Mechanisms of folate homeostasis

Steinberg, Stephen E.

doi:10.1152/ajpgi.1984.246.4.g319

Cited by 62 publications

(62 citation statements)

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“…Total hepatic folate levels was not changed, but there occurred a shift of H4PteGlu to its 5-methyl derivative in these rats. This suggests that a phenomenon known as the methylfolate trap (18)(19)(20) might occur, and a folate homeostasis has also been maintained in these rats as well as in normal animals (21). This evidence suggests that a 5 methylfolylpolyglutamate might be accumulated in the liver of rats which have impared histidine catabolism and fed a restricted methionine level.…”

Section: Discussionmentioning

confidence: 96%

Effect of a histidine-excess diet on a tetrahydrofolylpolyglutamate pattern in rat liver.

Kohashi

Takahashi

Iwai

1990

Journal of Nutritional Science and Vitaminology, J Nutr Sci Vit

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SummaryThe effect of a histidine-excess diet on the hepatic folylpol yglutamate pattern in rat was studied. Rats were fed ad libitum 9.7 casein basal diets with 0.6% methionine (controls) or the basal diets with 3.5% histidine. The average daily weight gain and the food intake in histidine-supplemented rats (His-rats) did not significantly differ from controls. The liver weight in His-rats, however, was 50% higher than controls.Hepatic methyltetrahydropteroylpentaglutamate (CH3 H4PteGlu5), and tetrahydropteroylmonoglutamate concentrations in His rats was 5.7 and 2-fold higher than controls, respectively. The tetrahyd ropteroylpentaglutamate (H4PteGlu5) concentration in the His-rats was 74% lower than controls. Considering the homeostasis of folate cofactors in tissues, these results suggest that the hepatic regeneration systems for H4PteGlu5 in His-rats might be repressed and an apparent methylfolate trap might be attained rather on a pteroylpentaglutamate level than a monoglutamate level, and that the activity for catabolizing the excess histidine might exceed the regenerating activity for folate cofactors. Key Words excess-histidine, liver, tetrahydrofolylpolyglutamate, methyl tetrahydrofolylpolyglutamate, methyl trapThe growth retardation, liver enlargement, and stimulation of cholestero genesis has been observed in rats fed excess-histidine diets (1). There are a few reports on the effect of an excess-histidine diet on folate metabolism.An in vivo catabolism of histidine through the one-carbon pool is mediated by folate-dependent enzymes (2) and modulated by methionine metabolism (3-5). It is now accepted that folylpolyglutamates rather than the monoglutamate are the acceptors and donors of one-carbon units in amino acid and nucleotide metabolism

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Section: Discussionmentioning

confidence: 96%

Effect of a histidine-excess diet on a tetrahydrofolylpolyglutamate pattern in rat liver.

Kohashi

Takahashi

Iwai

1990

Journal of Nutritional Science and Vitaminology, J Nutr Sci Vit

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“…5-MTHF-Glu 1 is reabsorbed from the renal proximal tubules via receptor-mediated endocytosis and contributes to plasma 5-MTHF-Glu 1 levels. Due to the GGH enzyme in plasma, folylpolyglutamate is not found in plasma (3).…”

Section: Folate Transport 231 Transport In Plasmamentioning

confidence: 96%

Folate and homocysteine metabolisms and their roles in the biochemical basis of neuropsychiatry

Coşar¹,

İpçioğlu²,

Özcan³

et al. 2014

Turk J Med Sci

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This work aims to study recent climatic oscillations and their influence on sedimentation in the Ria de Vigo, a coastal embayment in Galicia, NW Spain. It is based on the study of clay mineral assemblages, in conjunction with other proxies (granulometric, geochemical, geochronological and microfaunal), in the core KSGX 24. A Benthic Foraminifera High Productivity (BFHP) proxy was used to determine changes in the flux of organic matter (OM) at the bottom of the study area. Total organic carbon (TOC) content is not a suitable proxy to estimate changes in the past supply of OM due to diagenetic processes. The sedimentation was finest in 3 sections: ~ 230-214 cm, ~ 185-73 cm and ~ 20-0 cm. These muddy sections are characterised, in general, by higher proportions of detrital minerals, concentrations of several chemical elements related to lithogenic sources and BFHP values. In addition, these sections are impoverished in carbonates, Ca, Sr and La when compared with the layers with the highest sand content. The clay mineral assemblage of the studied site, characterised by the dominance of illite, intermediate concentrations of kaolinite and minor amounts of smectite and chlorite, reveals the prevalence of a typical temperate humid climate in the last 3 ka BP, the estimated age for the core base. However, the quantities of illite and chlorite increase in the muddy layers. The characteristics of these muddy layers were interpreted as representing relatively cold climatic oscillations associated with the strengthening of northerly winds and the prevalence of an upwelling regime corresponding to well-known periods, such as the first cold period of the Upper Holocene (~ 2.9 ka cal BP), the Dark Ages (between ~ 2.2 -1.2 ka cal BP) and the Little Ice Age (~ 0.6 ka cal BP).

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“…This might have been indirectly caused by fasting during the ex eriment. It is generally accepted that, after the i testinal absorption of FA, there is a short delay before syst mic folates increase, since the absorbed FA is mainly taken up by the liver and metabolized in part to 5MF, which is released into the systemic circulation later (18,24). The present study also demonstrated a short delay before plasma THF levels increased.…”

Section: Plasma Active Folatesmentioning

confidence: 99%

Pharmacokinetics and bioavailability of folic acid and plasma levels of bioactive folates after folic acid administration to pigs

Kokue

Sekiya²,

Shimoda³

et al. 1994

Veterinary Quarterly

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SUMMARYAfter intravenous (1 mg/kg body weight), intramuscular (1 mg/kg body weight) and oral (1 and 50 mg/kg body weight) administration of folic acid (FA) to pigs, plasma levels of FA, tetrahydrofolic acid (THF), 5-methyltetrahydrofolic acid (5MF) were determined by using highperformance liquid chromatography. The pharmacokinetic profile of plasma FA after oral administration indicated an absorption rate-limited elimination, i.e., so called 'flip-flop' phenomenon. The bioavailability of FA was quite low after a high oral dose (F=0.01), in contrast to a high value after intramuscular administration (F=0.95). The plasma levels of biologically active, reduced forms of folates (THF and 5MF) were significantly increased over their basal levels after IV and IM administration to FA. The levels of these active folates were not increased after oral administration of a similair dose of FA. A 50 times higher dose was required to increase the active folates to the levels observed after IV and IM administration.

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Mechanisms of folate homeostasis

Cited by 62 publications

References 0 publications

Effect of a histidine-excess diet on a tetrahydrofolylpolyglutamate pattern in rat liver.

Effect of a histidine-excess diet on a tetrahydrofolylpolyglutamate pattern in rat liver.

Folate and homocysteine metabolisms and their roles in the biochemical basis of neuropsychiatry

Pharmacokinetics and bioavailability of folic acid and plasma levels of bioactive folates after folic acid administration to pigs

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