scholarly journals Exchange of phospholipids between brain membranes in vitro

1972 ◽  
Vol 126 (4) ◽  
pp. 823-835 ◽  
Author(s):  
E. K. Miller ◽  
R. M. C. Dawson
Keyword(s):  
Mitochondrial Fraction ◽  
Supernatant Fraction ◽  
Exchange Processes ◽  
Brain Microsomes ◽  
Phospholipid Transfer ◽  
Myelin Fraction ◽  
Macromolecular Component ◽  
The Brain ◽  
Guinea Pig Brain

1. When unlabelled mitochondria from guinea-pig brain were incubated with a 32P-labelled microsomal fraction from brain there was a transfer of phospholipid to the mitochondria, which could not be accounted for by an aggregation of microsomes and mitochondria or an exchange with microsomes contaminating the mitochondria. Under similar circumstances there was a transfer of phospholipid from 32P-labelled mitochondria to microsomes, indicating that the process was one of exchange. 2. The transfer from microsomes was greatly stimulated by a non-dialysable heat-labile macromolecular component in the brain supernatant fraction but not by the concentration of the particulate fractions. 3. Phospholipid-exchange processes occurred most readily between pH7 and 7.5 and were inhibited by the presence of myelin and on the addition of lysophosphatidylcholine. 4. The rates of transfer of individual phospholipids from brain microsomes to mitochondria were similar. 5. 32P-labelled microsomes could slowly donate phospholipid to the isolated synaptosomal (nerve-ending) fraction but the phospholipids of the myelin fraction did not exchange. 6. Subfractionation of the synaptosomal fraction after [32P]phospholipid transfer showed that the mitochondria were most actively labelled during the incubation. All of the isolated individual synaptosomal membranes were capable of acquiring phospholipid on incubation with a 32P-labelled brain supernatant fraction although a greater percentage was again exchanged by the mitochondrial fraction.

Ovarian production of progesterone and 20α-dihydroprogesterone in vitro following prostaglandin F2α induced luteolysis in the superluteinized rat

1984 ◽  
Vol 105 (2) ◽  
pp. 258-265 ◽  
Author(s):  
P. A. Torjesen ◽  
A. Aakvaag
Keyword(s):  
Adenylyl Cyclase ◽  
Prostaglandin F2α ◽  
Mitochondrial Fraction ◽  
Supernatant Fraction ◽  
Production Rates ◽  
Cyclic Monophosphate ◽  
Progesterone Production ◽  
Progesterone Secretion ◽  
Prostaglandin F

Abstract. Superluteinized rats were injected with the prostaglandin F2α (PGF2α) analogue cloprostenol to induce luteolysis. The treatment decreased progesterone production of ovarian homogenates from 8.9 ± 0.5 to 4.0 ± 0.7 nmol/ovary/10 min (mean ± sem) within 40 min. tochondrial fractions isolated from control and cloprostenol treated animals produced 4.7 ± 0.4 and 2.8 ± 0.3 nmol progesterone/ovary/10 min, respectively. Thus, the PGF2α analogue treatment significantly reduced mitochondrial progesterone production. Addition of the 15 000 × g supernatant fraction did not influence the progesterone production rates of the mitochondrial fraction. The basal progesterone secretion from quartered ovaries decreased from 1.50 ± 0.15 to 0.38 ± 0.05 nmol/ovary during the initial 15 min of incubation following cloprostenol administration. hCG and N6,O2'-dibutyryladenosine 3':5'-cyclic monophosphate (DBC) stimulated the progesterone secretion from quartered ovaries, but the response was delayed in ovaries obtained from cloprostenol treated animals. Although the response was delayed, the progesterone secretion following cloprostenol treatment was re-activated with cAMP either directly or via hCG. The increment in progesterone secretion above unstimulated controls in response to DBC was not influenced by the cloprostenol treatment while the increment caused by hCG was decreased. Our data suggest that: 1) PGF2α deactivates mitochondrial progesterone production, 2) this deactivation may be overcome by cAMP, and 3) PGF2α decreases gonadotrophin responsive adenylyl cyclase.

scholarly journals Adenosine as a constituent of the brain and of isolated cerebral tissues, and its relationship to the generation of adenosine 3′:5′-cyclic monophosphate

1977 ◽  
Vol 164 (1) ◽  
pp. 131-137 ◽  
Author(s):  
Michael Newman ◽  
Henry McIlwain
Keyword(s):  
Electrical Stimulation ◽  
Cyclic Amp ◽  
Guinea Pig ◽  
Room Temperature ◽  
Fold Increase ◽  
Electrical Excitation ◽  
Adenosine Concentration ◽  
The Brain ◽  
Guinea Pig Brain

1. Adenosine was determined in rapidly frozen rat and guinea-pig brain and in guinea-pig cerebral tissues after incubation in vitro. Adenosine concentrations were approx. 2nmol/g wet wt. in frozen tissue, diminished at room temperature, and returned to 2nmol/g on incubation in oxygenated glucose/salines. 2. Superfusion with noradrenaline then increased the tissue's adenosine concentration 2.5-fold, and hypoxia caused an 8-fold increase. 3. Electrical stimulation alone or in the presence of noradrenaline or histamine increased the tissue's adenosine and cyclic AMP, but adenosine concentrations reached their peak later and were maintained for longer than those of cyclic AMP. 4. Superfusion with l-glutamate with and without electrical excitation raised adenosine concentrations to 15–34nmol/g. The increases in cyclic AMP on electrical stimulation, superfusion with glutamate or a combination of these treatments were diminished by addition of adenosine deaminase or theophylline. 5. It is concluded that adenosine can be produced endogenously in cerebral systems, in sufficient concentrations to accelerate an adenosine-activated adenylate cyclase, and by this route can contribute to the cerebral actions of electrical stimulation and of the neurohumoral agents. In certain instances cyclic AMP as substrate contributes to an increase in adenosine.

Immunochemical and Biochemical Evidence for Expression of Phenobarbital-and 3-Methylcholanthrene-Inducible Isoenzymes of Cytochrome P450 in Rat Brain

1998 ◽  
Vol 17 (6) ◽  
pp. 619-630 ◽  
Author(s):  
Devendra Parmar ◽  
Alok Dhawan ◽  
Monika Dayal ◽  
Prahlad K. Seth
Keyword(s):  
Cytochrome P450 ◽  
Rat Brain ◽  
Western Blotting ◽  
Polyclonal Antibodies ◽  
Biochemical Evidence ◽  
Catalytic Activities ◽  
Brain Microsomes ◽  
The Brain

Expression of P450 1A1l 1A2 and 2 B1l 2B2 isoenzymes in rat brain was studied by Western blotting, using polyclonal antibodies raised against hepatic P450 1A1l 1A2 and 2B1l 2B2 isoenzymes. In addition, biochemical characterizations of the catalytic activities, pen toxyresorufin O-dealkylation (PROD) and ethoxyre-sorufin O-deethylation (EROD), selective for P450 2B1l 2B2 (PROD) and P450 1A1l 1A2 (EROD), were performed with rat brain microsomes. Control rat brain microsomes did not crossreact with either of the antibodies, whereas microsomes obtained from 3-methylcholanthrene (MC)-pretreated rats revealed significant immunoreactivity with anti-P450 1A1l 1A2. Similar results were observed with phenobarbital (PB)-pretreated rats, with the brain microsomes exhibiting significant immunoreactivity with anti-P450 2B1l 2B2. The induction in the P450 isoenzymes after PB or MC pretreatment was much less in the brain in comparison to the liver. Enzymatic studies indicated that the activities of PROD and EROD were induced in brain 3—4 fold by PB and MC pretreatment, respectively, and were almost completely inhibited on in vitro addition of anti-P450 2B1l 2B2 and 1A1l 1A2. These data demonstrate the expression of P4501A1l 1A2 and 2B1l 2B2 isoenzymes in the brain and indicate that, as in liver, these isoenzymes catalyze EROD and PROD, respectively, in the rat brain.

IN VITRO EVIDENCE FOR A PROGESTERONE AND CORTICOSTEROID BINDING PROTEIN IN THE HUMAN UTERUS

1974 ◽  
Vol 75 (3) ◽  
pp. 579-583 ◽  
Author(s):  
J. L. McGuire ◽  
C. D. Bariso ◽  
B. S. Fuller
Keyword(s):  
Guinea Pig ◽  
Medroxyprogesterone Acetate ◽  
Binding Protein ◽  
Supernatant Fraction ◽  
Human Uterus ◽  
Macromolecular Component

ABSTRACT When 3H-progesterone was incubated with the 273 000 g supernatant fraction from human uteri, labelled steroid was bound to a macromolecular component. Concomitant incubation with unlabelled corticosteroids, progesterone, testosterone and oestradiol-17β depressed binding of 3H-progesterone, whereas cholesterol and the synthetic progestins chlormadinone and medroxyprogesterone acetate did not competitively inhibit 3H-progesterone binding. These findings are consistent with the existence of a transcortin-like progesterone binder in uteri of lower species such as the rat, guinea pig and rabbit.

scholarly journals Basal Sodium-Dependent Vitamin C Transporter 2 polarization in choroid plexus explant cells in normal or scorbutic conditions

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Viviana Ulloa ◽  
Natalia Saldivia ◽  
Luciano Ferrada ◽  
Katterine Salazar ◽  
Fernando Martínez ◽  
...  
Keyword(s):  
Vitamin C ◽  
Choroid Plexus ◽  
Basolateral Membrane ◽  
Adult Brain ◽  
Epithelial Structure ◽  
The Brain ◽  
Guinea Pig Brain ◽  
Embryonic Brain Development

Abstract Vitamin C is incorporated into the cerebrospinal fluid (CSF) through choroid plexus cells. While the transfer of vitamin C from the blood to the brain has been studied functionally, the vitamin C transporter, SVCT2, has not been detected in the basolateral membrane of choroid plexus cells. Furthermore, it is unknown how its expression is induced in the developing brain and modulated in scurvy conditions. We concluded that SVCT2 is intensely expressed in the second half of embryonic brain development and postnatal stages. In postnatal and adult brain, SVCT2 is highly expressed in all choroidal plexus epithelial cells, shown by colocalization with GLUT1 in the basolateral membranes and without MCT1 colocalization, which is expressed in the apical membrane. We confirmed that choroid plexus explant cells (in vitro) form a sealed epithelial structure, which polarized basolaterally, endogenous or overexpressed SVCT2. These results are reproduced in vivo by injecting hSVCT2wt-EYFP lentivirus into the CSF. Overexpressed SVCT2 incorporates AA (intraperitoneally injected) from the blood to the CSF. Finally, we observed in Guinea pig brain under scorbutic condition, that normal distribution of SVCT2 in choroid plexus may be regulated by peripheral concentrations of vitamin C. Additionally, we observed that SVCT2 polarization also depends on the metabolic stage of the choroid plexus cells.

THE ACTION OF SERUM GONADOTROPHIN ON GLUTAMIC-OXALACETIC TRANSAMINASE IN THE RAT OVARY

1965 ◽  
Vol 49 (3) ◽  
pp. 379-387 ◽  
Author(s):  
B. Eckstein ◽  
Z. Paster
Keyword(s):  
Electrophoretic Mobility ◽  
Soluble Fraction ◽  
Mitochondrial Fraction ◽  
Supernatant Fraction ◽  
List Type ◽  
Differential Centrifugation ◽  
Glutamic Oxalacetic Transaminase ◽  
Enzyme Form ◽  
Rat Ovary

ABSTRACT The mechanism by which glutamic-oxalacetic transaminase (GOT) activity is increased in the rat ovary, following gonadotrophin treatment, was studied. It was found: Differential centrifugation of ovarian homogenate showed that there was an increased enzyme activity in the supernatant fraction. The GOT located in the mitochondrial fraction could be activated in vitro by incubating this fraction for several hours. Such treatment did not alter the activity of the enzyme in the supernatant fraction. Electrophoretic separation of the subcellular fractions showed the presence of the same two isoenzymes both in the mitochondrial and in the supernatant fractions. Only small amounts of the fast moving isoenzyme (GOT II) were present in the supernatant fraction, while the difference in quantity between the two isoenzymes in the mitochondria was less marked. Gonadotrophin stimulation intensified only the slow moving enzyme (GOT I) in the supernatant. Examination of the electrophoretic mobility of the enzyme released by the mitochondria into the incubation medium after in vitro activation showed that only GOT I was released by this treatment. The apparent Km for both L-aspartate as well as for α-ketoglutarate in the supernatant fraction remained unaltered by gonadotrophin stimulation, while the apparent Km were changed in the mitochondrial fraction of the hormone treated rats. These observations led to the hypothesis that gonadotrophin stimulation activates GOT in the rat ovary by transfering a latent mitochondrial GOT to the cell sap. In previous publications from this laboratory (Eckstein & Shain 1963; Eckstein 1963; and others), it was reported that gonadotrophins with follicle stimulating activity considerably enhance the glutamic-oxalacetic transaminase (GOT) activity in the rat ovary, while purified LH (NIH-LH-Sl) is inactive in this respect. Isoenzymes* of GOT have been reported for a great variety of organs (Boyd 1961, 1962; Katunuma 1962; Decker & Rau 1963; Fleisker et al. 1960; Augustinsson & Erne 1961). It has been shown (Boyd 1961), that two forms of GOT in the liver can be separated by differential centrifugation. One form adheres to the mitochondria, while the second enzyme is found in the soluble fraction. These two isoenzymes differ in their substrate affinities, pH dependance and electrophoretic mobility. The GOT in the mitochondria is in a latent form, and can be activated by release into the soluble fraction. The following experiments show that the rat ovary also contains at least two GOT isoenzymes; and that serum gonadotrophin (PMS) probably activates GOT by the release of one enzyme form from the mitochondria into the soluble fraction.

scholarly journals The effect of thyroxine isomers on the processes of free radical oxidation in the subcellular fractions of the rat cerebral cortex

2000 ◽  
Vol 46 (4) ◽  
pp. 32-34
Author(s):  
O. V. Galkina ◽  
V. M. Prokopenko ◽  
F. E. Putilina ◽  
N. D. Yeshchenko ◽  
A. V. Arutyunyan
Keyword(s):  
Cerebral Cortex ◽  
Free Radical ◽  
Free Radical Oxidation ◽  
Mitochondrial Fraction ◽  
Rat Cerebral Cortex ◽  
Radical Oxidation ◽  
Adult Rat ◽  
Synaptosomal Fraction ◽  
The Brain

Effective concentrations for D and L thyroxin isomers were determined by the chemiluminescent (CL) method and their effects on free radical oxidation in the mitochondrial and synaptosomal fraction of adult rat cerebral cortex were studied in vitro. A OA DT4 in a model system with riboflavin was 2.2 times higher than L-T4. Effective concentrations for both thyroxin forms were 1$q= = 7.43 x 10~5+/-0.71 M for D-T4 and 15q=15.47 x 10~5+/1.23 M for L-T4. Thyroxin effect on membranous fraction of the brain cortex was studied in vitro using luminol-dependent peroxide CL. In normal concentrations (1 x 108 M) both hormone forms exerted equally intensive antioxidant effect which was more pronounced in the mitochondrial fraction, where CL decreased by 69 and 66%, while in the synaptosomal fraction it decreased only by 45 and 46%. Since D form possesses no hormonal activity, this effect may be due to phenol origin of thyroxin.  

scholarly journals Seizure-Induced Acute Glial Activation in the in vitro Isolated Guinea Pig Brain

2021 ◽  
Vol 12 ◽  
Author(s):  
Diogo Vila Verde ◽  
Marco de Curtis ◽  
Laura Librizzi
Keyword(s):  
Guinea Pig ◽  
Serum Albumin ◽  
Morphological Changes ◽  
Brain Parenchyma ◽  
Arterial Perfusion ◽  
Pig Brain ◽  
Bbb Permeability ◽  
The Brain ◽  
Guinea Pig Brain

Introduction: It has been proposed that seizures induce IL-1β biosynthesis in astrocytes and increase blood brain barrier (BBB) permeability, even without the presence of blood borne inflammatory molecules and leukocytes. In the present study we investigate if seizures induce morphological changes typically observed in activated glial cells. Moreover, we will test if serum albumin extravasation into the brain parenchyma exacerbates neuronal hyperexcitability by inducing astrocytic and microglial activation.Methods: Epileptiform seizure-like events (SLEs) were induced in limbic regions by arterial perfusion of bicuculline methiodide (BMI; 50 μM) in the in vitro isolated guinea pig brain preparation. Field potentials were recorded in both the hippocampal CA1 region and the medial entorhinal cortex. BBB permeability changes were assessed by analyzing extravasation of arterially perfused fluorescein isothiocyanate (FITC)–albumin. Morphological changes in astrocytes and microglia were evaluated with tridimensional reconstruction and Sholl analysis in the ventral CA1 area of the hippocampus following application of BMI with or without co-perfusion of human serum albumin.Results: BMI-induced SLE promoted morphological changes of both astrocytes and microglia cells into an activated phenotype, confirmed by the quantification of the number and length of their processes. Human-recombinant albumin extravasation, due to SLE-induced BBB impairment, worsened both SLE duration and the activated glia phenotype.Discussion: Our study provides the first direct evidence that SLE activity per se is able to promote the activation of astro- and microglial cells, as observed by their changes in phenotype, in brain regions involved in seizure generation; we also hypothesize that gliosis, significantly intensified by h-recombinant albumin extravasation from the bloodstream to the brain parenchyma due to SLE-induced BBB disruption, is responsible for seizure activity reinforcement.

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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