scholarly journals Regional distribution of SGLT activity in rat brain in vivo

2013 ◽  
Vol 304 (3) ◽  
pp. C240-C247 ◽  
Author(s):  
Amy S. Yu ◽  
Bruce A. Hirayama ◽  
Gerald Timbol ◽  
Jie Liu ◽  
Ana Diez-Sampedro ◽  
...  
Keyword(s):  
Rat Brain ◽  
Ex Vivo ◽  
Osmotic Shock ◽  
Regional Distribution ◽  
The Body ◽  
Specific Substrate ◽  
Ex Vivo Autoradiography ◽  
Molecular Imaging Probe ◽  
The Brain

Na+-glucose cotransporter (SGLT) mRNAs have been detected in many organs of the body, but, apart from kidney and intestine, transporter expression, localization, and functional activity, as well as physiological significance, remain elusive. Using a SGLT-specific molecular imaging probe, α-methyl-4-deoxy-4-[18F]fluoro-d-glucopyranoside (Me-4-FDG) with ex vivo autoradiography and immunohistochemistry, we mapped in vivo the regional distribution of functional SGLTs in rat brain. Since Me-4-FDG is not a substrate for GLUT1 at the blood-brain barrier (BBB), in vivo delivery of the probe into the brain was achieved after opening of the BBB by an established procedure, osmotic shock. Ex vivo autoradiography showed that Me-4-FDG accumulated in regions of the cerebellum, hippocampus, frontal cortex, caudate nucleus, putamen, amygdala, parietal cortex, and paraventricular nucleus of the hypothalamus. Little or no Me-4-FDG accumulated in the brain stem. The regional accumulation of Me-4-FDG overlapped the distribution of SGLT1 protein detected by immunohistochemistry. In summary, after the BBB is opened, the specific substrate for SGLTs, Me-4-FDG, enters the brain and accumulates in selected regions shown to express SGLT1 protein. This localization and the sensitivity of these neurons to anoxia prompt the speculation that SGLTs may play an essential role in glucose utilization under stress such as ischemia. The expression of SGLTs in the brain raises questions about the potential effects of SGLT inhibitors under development for the treatment of diabetes.

scholarly journals Brain pharmacokinetics of two BBB penetrating bispecific antibodies of different size

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Rebecca Faresjö ◽  
Gillian Bonvicini ◽  
Xiaotian T. Fang ◽  
Ximena Aguilar ◽  
Dag Sehlin ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Elimination Rate ◽  
Brain Parenchyma ◽  
Bispecific Antibodies ◽  
Igg Antibody ◽  
Nuclear Track Emulsion ◽  
Ex Vivo Autoradiography ◽  
The Brain

Abstract Background Transferrin receptor (TfR1) mediated enhanced brain delivery of antibodies have been studied extensively in preclinical settings. However, the brain pharmacokinetics, i.e. brain entry, distribution and elimination are still not fully understood for this class of antibodies. The overall aim of the study was to compare the brain pharmacokinetics of two BBB-penetrating bispecific antibodies of different size (210 vs 58 kDa). Specifically, we wanted to investigate if the faster systemic clearance of the smaller non-IgG antibody di-scFv3D6-8D3, in comparison with the IgG-based bispecific antibody mAb3D6-scFv8D3, was also reflected in the brain. Methods Wild-type (C57/Bl6) mice were injected with 125I-iodinated ([125I]) mAb3D6-scFv8D3 (n = 46) or [125I]di-scFv3D6-8D3 (n = 32) and euthanized 2, 4, 6, 8, 10, 12, 16, or 24 h post injection. Ex vivo radioactivity in whole blood, peripheral organs and brain was measured by γ-counting. Ex vivo autoradiography and nuclear track emulsion were performed on brain sections to investigate brain and parenchymal distribution. Capillary depletion was carried out at 2, 6, and 24 h after injection of [125I]mAb3D6-scFv8D3 (n = 12) or [125I]di-scFv3D6-8D3 (n = 12), to estimate the relative levels of radiolabelled antibody in brain capillaries versus brain parenchyma. In vitro binding kinetics for [125I]mAb3D6-scFv8D3 or [125I]di-scFv3D6-8D3 to murine TfR were determined by LigandTracer. Results [125I]di-scFv3D6-8D3 showed faster elimination from blood, lower brain Cmax, and Tmax, a larger parenchymal-to-capillary concentration ratio, and a net elimination from brain at an earlier time point after injection compared with the larger [125I]mAb3D6-scFv8D3. However, the elimination rate from brain did not differ between the antibodies. The study also indicated that [125I]di-scFv3D6-8D3 displayed lower avidity than [125I]mAb3D6-scFv8D3 towards TfR1 in vitro and potentially in vivo, at least at the BBB. Conclusion A smaller size and lower TfR1 avidity are likely important for fast parenchymal delivery, while elimination of brain-associated bispecific antibodies may not be dependent on these characteristics.

scholarly journals Regional distribution of the enzymes of haem biosynthesis and the inhibition of 5-aminolaevulinate synthase by manganese in the rat brain

1980 ◽  
Vol 190 (2) ◽  
pp. 315-321 ◽  
Author(s):  
Mahin D. Maines
Keyword(s):  
Enzyme Activity ◽  
Cerebral Cortex ◽  
Rat Brain ◽  
Metal Ion ◽  
Regional Distribution ◽  
State Level ◽  
Haem Biosynthesis ◽  
The Brain

The activity of 5-aminolaevulinate synthase, the rate-limiting enzyme of haem biosynthesis, is differentially distributed in various regions of the rat brain. The cerebellum possessed the highest enzyme activity of the eight regions studied. The cerebral cortex and the midbrain also exhibited high 5-aminolaevulinate synthase activity; the septum, hypothalamus, thalamus, amygdala and the hippocampus possessed much lower enzyme activity. However, the total porphyrin and haem contents of the different brain segments did not vary greatly. Mn2+, when administered subcutaneously to rats, effectively inhibited the activity of 5-aminolaevulinate synthase in the cerebellum, midbrain and cerebral cortex; however, repeated injections of the metal ion neither decreased the haem and porphyrin contents of the brain nor induced haem oxygenase activity. Mn2+ was not an effective inhibitor of 5-aminolaevulinate synthase activity in vitro. On the other hand, studies carried out with the liver in vivo suggested that Mn2+ may alter the turnover rate of cellular haem and haemoproteins. In that event, it is likely that the inhibition of 5-aminolaevulinate synthase by Mn2+ was in part a result of the inhibition of protein synthesis by the metal ion. It is postulated that the haem and porphyrin contents of the brain are maintained at a steady-state level, due in part to the refractoriness to inducers of the regulatory mechanism for haem catabolic enzymes and in part to the ability of the organ to utilize haem precursors derived from extraneuronal sources.

The Role of Polyphenols in the Modulation of Plasma Non-Enzymatic Antioxidant Capacity (NEAC)

2012 ◽  
Vol 82 (3) ◽  
pp. 228-232 ◽  
Author(s):  
Mauro Serafini ◽  
Giuseppa Morabito
Keyword(s):  
Antioxidant Capacity ◽  
Dietary Intervention ◽  
Ex Vivo ◽  
The Body ◽  
Dietary Polyphenols ◽  
Enzymatic Antioxidant ◽  
Endogenous Antioxidant

Dietary polyphenols have been shown to scavenge free radicals, modulating cellular redox transcription factors in different in vitro and ex vivo models. Dietary intervention studies have shown that consumption of plant foods modulates plasma Non-Enzymatic Antioxidant Capacity (NEAC), a biomarker of the endogenous antioxidant network, in human subjects. However, the identification of the molecules responsible for this effect are yet to be obtained and evidences of an antioxidant in vivo action of polyphenols are conflicting. There is a clear discrepancy between polyphenols (PP) concentration in body fluids and the extent of increase of plasma NEAC. The low degree of absorption and the extensive metabolism of PP within the body have raised questions about their contribution to the endogenous antioxidant network. This work will discuss the role of polyphenols from galenic preparation, food extracts, and selected dietary sources as modulators of plasma NEAC in humans.

Neurochemical and Pharmacological Properties of Tianeptine, A Novel Antidepressant

1992 ◽  
Vol 160 (S15) ◽  
pp. 56-60 ◽  
Author(s):  
C. Labrid ◽  
E. Mocaër ◽  
A. Kamoun
Keyword(s):  
Rat Brain ◽  
Ex Vivo ◽  
Animal Experiments ◽  
Pyramidal Cells ◽  
Human Platelets ◽  
Clinical Findings ◽  
Tricyclic Antidepressant ◽  
Laboratory Animals ◽  
5 Ht Uptake

Tianeptine is a tricyclic antidepressant with an unusual chemical structure (a long lateral chain grafted on to a substituted dibenzothiazepin nucleus), and with biochemical and animal-behavioural properties which are strikingly different from those of classical tricyclics. Unlike the latter, which decrease serotonin (5-HT) uptake, acute and chronic tianeptine treatment enhances 5-HT uptake in rat brain and in rat and human platelets ex vivo. In vivo, tianeptine potentiates the depletion of rat brain 5-HT by 4-methyl-alpha-ethyl metatyramine and increases rat hippocampal 5-HIAA; 5-HT uptake inhibitors (e.g. fluoxetine) have opposite effects. On iontophoretic injection into CA1 pyramidal cells, tianeptine shortens the period of neuronal hypoactivity caused by GABA or 5-HT, whereas other tricyclics prolong it, and it enhances attention, learning, and memory in laboratory animals, while classical tricyclics have opposite effects. However, the relationships between these effects of tianeptine in animal experiments and their relevance to clinical findings remain to be determined.

scholarly journals A method for single-neuron chronic recording from the retina in awake mice

Science ◽  
2018 ◽  
Vol 360 (6396) ◽  
pp. 1447-1451 ◽  
Author(s):  
Guosong Hong ◽  
Tian-Ming Fu ◽  
Mu Qiao ◽  
Robert D. Viveros ◽  
Xiao Yang ◽  
...  
Keyword(s):  
Retinal Ganglion Cells ◽  
Visual Information ◽  
Single Neuron ◽  
Ganglion Cells ◽  
Ex Vivo ◽  
Neural Circuitry ◽  
Retinal Ganglion ◽  
Chronic Recording ◽  
The Brain

The retina, which processes visual information and sends it to the brain, is an excellent model for studying neural circuitry. It has been probed extensively ex vivo but has been refractory to chronic in vivo electrophysiology. We report a nonsurgical method to achieve chronically stable in vivo recordings from single retinal ganglion cells (RGCs) in awake mice. We developed a noncoaxial intravitreal injection scheme in which injected mesh electronics unrolls inside the eye and conformally coats the highly curved retina without compromising normal eye functions. The method allows 16-channel recordings from multiple types of RGCs with stable responses to visual stimuli for at least 2 weeks, and reveals circadian rhythms in RGC responses over multiple day/night cycles.

Ex Vivo Brain Preparation to Analyze Vocal Pathways of Xenopus Frogs

2021 ◽  
Vol 2021 (9) ◽  
pp. pdb.prot106872
Author(s):  
Ayako Yamaguchi
Keyword(s):  
Neural Activity ◽  
Ex Vivo ◽  
Neural Circuitry ◽  
Neural Basis ◽  
Vocal Production ◽  
Basic Principles ◽  
Electrophysiological Recordings ◽  
The Brain

Understanding the neural basis of behavior is a challenging task for technical reasons. Most methods of recording neural activity require animals to be immobilized, but neural activity associated with most behavior cannot be recorded from an anesthetized, immobilized animal. Using amphibians, however, there has been some success in developing in vitro brain preparations that can be used for electrophysiological and anatomical studies. Here, we describe an ex vivo frog brain preparation from which fictive vocalizations (the neural activity that would have produced vocalizations had the brain been attached to the muscle) can be elicited repeatedly. When serotonin is applied to the isolated brains of male and female African clawed frogs, Xenopus laevis, laryngeal nerve activity that is a facsimile of those that underlie sex-specific vocalizations in vivo can be readily recorded. Recently, this preparation was successfully used in other species within the genus including Xenopus tropicalis and Xenopus victorianus. This preparation allows a variety of techniques to be applied including extracellular and intracellular electrophysiological recordings and calcium imaging during vocal production, surgical and pharmacological manipulation of neurons to evaluate their impact on motor output, and tract tracing of the neural circuitry. Thus, the preparation is a powerful tool with which to understand the basic principles that govern the production of coherent and robust motor programs in vertebrates.

scholarly journals 4081 Quantifying pH buffering capacity and kinetics of tumor and healthy tissue to understand and exploit differences in biology

2020 ◽  
Vol 4 (s1) ◽  
pp. 15-15
Author(s):  
A. Colleen Crouch ◽  
Emily A. Thompson ◽  
Mark D. Pagel ◽  
Erik N.K. Cressman
Keyword(s):  
Tumor Tissue ◽  
Ex Vivo ◽  
Buffering Capacity ◽  
The Body ◽  
Healthy Tissue ◽  
Buffer System ◽  
Bicarbonate Buffer ◽  
Ph Buffering ◽  
Acidocest Mri

OBJECTIVES/GOALS: The purpose of this work is to investigate natural buffering capacity of liver tissue and tumors, to understand and exploit differences for therapy. Using this work, we will determine the concentrations of reagents (acids or bases) used in ablation treatment to optimize treatment by increasing tumor toxicity and minimizing healthy tissue toxicity. METHODS/STUDY POPULATION: For this preliminary study, two methods will be used: benchtop pH experiments ex vivo and non-invasive imaging using acidoCEST MRI in vivo. For ex vivo, two types of tissues will be tested: non-cancerous liver and tumor tissue from HepG2 inoculated mice (n = 10). After mice are euthanized, pH will be measured in tissue homogenates at baseline and then the homogenates will be placed in either acidic (acetic acid) or basic (sodium hydroxide) solutions with varied concentrations (0.5–10M) and time recorded until pH returns to baseline. For in vivo imaging, Mia PaCA-2 flank model mice (n = 10) will be imaged with acidoCEST MRI to quantify pH at baseline. Mice will then be injected intratumorally with (up to 100 μL of) acid or base at increasing concentrations and imaged to quantify pH changes in the tumor. RESULTS/ANTICIPATED RESULTS: For this study, buffering capacity is defined as the concentration threshold for which tissue can buffer pH back to within normal range. Non-cancerous tissue is likely to buffer a wider range of concentrations compared to tumor tissue. From the benchtop experiment, comparison of time-to-buffer will be made for each concentration of acid/base for the two tissue types. AcidoCEST MRI will provide in vivo buffering capacity and potentially demonstrate tumor heterogeneity of buffering capacity. For both experiments, a pH vs. concentration curve for the two tissue types will allow for comparison of ex vivo to in vivo experiments, which will differentiate contributions of local tissue buffering capacity from the full body’s natural bicarbonate buffer system that depends on respiration and blood flow. DISCUSSION/SIGNIFICANCE OF IMPACT: The pH of the body must be maintained within a narrow range. With cancer, impairment in regulation of tumor metabolism causes acidosis, lowering extracellular pH in tumors. It remains unclear if pH plays a role in local recurrence or tumor toxicity. This work will determine if acidoCEST MRI can measure deliberate alteration of pH and how this change affects biology.

scholarly journals Potential caveats of putative microglia-specific markers for assessment of age-related cerebrovascular neuroinflammation

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Pedram Honarpisheh ◽  
Juneyoung Lee ◽  
Anik Banerjee ◽  
Maria P. Blasco-Conesa ◽  
Parisa Honarpisheh ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Ex Vivo ◽  
Myeloid Cells ◽  
Amyloid Angiopathy ◽  
Future Studies ◽  
Age Related ◽  
In Vivo Animal Models ◽  
Intermediate Expression ◽  
The Brain

Abstract Background The ability to distinguish resident microglia from infiltrating myeloid cells by flow cytometry-based surface phenotyping is an important technique for examining age-related neuroinflammation. The most commonly used surface markers for the identification of microglia include CD45 (low-intermediate expression), CD11b, Tmem119, and P2RY12. Methods In this study, we examined changes in expression levels of these putative microglia markers in in vivo animal models of stroke, cerebral amyloid angiopathy (CAA), and aging as well as in an ex vivo LPS-induced inflammation model. Results We demonstrate that Tmem119 and P2RY12 expression is evident within both CD45int and CD45high myeloid populations in models of stroke, CAA, and aging. Interestingly, LPS stimulation of FACS-sorted adult microglia suggested that these brain-resident myeloid cells can upregulate CD45 and downregulate Tmem119 and P2RY12, making them indistinguishable from peripherally derived myeloid populations. Importantly, our findings show that these changes in the molecular signatures of microglia can occur without a contribution from the other brain-resident or peripherally sourced immune cells. Conclusion We recommend future studies approach microglia identification by flow cytometry with caution, particularly in the absence of the use of a combination of markers validated for the specific neuroinflammation model of interest. The subpopulation of resident microglia residing within the “infiltrating myeloid” population, albeit small, may be functionally important in maintaining immune vigilance in the brain thus should not be overlooked in neuroimmunological studies.

Antibodies to β-Amyloid Decrease the Blood-to-Brain Transfer of β-Amyloid Peptide1

2002 ◽  
Vol 227 (8) ◽  
pp. 609-615 ◽  
Author(s):  
Weihong Pan ◽  
Beka Solomon ◽  
Lawrence M. Maness ◽  
Abba J. Kastin
Keyword(s):  
Ex Vivo ◽  
Amyloid Β ◽  
Brain Perfusion ◽  
Brain Parenchyma ◽  
Amyloid Angiopathy ◽  
Β Amyloid ◽  
Blocking Antibodies ◽  
The Brain

Amyloid-β peptides (Aβ) play an important role in the pathophysiology of dementia of the Alzheimer's type and in amyloid angiopathy. Aβ outside the CNS could contribute to plaque formation in the brain where its entry would involve interactions with the blood-brain barrier (BBB). Effective antibodies to Aβ have been developed in an effort to vaccinate against Alzheimer's disease. These antibodies could interact with Aβ in the peripheral blood, block the passage of Aβ across the BBB, or prevent Aβ deposition within the CNS. To determine whether the blocking antibodies act at the BBB level, we examined the influx of radiolabeled Aβ (125I-Aβ1-40) into the brain after ex-vivo incubation with the antibodies. Antibody mAb3D6 (élan Company) reduced the blood-to-brain influx of Aβ after iv bolus injection. It also significantly decreased the accumulation of Aβ in brain parenchyma. To confirm the in-vivo study and examine the specificity of mAb3D6, in-situ brain perfusion in serum-free buffer was performed after incubation of 125I-Aβ1-40 with another antibody mAbmc1 (DAKO Company). The presence of mAbmc1 also caused significant reduction of the influx of Aβ into the brain after perfusion. Therefore, effective antibodies to Aβ can reduce the influx of Aβ1-40 into the brain.

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