the Drosophila dopamine transporter.
- 2013
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Ingår i: ACS chemical neuroscience. - : American Chemical Society (ACS). - 1948-7193. ; 4:4, s. 566-74
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Tidskriftsartikel (refereegranskat)abstract
- Although our understanding of the actions of cocaine in the brain has improved, an effective drug treatment for cocaine addiction has yet to be found. Methylphenidate binds the dopamine transporter and increases extracellular dopamine levels in mammalian central nervous systems similar to cocaine, but it is thought to elicit fewer addictive and reinforcing effects owing to slower pharmacokinetics for different routes of administration between the drugs. This study utilizes the fruit fly model system to quantify the effects of oral methylphenidate on dopamine uptake during direct cocaine exposure to the fly CNS. The effect of methylphenidate on the dopamine transporter has been explored by measuring the uptake of exogenously applied dopamine. The data suggest that oral consumption of methylphenidate inhibits the Drosophila dopamine transporter and the inhibition is concentration dependent. The peak height increased to 150% of control when cocaine was used to block the dopamine transporter for untreated flies but only to 110% for methylphenidate-treated flies. Thus, the dopamine transporter is mostly inhibited for the methylphenidate-fed flies before the addition of cocaine. The same is true for the rate of the clearance of dopamine measured by amperometry. For untreated flies the rate of clearance changes 40% when the dopamine transporter is inhibited with cocaine, and for treated flies the rate changes only 10%. The results were correlated to the in vivo concentration of methylphenidate determined by CE-MS. Our data suggest that oral consumption of methylphenidate inhibits the Drosophila dopamine transporter for cocaine uptake, and the inhibition is concentration dependent.
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| 4. |
- Cans, Ann-Sofie, 1971, et al.
(författare)
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Tools to monitor exocytosis: a focus on new fluorescent probes and methods
- 2010
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Ingår i: Cellscience Reviews. - 1742-8130. ; 6:3, s. 104-22
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Tidskriftsartikel (refereegranskat)abstract
- A great deal of research has been focused on unraveling the processes governing the exocytotic pathway and the extent of release during the process. Arguments abound for and against both the occurrence and significance of full release during exocytosis and partial release including kiss-and-run events. Several optical methods to directly observe the exocytosis process have been developed and here we focus on fluorescence methods and probes for this work. Although, fluorescence imaging has been used for cell experiments for decades, in the last two decades a plethora of new approaches has arrived on the scene. These include application of new microscopy techniques, like total internal reflectance and stimulated emission depletion that are offering new ways to circumvent the limits of far field microscopy with diffraction limit of 200 nm, and allow tracking of single synaptic vesicles. For selective imaging of synaptic vesicles the introduction of methods to stain the vesicular compartment have involved developing probes of the vesicular membrane and intravesicular solution, nanoparticle quantum dots that can be observed during exocytosis but not via the fusion pore, and fluorescent false neurotransmitters.
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| 5. |
- Dong, Yan, et al.
(författare)
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Probing Exocytosis at Single Cells using Electrochemistry
- 2010
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Ingår i: Chemical Cytometry: Ultrasensive Analysis of Single Cells (ed C. Lu). - Weinheim : Wiley-VCH Verlag GmbH & Co.. - 9783527324958 ; , s. 159-174
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Ewing, Andrew G, 1957
(författare)
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Electrochemical measurements of transmitters in flies, at cells, and from transmitter vesicles
- 2013
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Ingår i: Abstracts of Papers of the American Chemical Society (Conference: 246th National Meeting of the American-Chemical-Society (ACS)). - 0065-7727.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We have developed three electroanalytical methods to measure neurochemicals in ultrasmall biological environments. First, voltammetry in the fly brain has been used to understand the drug action. We have used this to study the action of methylphenidate on that of cocaine with an eventual goal of understanding and remediating cocaine addiction. Second, we have used small electrodes to measure neurotransmitter release from single cells, a method that has become commonplace after twenty years. Here, we have analyzed amperometric peaks corresponding to release at PC12 cells and found stable plateau currents during the decay of the peaks, indicating closing of the vesicle after incomplete release of the vesicular content. From careful analysis of these data, we have proposed a process for most exocytosis events where the vesicle partially opens to release transmitter and then closes directly again, leaving the possibility for both a stable pre and post spike foot to be observed with amperometry. Third, those experiments correlate well with those from the electrochemical cytometry method we developed to count electroactive molecules in individual synaptic vesicles in directly sampled populations from cells or brain tissue. With this method we can compare the total numbers of molecules to those released and only a fraction is in fact released both at cell models and in mammalian brains. Partial release is important in that it produces a new pharmaceutical paradigm and could be important in understanding learning and memory. It also makes it clear that the dynamics of vesicle opening, controlled largely by lipids, might be an important characteristic in neurotransmission.
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| 7. |
- Hanrieder, Jörg, 1980, et al.
(författare)
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High Resolution Metabolite Imaging in the Hippocampus Following Neonatal Exposure to the Environmental Toxin BMAA Using ToF-SIMS
- 2014
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Ingår i: Acs Chemical Neuroscience. - : American Chemical Society (ACS). - 1948-7193. ; 5:7, s. 568-575
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Tidskriftsartikel (refereegranskat)abstract
- The environmental neurotoxin beta-N-methylamino-L-alanine (BMAA) is suggested to be linked with neurodegenerative disease. In a rat model, neonatal exposure to BMAA induced selective uptake in the hippocampus and caused cell loss, mineralization and astrogliosis as well as learning and memory impairments in adulthood. Moreover, neonatal exposure resulted in increased protein ubiquitination in the cornus ammonis 1 (CA1) region of the adult hippocampus indicating that BMAA may induce protein aggregation. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) based imaging is a powerful technology for spatial profiling of small molecular weight compounds in biological tissues with high chemical specificity and high spatial resolution. The aim of this study was to characterize neurochemical changes in the hippocampus of six month-old rats treated neonatally (postnatal days 9-10) with BMAA. Multivariate data analysis of whole section ToF-SIMS scans was performed to delineate anatomical regions of interest based on their chemical distribution pattern. Further analysis of spectral data obtained from the outlined anatomical regions, including CA1 and dentate gyms (DG) revealed BMAA-induced long-term changes. Increased levels of phospholipids and protein fragments in the histopathologically altered CA1 region as well as phosphate depletion in the DG were observed. Moreover, high resolution SIMS imaging revealed a specific localization of phosphatidylcholine lipids, protein signals and potassium in the histopathologically altered CA1 These findings demonstrate that ToF-SIMS based imaging is a powerful approach for probing biochemical changes in situ and might serve as promising technique for investigating neurotoxin-induced brain pathology.
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| 8. |
- Hanrieder, Jörg, 1980, et al.
(författare)
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Imaging mass spectrometry in neuroscience.
- 2013
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Ingår i: ACS chemical neuroscience. - : American Chemical Society (ACS). - 1948-7193. ; 4:5, s. 666-79
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Tidskriftsartikel (refereegranskat)abstract
- Imaging mass spectrometry is an emerging technique of great potential for investigating the chemical architecture in biological matrices. Although the potential for studying neurobiological systems is evident, the relevance of the technique for application in neuroscience is still in its infancy. In the present Review, a principal overview of the different approaches, including matrix assisted laser desorption ionization and secondary ion mass spectrometry, is provided with particular focus on their strengths and limitations for studying different neurochemical species in situ and in vitro. The potential of the various approaches is discussed based on both fundamental and biomedical neuroscience research. This Review aims to serve as a general guide to familiarize the neuroscience community and other biomedical researchers with the technique, highlighting its great potential and suitability for comprehensive and specific chemical imaging.
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| 9. |
- Hanrieder, Jörg, 1980, et al.
(författare)
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Spatial Elucidation of Spinal Cord Lipid- and Metabolite-Regulations in Amyotrophic Lateral Sclerosis
- 2014
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Amyotrophic lateral sclerosis (ALS) is a devastating, rapidly progressing disease of the central nervous system that is characterized by motor neuron degeneration in the brain stem and the spinal cord. We employed time of flight secondary ion mass spectrometry (ToF-SIMS) to profile spatial lipid-and metabolite-regulations in post mortem human spinal cord tissue from ALS patients to investigate chemical markers of ALS pathogenesis. ToF-SIMS scans and multivariate analysis of image and spectral data were performed on thoracic human spinal cord sections. Multivariate statistics of the image data allowed delineation of anatomical regions of interest based on their chemical identity. Spectral data extracted from these regions were compared using two different approaches for multivariate statistics, for investigating ALS related lipid and metabolite changes. The results show a significant decrease for cholesterol, triglycerides, and vitamin E in the ventral horn of ALS samples, which is presumably a consequence of motor neuron degeneration. Conversely, the biogenic mediator lipid lysophosphatidylcholine and its fragments were increased in ALS ventral spinal cord, pointing towards neuroinflammatory mechanisms associated with neuronal cell death. ToF-SIMS imaging is a promising approach for chemical histology and pathology for investigating the subcellular mechanisms underlying motor neuron degeneration in amyotrophic lateral sclerosis.
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| 10. |
- Hanrieder, Jörg, 1980, et al.
(författare)
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Time-of-Flight Secondary Ion Mass Spectrometry Based Molecular Histology of Human Spinal Cord Tissue and Motor Neurons
- 2013
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 85:18, s. 8741-8748
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Tidskriftsartikel (refereegranskat)abstract
- Secondary ion mass spectrometry is a powerful method for imaging biological samples with high spatial resolution. Whole section time-of-flight-secondary ion mass spectrometry (TOF-SIMS) scans and multivariate data analysis have been performed on the human spinal cord in order to delineate anatomical regions of interest based on their chemical distribution pattern. TOF-SIMS analysis of thoracic spinal cord sections was performed at 5 μm resolution within 2 h. Multivariate image analysis by means of principal component analysis and maximum auto correlation factor analysis resulted in detection of more than 400 m/z peaks that were found to be significantly changed. Here, the results show characteristic biochemical distributions that are well in line with major histological regions, including gray and white matter. As an approach for iterative segmentation, we further evaluated previously outlined regions of interest as identified by multivariate image analysis. Here, further discrimination of the gray matter into ventral, lateral, and dorsal neuroanatomical regions was observed. TOF-SIMS imaging has been carried out at submicrometer resolution obtaining localization and characterization of spinal motor neurons based on their chemical fingerprint, including neurotransmitter precursors that serve as molecular indicators for motor neuron integrity. Thus, TOF-SIMS can be used as an approach for chemical histology and pathology. TOF-SIMS holds immense potential for investigating the subcellular mechanisms underlying spinal cord related diseases including chronic pain and amyotrophic lateral sclerosis.
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