493,488 research outputs found
Messenger RNA coding for only the alpha subunit of the rat brain Na channel is sufficient for expression of functional channels in Xenopus oocytes
Several cDNA clones coding for the high molecular weight (alpha) subunit of the voltage-sensitive Na channel have been selected by immunoscreening a rat brain cDNA library constructed in the expression vector lambda gt11. As will be reported elsewhere, the amino acid sequence translated from the DNA sequence shows considerable homology to that reported for the Electrophorus electricus electroplax Na channel. Several of the cDNA inserts hybridized with a low-abundance 9-kilobase RNA species from rat brain, muscle, and heart. Sucrose-gradient fractionation of rat brain poly(A) RNA yielded a high molecular weight fraction containing this mRNA, which resulted in functional Na channels when injected into oocytes. This fraction contained undetectable amounts of low molecular weight RNA. The high molecular weight Na channel RNA was selected from rat brain poly(A) RNA by hybridization to a single-strand antisense cDNA clone. Translation of this RNA in Xenopus oocytes resulted in the appearance of tetrodotoxin-sensitive voltage-sensitive Na channels in the oocyte membrane. These results demonstrate that mRNA encoding the alpha subunit of the rat brain Na channel, in the absence of any beta-subunit mRNA, is sufficient for translation to give functional channels in oocytes
Alterations of the giant pyramidal neurons (Betz cells) in brain cortex of rat offspring born from gestational diabetic dams: A morphometric study [Alteraciones de las Neuronas Piramidales Gigantes de la Corteza Cerebral en Crías de Ratas Nacidas de Hembras con Diabetes Gestacional: Un Estudio Morfométrico]
A few studies reported the adverse effects of gestational diabetes on hippocampus and spinal cord of rat offspring. Giant pyramidal neurons are giant pyramidal neurons located in fifth layers of the gray matter in the primary motor cortex. Therefore, this study was conducted to determine the effect of gestational diabetes on the giant pyramidal neurons and the thickness of internal pyramidal layer in the brain cortex of rat offspring. On day 1 of gestation, 10 Wistar rat dams were randomly allocated into two control and diabetic groups. Five animals in diabetic group received 40 mg/kg/BW of Streptozotocin (intraperitoneally) and control animals received normal saline. We randomly selected six offspring of every subject in both groups at day 28, 56 and 84. Rat offspring were scarified and then coronal sections were taken from the right brain cortex and sections were stained with Cresyl violet. The density of giant pyramidal neurons in brain cortex and thickness of internal pyramidal layer of brain cortex were evaluated. In P28, P56, P84 the Betz cells density of brain cortex were significantly reduced from 107.6±6.2, 131.6±4.6 and 143.5±4.0 in controls to 84.96±2.1, 109.8±7.3 and 121.05±5.6 in cases (p<0.05), respectively. The thickness of the internal pyramidal layer of brain cortex in P28, 56 and P84 was significantly higher in gestational diabetic group in comparison with the control group (p<0.05). This study showed that uncontrolled gestational diabetes reduces the giant pyramidal neurons density and internal pyramidal layer thickness in brain cortex of rat offspring. © 2015, International Journal of Morphology. All rights reserved
Segmental aging underlies the development of a Parkinson phenotype in the AS/AGU rat
There is a paucity of information on the molecular biology of aging processes in the brain. We have used biomarkers of aging (SA β-Gal, p16Ink4a, Sirt5, Sirt6, and Sirt7) to demonstrate the presence of an accelerated aging phenotype across different brain regions in the AS/AGU rat, a spontaneous Parkinsonian mutant of PKCγ derived from a parental AS strain. P16INK4a expression was significantly higher in AS/AGU animals compared to age-matched AS controls (p < 0.001) and displayed segmental expression across various brain regions. The age-related expression of sirtuins similarly showed differences between strains and between brain regions. Our data clearly show segmental aging processes within the rat brain, and that these are accelerated in the AS/AGU mutant. The accelerated aging, Parkinsonian phenotype, and disruption to dopamine signalling in the basal ganglia in AS/AGU rats, suggests that this rat strain represents a useful model for studies of development and progression of Parkinson's disease in the context of biological aging and may offer unique mechanistic insights into the biology of aging
Imaging glutathione depletion in the rat brain using ascorbate-derived hyperpolarized MR and PET probes.
Oxidative stress is a critical feature of several common neurologic disorders. The brain is well adapted to neutralize oxidative injury by maintaining a high steady-state concentration of small-molecule intracellular antioxidants including glutathione in astrocytes and ascorbic acid in neurons. Ascorbate-derived imaging probes for hyperpolarized 13C magnetic resonance spectroscopy and positron emission tomography have been used to study redox changes (antioxidant depletion and reactive oxygen species accumulation) in vivo. In this study, we applied these imaging probes to the normal rat brain and a rat model of glutathione depletion. We first studied hyperpolarized [1-13C]dehydroascorbate in the normal rat brain, demonstrating its robust conversion to [1-13C]vitamin C, consistent with rapid transport of the oxidized form across the blood-brain barrier. We next showed that the kinetic rate of this conversion decreased by nearly 50% after glutathione depletion by diethyl maleate treatment. Finally, we showed that dehydroascorbate labeled for positron emission tomography, namely [1-11C]dehydroascorbate, showed no change in brain signal accumulation after diethyl maleate treatment. These results suggest that hyperpolarized [1-13C]dehydroascorbate may be used to non-invasively detect oxidative stress in common disorders of the brain
Towards ultra-high resolution 3D reconstruction of a whole rat brain from 3D-PLI data
3D reconstruction of the fiber connectivity of the rat brain at microscopic
scale enables gaining detailed insight about the complex structural
organization of the brain. We introduce a new method for registration and 3D
reconstruction of high- and ultra-high resolution (64 m and 1.3 m
pixel size) histological images of a Wistar rat brain acquired by 3D polarized
light imaging (3D-PLI). Our method exploits multi-scale and multi-modal 3D-PLI
data up to cellular resolution. We propose a new feature transform-based
similarity measure and a weighted regularization scheme for accurate and robust
non-rigid registration. To transform the 1.3 m ultra-high resolution data
to the reference blockface images a feature-based registration method followed
by a non-rigid registration is proposed. Our approach has been successfully
applied to 278 histological sections of a rat brain and the performance has
been quantitatively evaluated using manually placed landmarks by an expert.Comment: 9 pages, Accepted at 2nd International Workshop on Connectomics in
NeuroImaging (CNI), MICCAI'201
Linoleic acid participates in the response to ischemic brain injury through oxidized metabolites that regulate neurotransmission.
Linoleic acid (LA; 18:2 n-6), the most abundant polyunsaturated fatty acid in the US diet, is a precursor to oxidized metabolites that have unknown roles in the brain. Here, we show that oxidized LA-derived metabolites accumulate in several rat brain regions during CO2-induced ischemia and that LA-derived 13-hydroxyoctadecadienoic acid, but not LA, increase somatic paired-pulse facilitation in rat hippocampus by 80%, suggesting bioactivity. This study provides new evidence that LA participates in the response to ischemia-induced brain injury through oxidized metabolites that regulate neurotransmission. Targeting this pathway may be therapeutically relevant for ischemia-related conditions such as stroke
MicroRNA-210 Suppresses Junction Proteins and Disrupts Blood-Brain Barrier Integrity in Neonatal Rat Hypoxic-Ischemic Brain Injury.
Cerebral edema, primarily caused by disruption of the blood-brain barrier (BBB), is one of the serious complications associated with brain injury in neonatal hypoxic-ischemic encephalopathy (HIE). Our recent study demonstrated that the hypoxic-ischemic (HI) treatment significantly increased microRNA-210 (miR-210) in the neonatal rat brain and inhibition of miR-210 provided neuroprotection in neonatal HI brain injury. The present study aims to determine the role of miR-210 in the regulation of BBB integrity in the developing brain. miR-210 mimic was administered via intracerebroventricular injection (i.c.v.) into the brain of rat pups. Forty-eight hours after the injection, a modified Rice-Vannucci model was conducted to produce HI brain injury. Post-assays included cerebral edema analysis, western blotting, and immunofluorescence staining for serum immunoglobulin G (IgG) leakage. The results showed that miR-210 mimic exacerbated cerebral edema and IgG leakage into the brain parenchyma. In contrast, inhibition of miR-210 with its complementary locked nucleic acid oligonucleotides (miR-210-LNA) significantly reduced cerebral edema and IgG leakage. These findings suggest that miR-210 negatively regulates BBB integrity i n the neonatal brain. Mechanistically, the seed sequences of miR-210 were identified complementary to the 3' untranslated region (3' UTR) of the mRNA transcripts of tight junction protein occludin and adherens junction protein β-catenin, indicating downstream targets of miR-210. This was further validated by in vivo data showing that miR-210 mimic significantly reduced the expression of these junction proteins in rat pup brains. Of importance, miR-210-LNA preserved the expression of junction proteins occludin and β-catenin from neonatal HI insult. Altogether, the present study reveals a novel mechanism of miR-210 in impairing BBB integrity that contributes to cerebral edema formation after neonatal HI insult, and provides new insights in miR-210-LNA mediated neuroprotection in neonatal HI brain injury
Involvement of the JNK/FOXO3a/Bim Pathway in Neuronal Apoptosis after Hypoxic-Ischemic Brain Damage in Neonatal Rats.
c-Jun N-terminal kinase (JNK) plays a key role in the regulation of neuronal apoptosis. Previous studies have revealed that forkhead transcription factor (FOXO3a) is a critical effector of JNK-mediated tumor suppression. However, it is not clear whether the JNK/FOXO3a pathway is involved in neuronal apoptosis in the developing rat brain after hypoxia-ischemia (HI). In this study, we generated an HI model using postnatal day 7 rats. Fluorescence immunolabeling and Western blot assays were used to detect the distribution and expression of total and phosphorylated JNK and FOXO3a and the pro-apoptotic proteins Bim and CC3. We found that JNK phosphorylation was accompanied by FOXO3a dephosphorylation, which induced FOXO3a translocation into the nucleus, resulting in the upregulation of levels of Bim and CC3 proteins. Furthermore, we found that JNK inhibition by AS601245, a specific JNK inhibitor, significantly increased FOXO3a phosphorylation, which attenuated FOXO3a translocation into the nucleus after HI. Moreover, JNK inhibition downregulated levels of Bim and CC3 proteins, attenuated neuronal apoptosis and reduced brain infarct volume in the developing rat brain. Our findings suggest that the JNK/FOXO3a/Bim pathway is involved in neuronal apoptosis in the developing rat brain after HI. Agents targeting JNK may offer promise for rescuing neurons from HI-induced damage
Mechanisms of modulation of brain microvascular endothelial cells function by thrombin.
Brain microvascular endothelial cells are a critical component of the blood-brain barrier. They form a tight monolayer which is essential for maintaining the brain homeostasis. Blood-derived proteases such as thrombin may enter the brain during pathological conditions like trauma, stroke, and inflammation and further disrupts the permeability of the blood-brain barrier, via incompletely characterized mechanisms. We examined the underlying mechanisms evoked by thrombin in rat brain microvascular endothelial cells (RBMVEC). Our results indicate that thrombin, acting on protease-activated receptor 1 (PAR1) increases cytosolic C
Depolarization increases cellular light transmission
Application of optical methods to human brain tissue in vivo, e.g., measuring oxyhemoglobin and deoxyhemoglobin concentration changes with near-infrared spectroscopy (NIRS), requires the a priori assumption that background optical properties remain unchanged during measurements1,2. However, fundamental knowledge about light scattering by brain cells per se remains sparse; many factors influence light transmission changes through living brain tissue, bringing into question what is being measured. We have observed slow wave-ring spreads of light transmission changes on the rat cerebral cortex during potassium-induced cortical spreading depression (CSD) and ascribed them to squeezing-out of blood from capillaries by swollen brain cells3,4. However, in rat hippocampal slices, where no blood components were involved, similar light transmission changes were observed during K+-induced CSD and ascribed to cell swelling and dendritic beading5,6,7. Here we show that two-dimensional light scattering changes occur through suspensions of osmotically swollen (depolarized) red blood cells, apparently arising from light scattering changes at the less curved, swollen surface of the steep electrochemical gradient coupled with water activity difference across the plasmic membrane. These optical property changes are likely to be relevant to interpretation of photometry or spectroscopy findings of brain tissue in vivo, where neurons are polarizing and depolarizing during brain function
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