Differential Uptake of Volatile Agents into Brain Tissue In Vitro 

2003 ◽  
Vol 99 (1) ◽  
pp. 122-130 ◽  
Author(s):  
Michael A. Chesney ◽  
Misha Perouansky ◽  
Robert A. Pearce
Keyword(s):  
Computational Modeling ◽  
Brain Tissue ◽  
Tissue Concentration ◽  
Hippocampal Slices ◽  
Drug Application ◽  
Brain Slices ◽  
Excitatory Postsynaptic Potential ◽  
Drug Actions ◽  
Sites Of Action

Background The rate of onset of drug actions in experiments with brain slices in vitro can vary widely. One factor that influences the rate is access to tissue sites of action. To study the effects of the nonimmobilizer 1,2-dichlorohexafluorocyclobutane (F6, also termed 2N in the literature) on physiologic processes under defined tissue concentrations, the authors performed electrophysiologic measurements of the effects of F6 and halothane, measured the uptake of these agents into brain tissue, and performed computational modeling to determine concentration-depth profiles during drug application. Methods Hippocampal brain slices 500 microm thick were prepared from adult rats. Evoked population responses in the CA1 region were obtained using extracellular recordings and electrical stimulation of the Schaffer collateral pathway. F6 (24 microm) and halothane (270 microm) were applied via superfusion for 40 min. Uptake of drug into tissue slices was measured using gas chromatography. Computational modeling was used to obtain estimates of drug diffusion coefficients in brain tissue and to calculate tissue concentration as a function of time and depth during drug application. Results Halothane reduced the amplitude of the evoked population spike and reduced the population excitatory postsynaptic potential slope. F6 had no effect on either measure. Uptake experiments yielded a diffusion coefficient of 0.1 x 10-6 cm2/s for F6 and 0.8 x 10-6 cm2/s for halothane. After 40 min of drug application, the concentration reached at tissue depths from which physiologic signals were obtained, approximately the top 200 microm of the slice, was estimated to be 58% of the final equilibrium value for F6 and 93% for halothane. Conclusions Diffusion into tissue is substantially slower for F6 than for halothane, and its impact is great enough that this must be considered when designing or interpreting in vitro experiments. However, impaired access does not account for the lack of effect of F6 on electrophysiologic responses in rat hippocampal slices.

scholarly journals Determination of Diffusion Kinetics of Ketamine in Brain Tissue: Implications for in vitro Mechanistic Studies of Drug Actions

2021 ◽  
Vol 15 ◽  
Author(s):  
Zachary Geiger ◽  
Brett VanVeller ◽  
Zarin Lopez ◽  
Abdel K. Harrata ◽  
Kathryn Battani ◽  
...  
Keyword(s):  
Brain Tissue ◽  
High Performance ◽  
Brain Slices ◽  
General Anesthetic ◽  
Adult Mice ◽  
Drug Concentrations ◽  
Drug Actions ◽  
Diffusion Properties

Ketamine has been in use for over 50 years as a general anesthetic, acting primarily through blockade of N-methyl-D-aspartate receptors in the brain. Recent studies have demonstrated that ketamine also acts as a potent and rapid-acting antidepressant when administered at sub-anesthetic doses. However, the precise mechanism behind this effect remains unclear. We examined the diffusion properties of ketamine in brain tissue to determine their effects in in vitro studies related to the antidepressant action of ketamine. Brain slices from adult mice were exposed to artificial cerebrospinal fluid (aCSF) containing ∼17 μM ketamine HCl for varying amounts of time. The amount of ketamine within each slice was then measured by tandem high-performance liquid chromatography – mass spectrometry to characterize the diffusion of ketamine into brain tissue over time. We successfully modeled the diffusion of ketamine into brain tissue using a mono-exponential function with a time constant of τ = 6.59 min. This curve was then compared to a one-dimensional model of diffusion yielding a diffusion coefficient of approximately 0.12 cm2⋅s–1 for ketamine diffusing into brain tissue. The brain:aCSF partition coefficient for ketamine was determined to be approximately 2.76. Our results suggest that the diffusion properties of ketamine have a significant effect on drug concentrations achieved within brain tissue during in vitro experiments. This information is vital to determine the ketamine concentration necessary for in vitro slice preparation to accurately reflect in vivo doses responsible for its antidepressant actions.

scholarly journals Investigating the Central Nervous System Disposition of Actinomycin D: Implementation and Evaluation of Cerebral Microdialysis and Brain Tissue Measurements Supported by UPLC-MS/MS Quantification

Pharmaceutics ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1498
Author(s):  
Julia Benzel ◽  
Gzona Bajraktari-Sylejmani ◽  
Philipp Uhl ◽  
Abigail Davis ◽  
Sreenath Nair ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Brain Tissue ◽  
Actinomycin D ◽  
Tissue Concentration ◽  
Cerebral Microdialysis ◽  
Tissue Homogenate ◽  
In Vitro Experiments ◽  
Plasma Ratio

Actinomycin D is a potent cytotoxic drug against pediatric (and other) tumors that is thought to barely cross the blood–brain barrier. To evaluate its potential applicability for the treatment of patients with central nervous system (CNS) tumors, we established a cerebral microdialysis model in freely moving mice and investigated its CNS disposition by quantifying actinomycin D in cerebral microdialysate, brain tissue homogenate, and plasma. For this purpose, we developed and validated an ultraperformance liquid chromatography–tandem mass spectrometry assay suitable for ultra-sensitive quantification of actinomycin D in the pertinent biological matrices in micro-samples of only 20 µL, with a lower limit of quantification of 0.05 ng/mL. In parallel, we confirmed actinomycin D as a substrate of P-glycoprotein (P-gp) in in vitro experiments. Two hours after intravenous administration of 0.5 mg/kg, actinomycin D reached total brain tissue concentrations of 4.1 ± 0.7 ng/g corresponding to a brain-to-plasma ratio of 0.18 ± 0.03, while it was not detectable in intracerebral microdialysate. This tissue concentration exceeds the concentrations of actinomycin D that have been shown to be effective in in vitro experiments. Elimination of the drug from brain tissue was substantially slower than from plasma, as shown in a brain-to-plasma ratio of approximately 0.53 after 22 h. Because actinomycin D reached potentially effective concentrations in brain tissue in our experiments, the drug should be further investigated as a therapeutic agent in potentially susceptible CNS malignancies, such as ependymoma.

scholarly journals Ginkgo Extract EGb761 Confers Neuroprotection by Reduction of Glutamate Release in Ischemic Brain

2012 ◽  
Vol 15 (1) ◽  
pp. 94 ◽  
Author(s):  
Alexander Mdzinarishvili ◽  
Rachita K. Sambria ◽  
Dorothee Lang ◽  
Jochen Klein
Keyword(s):  
Glutamate Release ◽  
Hippocampal Slices ◽  
Brain Slices ◽  
Cell Swelling ◽  
Experimental Stroke ◽  
Cell Degeneration ◽  
Edema Formation ◽  
Ginkgo Extract

Purpose - Ginkgo extract EGb761 has shown anti-edema and anti-ischemic effects in various experimental models. In the present study, we demonstrate neuroprotective effects of EGb761 in experimental stroke while monitoring brain metabolism by microdialysis. Methods - We have used oxygen-glucose deprivation in brain slices in vitro and middle cerebral artery occlusion (MCAO) in vivo to induce ischemia in mouse brain. We used microdialysis in mouse striatum to monitor extracellular concentrations of glucose and glutamate. Results - In vitro, EGb761 reduced ischemia-induced cell swelling in hippocampal slices by 60%. In vivo, administration of EGb761 (300 mg/kg) reduced cell degeneration and edema formation after MCAO by 35-50%. Immediately following MCAO, striatal glucose levels dropped to 25% of controls, and this reduction was not significantly affected by EGb761. Striatal glutamate levels, in contrast, increased 15-fold after MCAO; after pretreatment with EGb761, glutamate levels only increased by 4-5fold. Conclusions - We show that pretreatment with EGb761 strongly reduces cellular edema formation and neurodegeneration under conditions of ischemia. The mechanism of action seems to be related to a reduction of excitotoxicity, because ischemia-induced release of glutamate was strongly suppressed. Ginkgo extracts such as EGb761 may be valuable to prevent ischemia-induced damage in stroke-prone patients. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

Extracellular Magnesium Ion Modifies the Actions of Volatile Anesthetics in Area CA1 of Rat Hippocampus In Vitro 

2002 ◽  
Vol 96 (3) ◽  
pp. 681-687 ◽  
Author(s):  
Rika Sasaki ◽  
Koki Hirota ◽  
Sheldon H. Roth ◽  
Mitsuaki Yamazaki
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Hippocampal Slices ◽  
Volatile Anesthetics ◽  
Population Spike ◽  
Magnesium Ion ◽  
Excitatory Postsynaptic Potential ◽  
Aspartate Receptor ◽  
Postsynaptic Potential

Background Magnesium ion (Mg2+) is involved in important processes as modulation of ion channels, receptors, neurotransmitter release, and cell excitability in the central nervous system. Although extracellular Mg2+ concentration ([Mg2+]o) can be altered during general anesthesia, there has been no evidence for [Mg2+]o-dependent modification of anesthetic actions on neural excitability in central nervous system preparations. The purpose of current study was to determine whether the effects of volatile anesthetics are [Mg2+]o-dependent in mammalian central nervous system. Methods Extracellular electrophysiologic recordings from CA1 neurons in rat hippocampal slices were used to investigate the effects of [Mg2+]o and anesthetics on population spike amplitude and excitatory postsynaptic potential slope. Results The depression of population spike amplitudes and excitatory postsynaptic potential slopes by volatile anesthetics were significantly dependent on [Mg2+]o. The effects were attenuated in the presence of a constant [Mg2+]o/extracellular Ca2+ concentration ratio. However, neither N-methyl-d-aspartate receptor antagonists nor a non-N-methyl-d-aspartate receptor antagonist altered the [Mg2+]o-dependent anesthetic-induced depression of population spikes. Volatile anesthetics produced minimal effects on input-output (excitatory postsynaptic potential-population spike) relations or the threshold for population spike generation. The effects were not modified by changes in [Mg2+]o. In addition, the population spike amplitudes, elicited via antidromic (nonsynaptic) stimulation, were not influenced by [Mg2+]o in the presence of volatile anesthetics. Conclusions These results provide support that alteration of [Mg2+]o modifies the actions of volatile anesthetics on synaptic transmission and that the effects could be, at least in part, a result of presynaptic Ca2+ channel-related mechanisms.

scholarly journals Brain-Targeted Polysorbate 80-Emulsified Donepezil Drug-Loaded Nanoparticles for Neuroprotection

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Xiaojun Tao ◽  
Siyu Mao ◽  
Qiufang Zhang ◽  
Hongyuan Yu ◽  
Yu Li ◽  
...  
Keyword(s):  
Brain Tissue ◽  
Tissue Concentration ◽  
In Vitro Release ◽  
Brain Targeting ◽  
Titration Calorimetry ◽  
Size Analysis ◽  
Polysorbate 80 ◽  
Perpetual Motion ◽  
Optimal Dosing

AbstractMost Alzheimer’s disease drugs do not work efficiently because of the blood–brain barrier. Therefore, we designed a new nanopreparation (PS-DZP-CHP): cholesterol-modified pullulan (CHP) nanoparticle with polysorbate 80(PS) surface coverage, as donepezil (DZP) carrier to realize brain tissue delivery. By size analysis and isothermal titration calorimetry, we chose the optimal dosing ratio of the drug with nanomaterials (1:5) and designed a series of experiments to verify the efficacy of the nanoparticles. The results of in vitro release experiments showed that the nanoparticles can achieve continuous drug release within 72 h. The results of fluorescence observation in mice showed a good brain targeting of PS-DZP-CHP nanoparticles. Furthermore, the nanoparticle can enhance the drug in the brain tissue concentration in mice. DZP-CHP nanoparticles were used to pretreat nerve cells with Aβ protein damage. The concentration of lactate dehydrogenase was determined by MTT, rhodamine 123 and AO-EB staining, which proved that DZP-CHP nanoparticles had a protective effect on the neurotoxicity induced by Aβ25–35 and were superior to free donepezil. Microthermal perpetual motion meter test showed that PS-DZP-CHP nanoparticles have an affinity with apolipoprotein E, which may be vital for this nanoparticle targeting to brain tissue.

Biochemistry

1936 ◽  
Vol 82 (339) ◽  
pp. 431-433
Author(s):  
J. H. Quastel
Keyword(s):  
Nervous System ◽  
Brain Tissue ◽  
Brain Slice ◽  
Brain Slices ◽  
Ringer Solution ◽  
Living Animal ◽  
Dominant Form ◽  
Straight Line ◽  
The Brain

I want to speak of the work we have been doing in Cardiff on the metabolism of the nervous system. The work was carried out there because of the importance of the narcosis treatment. It seemed to us there a pity that a treatment such as that should be given up because of the considerable toxicity possible in relation to it. The research was undertaken to see if we could diminish the toxicity, at the same time seeking an idea as to how narcotics work. I ask that you will realize that the main substance burned by the brain is glucose. The dominant form of metabolism in the nervous system is connected with the breakdown of glucose and lactic acid, and this can be proved by experiment in the living animal and with brain-tissue in vitro. In doing experiments we are not able to carry out work with human brain, because we cannot get human tissue fresh enough, so we have to carry out experiments with animals. They are carried out in this way. We cut slices of the cortex of the brain as soon as the animal is dead, that is to say, within ten minutes of death the brain is out and slices have been cut. They are placed in a physiological medium in the presence of glucose, and we follow the metabolism of that tissue, which allows us to estimate the amount of oxygen being taken up by the brain. If luminal, chloretone, hyoscine or somnifaine be placed with the brain-tissue, then the respiration, instead of being at the usual level, starts lower down, and maintains a straight line. We wanted to see whether this action is reversible or irreversible. If the latter, then on removing the brain-slices from the narcotic it should no longer behave like a normal piece of tissue. Actually, when the brain-slice is removed and placed in Ringer solution, with no narcotic, the respiration goes up and becomes equal to that shown by the slice which had no narcotic. That is to say, the process is reversible.

Effects of low concentrations of 4-aminopyridine on CA1 pyramidal cells of the hippocampus

1989 ◽  
Vol 61 (5) ◽  
pp. 953-970 ◽  
Author(s):  
P. Perreault ◽  
M. Avoli
Keyword(s):  
High Frequency ◽  
Hippocampal Slices ◽  
Extracellular Recording ◽  
Pyramidal Cells ◽  
Input Resistance ◽  
Peak Latency ◽  
Excitatory Postsynaptic Potential ◽  
Average Value ◽  
Bath Application

1. Intracellular and extracellular recording techniques were used to study the effects of bath application of 4-aminopyridine (4-AP) on pyramidal cells of the CA1 subfield of rat hippocampal slices maintained in vitro. The concentration of 4-AP used in most experiments was 50 microM. However, similar results were obtained with a concentration ranging from 5 to 100 microM. 2. Following 4-AP application, cells impaled with K-acetate-filled microelectrodes hyperpolarized by an average of 2.6 mV (from -68.7 to -71.3 mV, P less than or equal to 0.01). This change was accompanied by the appearance of high-frequency spontaneous hyperpolarizations. Conversely, when KCl-filled microelectrodes were used, an average depolarization of 5.8 mV [from -73.1 to -67.3 mV, not significant (NS)] associated with the occurrence of repetitive depolarizing potentials was observed. In both cases, these changes were concomitant with a small decrease in membrane input resistance, which was statistically significant only for cells impaled with K-acetate-filled microelectrodes. When synaptic transmission was blocked by tetrodotoxin (TTX), 4-AP induced in cells studied with K-acetate microelectrodes an average depolarization of 2.4 mV (from -62.8 to -60.4 mV, P less than or equal to 0.01) accompanied by a small increase in input resistance (from 32.0 to 35.8 M omega, P less than or equal to 0.05). High-frequency spontaneous potentials failed to occur under these conditions. During 4-AP application, the threshold and the latency of action potentials elicited by a depolarizing current pulse increased in 36% of the neurons studied (n = 14). 3. The amplitude of the stratum (s.) radiatum-induced excitatory postsynaptic potential (EPSP) was augmented by 4-AP. Both the early and late inhibitory postsynaptic potentials (IPSPs) evoked by orthodromic stimuli were also increased in amplitude and duration. In addition, a late (peak latency, 150-600 ms) and long-lasting (duration, 600-1,500 ms) depolarizing potential appeared between the early and the late IPSPs and progressively increased until it partially masked these hyperpolarizations. This long-lasting depolarization (LLD) could also be induced by antidromic stimulation, although in this case it was preceded by an additional, fast-rising, brief depolarization. 4. A similar brief depolarization preceded the orthodromically induced LLD in 69% of the neurons bathed in the presence of 4-AP. The average value of the peak latency of this potential was 62 +/- 27 (SD) ms for orthodromic and 110 +/- 70 ms for antidromic responses.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals TMOD-12. THE ROLE OF INTEGRIN α V AND CD44 IN GBM MIGRATION USING HUMAN ORGANOTYPIC SLICES

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi265-vi265
Author(s):  
Zev Binder ◽  
Sarah Hyun Ji Kim ◽  
Pei-Hsun Wu ◽  
Anjil Giri ◽  
Gary Gallia ◽  
...  
Keyword(s):  
Human Brain ◽  
Cell Motility ◽  
Brain Tissue ◽  
Brain Slices ◽  
Model System ◽  
Model Systems ◽  
In Vivo Model ◽  
Human Brain Tissue

Abstract Current model systems used for GBM research include traditional in vitro cell line-based assays and in vivo animal studies. In vitro model systems offer the advantages of being easy to use, relatively inexpensive, and fast growing. However, these models lack key elements of the pathology they are attempting to model, including the biochemical and biophysical microenvironment and three-dimensional structure inherent to human brain tissue. In vivo model systems address these limitations, but have restrictions of their own. Species differences may result in non-applicable results and animal experiments are often not designed like clinical trials. Evidence of the limitations of current GBM models is found in the disparity between basic research findings and successful new treatments for GBMs in the clinic. Here we present an alternative model system for the study of human GBM cell motility and invasion, which features advantages of both in vitro and in vivo model systems. Using human organotypic brain slices as scaffolding for tumor growth, we explored the dynamic process of GBM cell invasion within human brain tissue. To demonstrate the utility of the model system, we investigated the effects of depletion of integrin α V (ITGAV) and CD44 on GBM cell motility. These two cell-surface proteins have been identified to have key functions in GBM cell motility. However, knockdown of ITGAV had little effect on tumor cell motility in organotypics while CD44 knockdown significantly reduced cell movement. Finally, we compare motility results from cells in human brain slices to those from cells growing on standard Matrigel and in mouse brain organotypics. We found significant differences in motility depending on the substrate in which the cells were moving. Our findings highlight the physiologic characteristics of human brain organotypics and demonstrate the use of real-time imaging in the ex vivo system.

Brain tissue hydrolysate acts on presynaptic adenosine receptors in the rat hippocampus

1995 ◽  
Vol 73 (8) ◽  
pp. 1194-1197 ◽  
Author(s):  
H. Xiong ◽  
J.M. WoJtwics ◽  
A. Baskys
Keyword(s):  
Synaptic Transmission ◽  
Brain Tissue ◽  
Hippocampal Slices ◽  
Brain Slices ◽  
Major Effect ◽  
Detectable Amount ◽  
Commissural Pathway ◽  
Ca1 Area ◽  
The Brain ◽  
Porcine Brain Tissue

Adenosine is a potent inhibitory modulator in the brain. It suppresses glutarnatergic synaptic transmission and possibly acts as a brain endogenous neuroprotective agent. In this study we have examined the effects of a clinically used porcine brain tissue hydrolysate, Cerebrolysin™, on synaptic transmission in the CA1 area of rat hippocampal slices. A major effect of the drug at doses approximating those administered clinically to demented patients was a depression of synaptic transmission at the Schaffer collateral–commissural pathway in CA1. Detailed analysis showed that the inhibition is presynaptic and can be reduced by low doses of a specific blocker of adenosine A1 receptors, 8-cyclopentyltheophylline. Because Cerebrolysin™ does not contain a detectable amount of adenosine, the effect on adenosine A1 receptors must be indirect, perhaps by release of the endogenous agonist. This action of Cerebrolysin™ is consistent with a putative neuroprotective action underlying its clinical usage.Key words: adenosine, Cerebrolysin™, hippocampus, brain slices, synaptic transmission.

Direct Evidence for Central Sites of Action of Zolmitriptan (311C90)

Cephalalgia ◽  
1997 ◽  
Vol 17 (3) ◽  
pp. 153-158 ◽  
Author(s):  
PJ Goadsby ◽  
YE Knight
Keyword(s):  
Ex Vivo ◽  
Cervical Spinal Cord ◽  
Specific Binding ◽  
Femoral Vein ◽  
Brain Slices ◽  
Trigeminal Nucleus ◽  
Trigeminal Nucleus Caudalis ◽  
Dorsal Horns ◽  
Sites Of Action

The trigeminovascular system consists of bipolar neurons which innervate pain-sensitive intracranial structures and projecting to neurons in the superficial laminae of the caudal trigeminal nucleus and of the dorsal horns of C1 and C2. The serotonin (5HT1B/D) agonist zolmitriptan (311C90) has been shown to be effective in the treatment of acute attacks of migraine and experimental data suggest that it may have both peripheral and central sites of action. This study sought to further investigate possible central effects of zolmitriptan (311C90) by examining its distribution in the central nervous system. Specific binding of [3H]-zolmitriptan was determined both ex vivo and in vitro in the cat brain. For the ex vivo studies, cats were anaesthetized with halothane and -chloralose (60 mg/kg intraperitoneal). A femoral vein catheter was inserted for injection of the [3H]-zolmitriptan and then 1 h after injection the brain removed. For the in vitro studies fresh frozen brain slices were incubated with labelled and masking concentrations of zolmitriptan. The distribution of [3H]-zolmitriptan was determined using quantitative autoradiographic methods. The in vitro work demonstrated specific binding of [3H]-zolmitriptan in the superficial laminae of the trigeminal nucleus caudalis and dorsal horns of the C and C2 cervical spinal cord. The density of binding was 53 9 fmol/mg for the trigeminal nucleus caudalis, 47 7 fmol/mg for C1 and 50 6 fmol/mg for C2. The ex vivo work demonstrated binding in anatomically identical areas which was less dense than that seen with the in vitro method. These data confirm the existence of a population of receptors that specifically bind zolmitriptan following systemic administration. These receptors may, in part, be responsible for its clinical efficacy and reinforce the importance of central trigeminal neurons as a possible site of action of anti-migraine drugs.

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