PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Choline”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1975

Inhibition of choline transport into human erythrocytes by choline mustard aziridinium ion.

Acetylcholine mustard aziridinium ion inhibited the transport of [3H]choline into human erythrocytes. Treatment of the erythrocytes with 1 X 10(-4) M tetraethylpyrophosphate prevented the inhibition of [3H]choline transport by acetylcholine mustard aziridinium ion. Hydrolyzed acetylcholine mustard aziridinium ion inhibited choline transport both in the presence and absence of 1 X 10(-4) M tetraethylpyrophosphate. The product of hydrolysis was equipotent with acetylcholine mustard in its ability to inhibit choline transport; incubation of this product with sodium thiosulfate prevented inhibition of choline transport thereby indicating the presence of an aziridinium ion. The hydrolysis product is likely to be choline mustard aziridinium ion. Results on the efflux of [3H]choline from erythrocytes in the presence of the proposed choline mustard aziridinium ion showed that the mustard moiety was transported into the red cells on the choline carrier. The rate of efflux of [3H]choline produced by choline mustard aziridinium ion was 55% of that produced by the same concentration of choline. It is concluded that acetylcholinesterase (EC 3.1.1.7) of red cells rapidly hydrolyzes acetylcholine mustard aziridinium ion to acetate and choline mustard aziridinium and the latter compound can act as a potent inhibitor of choline transport. This finding would indicate that the hemicholinium-like toxicity of acetylcholine mustard in the mouse is due to the formation of choline mustard aziridinium ion.

Biological Transport↗
PubMed1976

Equilibrium constants under physiological conditions for the reactions of choline kinase and the hydrolysis of phosphorylcholine to choline and inorganic phosphate.

The observed equilibrium constants (Kobs) of the P-choline hydrolysis reaction have been determined under physiological conditions of temperature (38 degrees) and ionic strength (0.25 M) and physiological ranges of pH and free [Mg2+]. Using sigma and square brackets to indicate total concentrations: (see article.) The value of Kobs has been found to be relatively insensitive to variations in pH and free [Mg2+]. At pH 7.0 and taking the standard state of liquid water to have unit activity ([H2O] = 1), Kobs = 26.6 M at free [Mg2+] = 0 [epsilon G0obs = -2.03 kcal/mol(-8.48 kJ/mol)], 26.8 M at free [Mg2+] = 10(-3) M, and 28.4 M at free [Mg2+] = 10(-2) M. At pH 8.0, Kobs = 18.8 M at free [Mg2+] = 0, 19.2 M at free [Mg2+] = 10(-3), and 22.2 M at free [Mg2+] = 10(-2) M. These values apply only to situations where choline and Pi concentrations are both relatively low (such as the conditions found in most tissues). At higher concentrations of phosphate and choline, the value of Kobs becomes significantly increased since HPO42- complexes choline weakly (association constant = 3.3 M-1). The value of K at 38 degrees and I = 0.25 M is calculated to be 16.4 +/- 0.3 M [epsilonG0 = 1.73 kcal/mol (-7.23 kJ/mol)]. The K for the P-choline hydrolysis reaction has been combined with the K for the ATP hydrolysis reaction determined previously under physiological conditions to calculate a value of 4.95 X 10(-3 M [deltaG0 j.28 kcal/mol (13.7 kJ/mol] for the K of the choline kinase reaction (EC 2.7.1.32), an important step in phospholipid metabolism: (see article.) Likewise, values for Kobs for the choline kinase reaction at 38 degrees, pH 7.0, and I = 0.25 M have been calculated to be 5.76 X 10(4) [deltaG0OBS = -6.77 KCAL/MOL (-28.3 KJ/mol)] at [Mg2+] = 0; 1.24 X 10(4) [deltaG0obs = -5.82 kcal/mol (-24.4 kJ/mol)] at [Mg2+] = 10(-3) M and 8.05 X 10(3) [delta G0obs = -5.56 kcal/mol (-23.3 kJ/mol)] at [Mg2+ = 10(-2) M. Attempts to determine the Kobs of the choline kinase reaction directly were unsuccessful because of the high value of the constant. The results indicate that in contrast to the high deltaG0obs for the hydrolysis of the ester bond of acetylcholine, the deltaG0obs for the hydrolysis of the ester bond of P-choline is quite low, among the lowest known for phosphate ester bonds of biological interest.

Binding Sites↗
PubMed1977

Trans-synaptic induction of adrenomedullary tyrosine hydroxylase activity by choline: evidence that choline administration can increase cholinergic transmission.

Twenty-four hours after rats receive choline chloride (20 mmol/kg, by stomach tube) the activity of tyrosine hydroxylase [tyrosine 3-monooxygenase; L-tyrosine, tetrahydropteridine:oxygen oxidoreductase (3-hydroxylating), EC 1.14.16.2] increases by 31% within adrenomedullary chromaffin cells. This treatment also causes major elevations in the levels of choline and acetylcholine within the adrenal gland; however, acetylcholine levels return to normal by 16 hr after the choline is given. The daily administration of 10 or 20 mmol/kg of choline for 4 days elevates adrenal tyrosine hydroxylase activity by 29% or 51%, respectively. Such increases in tyrosine hydroxylase activity are not observed in animals given ammonium chloride, another basic chloride-containing compound, by stomach tube or in animals treated with cycloheximide, an inhibitor of adrenal protein synthesis. They are also absent in denervated adrenals. These observations demonstrate that the increase in presynaptic acetylcholine levels produced by giving animals the neurotransmitter's precursor (choline) can be associated with parallel changes in the transmission of signals across cholinergic synapses, probably because more of the transmitter is released per nerve impulse.

Adrenal Medulla↗
PubMed1977

Transport and oxidation of choline by liver mitochondria.

1. Rapid choline oxidation and the onset of P(i)-induced swelling by liver mitochondria, incubated in a sucrose medium at or above pH7.0, required the addition of both P(i) and an uncoupling agent. Below pH7.0, P(i) alone was required for rapid choline oxidation and swelling. 2. Choline oxidation was inhibited by each of several reagents that also inhibited P(i)-induced swelling under similar conditions of incubation, including EGTA, mersalyl, Mg(2+), the Ca(2+)-ionophore A23187, rotenone and nupercaine. None of these reagents had any significant effect on the rate of choline oxidation by sonicated mitochondria. There was therefore a close correlation between the conditions required for rapid choline oxidation and for P(i)-induced swelling to occur, suggesting that in the absence of mitochondrial swelling the rate of choline oxidation is regulated by the rate of choline transport across the mitochondrial membrane. 3. Respiratory-chain inhibitors, uncoupling agents (at pH6.5) and ionophore A23187 caused a loss of endogenous Ca(2+) from mitochondria, whereas nupercaine and Mg(2+) had no significant effect on the Ca(2+) content. Inhibition of choline oxidation and mitochondrial swelling by ionophore A23187 was reversed by adding Ca(2+), but not by Mg(2+). It is concluded that added P(i) promotes the Ca(2+)-dependent activation of mitochondrial membrane phospholipase activity in respiring mitochondria, causing an increase in the permeability of the mitochondrial inner membrane to choline and therefore enabling rapid choline oxidation to occur. Nupercaine and Mg(2+) appear to block choline oxidation and swelling by inhibiting phospholipase activity. 4. Choline was oxidized slowly by tightly coupled mitochondria largely depleted of their endogenous adenine nucleotides, suggesting that these compounds are not directly concerned in the regulation of choline oxidation. 5. The results are discussed in relation to the possible mechanism of choline transport across the mitochondrial membrane in vivo and the influence of this process on the pathways of choline metabolism in the liver.

Adenine Nucleotides↗
PubMed1979

A possible mechanism for the increased oxidation of choline after chronic ethanol ingestion.

An attempt has been made to determine the location of the site at which the metabolism of ethanol interacts with that of choline to produce an increase in the oxidation of choline. The first enzyme in the oxidation pathway for choline, choline dehydrogenase, was assayed using a newly developed spectrophotometric assay and freshly isolated intact rat liver mitochondria. No changes were observed in either 'apparent' V or the 'apparent' Km values of choline dehydrogenase for choline after ethanol ingestion. However, when the choline oxidase system was assayed, a 28% decrease in 'apparent' Km for choline and a 53% increase in 'apparent' V was observed. The effects of ATP on choline oxidase were studied further, and a 29.4% decrease was observed in mitochondrial ATP levels from freshly isolated mitochondria from the ethanol-treated rats. In vitro aging of mitochondria further decreased the level of ATP, and the rate of decrease was considerably faster during the first hour in the mitochondria from the ethanol-treated animals. The decreases in ATP from both control and experimental mitochondria were accompanied by increases in choline oxidase activity. The initial decrease in ATP was correlated with an increase in mitochondrial ATPase activity which may be related to an increase in mitochondria Mg2+. Because chronic ethanol ingestion has resulted in decreased oxidation rates of succinate and beta-hydroxybutyrate while at the same time increasing the oxidation rates of choline, the studies reported here suggest that the effect of chronic ethanol ingestion is primarily on a step that is unique to choline and which probably exists prior to the electron transport chain.

Adenosine Triphosphatases↗
PubMed1976

Effect of ethanol ingestion on choline phosphotransferase and phosphatidyl ethanolamine methyltransferase activities in liver microsomes.

The effect of ethanol ingestion on choline phosphotransferase and phosphatidyl ethanolamine methyltransferase activities, the two enzymes involved in phosphatidyl choline biosynthesis in liver microsomes, has been investigated. Female rats were fed a 5% ethanol-liquid diet containing amino acids, minerals, vitamins, with and without choline, for 2, 6 and 10 weeks. Control animals were pair-fed the same isocaloric diet with 5% sucrose with and without choline. Ethanol administration with or without dietary choline stimulated significantly (P less than 0.001) the specific activities of phosphatidyl ethanolamine methyltransferase in liver microsomes in the animals fed 5% ethanol for 2, 6, and 10 weeks, when compared to those control animals pair-fed the isocaloric diet with or without choline. Ethanol administration with or without dietary choline for 2 weeks stimulated significantly (P less than 0.02) the specific activities of choline phosphotransferase. The specific activities of phosphatidyl ethanolamine methyltransferase continued to increase in the liver microsomes from the animals in which dietary choline was omitted for 2, 6, and 10 weeks in the sucrose controls and alcohol-fed animals. Ethanol administration stimulates significantly (P less than 0.001) the phosphatidyl ethanolamine methyltransferase specific activities in liver microsomes of animals fed the liquid diet with dietary omission of choline and methionine for 2 weeks.

Alcohol Drinking↗
PubMed1976

Phospholipid synthesis in mammary tissue. Choline and ethanolamine kinases: kinetic evidence for two discrete active sites.

Choline and ethanolamine kinases are located in the high speed supernatant of lactating bovine mammary gland. Maximum activities of choline and ethanolamine kinases were observed at pH 9.2 and 8.0, respectively, with the rate of ethanolamine phosphorylation being 1/15 that of choline phosphorylation. Activation energies of 29 joules (Q10--1.5) and 31 joules (Q10 = 1.5) were calculated between 3.4 and 31.3 C for choline kinase and ethanolamine kinase, respectively. Above 31.3 C, the Arrhenius plot deviated from linearity for both enzymes, suggesting that denaturation was occurring. An apparent Km of 0.25 mM for choline was obtained for choline kinase activity. The apparent Km of ethanolamine kinase for ethanolamine was unusually high (17 mM), the activity was not linear with increasing protein concentration. Activity was tripled and the Km decreased to 2.5 mM when the enzyme preparation was washed with butanol: benzene mixture, suggesting the presence of an endogenous competitive inhibitor(s), with respect to ethanolamine. Choline kinase was not affected by the solvent wash. Substrate competition studies revealed that choline kinase was slightly inhibited competitively by ethanolamine (apparent Ki = 19-21 mM), whereas choline was a potent competitive inhibitor of ethanolamine kinase (apparent Ki = 0.33-0.50 mM). The results indicated that these two kinase activities were mediated by two distinct active sites, possibly on a single protein. The significance of choline in the regulation of phosphatidylethanolamine synthesis is discussed.

Animals↗
PubMed1975

[A spectrophotometric method for the determination of serum cholinesterase variants with succinyl choline as substrate (author's transl)].

A simple and rapid method for the estimation of the hydrolysis of succinyl choline by serum cholinesterase variants is described. Succinyl choline, as substrate for the enzyme assay, has many advantages over other substrates (acetyl choline, benzoyl choline and butyryl choline) which have no clinical application. Choline, the hydrolytic product of succinyl choline, is oxidized to betaine aldehyde by choline oxidase (EC 1.1.99.1), a rat liver mitochondrial preparation; this is coupled to the reduction of cytochrome c which is measured at 550 nm. Fifty normal sera (UU), 17 heterozygous (UA) and 8 atypical (AA) were tested with this method, and on the basis of resistance to dibucaine (Cinchocain; Kalow, W. & Genest, K. (1957) Canad. J. Biochem. Physiol. 35, 339-346) inhibition, three distinct groups could be established using succinyl choline as substrate. These results are comparable with the standard optical method of Kalow & Genest (cf. above) using benzoyl choline as substrate.

Anesthesia↗
PubMedDate not supplied

Effect of ethanol on the renal excretion and metabolism of choline in the isolated perfused rat kidney.

The isolated perfused rat kidney was used to investigate the effect of ethanol on the renal excretion and metabolism of choline. Choline at an initial perfusate concentration of 2.8 mM, with tracer amounts of [methyl-14C]choline, was recirculated through kidneys and radioactivity measured in perfusate, urine, and kidney. 14C-Choline and its metabolites were identified by chromatographic and electrophoretic procedures. Tubular excretion of choline was demonstrated and a transport maximum (Tm) of 1.6 mumol/kidney/min was reached at a choline perfusate concentration of 1.2 mM. Addition of 50 mM ethanol resulted in a 56% increase in the choline Tm and 100 mM ethanol decreased the choline Tm by 25%. The rate of loss of 14C-choline from the perfusate was increased by the lower ethanol concentration and decreased by the higher ethanol concentration. Ethanol at both concentrations diminished the amount of 14C remaining in the kidney. 14C-Betaine was the major choline metabolite and the only 14C-metabolite present in perfusate or urine. Addition of either 50 or 100 mM ethanol increased both glomerular filtration rate and urine volume.

Animals↗
PubMed2026

Source- and Solubility-specific Choline, Gut Microbiota, and Dyslipidemia Risk: Trimethylamine N-oxide-associated and Non-trimethylamine N-oxide-Associated Patterns in a Prospective Cohort Study.

BACKGROUND: Dietary choline, a major precursor of the gut microbial metabolite trimethylamine N-oxide (TMAO), is implicated in dyslipidemia risk; however, source- and form-specific associations and interactions with gut microbiota remain unclear. OBJECTIVES: The aim of this study was to examine longitudinal associations of source- and form-specific dietary choline with plasma TMAO and dyslipidemia and to identify gut microbiota interactions. METHODS: Using data from the China Health and Nutrition Survey (2018-2023), dietary intake was assessed via 3 consecutive 24-h recalls in this prospective cohort study. Two-level generalized linear mixed-effects models were applied in 4828 adults (mean age: 55.9 ± 12.6 y, 56.6% females) to assess choline-dyslipidemia associations. Choline-TMAO and TMAO-dyslipidemia analyses were conducted in 1091 participants free of dyslipidemia at baseline. Among 7169 adults with gut microbiome data, Least Absolute Selection and Shrinkage Operator and logistic regression identified lipid-associated gut genera; TMAO relationships were examined in a subset of 693 participants. RESULTS: Higher intakes of total [Q4 compared with Q1: odds ratio (OR) = 1.261; 95% confidence interval (CI): 1.007, 1.580], red meat-derived (OR: 1.753; 95% CI: 1.196, 2.568), and lipid-soluble choline (OR: 1.304; 95% CI: 1.047, 1.624) were associated with higher risk of elevated low-density lipoprotein cholesterol (LDL cholesterol), whereas vegetable-derived choline was inversely associated. Egg-derived and lipid-soluble choline were positively associated with plasma TMAO, which was prospectively associated with 5-y incident dyslipidemia (Q4 compared with Q1-OR: 1.620; 95% CI: 1.047, 2.509), elevated LDL cholesterol (Q3 compared with Q1-OR: 2.478; 95% CI: 1.187, 5.174), and hypertriglyceridemia (Q4 compared with Q1-OR: 1.829; 95% CI: 1.028, 3.225). Three TMAO-associated genera were identified: Lachnospiraceae and Phascolarctobacterium as pro-risk taxa and Turicibacter as protective. The adverse LDLcholesterol association of egg-derived choline was observed exclusively in Phascolarctobacterium-enriched individuals. CONCLUSIONS: Dietary choline source and solubility differentially associated with dyslipidemia risk through TMAO-associated and non-TMAO-associated patterns, with gut microbiota as key modulators.

Humans↗
PubMed1977

Lecithin consumption raises serum-free-choline levels.

Consumption of choline by rats sequentially increases serum-choline, brain-choline, and brain-acetylcholine concentrations. In man consumption of choline increases in levels in the serum and cerebrospinal fluid; its administration is an effective way of treating tardive dyskinesia. We found that oral lecithin is considerably more effective in raising human serum-choline levels than an equivalent quantity of choline chloride. 30 minutes after ingestion of choline chloride (2-3 g free base), serum-choline levels rose by 86% and returned to normal values within 4 hours; 1 hour after lecithin ingestion, these levels rose by 265% and remained significantly raised for 12 hours. Lecithin may therefore be the method of choice for accelerating acetylcholine synthesis by increasing the availability of choline, its precursor in the blood.

Acetylcholine↗
PubMed1975

Lipd profiles of plasma lipoproteins of fasted and fed normal and choline-deficient rats.

Three major density classes of lipoproteins and a residual protein (d greater than 1.21) were isolated by ultracentrifugation from plasma of fasted, fed normal, and choline-deficient rats. Lipid extracts were obtained from total plasma and the various density classes of lipoproteins, and each extract was examined in detail by thin layer and gas chromatographies. The results indicated essentially identical compositions of molecular species of phosphatidyl choline, which suggested their rapid equilibration among the different plasma lipoprotein classes. In contrast, the molecular species of the triacylglycerols and cholesteryl esters showed significant differences among the chylomicrons, very low and low, and high density lipoproteins, which excluded the possibility of their ready equilibration in vivo. Omission of choline from diet resulted in a sharp and statistically significant decrease in all lipid components of the very low and low density lipoproteins with 2 days. After 10 days of choline deficiency, the lipid levels of chylomicrons and very low and low density lipoproteins were ca. one-half the levels found in the choline supplemented animals, and there were discernible distortions in their lipid composition. Reintroduction of choline led to a prompt return to normal levels and lipid composition of both chylomicron and very low and low density lipoprotein fractions. The lack of equilibration of the triacylglycerols among the lipoprotein classes under normal conditions and in choline deficiency demonstrates an as yet unrecgnized source of compartmentation of plasma lipids.

Body Weight↗
PubMed2026

Gut bacteria associated with an atherogenic TMAO-dietary pattern and choline-rich foods among aging women.

BACKGROUND AND AIMS: Choline can be metabolized by gut bacteria with a choline utilization gene, CutC, as identified through genome sequencing studies. This metabolism produces trimethylamine, the precursor to the atherosclerotic metabolite trimethylamine N-oxide (TMAO). Bacterial species involved in trimethylamine production in free-living humans have been under-investigated. We previously developed the TMAO dietary pattern (TMAO-DP), which is predictive of plasma TMAO and choline. We evaluated associations between the TMAO-DP, dietary choline, and choline-rich foods (fish, red meat, eggs) with the abundance of species with CutC. We also explored associations between the TMAO-DP and microbiome diversity. METHODS AND RESULTS: This cross-sectional analysis included 287 women (mean age = 79.6 years) from the Women's Health Initiative. Diet was assessed using a food frequency questionnaire. Stool samples were collected and the V3-V4 regions of the 16S ribosomal RNA were sequenced. Adjusted linear regression models evaluated associations between the TMAO-DP with the CLR-transformed abundance of species with CutC and with alpha-diversity indices. For beta-diversity, PERMANOVA examined measures of Aitchison distance within and between quartiles of the TMAO-DP. Associations between dietary choline and choline-rich foods with the abundance of species were evaluated using linear regression. The TMAO-DP was associated with Acidaminococcus intestini [Beta (SE): 0.23 (0.09), p-value = 0.035] and Desulfovibrio desulfuricans [Beta (SE): 0.16 (0.6), p = 0.035]. The TMAO-DP was not associated with alpha- or beta-diversity. CONCLUSION: This study provides evidence that Desulfovibrio desulfuricans and Acidaminococcus intestini, two species identified as having CutC by gene sequencing, may produce trimethylamine from diet in free-living women.

Humans↗