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Rudge JD. The Lipid Invasion Model: Growing Evidence for This New Explanation of Alzheimer's Disease. J Alzheimers Dis 2023:JAD221175. [PMID: 37302030 PMCID: PMC10357195 DOI: 10.3233/jad-221175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The Lipid Invasion Model (LIM) is a new hypothesis for Alzheimer's disease (AD) which argues that AD is a result of external lipid invasion to the brain, following damage to the blood-brain barrier (BBB). The LIM provides a comprehensive explanation of the observed neuropathologies associated with the disease, including the lipid irregularities first described by Alois Alzheimer himself, and accounts for the wide range of risk factors now identified with AD, all of which are also associated with damage to the BBB. This article summarizes the main arguments of the LIM, and new evidence and arguments in support of it. The LIM incorporates and extends the amyloid hypothesis, the current main explanation of the disease, but argues that the greatest cause of late-onset AD is not amyloid-β (Aβ) but bad cholesterol and free fatty acids, let into the brain by a damaged BBB. It suggests that the focus on Aβ is the reason why we have made so little progress in treating the disease in the last 30 years. As well as offering new perspectives for further research into the diagnosis, prevention, and treatment of AD, based on protecting and repairing the BBB, the LIM provides potential new insights into other neurodegenerative diseases such as Parkinson's disease and amyotrophic lateral sclerosis/motor neuron disease.
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Rudge JD. A New Hypothesis for Alzheimer’s Disease: The Lipid Invasion Model. J Alzheimers Dis Rep 2022; 6:129-161. [PMID: 35530118 PMCID: PMC9028744 DOI: 10.3233/adr-210299] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 02/05/2022] [Indexed: 02/07/2023] Open
Abstract
This paper proposes a new hypothesis for Alzheimer’s disease (AD)—the lipid invasion model. It argues that AD results from external influx of free fatty acids (FFAs) and lipid-rich lipoproteins into the brain, following disruption of the blood-brain barrier (BBB). The lipid invasion model explains how the influx of albumin-bound FFAs via a disrupted BBB induces bioenergetic changes and oxidative stress, stimulates microglia-driven neuroinflammation, and causes anterograde amnesia. It also explains how the influx of external lipoproteins, which are much larger and more lipid-rich, especially more cholesterol-rich, than those normally present in the brain, causes endosomal-lysosomal abnormalities and overproduction of the peptide amyloid-β (Aβ). This leads to the formation of amyloid plaques and neurofibrillary tangles, the most well-known hallmarks of AD. The lipid invasion model argues that a key role of the BBB is protecting the brain from external lipid access. It shows how the BBB can be damaged by excess Aβ, as well as by most other known risk factors for AD, including aging, apolipoprotein E4 (APOE4), and lifestyle factors such as hypertension, smoking, obesity, diabetes, chronic sleep deprivation, stress, and head injury. The lipid invasion model gives a new rationale for what we already know about AD, explaining its many associated risk factors and neuropathologies, including some that are less well-accounted for in other explanations of AD. It offers new insights and suggests new ways to prevent, detect, and treat this destructive disease and potentially other neurodegenerative diseases.
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Affiliation(s)
- Jonathan D’Arcy Rudge
- School of Biological Sciences, University of Reading, Reading, Berkshire, United Kingdom
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Wang Z, Yuan K, Ji YB, Li SX, Shi L, Wang Z, Zhou XY, Bao YP, Xie W, Han Y, Shi J, Lu L, Yan W, Chen WH. Alterations of the Gut Microbiota in Response to Total Sleep Deprivation and Recovery Sleep in Rats. Nat Sci Sleep 2022; 14:121-133. [PMID: 35115853 PMCID: PMC8800865 DOI: 10.2147/nss.s334985] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 12/31/2021] [Indexed: 12/13/2022] Open
Abstract
INTRODUCTION Accumulating evidence suggests that both sleep loss and gut dysbiosis can lead to metabolic disorders. However, less is known about the impact of total sleep deprivation (SD) and sleep recovery on the composition, function, and metabolic dynamics of the gut microbiota. METHODS Specific-pathogen free Sprague-Dawley rats were subjected to 48 h of SD with gentle handling and then allowed to recover for 1 week. Taxonomic profiles of fecal microbiota were obtained at baseline, 24 h of SD, 48 h of SD, and 1 week of recovery. We used 16S rRNA gene sequencing to analyze the gut microbial composition and function and further characterize microbiota-derived metabolites in rats. RESULTS The microbiota composition analysis revealed that gut microbial composition and metabolites did not change in the rats after 24 h of SD but were significantly altered after 48 h of SD. These changes were reversible after 1 week of sleep recovery. A functional analysis was performed based on Kyoto Encyclopedia of Genes and Genomes (KEGG) annotations, indicating that 19 KEGG pathways were significantly altered in the gut microbiota in SD rats. These functional changes occurred within 24 h of SD, were more apparent after 48 h of SD, and did not fully recover after 1 week of sleep recovery. CONCLUSION These results indicate that acute total SD leads to significant compositional and functional changes in the gut microbiota, and these changes are reversible.
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Affiliation(s)
- Zhong Wang
- Peking University Sixth Hospital, Peking University Institute of Mental Health, NHC Key Laboratory of Mental Health (Peking University), National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Peking University, Beijing, 100191, People's Republic of China
| | - Kai Yuan
- Peking University Sixth Hospital, Peking University Institute of Mental Health, NHC Key Laboratory of Mental Health (Peking University), National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Peking University, Beijing, 100191, People's Republic of China
| | - Yan-Bin Ji
- Department of Neurology, Qilu Hospital of Shandong University, Shandong University, Jinan, 250012, People's Republic of China
| | - Su-Xia Li
- National Institute on Drug Dependence and Beijing Key Laboratory of Drug Dependence, Peking University, Beijing, 100191, People's Republic of China
| | - Le Shi
- Peking University Sixth Hospital, Peking University Institute of Mental Health, NHC Key Laboratory of Mental Health (Peking University), National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Peking University, Beijing, 100191, People's Republic of China
| | - Zhe Wang
- Peking University Sixth Hospital, Peking University Institute of Mental Health, NHC Key Laboratory of Mental Health (Peking University), National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Peking University, Beijing, 100191, People's Republic of China
| | - Xin-Yu Zhou
- Department of Psychiatry, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, People's Republic of China
| | - Yan-Ping Bao
- National Institute on Drug Dependence and Beijing Key Laboratory of Drug Dependence, Peking University, Beijing, 100191, People's Republic of China
| | - Wen Xie
- Mental Health Center of Anhui Province, Hefei, 230032, People's Republic of China
| | - Ying Han
- National Institute on Drug Dependence and Beijing Key Laboratory of Drug Dependence, Peking University, Beijing, 100191, People's Republic of China
| | - Jie Shi
- National Institute on Drug Dependence and Beijing Key Laboratory of Drug Dependence, Peking University, Beijing, 100191, People's Republic of China
| | - Lin Lu
- Peking University Sixth Hospital, Peking University Institute of Mental Health, NHC Key Laboratory of Mental Health (Peking University), National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Peking University, Beijing, 100191, People's Republic of China.,National Institute on Drug Dependence and Beijing Key Laboratory of Drug Dependence, Peking University, Beijing, 100191, People's Republic of China.,Peking-Tsinghua Center for Life Sciences and PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, People's Republic of China
| | - Wei Yan
- Peking University Sixth Hospital, Peking University Institute of Mental Health, NHC Key Laboratory of Mental Health (Peking University), National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Peking University, Beijing, 100191, People's Republic of China
| | - Wen-Hao Chen
- Peking University Sixth Hospital, Peking University Institute of Mental Health, NHC Key Laboratory of Mental Health (Peking University), National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Peking University, Beijing, 100191, People's Republic of China
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Associations between fecal short-chain fatty acids and sleep continuity in older adults with insomnia symptoms. Sci Rep 2021; 11:4052. [PMID: 33603001 PMCID: PMC7893161 DOI: 10.1038/s41598-021-83389-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 02/02/2021] [Indexed: 12/18/2022] Open
Abstract
Insomnia is a disorder characterized by difficulty falling asleep and poor sleep continuity and is associated with increased risks for physical and cognitive decline. Insomnia with short sleep duration is considered the most biologically severe phenotype of the disorder. Evidence suggests that short-chain fatty acids (SCFAs), the main byproducts of fiber fermentation in the gut, may affect sleep via gut–brain communications. This study explores associations between SCFAs and sleep continuity and compares SCFA concentrations in short vs. normal sleep insomnia phenotypes in older adults. Fifty-nine participants with insomnia symptoms (≥ 65 years), completed 2 weeks of objective sleep monitoring (actigraphy), and were divided into short and normal sleep duration phenotypes via cluster analysis. Sleep measures included total sleep time (TST), sleep onset latency (SOL), sleep efficiency (SE), and wake after sleep onset (WASO). Stool samples were collected and fecal SCFA concentrations were determined by gas-chromatography-mass-spectrometry (GCMS). Higher concentrations of acetate, butyrate, and propionate, and total SCFAs, were associated with lower SE and longer SOL after controlling for Body Mass Index (BMI). Concentrations were higher in the short sleep duration phenotype. Age, BMI, TST, and SOL explained 40.7% of the variance in total SCFAs. Findings contribute to understanding pathways along the gut–brain axis and may lead to the use of SCFAs as biomarkers of insomnia phenotypes.
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Szentirmai É, Millican NS, Massie AR, Kapás L. Butyrate, a metabolite of intestinal bacteria, enhances sleep. Sci Rep 2019; 9:7035. [PMID: 31065013 PMCID: PMC6504874 DOI: 10.1038/s41598-019-43502-1] [Citation(s) in RCA: 98] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 04/25/2019] [Indexed: 12/17/2022] Open
Abstract
Emerging evidence suggests that the intestinal microbiota is a source of sleep-promoting signals. Bacterial metabolites and components of the bacterial cell wall are likely to provide important links between the intestinal commensal flora and sleep-generating mechanisms in the brain. Butyrate is a short-chain fatty acid produced by the intestinal bacteria by the fermentation of nondigestible polysaccharides. We tested the hypothesis that butyrate may serve as a bacterial-derived sleep-promoting signal. Oral gavage administration of tributyrin, a butyrate pro-drug, elicited an almost 50% increase in non-rapid-eye movement sleep (NREMS) in mice for 4 hours after the treatment. Similarly, intraportal injection of butyrate led to prompt and robust increases in NREMS in rats. In the first 6 hours after the butyrate injection, NREMS increased by 70%. Both the oral and intraportal administration of butyrate led to a significant drop in body temperature. Systemic subcutaneous or intraperitoneal injection of butyrate did not have any significant effect on sleep or body temperature. The results suggest that the sleep-inducing effects of butyrate are mediated by a sensory mechanism located in the liver and/or in the portal vein wall. Hepatoportal butyrate-sensitive mechanisms may play a role in sleep modulation by the intestinal microbiota.
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Affiliation(s)
- Éva Szentirmai
- Elson S. Floyd College of Medicine, Department of Biomedical Sciences, Washington State University, Spokane, Washington, United States of America.
- Sleep and Performance Research Center, Washington State University, Spokane, Washington, United States of America.
| | - Nicklaus S Millican
- Elson S. Floyd College of Medicine, Department of Biomedical Sciences, Washington State University, Spokane, Washington, United States of America
| | - Ashley R Massie
- Elson S. Floyd College of Medicine, Department of Biomedical Sciences, Washington State University, Spokane, Washington, United States of America
| | - Levente Kapás
- Elson S. Floyd College of Medicine, Department of Biomedical Sciences, Washington State University, Spokane, Washington, United States of America
- Sleep and Performance Research Center, Washington State University, Spokane, Washington, United States of America
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The role of the brown adipose tissue in β3-adrenergic receptor activation-induced sleep, metabolic and feeding responses. Sci Rep 2017; 7:958. [PMID: 28424466 PMCID: PMC5430421 DOI: 10.1038/s41598-017-01047-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 03/22/2017] [Indexed: 01/08/2023] Open
Abstract
Brown adipose tissue (BAT) is regulated by the sympathetic nervous system via β3-adrenergic receptors (β3-AR). Here we tested the hypothesis that pharmacological stimulation of β3-ARs leads to increased sleep in mice and if this change is BAT dependent. In wild-type (WT) animals, administration of CL-316,243, a selective β3-AR agonist, induced significant increases in non-rapid-eye movement sleep (NREMS) lasting for 4–10 h. Simultaneously, electroencephalographic slow-wave activity (SWA) was significantly decreased and body temperature was increased with a delay of 5–6 h. In uncoupling protein 1 (UCP-1) knockout mice, the middle and highest doses of the β3-AR agonist increased sleep and suppressed SWA, however, these effects were significantly attenuated and shorter-lasting as compared to WT animals. To determine if somnogenic signals arising from BAT in response to β3-AR stimulation are mediated by the sensory afferents of BAT, we tested the effects of CL-316,243 in mice with the chemical deafferentation of the intra-scapular BAT pads. Sleep responses to CL-316,243 were attenuated by ~50% in intra-BAT capsaicin-treated mice. Present findings indicate that the activation of BAT via β3-AR leads to increased sleep in mice and that this effect is dependent on the presence of UCP-1 protein and sleep responses require the intact sensory innervation of BAT.
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Abstract
Lactulose is one of the most frequently utilised agents in the treatment of constipation and hepatic encephalopathy because of its efficacy and good safety profile. The key to understanding the possible modes of action by which lactulose achieves its therapeutic effects in these disorders lies in certain pharmacological phenomena: (a) lactulose is a synthetic disaccharide that does not occur naturally; (b) there is no disaccharidase on the microvillus membrane of enterocytes in the human small intestine that hydrolyses lactulose; and (c) lactulose is not absorbed from the small intestine. Thus, the primary site of action is the colon in which lactulose is readily fermented by the colonic bacterial flora with the production of short-chain fatty acids and various gases. The purpose of this review is to focus on some pertinent basic aspects of the clinical pharmacology of lactulose and to discuss the possible mechanisms by which lactulose benefits patients with constipation and hepatic encephalopathy.
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Affiliation(s)
- M R Clausen
- Department of Medicine CA, Rigshospitalet, University of Copenhagen, Denmark
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Lai JC, Liang BB, Zhai S, Jarvi EJ, Lu DR. Brain mitochondrial citrate synthase and glutamate dehydrogenase: differential inhibition by fatty acyl coenzyme A derivatives. Metab Brain Dis 1994; 9:143-52. [PMID: 8072462 DOI: 10.1007/bf01999767] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Organic acidemia is found in several metabolic encephalopathies (e.g., hepatic and valproate encephalopathies, Reye's syndrome, and hereditary organic acidemias). Although fatty acids are known to be neurotoxic, the underlying mechanisms have not been fully elucidated. It has been hypothesized that one mechanism underlying fatty acid neurotoxicity is the selective inhibition of rate-limiting and/or regulated tricarboxylic acid (TCA) cycle and related enzymes by fatty acyl-coenzyme A (CoA) derivatives. To test the hypothesis, this study has examined the effects of several fatty acyl-CoAs on citrate synthase (CS) and glutamate dehydrogenase (GDH) in brain mitochondria. At levels higher than 100 microM, butyryl-CoA (BCoA; a short-chain acyl-CoA; IC50 approximately 640 microM), octanoyl-CoA (OCoA; a medium-chain acyl-CoA; IC50 approximately 380 microM), n-decanoyl-CoA (DCoA; a medium-chain acyl-CoA; IC50 approximately 436 microM), and palmitoyl-CoA (PCoA; a long-chain acyl-CoA; IC50 approximately 340 microM) inhibited brain mitochondrial CS activity in a concentration-related manner. However, these fatty acyl-CoAs were less effective inhibitors (IC50 values for OCoA, DCoA, and PCoA being approximately 1260, 420, and 720 microM, respectively) of brain mitochondrial GDH activity. Compared to the other three acyl-CoAs investigated, BCoA was a very poor inhibitor of GDH. These results demonstrate that fatty acyl-CoAs are inhibitors of brain mitochondrial CS and GDH activities only at pathological/toxicological levels. Thus, the fatty acyl-CoA inhibition of brain mitochondrial CS and GDH is unlikely to assume major pathophysiological and/or pathogenetic importance.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J C Lai
- Department of Pharmaceutical Sciences, College of Pharmacy, Idaho State University, Pocatello 93209-8334
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10
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Mitkov D. Short chain fatty acid-induced hyperventilation is due to PGF2-alpha. Prostaglandins Leukot Essent Fatty Acids 1993; 49:833-5. [PMID: 8302916 DOI: 10.1016/0952-3278(93)90205-b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
While studying the significance of the short chain fatty acids (SCFAs) in the pathogenesis of hyperventilation, we have found that experimental rabbits injected with SCFA sodium salt (4 mmol/kg b.wt) develop hyperventilation 20 min later. This hyperventilation results in a decrease of PCO2 in the arterial blood from 32.05 +/- 1.18 to 24.55 +/- 0.83 (p < 0.001). The SCFAs also bring about pronounced mixed alkalosis. The prostaglandin F2-alpha (PGF2-alpha) in both the arterial and venous blood of rabbits increased significantly after treatment with SCFAs salts. If the rabbits are pretreated with indomethacin (10 mg/kg), the SCFAs do not cause hyperventilation. Therefore we can conclude, that the SCFAs bring about hyperventilation through an increase in the PGF2-alpha synthesis.
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Affiliation(s)
- D Mitkov
- Department of Pathophysiology, Faculty of Medicine, Plovdiv, Bulgaria
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11
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Abstract
1. Administration of the endogenous compound gamma-hydroxybutyric acid (GHB) can induce a sleep-like state in experimental animals and, indeed, it has been used as a general anaesthetic in clinical medicine. 2. Although GHB appears to be a CNS depressant, there is evidence it possesses epileptiform activity resembling petit mal epilepsy. In the brain GHB is evidently derived from GABA, the final step being catalyzed by succinic semialdehyde reductase, a cytosolic NADP(+)-dependent enzyme. 3. Two different oxidoreductases, GHB dehydrogenase and hydroxyacid-ketoacid dehydrogenase, acting independently, are responsible for the reverse reaction when GHB is being metabolically inactivated. 4. Brain contains a Na(+)-dependent GHB uptake system which exhibits two components, one with a Km of 46 microM and the other with a Km of 325 microM. GHB also binds to receptor sites in brain homogenates and exhibits two distinct affinities. One binding site displays a Kd of 95 nM whereas the second site has a Kd of 16 microM. Binding to both sites is inhibited in the presence of NCS-382, a GHB receptor antagonist. 5. GHB might play a role as a neurotransmitter, particularly being involved in influencing dopamine release in the substantia nigra.
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Affiliation(s)
- G Tunnicliff
- Laboratory of Neurochemistry, Indiana University School of Medicine, Evansville 47712
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Lai JC, Cooper AJ. Neurotoxicity of ammonia and fatty acids: differential inhibition of mitochondrial dehydrogenases by ammonia and fatty acyl coenzyme A derivatives. Neurochem Res 1991; 16:795-803. [PMID: 1944769 DOI: 10.1007/bf00965689] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In several metabolic encephalopathies, hyperammonemia and organic acidemia are consistently found. Ammonia and fatty acids (FAs) are neurotoxic: previous workers have shown that ammonia and FAs can act singly, in combination, or synergistically, in inducing coma in experimental animals. However, the biochemical mechanisms underlying the neurotoxicity of ammonia and FAs have not been fully elucidated. FAs are normally converted to their corresponding CoA derivatives (CoAs) once they enter cells and it is known that these fatty acyl CoAs can alter intermediary metabolism. The present study was initiated to determine the effects of ammonia and fatty acyl CoAs on brain mitochondrial dehydrogenases. At a pathophysiological level (2 mM), ammonia is a potent inhibitor of brain mitochondrial alpha-ketoglutarate dehydrogenase complex (KGDHC). Only at toxicological levels (10-20 mM) does ammonia inhibit brain mitochondrial NAD(+)- and NADP(+)- linked isocitrate dehydrogenase (NAD-ICDH, NADP-ICDH), and NAD(+)-linked malate dehydrogenase (MDH) and liver mitochondrial NAD-ICDH. Butyryl- (BCoA), octanoyl- (OCoA), and palmitoyl (PCoA) CoA were potent inhibitors of brain mitochondrial KGDHC, with IC50 values of 11, 20, and 25 microM, respectively; moreover, the inhibitory effect of fatty acyl CoAs and ammonia were additive. At levels of 250 microM or higher, both OCoA (IC50 = 1.15 mM) and PCoA (IC50 = 470 microM) inhibit brain mitochondrial NADP-ICDH; only at higher levels (0.5-1 mM) does BCoA inhibit this enzyme (by 30-45%). Much less sensitive than KGDHC and NADP-ICDH, brain mitochondrial NAD-ICDH is only inhibited by 1 mM BCoA, OCoA, and PCoA by 22%, 35%, and 44%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J C Lai
- Department of Biochemistry, Cornell University Medical College, New York, NY 10021
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White RP, el-Bauomy AM, Wood WB. Capric acid as a potent dilator of canine vessels in vitro and in vivo. GENERAL PHARMACOLOGY 1991; 22:741-8. [PMID: 1936910 DOI: 10.1016/0306-3623(91)90089-o] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
1. Pharmacodynamic effects of even numbered saturated fatty acids, C4-C16, were determined on isolated canine basilar and femoral arteries precontracted with PGF2 alpha. 2. The fatty acids relaxed the precontracted vessels. 3. The basilar artery was the most sensitive vessel and caprate (C10) was the most potent acid with an EC50 of 49 microM. 4. The relaxant effect was endothelium-independent. 5. Contractions elicited by norepinephrine, serotonin, and U46619 were also inhibited. 6. Caprate (C10) given intra-arterially increased femoral blood flow in a dose-dependent manner and the dose computed to increase blood flow 50% was 1.27 microM/kg.
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Affiliation(s)
- R P White
- Department of Pharmacology, University of Tennessee Medical Center, Memphis 38163
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Mortensen PB, Holtug K, Bonnén H, Clausen MR. The degradation of amino acids, proteins, and blood to short-chain fatty acids in colon is prevented by lactulose. Gastroenterology 1990; 98:353-60. [PMID: 2295390 DOI: 10.1016/0016-5085(90)90825-l] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Short-chain (C2-C5) fatty acids account for 60%-70% of the anions in the colon. Acetate (C2) is nontoxic in contrast to C(3)4-C5 fatty acids (propionate, butyrate, isobutyrate, valerate, and isovalerate), which induce coma in animals and may be important in the pathogenesis of hepatic coma in humans. An in-vitro fecal incubation system was used to map out short-chain fatty acid production in the presence of lactulose, amino acids, albumin, or blood. Albumin and blood increased production of all C2-C5 fatty acids. In contrast, lactulose was converted to acetate only and increased fecal acidity. The degradation of amino acids, albumin, and blood to short-chain fatty acids was completely inhibited by 10-25 mM lactulose. This was caused mainly by the acidifying effect of lactulose. pH-independent inhibition of blood and amino acid degradation to short-chain fatty acids required concentrations of lactulose exceeding 50-100 mM. Thus, the effect of lactulose in the treatment of hepatic coma may be related to its rapid fermentation into organic acids at rates exceeding colonic buffering capacity. This probably reduces formation of toxic fatty acids and ammonia from amino acids, polypeptides, and blood in the colon.
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Affiliation(s)
- P B Mortensen
- Department of Medicine A, Rigshospitalet, University of Copenhagen, Denmark
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Bach AC, Frey A, Lutz O. Clinical and experimental effects of medium-chain-triglyceride-based fat Emulsions—A review. Clin Nutr 1989; 8:223-35. [PMID: 16837294 DOI: 10.1016/0261-5614(89)90032-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/1988] [Accepted: 01/23/1989] [Indexed: 11/17/2022]
Abstract
Although total parenteral nutrition usually includes lipids, traditional long-chain triglyceride (LCT) emulsions do not fulfil the energy-providing role allotted to them. The special properties of medium-chain triglycerides (MCTs) and fatty acids led to replacement of part of the infused LCTs by MCTs. The present review shows that: 1. MCT/LCT emulsions are as safe and as well tolerated as the traditional emulsions, and contain enough essential fatty acids to meet patients' needs. 2. Relative to LCT emulsions, MCT/LCT emulsions exhibit a number of differences: * More rapid clearance from the circulation. Lipoprotein lipase and hepatic lipase hydrolyse them preferentially. * Decreased liability to be deposited as fat, in adipose tissue and liver. They do not overload the reticula-endothelial system, which may better preserve its capacity to phagocytose bacteria. * More rapid and complete oxidation, Faster energy provision for all tissues, even though a small part is dissipated in a clinical non-relevant thermogenesis and by o-oxidation. They are ketogenic if infused alone. * Concomitant administration of glucose does not influence their clearance rate, only slightly decreases their oxidation rate, but prevents the acceleration of ketogenesis. Two other properties of MCT/LCT emulsions are probable, though not confirmed: * exchanges of lipids between artificial fat particles and plasma lipoproteins may be less with these emulsions than with LCTs, though it is not yet known what effect diminished disturbance of lipoprotein homeostasis has on the organism. * The nitrogen-sparing effect of a TPN regimen containing MCTs/LCTs seems better than a regimen providing LCTs only.
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Affiliation(s)
- A C Bach
- Laboratoire de la Clinique Médicale A, Hôpital Civil, 67091 Strasbourg Cedex, France
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Mortensen PB, Rasmussen HS, Holtug K. Lactulose detoxifies in vitro short-chain fatty acid production in colonic contents induced by blood: implications for hepatic coma. Gastroenterology 1988; 94:750-4. [PMID: 3338644 DOI: 10.1016/0016-5085(88)90250-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Short-chain (C2-C6) fatty acids constitute the major anions of colonic contents. Acetate is nontoxic in contrast to C(3)4-C6 fatty acids, which induce coma in animals and have been reported to be of importance in the development of hepatic coma in humans. An in vitro fecal incubation system was used to demonstrate how blood, hemoglobin, albumin, lactulose, galactose, fructose, and glucose influence short-chain fatty acid production in the colon. Blood, hemoglobin, and albumin caused increased production of all C2-C6 fatty acids, with the most pronounced increase (fourfold) in C4-C6 fatty acids. Lactulose was converted to acetate only, as were its monosaccharide components, D-galactose and D-fructose. In assays incubated with blood, the production of C4-C6 fatty acids was completely inhibited by lactulose, D-galactose, D-fructose, and D-glucose, respectively, whereas the production of acetate was increased. Lactulose thus "detoxified" the profile of short-chain fatty acids produced in the presence of blood and proteins, indicating that colonic fermentative bacteria prefer lactulose to blood when both substrates are available. The effect of lactulose in the treatment of hepatic coma caused by episodes of gastrointestinal bleeding may therefore be due to a shift in bacterial metabolism from blood or proteins, or both, to lactulose in the colon, resulting in a simultaneous reduction in toxic nitrogenous and organic acid products.
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Affiliation(s)
- P B Mortensen
- Department of Medicine, Hvidovre Hospital, University of Copenhagen, Denmark
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Kim CS, Keizer RF, Pritchard JB. 2,4-Dichlorophenoxyacetic acid intoxication increases its accumulation within the brain. Brain Res 1988; 440:216-26. [PMID: 3359212 DOI: 10.1016/0006-8993(88)90989-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Exposure to the phenoxyacetic acid herbicides has been shown to produce neurotoxicity. Therefore, adult mice (pregnant) and rabbits were used to examine the accumulation and regional distribution of 2,4-dichlorophenoxyacetic acid (2,4-D) within the brain following intraperitoneal injection of a low dose (0.2-0.4 mg/kg) of [14C]2,4-D. Controls, i.e. animals not previously exposed to 2,4-D, were compared to animals acutely pretreated with higher doses (40-160 mg/kg) of unlabeled 2,4-D. Both autoradiography and direct tissue analysis showed that in control animals brain levels were much lower than plasma in both adult (approximately 4%) and fetus (approximately 8%). In both species, small variations were seen between the brain regions, with brainstem and cerebellum somewhat higher than other regions. Pretreatment with unlabeled 2,4-D caused a 5- to 10-fold increase in accumulation of [14C]2,4-D in both mice and rabbits. On the other hand, 2-deoxyglucose entry into the brain was not altered by 2,4-D pretreatment. Thus, there was no generalized increase in blood-brain barrier permeability. Instead, increased 2,4-D accumulation appeared to be caused by its decreased elimination from the brain. Pretreatment with 40 mg/kg led to a CSF 2,4-D concentration of 10 microM, a concentration sufficient to inhibit choroid plexus transport of [14C]2,4-D by nearly 50% in vitro. These results suggest that exposure to organic anions like 2,4-D may lead to the retention of potentially toxic anions within the CNS via competitive inhibition of the organic anion transport system which normally reduces their brain and CSF concentrations to very low levels.
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Affiliation(s)
- C S Kim
- Biological Sciences Research Center, University of North Carolina School of Medicine, Chapel Hill 27514
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Swartzentruber MS, Harris RA. Inhibition of metabolic processes by coenzyme-A-sequestering aromatic acids. Prevention by para-chloro- and para-nitrobenzoic acids. Biochem Pharmacol 1987; 36:3147-53. [PMID: 3117062 DOI: 10.1016/0006-2952(87)90625-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Octanoate, salicylate, valproic acid, p-octyl-, p-nitro-, and p-chlorobenzoic acids were effective inhibitors of benzoic acid activation to benzoyl-CoA by mitochondrial extracts. p-Aminobenzoic acid was much less effective. Of these compounds, only salicylate and p-nitrobenzoic acid were not activated to their respective CoA esters. Salicylate, p-chloro- and p-nitrobenzoic acids effectively prevented inhibition of glucose synthesis and alpha-keto[1-14C]isovalerate oxidation by valproic acid, p-octyl-, and p-aminobenzoic acids, p-Octyl- and p-aminobenzoic acids greatly depleted hepatocyte free CoA and acetyl-CoA contents and increased the content of acid-insoluble and acid-soluble CoA esters respectively. p-Chloro- and p-nitrobenzoic acids prevented the sequestration of CoA as p-octylbenzoyl-CoA or p-aminobenzoyl-CoA in hepatocytes incubated with these compounds. p-Chlorobenzoic acid not only prevented but also reversed the inhibition of gluconeogenesis in hepatocytes incubated with p-octylbenzoic acid. These results suggest that p-chloro- or p-nitrobenzoic acids might be effectively used to reverse some of the hepatotoxic effects of the CoA esters of valproic acid or naturally-occurring organic acids, such as those which accumulate in Reye's Syndrome or organic acidemias.
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Affiliation(s)
- M S Swartzentruber
- Department of Biochemistry, Indiana University School of Medicine, Indianapolis 46223
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Drewes LR, Leino RL. Neuron-specific mitochondrial degeneration induced by hyperammonemia and octanoic acidemia. Brain Res 1985; 340:211-8. [PMID: 4027650 DOI: 10.1016/0006-8993(85)90916-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The neuropathological consequences of acute exposure to the neurotoxicants ammonia and octanoic acid were investigated with the isolated, perfused canine brain preparation. After 1 h of combined hyperammonemia and octanoic acidemia, ultrastructural changes were apparent in all brain regions examined. The cell bodies of neurons were the primary sites of these alterations. Neuronal mitochondria were distended, and the lamellae of the mitochondrial cristae were separated. In some cases the lamellae had completely dispersed, leaving only matrix remnants. Mitochondria of adjacent astrocytes appeared normal. Thus, a characteristic population of brain mitochondria is selectively vulnerable to a combination of hyperammonemia and octanoic acidemia and may be related to the biochemical mechanisms underlying encephalopathies of hepatic origin.
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Kintner D, Fitzpatrick JH, Louie JA, Gilboe DD. Cerebral oxygen and energy metabolism during and after 30 minutes of moderate hypoxia. THE AMERICAN JOURNAL OF PHYSIOLOGY 1984; 247:E475-82. [PMID: 6496668 DOI: 10.1152/ajpendo.1984.247.4.e475] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Sixty-four isolated canine brain preparations were subjected to either 15 or 30 min of perfusion with blood equilibrated at either Pao2 30 mmHg or Pao2 40 mmHg followed by up to 60 min of reoxygenation with blood having a Pao2 greater than 100 mmHg. Pao2 30 mmHg perfusion decreased oxygen availability and the cerebral metabolic rate for oxygen (CMRo2) to 44 and 49% of normal, respectively, whereas Pao2 40 mmHg perfusion decreased oxygen availability and CMRo2 to 64 and 70% of normal, respectively. Creatine phosphate was markedly decreased (0.6 and 4% of normal, respectively) and ATP was only slightly decreased (73 and 90% of normal, respectively) in these preparations during the hypoxic period. Although ATP returned to normal during the reoxygenation period in both groups, creatine phosphate and CMRo2 returned to normal only in the Pao2 40 mmHg preparations. In brains perfused at various Pao2 levels for periods ranging from 6 to 30 min, the total oxygen deficit (the cumulative difference over time between normal and actual CMRo2) rather than tissue lactate levels appeared to influence the restoration of CMRo2 to normal following hypoxia. An oxygen deficit in excess of 25 mumol/g precluded return to a normal CMRo2 following reoxygenation.(ABSTRACT TRUNCATED AT 250 WORDS)
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Abstract
The organic anion transport system in the choroid plexus is responsible for excretion of organic anions from brain to plasma. Disruption of this system could then result in accumulation of encephalopathic acyl groups in brain in a variety of metabolic disorders. Octanoate produced inhibition of this transport system associated with disruption of mitochondrial ultrastructure. Octanoylcarnitine and L-carnitine had no effect. These compounds represent those seen in the medium chain acyl CoA dehydrogenase deficiency. L-Carnitine may be useful for protecting the central nervous system through formation of the non-toxic acylcarnitine in this and other metabolic disorders characterized by accumulation of encephalopathic metabolites.
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Abstract
The effects of gamma-hydroxybutyrate (GHB) upon sleep wakefulness patterns and quantified nuchal muscle activity were examined in the rabbit in a dose-response paradigm (25-1,000 mg/kg). Relative to control (saline) values, there was no facilitation of sleep onset or epileptogenic activity at any of the dosages studied. However, at the higher GHB concentrations, slow wave sleep and tonic muscle activity were enhanced and a high amplitude, slow activity was superimposed on background EEG patterns. The highest concentration of GHB (1,000 mg/kg) was associated with depression of motor activity. An enhancement of paradoxical sleep observed at lower GHB levels in other species occurred in attenuated form in the rabbit. The results indicate dose-related effects on both sleep and motor activation in the rabbit, but the absence of seizure activity for the concentrations of GHB studied.
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Billington D, Osmundsen H, Sherratt HS. Mechanisms of the metabolic disturbances caused by hypoglycin and by pent-4-enoic acid. In vivo studies. Biochem Pharmacol 1978; 27:2891-900. [PMID: 736982 DOI: 10.1016/0006-2952(78)90205-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Trauner D, Sweetman L, Holm J, Kulovich S, Nyhan WL. Biochemical correlates of illness and recovery in Reye's syndrome. Ann Neurol 1977; 2:238-41. [PMID: 617569 DOI: 10.1002/ana.410020310] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Eight patients with Reye's syndrome were followed through the course of their disease with serial measurements of serum concentrations of ammonia, short-chain organic acids, and amino acids. Correlations were made between clinical status and biochemical alterations. Elevated short-chain fatty acids, hyperammonemia, and hyperaminoacidemia were found in all patients studied. Clinical improvement appeared to correlate most closely with clearance of short-chain fatty acids from the serum. These observations suggest that the clinical symptoms are at least in part related to organic acidemia and that treatment directed toward the rapid clearance of these compounds from the system is reasonable.
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Abstract
A floppy infant is described who has an inborn error of organic acid metabolism due to defective activity of the enzyme beta-methylcrotonyl CoA carboxylase. She presented with hyperventilation, hypotonia, and regression of motor and intellectual development. She responded to treatment with biotin.
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Yamada T, Tucker RP, Kooi KA. Fourteen and six c/sec positive bursts in comatose patients. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1976; 40:645-53. [PMID: 57050 DOI: 10.1016/0013-4694(76)90139-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Of ten patients with Reye's syndrome, there were five with stage II or III coma where EEGs revealed 14 c/sec positive bursts in a background of diffuse delta waves. Positive bursts disappeared upon EEG improvement in two survivors and when the EEG became nearly isoelectric in two other patients. Although 14 and 6 c/sec positive bursts are seen commonly during sleep in normal young persons, their occurence in association with diffuse delta waves in acutely ill, comatose patients has been rarely reported. It is not certain whether the present findings should be regarded as selective preservation of a type of sleep pattern or whether there are special factors that enhance positive bursts in stage II or III coma of Reye's syndrome.
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Marcus RJ, Winters WD, Hultin E. Neuropharmacological effects induced by butanol, 4-hydroxybutyrate, 4-mercaptobutyric acid thiolactone, tetrahydrofuran, pyrrolidine, 2-deoxy-d-glucose and related substances in the rat. Neuropharmacology 1976; 15:29-38. [PMID: 1256638 DOI: 10.1016/0028-3908(76)90094-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Speciale SG, Friedman AH. Gamma-butyrolactone sleep: A 24-hour rhythm paralleling normal sleep in the rat and CNS amine changes. Pharmacol Biochem Behav 1975; 3:761-4. [PMID: 1208618 DOI: 10.1016/0091-3057(75)90103-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The duration of sleep induced by a fixed dose of gamma-butyrolactone (GBL) (350 mg/kg, IP) FOllows the normal circadian sleep pattern of rats. GBL sleep duration is maximal at 1800 hr and minimal at 0600 hr. CNS amine changes are not extensive, but when normal sleep is anticipated, GBL treatment increases dopamine and serotonin levels and decreases norepinephrine levels.
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Abstract
The oral administration of short (C(6)) and medium (C(8) and (C(10)) chain triglycerides produced no clinical or electroencephalographic changes in patients with cirrhosis of the liver. Arterial ammonia levels were also monitored in these patients and showed no significant change after medium chain triglycerides. It was concluded that medium chain triglycerides, known to be of potential value in the treatment of malabsorption in patients with cirrhosis, are not clinically contraindicated, even in patients with evidence of hepatic encephalopathy.
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Jouvet M. The role of monoamines and acetylcholine-containing neurons in the regulation of the sleep-waking cycle. ERGEBNISSE DER PHYSIOLOGIE, BIOLOGISCHEN CHEMIE UND EXPERIMENTELLEN PHARMAKOLOGIE 1972; 64:166-307. [PMID: 4403272 DOI: 10.1007/3-540-05462-6_2] [Citation(s) in RCA: 80] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Matsuzaki M. Differential effects of sodium butyrate and physostigmine upon the activities of para-sleep in acute brain stem preparations. Brain Res 1969; 13:247-65. [PMID: 4306272 DOI: 10.1016/0006-8993(69)90285-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Marcus RJ, Winters WD, Mori K, Spooner CE. EEG and behavioral comparison of the effects of gamma-hydroxybutyrate, gamma-butyrolactone and short chain fatty acids in the rat. INTERNATIONAL JOURNAL OF NEUROPHARMACOLOGY 1967; 6:175-85. [PMID: 6037525 DOI: 10.1016/0028-3908(67)90003-2] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Tanaka K, Budd MA, Efron ML, Isselbacher KJ. Isovaleric acidemia: a new genetic defect of leucine metabolism. Proc Natl Acad Sci U S A 1966; 56:236-42. [PMID: 5229850 PMCID: PMC285701 DOI: 10.1073/pnas.56.1.236] [Citation(s) in RCA: 220] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
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Tokizane T. Studies on the paradoxical phase of sleep in the cat. PROGRESS IN BRAIN RESEARCH 1966; 21:230-68. [PMID: 5917282 DOI: 10.1016/s0079-6123(08)64233-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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MATSUZAKI M, TAKAGI H, TOKIZANE T. Paradoxical Phase of Sleep: Its Artificial Induction in the Cat by Sodium Butyrate. Science 1964; 146:1328-9. [PMID: 14207466 DOI: 10.1126/science.146.3649.1328] [Citation(s) in RCA: 46] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In intact cats and cats with the mesencephalon transected the intravenous administration of sodium butyrate and related compounds (0.3 to 3 millimoles per kilogram) induced the so-called paradoxical phase of the sleep, as indicated by electroencephalograms, electromyograms, heart rate, respiration, and eye movement. This phase appeared after a 3- to 5-minute period of sleep characterized by slow waves, and continued for 4 to 15 minutes.
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HOLMQUIST B, INGVAR DH. Effects of short chain fatty acid anions upon cortical blood flow and EEG in cats. Cell Mol Life Sci 1957; 13:331-3. [PMID: 13461885 DOI: 10.1007/bf02296830] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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