scholarly journals Phasic oxygen dynamics confounds fast choline-sensitive biosensor signals in the brain of behaving rodents

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Ricardo M Santos ◽  
Anton Sirota
Keyword(s):  
Field Potential ◽  
Choline Oxidase ◽  
Fast Time ◽  
In Vivo Experiments ◽  
Highly Sensitive ◽  
Cortical Physiology ◽  
Oxygen Dynamics ◽  
The Brain

Cholinergic fast time-scale modulation of cortical physiology is critical for cognition, but direct local measurement of neuromodulators in vivo is challenging. Choline oxidase (ChOx)-based electrochemical biosensors have been used to capture fast cholinergic signals in behaving animals. However, these transients might be biased by local field potential and O2-evoked enzymatic responses. Using a novel Tetrode-based Amperometric ChOx (TACO) sensor, we performed highly sensitive and selective simultaneous measurement of ChOx activity (COA) and O2. In vitro and in vivo experiments, supported by mathematical modeling, revealed that non-steady-state enzyme responses to O2 give rise to phasic COA dynamics. This mechanism accounts for most of COA transients in the hippocampus, including those following locomotion bouts and sharp-wave/ripples. Our results suggest that it is unfeasible to probe phasic cholinergic signals under most behavioral paradigms with current ChOx biosensors. This confound is generalizable to any oxidase-based biosensor, entailing rigorous controls and new biosensor designs.

scholarly journals Phasic oxygen dynamics underlies fast choline-sensitive biosensor signals in the brain of behaving rodents

2020 ◽  
Author(s):  
Ricardo M. Santos ◽  
Anton Sirota
Keyword(s):  
Field Potential ◽  
Choline Oxidase ◽  
Fast Time ◽  
Freely Moving ◽  
Highly Correlated ◽  
Brain Measurements ◽  
Oxygen Dynamics ◽  
The Brain

AbstractFast time-scale modulation of synaptic and cellular physiology by acetylcholine is critical for many cognitive functions, but direct local measurement of neuromodulator dynamics in freely-moving behaving animals is technically challenging. Recent in vivo brain measurements using choline oxidase (ChOx)-based electrochemical biosensors have reported surprising fast cholinergic transients associated with reward-related behavioral events. However, in vivo recordings with conventional ChOx biosensors could be biased by phasic local field potential and O2-evoked enzymatic responses. Here, we have developed a Tetrode-based Amperometric ChOx (TACO) sensor enabling minimally invasive artifact-free simultaneous measurement of cholinergic activity and O2. Strikingly, the TACO sensor revealed highly-correlated O2 and ChOx transients following spontaneous locomotion and sharp-wave/ripples fluctuations in the hippocampus of behaving rodents. Quantitative analysis of spontaneous activity, in vivo and in vitro exogenous O2 perturbations revealed a directional effect of O2 on ChOx phasic signals. Mathematical modeling of biosensors identified O2-evoked non-steadystate ChOx kinetics as a mechanism underlying artifactual biosensor phasic transients. This phasic O2-dependence of ChOx-based biosensor measurements confounds phasic cholinergic dynamics readout in vivo, challenging previously proposed ACh role in reward-related learning. The discovered mechanism and quantitative modeling is generalizable to any oxidase-based biosensor, entailing rigorous controls and new biosensor designs.

Inhibition of testosterone metabolism in the brain and cloacal gland of the quail by specific inhibitors and antihormones

1987 ◽  
Vol 112 (2) ◽  
pp. 189-195 ◽  
Author(s):  
C. Alexandre ◽  
J. Balthazart
Keyword(s):  
Reductase Inhibitor ◽  
Aromatase Activity ◽  
Testosterone Metabolism ◽  
In Vivo Experiments ◽  
High Doses ◽  
The Brain ◽  
Very High ◽  
Cloacal Gland

ABSTRACT The effects of antioestrogens, antiandrogens and of various inhibitors of testosterone metabolism on testosterone metabolism in the quail hypothalamus and cloacal gland were studied by an in-vitro radio-enzymatic assay. It was found that antioestrogens and antiandrogens generally had little or no effect on aromatase and 5α- and 5β-reductases of testosterone, except when used at very high doses. The 5α-reductase inhibitor, 17β-N,N-diethylcarbamoyl-4-methyl-4-aza-5α-androstan-3-one, inhibited both 5α- and 5β-dihydrotestosterone production without markedly affecting aromatase activity. Surprisingly, the aromatase inhibitor, 1,4,6-androstatriene-3,17-dione, inhibited not only the production of oestradiol but also that of 5β-dihydrotestosterone and, to a lesser extent, 5α-dihydrotestosterone. These unexpected properties should be taken into account when interpreting the results of in-vivo experiments using these compounds. J. Endocr. (1987) 112, 189–195

scholarly journals Multifunctional Superparamagnetic Stiff Nanoreservoirs for Blood Brain Barrier Applications

Nanomaterials ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 449 ◽  
Author(s):  
Zulema Vargas-Osorio ◽  
Andrés Da Silva-Candal ◽  
Yolanda Piñeiro ◽  
Ramón Iglesias-Rey ◽  
Tomas Sobrino ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Vascular Endothelial Cells ◽  
Neurological Diseases ◽  
Developed Countries ◽  
Large Set ◽  
In Vivo Experiments ◽  
Liver And Kidney ◽  
The Brain

Neurological diseases (Alzheimer’s disease, Parkinson’s disease, and stroke) are becoming a major concern for health systems in developed countries due to the increment of ageing in the population, and many resources are devoted to the development of new therapies and contrast agents for selective imaging. However, the strong isolation of the brain by the brain blood barrier (BBB) prevents not only the crossing of pathogens, but also a large set of beneficial drugs. Therefore, an alternative strategy is arising based on the anchoring to vascular endothelial cells of nanoplatforms working as delivery reservoirs. In this work, novel injectable mesoporous nanorods, wrapped by a fluorescent magnetic nanoparticles envelope, are proposed as biocompatible reservoirs with an extremely high loading capacity, surface versatility, and optimal morphology for enhanced grafting to vessels during their diffusive flow. Wet chemistry techniques allow for the development of mesoporous silica nanostructures with tailored properties, such as a fluorescent response suitable for optical studies, superparamagnetic behavior for magnetic resonance imaging MRI contrast, and large range ordered porosity for controlled delivery. In this work, fluorescent magnetic mesoporous nanorods were physicochemical characterized and tested in preliminary biological in vitro and in vivo experiments, showing a transversal relaxivitiy of 324.68 mM−1 s−1, intense fluorescence, large specific surface area (300 m2 g−1), and biocompatibility for endothelial cells’ uptake up to 100 µg (in a 80% confluent 1.9 cm2 culture well), with no liver and kidney disability. These magnetic fluorescent nanostructures allow for multimodal MRI/optical imaging, the allocation of therapeutic moieties, and targeting of tissues with specific damage.

scholarly journals Modulation of Hippocampal Astroglial Activity by Synaptamide in Rats with Neuropathic Pain

2021 ◽  
Vol 11 (12) ◽  
pp. 1561
Author(s):  
Igor Manzhulo ◽  
Olga Manzhulo ◽  
Anna Tyrtyshnaia ◽  
Arina Ponomarenko ◽  
Sophia Konovalova ◽  
...  
Keyword(s):  
Chronic Constriction Injury ◽  
Hippocampal Neurogenesis ◽  
Liquid Chromatography Mass Spectrometry ◽  
Cold Allodynia ◽  
In Vivo Experiments ◽  
Mass Spectrometry Technique ◽  
Spectrometry Technique ◽  
The Brain

The present study demonstrates that synaptamide (N-docosahexaenoylethanolamine), an endogenous metabolite of docosahexaenoic acid, when administered subcutaneously (4 mg/kg/day, 14 days), exhibits analgesic activity and promotes cognitive recovery in the rat sciatic nerve chronic constriction injury (CCI) model. We analyzed the dynamics of GFAP-positive astroglia and S100β-positive astroglia activity, the expression of nerve growth factor (NGF), and two subunits of the NMDA receptor (NMDAR1 and NMDAR2A) in the hippocampi of the experimental animals. Hippocampal neurogenesis was evaluated by immunohistochemical detection of DCX. Analysis of N-acylethanolamines in plasma and in the brain was performed using the liquid chromatography-mass spectrometry technique. In vitro and in vivo experiments show that synaptamide (1) reduces cold allodynia, (2) improves working memory and locomotor activity, (3) stabilizes neurogenesis and astroglial activity, (4) enhances the expression of NGF and NMDAR1, (5) increases the concentration of Ca2+ in astrocytes, and (6) increases the production of N-acylethanolamines. The results of the present study demonstrate that synaptamide affects the activity of hippocampal astroglia, resulting in faster recovery after CCI.

scholarly journals Targeted Overexpression of a Golli-Myelin Basic Protein Isoform to Oligodendrocytes Results in Aberrant Oligodendrocyte Maturation and Myelination

ASN NEURO ◽  
2009 ◽  
Vol 1 (4) ◽  
pp. AN20090029 ◽  
Author(s):  
Erin C Jacobs ◽  
Samuel D Reyes ◽  
Celia W Campagnoni ◽  
M Irene Givogri ◽  
Kathy Kampf ◽  
...  
Keyword(s):  
Cell Death ◽  
Extended Period ◽  
Ultrastructural Studies ◽  
In Vivo Experiments ◽  
Protein Isoform ◽  
Immunohistochemical Studies ◽  
The Brain

Recently, several in vitro studies have shown that the golli-myelin basic proteins regulate Ca2+ homoeostasis in OPCs (oligodendrocyte precursor cells) and immature OLs (oligodendrocytes), and that a number of the functions of these cells are affected by cellular levels of the golli proteins. To determine the influence of golli in vivo on OL development and myelination, a transgenic mouse was generated in which the golli isoform J37 was overexpressed specifically within OLs and OPCs. The mouse, called JOE (J37-overexpressing), is severely hypomyelinated between birth and postnatal day 50. During this time, it exhibits severe intention tremors that gradually abate at later ages. After postnatal day 50, ultrastructural studies and Northern and Western blot analyses indicate that myelin accumulates in the brain, but never reaches normal levels. Several factors appear to underlie the extensive hypomyelination. In vitro and in vivo experiments indicate that golli overexpression causes a significant delay in OL maturation, with accumulation of significantly greater numbers of pre-myelinating OLs that fail to myelinate axons during the normal myelinating period. Immunohistochemical studies with cell death and myelin markers indicate that JOE OLs undergo a heightened and extended period of cell death and are unable to effectively myelinate until 2 months after birth. The results indicate that increased levels of golli in OPC/OLs delays myelination, causing significant cell death of OLs particularly in white matter tracts. The results provide in vivo evidence for a significant role of the golli proteins in the regulation of maturation of OLs and normal myelination.

scholarly journals Genomic and Biochemical Studies Demonstrating the Absence of an Alkane-Producing Phenotype in Vibrio furnissii M1

2007 ◽  
Vol 73 (22) ◽  
pp. 7192-7198 ◽  
Author(s):  
Lawrence P. Wackett ◽  
Janice A. Frias ◽  
Jennifer L. Seffernick ◽  
David J. Sukovich ◽  
Stephan M. Cameron
Keyword(s):  
Genomic Analysis ◽  
Gas Chromatography Mass Spectrometry ◽  
Rrna Gene ◽  
In Vivo Experiments ◽  
Cell Extracts ◽  
Highly Sensitive ◽  
Vibrio Furnissii ◽  
The 16S Rrna Gene

ABSTRACT Vibrio furnissii M1 was recently reported to biosynthesize n-alkanes when grown on biopolymers, sugars, or organic acids (M. O. Park, J. Bacteriol. 187:1426-1429, 2005). In the present study, V. furnissii M1 was subjected to genomic analysis and studied biochemically. The sequence of the 16S rRNA gene and repetitive PCR showed that V. furnissii M1 was not identical to other V. furnissii strains tested, but the level of relatedness was consistent with its assignment as a V. furnissii strain. Pulsed-field gel electrophoresis showed chromosomal bands at approximately 3.2 and 1.8 Mb, similar to other Vibrio strains. Complete genomic DNA from V. furnissii M1 was sequenced with 21-fold coverage. Alkane biosynthetic and degradation genes could not be identified. Moreover, V. furnissii M1 did not produce demonstrable levels of n-alkanes in vivo or in vitro. In vivo experiments were conducted by growing V. furnissii M1 under different conditions, extracting with solvent, and analyzing extracts by gas chromatography-mass spectrometry. A highly sensitive assay was used for in vitro experiments with cell extracts and [14C]hexadecanol. The data are consistent with the present strain being a V. furnissii with properties similar to those previously described but lacking the alkane-producing phenotype. V. furnissii ATCC 35016, also reported to biosynthesize alkanes, was found in the present study not to produce alkanes.

scholarly journals An Open-Source Wireless Electrophysiological Complex for In Vivo Recording Neuronal Activity in the Rodent’s Brain

Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 7189
Author(s):  
Alexander Erofeev ◽  
Dmitriy Kazakov ◽  
Nikita Makarevich ◽  
Anastasia Bolshakova ◽  
Evgenii Gerasimov ◽  
...  
Keyword(s):  
Open Source ◽  
Neuronal Activity ◽  
Ex Vivo ◽  
Electrode Arrays ◽  
Charging Station ◽  
In Vivo Experiments ◽  
The Brain ◽  
Schematic Diagrams

Multi-electrode arrays (MEAs) are a widely used tool for recording neuronal activity both in vitro/ex vivo and in vivo experiments. In the last decade, researchers have increasingly used MEAs on rodents in vivo. To increase the availability and usability of MEAs, we have created an open-source wireless electrophysiological complex. The complex is scalable, recording the activity of neurons in the brain of rodents during their behavior. Schematic diagrams and a list of necessary components for the fabrication of a wireless electrophysiological complex, consisting of a base charging station and wireless wearable modules, are presented.

scholarly journals Astrocytes regulate brain extracellular pH via a neuronal activity-dependent bicarbonate shuttle

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Shefeeq M. Theparambil ◽  
Patrick S. Hosford ◽  
Iván Ruminot ◽  
Olga Kopach ◽  
James R. Reynolds ◽  
...  
Keyword(s):  
Neuronal Activity ◽  
Extracellular Ph ◽  
Ph Homeostasis ◽  
Sodium Bicarbonate Cotransporter ◽  
Highly Sensitive ◽  
Activity Dependent ◽  
The Brain ◽  
Local Brain

Abstract Brain cells continuously produce and release protons into the extracellular space, with the rate of acid production corresponding to the levels of neuronal activity and metabolism. Efficient buffering and removal of excess H+ is essential for brain function, not least because all the electrogenic and biochemical machinery of synaptic transmission is highly sensitive to changes in pH. Here, we describe an astroglial mechanism that contributes to the protection of the brain milieu from acidification. In vivo and in vitro experiments conducted in rodent models show that at least one third of all astrocytes release bicarbonate to buffer extracellular H+ loads associated with increases in neuronal activity. The underlying signalling mechanism involves activity-dependent release of ATP triggering bicarbonate secretion by astrocytes via activation of metabotropic P2Y1 receptors, recruitment of phospholipase C, release of Ca2+ from the internal stores, and facilitated outward HCO3− transport by the electrogenic sodium bicarbonate cotransporter 1, NBCe1. These results show that astrocytes maintain local brain extracellular pH homeostasis via a neuronal activity-dependent release of bicarbonate. The data provide evidence of another important metabolic housekeeping function of these glial cells.

Effect of pH and inhibitors on beta-amyloid fibril assembly

1996 ◽  
Vol 54 ◽  
pp. 752-753
Author(s):  
Beverly E. Maleeff ◽  
Timothy K. Hart ◽  
Stephen J. Wood ◽  
Ronald Wetzel
Keyword(s):  
Amyloid Fibril ◽  
Peptide Fragment ◽  
Hydrophobic Peptides ◽  
Amyloid Fibril Formation ◽  
Effects Of Ph ◽  
Severity Of The Disease ◽  
Kinetics Of ◽  
The Brain

Alzheimer's disease is characterized post-mortem in part by abnormal extracellular neuritic plaques found in brain tissue. There appears to be a correlation between the severity of Alzheimer's dementia in vivo and the number of plaques found in particular areas of the brain. These plaques are known to be the deposition sites of fibrils of the protein β-amyloid. It is thought that if the assembly of these plaques could be inhibited, the severity of the disease would be decreased. The peptide fragment Aβ, a precursor of the p-amyloid protein, has a 40 amino acid sequence, and has been shown to be toxic to neuronal cells in culture after an aging process of several days. This toxicity corresponds to the kinetics of in vitro amyloid fibril formation. In this study, we report the biochemical and ultrastructural effects of pH and the inhibitory agent hexadecyl-N-methylpiperidinium (HMP) bromide, one of a class of ionic micellar detergents known to be capable of solubilizing hydrophobic peptides, on the in vitro assembly of the peptide fragment Aβ.

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