Characterization of alpha-keto acid transport across blood-brain barrier in rats

1983 ◽  
Vol 245 (3) ◽  
pp. E253-E260 ◽  
Author(s):  
A. R. Conn ◽  
D. I. Fell ◽  
R. D. Steele
Keyword(s):  
Blood Brain Barrier ◽  
Ketone Bodies ◽  
Reciprocal Inhibition ◽  
Brain Barrier ◽  
Brain Uptake ◽  
Sprague Dawley ◽  
Monocarboxylic Acids ◽  
Blood Brain ◽  
Keto Acids ◽  
The Brain

The transport of keto acids, monocarboxylic acids, and ketone bodies was studied in barbiturate-anesthetized, adult male Sprague-Dawley rats. [1-14C]propionate and D-3-[3-14C]hydroxybutyrate were found to cross the blood-brain barrier with brain uptake indexes of 43.53 and 7.10%, respectively. Transport of both of these substrates was saturable, with the values of transport Km being 2.03 and 6.54 mM, respectively. A Ki of 0.68 mM was derived from competition data measuring the uptake of [1-14C]alpha-ketoisocaproate in the presence of unlabeled alpha-ketobutyrate. This finding and results from classical inhibition studies support competition for transport of keto acids for a common carrier. The brain uptake of [1-14C]propionate was significantly reduced by keto acids and ketone bodies and the transport of D-3-[3-14C]hydroxybutyrate was significantly inhibited by unlabeled monocarboxylic acids, keto acids, and acetoacetate. Evidence for competitive transport of alpha-keto acids, monocarboxylic acids, and ketone bodies is presented in the form of classical double-reciprocal inhibition plots and of labeled monocarboxylic acids and ketone bodies by an increasing concentration of unlabeled alpha-ketoisocaproate, the latter method yielding Ki values of 0.29 and 0.63 mM, respectively. The brain uptake of labeled propionate was inhibited by unlabeled D-3-hydroxybutyrate. A Ki of 6.43 mM, derived from this data, approximated the Km of transport of D-3-hydroxybutyrate, suggesting that ketone bodies and monocarboxylic acids compete for transport via the same carrier that is operative for keto acids.

Regional blood-brain barrier transport of ketone bodies in portacaval-shunted rats

1991 ◽  
Vol 261 (5) ◽  
pp. E647-E652 ◽  
Author(s):  
R. A. Hawkins ◽  
A. M. Mans
Keyword(s):  
Blood Brain Barrier ◽  
Ketone Bodies ◽  
Monocarboxylic Acid ◽  
Brain Barrier ◽  
Substantial Contribution ◽  
Sham Operation ◽  
Acid System ◽  
Portacaval Shunting ◽  
Blood Brain ◽  
The Brain

The permeability of the blood-brain barrier to ketone bodies, substrates of the monocarboxylic acid carrier, was measured in individual brain structures of control and portacaval-shunted rats. The measurements were made 5-7 wk after the shunt or sham operation by quantitative autoradiography. Portacaval shunting caused the permeability to ketone bodies to decrease throughout the brain by approximately 70%. There was a striking change in the transport pattern in the cerebral cortex; deeper cortical layers were affected more than superficial layers. Ketone body consumption by brain is limited by the transport capacity of the monocarboxylic acid system. Therefore, in portacaval-shunted rats the very low activity of this system makes it unlikely that ketone bodies can make a substantial contribution during situations such as fasting. Likewise, other substrates of the monocarboxylic acid system, e.g., lactate and pyruvate, will have greatly restricted access to the brain after portacaval shunting. If the carrier is symmetrical, another consequence will be that exit of endogenously produced lactate will be retarded.

Transport of alpha-keto analogues of amino acids across blood-brain barrier in rats

1982 ◽  
Vol 243 (4) ◽  
pp. E272-E277
Author(s):  
A. R. Conn ◽  
R. D. Steele
Keyword(s):  
Blood Brain Barrier ◽  
Transport System ◽  
Ketone Bodies ◽  
Brain Barrier ◽  
Sodium Pentobarbital ◽  
Keto Acid ◽  
Dual Isotope ◽  
Common System ◽  
Blood Brain ◽  
Keto Acids

The transport of 14C-labeled alpha-keto acids across the blood-brain barrier (BBB) was studied in rats anesthetized with sodium pentobarbital using a modification of a single-injection dual-isotope technique. alpha-Keto acids were found to cross the BBB via a saturable carrier-mediated transport system that may be specific based on lack of inhibition by glucose, isoleucine, and ketone bodies on the uptake of tracer levels of 14C-labeled alpha-keto acids. alpha-Ketobutyrate and alpha-keto-gamma-methiolbutyrate, both straight chain keto acids, and alpha-ketoisocaproate, a branched-chain keto acid, appeared to cross the barrier by a common carrier based on cross-inhibition studies. Aromatic keto acids had no effect on the uptake of tracer levels of these 14C-keto acids. The Km of transport of alpha-ketobutyrate, alpha-ketoisocaproate, and alpha-keto-gamma-methiolbutyrate, was 0.11, 0.60, and 0.33 mM, respectively. The corresponding Vmax was 15.7, 73.3, and 30.2 nmol . g-1 . min-1. Phenylpyruvate was found not to cross the BBB. Inhibition of brain uptake of alpha-keto acids by propionate and pyruvate, and not by DL-beta-hydroxybutyrate suggests that alpha-keto acids and monocarboxylic acids are transported either via a common system independent of ketone bodies or share an affinity with a monocarboxylic acid and an alpha-keto acid transport system.

Metabolic fuel and amino acid transport into the brain in experimental hypothyroidism

1990 ◽  
Vol 122 (2) ◽  
pp. 156-162 ◽  
Author(s):  
Arshag D. Mooradian
Keyword(s):  
Amino Acids ◽  
Blood Brain Barrier ◽  
Brain Barrier ◽  
Transport Systems ◽  
Brain Uptake ◽  
Acid Transport ◽  
Brain Extraction ◽  
Blood Brain ◽  
Brain Uptake Index ◽  
The Brain

Abstract The effect of hypothyroidism in the adult rat on blood-brain barrier and muscle transport of hexoses, neutral amino acids, basic amino acids, monocarboxylic acids, and ketone bodies was examined using single arterial injection-tissue sampling technique. The cerebral blood flow and brain extraction of 3H2O (internal reference substance) was not altered in 3-month-old hypothyroid rats maintained on methimazole, 0.025% in the drinking water, for 7 weeks. The brain uptake index of D-β-hydroxybutyrate was significantly reduced in hypothyroid rats (2.4 ± 0.3 vs 4.6 ± 0.6% p<0.001). Hypothyroid rats given thyroid hormone replacement therapy had normal brain uptake of D-β-hydroxybutyrate (4.4 ± 0.8%). The brain uptake index of butyrate was also significantly reduced in hypothyroid rats (39.3 ± 2.1 vs 47.2 ± 0.74%, p<0.001). The brain uptake index of other test substances and muscle uptake of nutrients examined were not altered in hypothyroid rats. These studies indicate that of the four transport systems examined in two tissues, the blood-brain barrier monocarboxylic acid transport system is most susceptible to the hypothyroidism-induced changes.

scholarly journals Ketone Bodies Promote Amyloid-β1–40 Clearance in a Human in Vitro Blood–Brain Barrier Model

2020 ◽  
Vol 21 (3) ◽  
pp. 934 ◽  
Author(s):  
Romain Versele ◽  
Mariangela Corsi ◽  
Andrea Fuso ◽  
Emmanuel Sevin ◽  
Rita Businaro ◽  
...  
Keyword(s):  
Blood Brain Barrier ◽  
Ketone Bodies ◽  
Amyloid Β ◽  
Brain Barrier ◽  
Therapeutic Approaches ◽  
Protein Levels ◽  
Blood Brain ◽  
Aβ Clearance ◽  
The Brain

Alzheimer’s disease (AD) is characterized by the abnormal accumulation of amyloid-β (Aβ) peptides in the brain. The pathological process has not yet been clarified, although dysfunctional transport of Aβ across the blood–brain barrier (BBB) appears to be integral to disease development. At present, no effective therapeutic treatment against AD exists, and the adoption of a ketogenic diet (KD) or ketone body (KB) supplements have been investigated as potential new therapeutic approaches. Despite experimental evidence supporting the hypothesis that KBs reduce the Aβ load in the AD brain, little information is available about the effect of KBs on BBB and their effect on Aβ transport. Therefore, we used a human in vitro BBB model, brain-like endothelial cells (BLECs), to investigate the effect of KBs on the BBB and on Aβ transport. Our results show that KBs do not modify BBB integrity and do not cause toxicity to BLECs. Furthermore, the presence of KBs in the culture media was combined with higher MCT1 and GLUT1 protein levels in BLECs. In addition, KBs significantly enhanced the protein levels of LRP1, P-gp, and PICALM, described to be involved in Aβ clearance. Finally, the combined use of KBs promotes Aβ efflux across the BBB. Inhibition experiments demonstrated the involvement of LRP1 and P-gp in the efflux. This work provides evidence that KBs promote Aβ clearance from the brain to blood in addition to exciting perspectives for studying the use of KBs in therapeutic approaches.

Blood-brain barrier permeability of glucose and ketone bodies during short-term starvation in humans

1995 ◽  
Vol 268 (6) ◽  
pp. E1161-E1166 ◽  
Author(s):  
S. G. Hasselbalch ◽  
G. M. Knudsen ◽  
J. Jakobsen ◽  
L. P. Hageman ◽  
S. Holm ◽  
...  
Keyword(s):  
Glucose Transport ◽  
Blood Brain Barrier ◽  
Plasma Glucose ◽  
Ketone Bodies ◽  
Brain Barrier ◽  
Affinity Constant ◽  
Indicator Method ◽  
Blood Brain ◽  
The Brain ◽  
Expected Increase

The blood-brain barrier (BBB) permeability for glucose and beta-hydroxybutyrate (beta-OHB) was studied by the intravenous double-indicator method in nine healthy subjects before and after 3.5 days of starvation. In fasting, mean arterial plasma glucose decreased and arterial concentration of beta-OHB increased, whereas cerebral blood flow remained unchanged. The permeability-surface area product for BBB glucose transport from blood to brain (PS1) increased by 55 +/- 31%, whereas no significant change in the permeability from brain back to blood (PS2) was found. PS1 for beta-OHB remained constant during starvation. The expected increase in PS1 due to the lower plasma glucose concentration was calculated to be 22% using previous estimates of maximal transport velocity and Michaelis-Menten affinity constant for glucose transport. The determined increase was thus 33% higher than the expected increase and can only be partially explained by the decrease in plasma glucose. It is concluded that a modest upregulation of glucose transport across the BBB takes place after starvation. Brain transport of beta-OHB did not decrease as expected from the largely increased beta-OHB arterial level. This might be interpreted as an increase in brain transport of beta-OHB, which could be caused by induction mechanisms, but the large nonsaturable component of beta-OHB transport makes such a conclusion difficult. However, beta-OHB blood concentration and beta-OHB influx into the brain increased by > 10 times. This implies that the influx of ketone bodies into the brain is largely determined by the amount of ketones present in the blood, and any condition in which ketonemia occurs will lead to an increased ketone influx.

scholarly journals Impact of P-Glycoprotein Inhibition and Lipopolysaccharide Administration on Blood-Brain Barrier Transport of Colistin in Mice

2010 ◽  
Vol 55 (2) ◽  
pp. 502-507 ◽  
Author(s):  
Liang Jin ◽  
Jian Li ◽  
Roger L. Nation ◽  
Joseph A. Nicolazzo
Keyword(s):  
Blood Brain Barrier ◽  
Systemic Inflammation ◽  
Brain Barrier ◽  
Brain Uptake ◽  
P Glycoprotein ◽  
Blood Brain ◽  
Colistin Sulfate ◽  
The Brain ◽  
Concentration Ratios

ABSTRACTThe aim of this study was to investigate the factors limiting the blood-brain barrier (BBB) transport of colistin in healthy mice and to assess the impact of systemic inflammation on the transport of this antibiotic across the BBB. Colistin sulfate (40 mg/kg) was administered subcutaneously to Swiss outbred mice as single and multiple doses to determine any relationship between brain uptake and plasma concentrations of colistin. To assess the effect of P-glycoprotein (P-gp) on BBB transport, colistin sulfate (5 mg/kg) was concomitantly administered intravenously with PSC833 or GF120918 (10 mg/kg). Systemic inflammation was induced by three intraperitoneal injections of lipopolysaccharide (LPS; 3 mg/kg), and BBB transport of colistin was subsequently measured following subcutaneous administration and by anin situbrain perfusion. The brain uptake of colistin was low following single and multiple subcutaneous doses, with brain-to-plasma concentration ratios ranging between 0.021 and 0.037, and this was not significantly enhanced by coadministration of GF120918 or PSC833 (P> 0.05). LPS significantly increased the brain uptake of subcutaneously administered colistin with area under the brain concentration time curve (AUCbrain) values of 11.7 ± 2.7 μg·h/g and 4.0 ± 0.3 μg·h/g for LPS- and saline-treated mice, respectively (mean ± standard deviation). Similarly,in situperfusion of colistin led to higher antibiotic brain concentrations in LPS-treated animals than in saline-treated animals, with colistin brain-to-perfusate concentration ratios of 0.019 ± 0.001 and 0.014 ± 0.001, respectively. This study demonstrates that the BBB transport of colistin is negligible in healthy mice; however, brain concentrations of colistin can be significantly enhanced during systemic inflammation, as might be observed in infected patients.

Induction processes in blood-brain transfer of ketone bodies during starvation

1975 ◽  
Vol 229 (5) ◽  
pp. 1165-1169 ◽  
Author(s):  
A Gjedde ◽  
C Crone
Keyword(s):  
Blood Brain Barrier ◽  
Ketone Bodies ◽  
Transport Rate ◽  
Starvation Period ◽  
Brain Uptake ◽  
Uptake Mechanism ◽  
Blood Brain ◽  
Brain Uptake Index ◽  
The Brain ◽  
Total Concentrations

Fed and starved rats were studied on successive days during a 5-day starvation period. The ability of ketone bodies to pass the blood-brain barrier was estimated by single common carotid injections of labeled ketone bodies and water, and results were expressed as the ratio between the normalized activities of tracers in tissue and blood, the brain uptake index (BUI). BUI of D-3-hydroxybutyrate and acetoacetate decreased as their total concentrations increased in the injectate bolus: BUI of D-3-hydroxybutyrate decreased significantly from 8% at 0.2 mM to 3--4% at 20.2 mM in fed rats and from 11.5% at 0.2 mM to 6% at 20.2 mM in starved rats, indicating saturation of the uptake mechanism. The BUI of both ketone bodies increased significantly with increasing duration of starvation, indicating adaptation to ketonemia. Enzymatic kinetics explained the uptake behavior of D-3-hydroxybutyrate in both fed and starved rats and involved a rise of Km and Vmax during starvation consistent with a doubling of the transport rate at the degree of ketonemia found in starved rats. The uptake of glucose was not influenced by starvation or ketonemia.

scholarly journals Species-Dependent Blood-Brain Barrier Disruption of Lipopolysaccharide: Amelioration by ColistinIn VitroandIn Vivo

2013 ◽  
Vol 57 (9) ◽  
pp. 4336-4342 ◽  
Author(s):  
Liang Jin ◽  
Roger L. Nation ◽  
Jian Li ◽  
Joseph A. Nicolazzo
Keyword(s):  
Blood Brain Barrier ◽  
Bacterial Species ◽  
Specific Effect ◽  
Brain Barrier ◽  
Brain Uptake ◽  
Necrosis Factor Alpha ◽  
Content Type ◽  
Blood Brain ◽  
The Impact ◽  
The Brain

ABSTRACTThe aim of this study was to usein vitroandin vivomodels to assess the impact of lipopolysaccharide (LPS) from two different bacterial species on blood-brain barrier (BBB) integrity and brain uptake of colistin. Following repeated administration of LPS fromPseudomonas aeruginosa, the brain-to-plasma ratio of [14C]sucrose in Swiss outbred mice was not significantly increased. Furthermore, while the brain uptake of colistin in mice increased 3-fold following administration of LPS fromSalmonella enterica, LPS fromP. aeruginosahad no significant effect on colistin brain uptake. This apparent species-dependent effect did not appear to correlate with differences in plasma cytokine levels, as the concentrations of tumor necrosis factor alpha and interleukin-6 following administration of each LPS were not different (P> 0.05). To clarify whether this species-specific effect of LPS was due to direct effects on the BBB, human brain capillary endothelial (hCMEC/D3) cells were treated with LPS fromP. aeruginosaorS. entericaand claudin-5 expression was measured by Western blotting.S. entericaLPS significantly (P< 0.05) reduced claudin-5 expression at a concentration of 7.5 μg/ml. In contrast,P. aeruginosaLPS decreased (P< 0.05) claudin-5 expression only at the highest concentration tested (i.e., 30 μg/ml). Coadministration of therapeutic concentrations of colistin ameliorated theS. entericaLPS-induced reduction in claudin-5 expression in hCMEC/D3 cells and the perturbation in BBB function in mice. This study demonstrates that BBB disruption induced by LPS is species dependent, at least betweenP. aeruginosaandS. enterica, and can be ameliorated by colistin.

Effects of the Ketogenic Diet on the Blood-Brain Barrier

2016 ◽  
Author(s):  
Manoj Banjara ◽  
Damir Janigro
Keyword(s):  
Blood Brain Barrier ◽  
Ketogenic Diet ◽  
Prolonged Exposure ◽  
Ketone Bodies ◽  
Brain Barrier ◽  
Capillary Endothelium ◽  
Brain Uptake ◽  
Metabolic Demand ◽  
Therapeutic Benefits ◽  
Blood Brain

Ketone bodies (KBs) are always present in the blood, and their levels increase after high-fat diet intake, prolonged exercise, or extended fasting. Thus, one can predict effects on the brain capillary endothelium from high levels of ketones in the blood. Prolonged exposure of blood-brain barrier (BBB) endothelial cells to KBs induces expression of monocarboxylate transporters and enhances brain uptake of KBs. In addition, cell migration and expression of gap junction proteins are up-regulated by KBs. Thus, beneficial effects of the ketogenic diet may depend on increased brain uptake of KBs to match metabolic demand and repair of a disrupted BBB. As the effects of KBs on the BBB and their transport mechanisms across the BBB are better understood, it will be possible to develop alternative strategies to optimize the therapeutic benefits of KBs for brain disorders where the BBB is compromised.

scholarly journals Brain Bioavailability of Human Intravenous Immunoglobulin and its Transport through the Murine Blood–Brain Barrier

2013 ◽  
Vol 33 (12) ◽  
pp. 1983-1992 ◽  
Author(s):  
Isabelle St-Amour ◽  
Isabelle Paré ◽  
Wael Alata ◽  
Katherine Coulombe ◽  
Cassandra Ringuette-Goulet ◽  
...  
Keyword(s):  
Intravenous Immunoglobulin ◽  
Blood Brain Barrier ◽  
Elimination Rate ◽  
Therapeutic Targets ◽  
Brain Barrier ◽  
Enzyme Linked Immunosorbent Assay ◽  
Brain Uptake ◽  
Blood Brain ◽  
Qualitative Methodologies ◽  
The Brain

Intravenous immunoglobulin (IVIg) is currently evaluated in clinical trials for the treatment of various disorders of the central nervous system. To assess its capacity to reach central therapeutic targets, the brain bioavailability of IVIg must be determined. We thus quantified the passage of IVIg through the blood–brain barrier (BBB) of C57Bl/6 mice using complementary quantitative and qualitative methodologies. As determined by enzyme-linked immunosorbent assay, a small proportion of systemically injected IVIg was detected in the brain of mice (0.009±0.001% of injected dose in the cortex) whereas immunostaining revealed localization mainly within microvessels and less frequently in neurons. Pharmacokinetic analyses evidenced a low elimination rate constant (0.0053  per hour) in the cortex, consistent with accumulation within cerebral tissue. In situ cerebral perfusion experiments revealed that a fraction of IVIg crossed the BBB without causing leakage. A dose-dependent decrease of brain uptake was consistent with a saturable blood-to-brain transport mechanism. Finally, brain uptake of IVIg after a subchronic treatment was similar in the 3xTg-AD mouse model of Alzheimer disease compared with nontransgenic controls. In summary, our results provide evidence of BBB passage and bioavailability of IVIg into the brain in the absence of BBB leakage and in sufficient concentration to interact with the therapeutic targets.

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