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Suzuki M, Tomita M. Genetic Variations of Vitamin A-Absorption and Storage-Related Genes, and Their Potential Contribution to Vitamin A Deficiency Risks Among Different Ethnic Groups. Front Nutr 2022; 9:861619. [PMID: 35571879 PMCID: PMC9096837 DOI: 10.3389/fnut.2022.861619] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 03/23/2022] [Indexed: 12/01/2022] Open
Abstract
Vitamin A, an essential fat-soluble micronutrient, plays a critical role in the body, by regulating vision, immune responses, and normal development, for instance. Vitamin A deficiency (VAD) is a major cause of xerophthalmia and increases the risk of death from infectious diseases. It is also emerging that prenatal exposure to VAD is associated with disease risks later in life. The overall prevalence of VAD has significantly declined over recent decades; however, the rate of VAD is still high in many low- and mid-income countries and even in high-income countries among specific ethnic/race groups. While VAD occurs when dietary intake is insufficient to meet demands, establishing a strong association between food insecurity and VAD, and vitamin A supplementation is the primary solution to treat VAD, genetic contributions have also been reported to effect serum vitamin A levels. In this review, we discuss genetic variations associated with vitamin A status and vitamin A bioactivity-associated genes, specifically those linked to uptake of the vitamin in the small intestine and its storage in the liver, as well as their potential contribution to vitamin A deficiency risks among different ethnic groups.
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Affiliation(s)
- Masako Suzuki
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, United States
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Kim DH, Ahn J, Suh Y, Ziouzenkova O, Lee JW, Lee K. Retinol Binding Protein 7 Promotes Adipogenesis in vitro and Regulates Expression of Genes Involved in Retinol Metabolism. Front Cell Dev Biol 2022; 10:876031. [PMID: 35493071 PMCID: PMC9047791 DOI: 10.3389/fcell.2022.876031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 03/30/2022] [Indexed: 11/22/2022] Open
Abstract
Retinol is an essential nutrient in animals. Its metabolites, specifically retinoic acid (RA), are crucial for cell differentiation, including adipogenesis. Retinol binding protein 7 (Rbp7) is under the control of PPARγ, the master regulator of adipogenesis. However, the role of RBP7 in adipogenesis is unclear. Our study showed that Rbp7 was abundantly expressed in white and brown mouse adipose tissues and had a higher expression in adipocytes than in stromal vascular fraction. Rbp7 overexpression promoted 3T3-L1 preadipocyte differentiation with increased triglyceride accumulation and up-regulation of Pparγ, Fabp4, C/ebpα, and AdipoQ. Rbp7 deficient adipocytes had opposite effects of the overexpression, which were rescued by RA supplementation. Indirect assessment of relative nuclear RA levels using RAR response element (RARE)-Luc reporter assay demonstrated that Rbp7 overexpression significantly increased RARE-Luc reporter activity. Rbp7 overexpression significantly increased expression of Raldh1, responsible for RA production, and up-regulation of Lrat and Cyp26a1, involved in retinol storage and RA catabolism, respectively, in 3T3-L1 adipocytes. Rbp7 deficient adipocytes had opposite effects of the overexpression of those genes involved in retinol metabolism. These data suggest that RBP7 increases transcriptional activity of RARE that may induce negative feedback responses via regulation of the gene expression for retinol homeostasis. Our data indicate critical RBP7 functions in adipocytes: regulation of transcriptional activity of RARE and adipocytes differentiation, potentially providing a new target for obesity therapy.
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Affiliation(s)
- Dong-Hwan Kim
- Biotherapeutics Translational Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea
- Department of Functional Genomics, University of Science and Technology, Daejeon, South Korea
- Department of Animal Sciences, The Ohio State University, Columbus, OH, United States
| | - Jinsoo Ahn
- Department of Animal Sciences, The Ohio State University, Columbus, OH, United States
| | - Yeunsu Suh
- Department of Animal Sciences, The Ohio State University, Columbus, OH, United States
| | - Ouliana Ziouzenkova
- Department of Human Sciences, The Ohio State University, Columbus, OH, United States
| | - Jeong-Woong Lee
- Biotherapeutics Translational Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea
- Department of Functional Genomics, University of Science and Technology, Daejeon, South Korea
- *Correspondence: Jeong-Woong Lee, ; Kichoon Lee,
| | - Kichoon Lee
- Department of Animal Sciences, The Ohio State University, Columbus, OH, United States
- The Ohio State University Interdisciplinary Human Nutrition Program, The Ohio State University, Columbus, OH, United States
- *Correspondence: Jeong-Woong Lee, ; Kichoon Lee,
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The Seaweed Diet in Prevention and Treatment of the Neurodegenerative Diseases. Mar Drugs 2021; 19:md19030128. [PMID: 33652930 PMCID: PMC7996752 DOI: 10.3390/md19030128] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 02/20/2021] [Accepted: 02/24/2021] [Indexed: 02/06/2023] Open
Abstract
Edible marine algae are rich in bioactive compounds and are, therefore, a source of bioavailable proteins, long chain polysaccharides that behave as low-calorie soluble fibers, metabolically necessary minerals, vitamins, polyunsaturated fatty acids, and antioxidants. Marine algae were used primarily as gelling agents and thickeners (phycocolloids) in food and pharmaceutical industries in the last century, but recent research has revealed their potential as a source of useful compounds for the pharmaceutical, medical, and cosmetic industries. The green, red, and brown algae have been shown to have useful therapeutic properties in the prevention and treatment of neurodegenerative diseases: Parkinson, Alzheimer’s, and Multiple Sclerosis, and other chronic diseases. In this review are listed and described the main components of a suitable diet for patients with these diseases. In addition, compounds derived from macroalgae and their neurophysiological activities are described.
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Farnesoid X receptor and bile acids regulate vitamin A storage. Sci Rep 2019; 9:19493. [PMID: 31862954 PMCID: PMC6925179 DOI: 10.1038/s41598-019-55988-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 11/29/2019] [Indexed: 12/18/2022] Open
Abstract
The nuclear receptor Farnesoid X Receptor (FXR) is activated by bile acids and controls multiple metabolic processes, including bile acid, lipid, carbohydrate, amino acid and energy metabolism. Vitamin A is needed for proper metabolic and immune control and requires bile acids for efficient intestinal absorption and storage in the liver. Here, we analyzed whether FXR regulates vitamin A metabolism. Compared to control animals, FXR-null mice showed strongly reduced (>90%) hepatic levels of retinol and retinyl palmitate and a significant reduction in lecithin retinol acyltransferase (LRAT), the enzyme responsible for hepatic vitamin A storage. Hepatic reintroduction of FXR in FXR-null mice induced vitamin A storage in the liver. Hepatic vitamin A levels were normal in intestine-specific FXR-null mice. Obeticholic acid (OCA, 3 weeks) treatment rapidly reduced (>60%) hepatic retinyl palmitate levels in mice, concurrent with strongly increased retinol levels (>5-fold). Similar, but milder effects were observed in cholic acid (12 weeks)-treated mice. OCA did not change hepatic LRAT protein levels, but strongly reduced all enzymes involved in hepatic retinyl ester hydrolysis, involving mostly post-transcriptional mechanisms. In conclusion, vitamin A metabolism in the mouse liver heavily depends on the FXR and FXR-targeted therapies may be prone to cause vitamin A-related pathologies.
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High dietary fat–induced obesity in Wistar rats and type 2 diabetes in nonobese Goto-Kakizaki rats differentially affect retinol binding protein 4 expression and vitamin A metabolism. Nutr Res 2016; 36:262-70. [DOI: 10.1016/j.nutres.2015.11.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 11/23/2015] [Accepted: 11/26/2015] [Indexed: 12/12/2022]
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Wray AE, Okita N, Ross AC. Cortical and trabecular bone, bone mineral density, and resistance to ex vivo fracture are not altered in response to life-long vitamin A supplementation in aging rats. J Nutr 2011; 141:660-6. [PMID: 21310867 PMCID: PMC3056581 DOI: 10.3945/jn.110.132126] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
High vitamin A (VA) intakes have been correlated with increased risk of bone fracture. Over 50% of the U.S. adult population reports use of dietary supplements, which can result in VA intakes > 200% of the RDA. In this study, 2 experiments were designed to determine the effect of dietary VA on cortical and trabecular bone properties and resistance to ex vivo fracture. In Expt. 1, we investigated whether orally administered VA accumulates in bone. Seven-week-old rats were treated daily with VA (6 mg/d for 14 d). Total retinol increased in both the tibia and femur (P < 0.01). In Expt. 2, we conducted a longitudinal study in which rats were fed 1 of 3 levels of dietary VA (marginal, adequate, and supplemented, equal to 0.35, 4, and 50 μg retinol/g diet, respectively) from weaning until the ages of 2-3 mo (young), 8-10 mo (middle-age), and 18-20 mo (old). Tibial trabecular and cortical bone structure, bone mineral density, and resistance to fracture were measured using micro-computed tomography and material testing system analysis, respectively. The VA-marginal diet affected measures of cortical bone dimension, suggesting bone remodeling was altered. VA supplementation increased medullary area and decreased cortical thickness in young rats (P < 0.05), but these changes were not present during aging. VA supplementation did not affect resistance to fracture or bone mineral content in old rats. From these results, we conclude that VA-marginal status affects trabecular bone more than cortical bone, and VA supplementation at a moderate level over the lifetime is unlikely to increase the risk of age-related bone fracture in rats.
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Affiliation(s)
- Amanda E. Wray
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA 16802
| | - Nori Okita
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA 16802
| | - A. Catharine Ross
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA 16802,To whom correspondence should be addressed. E-mail:
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Abstract
A properly formulated diet is an essential underpinning for all in vivo research. This chapter focuses on the use of diet in retinoid research from two perspectives: human research, in which diet is usually variable and analysis of dietary intake is paramount to interpreting the study's results, and animal (rodent) research, in which diet is imposed as a factor in the experimental design, and the diet consumed is usually monotonous. Many standard rodent diets are nonpurified and the amount of vitamin A in the diet is unknown. Moreover, it is likely to be much higher than expected from the label. By using a well-formulated purified diet with an exact amount of vitamin A, retinoid status in rodents can be closely controlled to create specific physiological conditions that represent the wide range of vitamin A status present in human populations.
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Affiliation(s)
- A. Catharine Ross
- Department of Nutritional Sciences and Huck Institute for the Life Sciences, Pennsylvania State University
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ROSS ACATHARINE, RUSSELL ROBERTM, MILLER SANFORDA, MUNRO IANC, RODRICKS JOSEPHV, YETLEY ELIZABETHA, JULIEN ELIZABETH. Application of a key events dose-response analysis to nutrients: a case study with vitamin A (retinol). Crit Rev Food Sci Nutr 2009; 49:708-17. [PMID: 19690996 PMCID: PMC2840874 DOI: 10.1080/10408390903098749] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
The methodology used to establish tolerable upper intake levels (UL) for nutrients borrows heavily from risk assessment methods used by toxicologists. Empirical data are used to identify intake levels associated with adverse effects, and Uncertainty Factors (UF) are applied to establish ULs, which in turn inform public health decisions and standards. Use of UFs reflects lack of knowledge regarding the biological events that underlie response to the intake of a given nutrient, and also regarding the sources of variability in that response. In this paper, the Key Events Dose-Response Framework (KEDRF) is used to systematically consider the major biological steps that lead from the intake of the preformed vitamin A to excess systemic levels, and subsequently to increased risk of adverse effects. Each step is examined with regard to factors that influence whether there is progression toward the adverse effect of concern. The role of homeostatic mechanisms is discussed, along with the types of research needed to improve understanding of dose-response for vitamin A. This initial analysis illustrates the potential of the KEDRF as a useful analytical tool for integrating current knowledge regarding dose-response, generating questions that will focus future research efforts, and clarifying how improved knowledge and data could be used to reduce reliance on UFs.
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Affiliation(s)
- A. CATHARINE ROSS
- Department of Nutritional Sciences, Pennsylvania State University, University Park, PA, USA
| | | | - SANFORD A. MILLER
- Central for Food, Nutrition, and Agriculture Policy, University of Maryland, College Park, MD, USA
| | - IAN C. MUNRO
- CANTOX Health Sciences International, ON, Canada
| | | | - ELIZABETH A. YETLEY
- Office of Dietary Supplements, National Institute of Health, Bethesda, MD, USA
| | - ELIZABETH JULIEN
- International Life Sciences Institute Research Foundation, Washington, DC, USA
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Arukwe A, Nordbø B. Hepatic biotransformation responses in Atlantic salmon exposed to retinoic acids and 3,3',4,4'-tetrachlorobiphenyl (PCB congener 77). Comp Biochem Physiol C Toxicol Pharmacol 2008; 147:470-82. [PMID: 18373956 DOI: 10.1016/j.cbpc.2008.02.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Revised: 02/07/2008] [Accepted: 02/09/2008] [Indexed: 01/15/2023]
Abstract
Active derivatives of vitamin A are essential in physiological processes such as cell growth, differentiation, morphogenesis and development. The biological functions of vitamin A are mediated through the retinoid acid receptors (RARs) and retinoid X receptors (RXRs). Aryl hydrocarbon receptor (AhR) agonists such as planar halogenated compounds are known to interfere with vitamin A homeostasis in both field and laboratory studies. In this study, we have investigated the molecular interactions between vitamin A and AhR signalling pathways using juvenile Atlantic salmon and agonists for both receptor pathways. Groups of juvenile salmon were treated with all-trans- and 9-cis-retinoic acid mixture (7:3 ratio) dissolved in DMSO (dimethyl sulfoxide) at 0.1, 1 and 10 mg/kg fish weight. The mixture was force fed singly or in combination with 0.1 mg 3,3',4,4'-tetrachlorobiphenyl (co-planar congener 77)/kg fish weight dissolved in DMSO. Liver samples were collected 3 days after PCB-77 exposure. A separate group exposed to combined retinoic acid (1 mg/kg for 5 days) and PCB-77, was sampled at 3, 7 and 14 days after PCB-77 exposure. Liver samples collected from all exposure groups were analyzed for gene (RARalpha, AhR2alpha, AhR2beta, CYP1A1, UGT1 and GSTpi) expression using real-time PCR and activity (7-ethoxyresorufin O-deethylase (EROD), UGT and GST) using biochemical methods with specific substrates. Our data showed that exposure to RA alone did not produce a significant increase of RARalpha mRNA levels, and the presence of PCB-77 attenuated the expression of RARalpha in RA dose- and time-specific manner. In addition, RA produced a dose-dependent increase of CYP1A1 mRNA and activity (EROD) levels without concomitant increase in AhR2 isoforms. When administered alone, PCB-77 produced increased CYP1A1, UGT1 and GSTpi mRNA and enzyme levels. The PCB-77-induced CYP1A1, UGT1 and GSTpi (mRNA and activity) levels were modulated by RA, in a parameter and dose-specific manner. In general, our data show an interaction between vitamin A and AhR signalling that may affect retinoid homeostasis in fish.
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Affiliation(s)
- Augustine Arukwe
- Department of Biology, Norwegian University of Science and Technology (NTNU), Høyskoleringen 5, 7491 Trondheim, Norway.
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Zambonin L, Prata C, Cabrini L, Maraldi T, Fiorentini D, Vieceli Dalla Sega F, Hakim G, Landi L. Effect of radical stress and ageing on the occurrence of trans fatty acids in rats fed a trans-free diet. Free Radic Biol Med 2008; 44:594-601. [PMID: 18021747 DOI: 10.1016/j.freeradbiomed.2007.10.034] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Revised: 09/11/2007] [Accepted: 10/16/2007] [Indexed: 11/16/2022]
Abstract
In a previous paper, we demonstrated that tissue trans fatty acids can not only derive from the diet but also be endogenously formed. The central focus of this study was to prove that the in vivo isomerization occurs via a radical process. Two different models of radical insult were used: CCl(4) and AAPH injection to rats fed a diet completely free of trans isomers. Following this acute radical stress, a significant increase in unnatural trans fatty acid content of erythrocyte, kidney, and heart, but not liver, was observed. These results can be mainly explained by the high content, particularly in the liver, of antioxidant vitamins A and E that exhibit also an "anti-isomerizing" effect. Since during ageing cellular components are exposed to increasing radical insults, the observation of a significant trans fatty acid accumulation in 30-month-old rats could confirm that the in vivo formation of unnatural isomers is due to a radical process. Trans fatty acids can influence the physical characteristics of bilayer microdomains, affecting membrane properties and functions; thus, knowledge of biological radical species responsible for cis/trans isomerization and their possible sources can provide protective systems for preserving lipid geometry.
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Affiliation(s)
- Laura Zambonin
- Dipartimento di Biochimica, Alma Mater Studiorum Università di Bologna, Via Irnerio 48, 40126 Bologna, Italy
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11
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Ross AC, Li NQ. Lung retinyl ester is low in young adult rats fed a vitamin A deficient diet after weaning, despite neonatal vitamin A supplementation and maintenance of normal plasma retinol. J Nutr 2007; 137:2213-8. [PMID: 17885000 PMCID: PMC3843128 DOI: 10.1093/jn/137.10.2213] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Although it is understood that plasma retinol concentration is not proportional to the concentration of vitamin A stored in liver, plasma retinol still is often used as an indicator of vitamin A status. An aim of vitamin A supplementation strategies is to maintain plasma retinol concentration in a range considered adequate, generally >1.05 micromol/L in humans, with some adjustment for age. In the present study in rats, we addressed the following question: Does lung vitamin A increase postnatally, as is observed in rats fed a vitamin A-adequate diet, if plasma retinol is maintained at approximately 1 micromol/L by supplementation at neonatal age, but the weaning diet is deficient in vitamin A? We treated rats on postnatal d 6, 7, and 8 with placebo (oil), vitamin A, retinoic acid (RA), and a nutrient-metabolite combination of vitamin A and RA, VARA, after which tissues were analyzed on d 9. Other rats treated identically as neonates were fed a vitamin A-deficient diet from 3-9 wk of age, and in parallel, another group of rats was fed a vitamin A-adequate diet. Although supplementation with vitamin A or VARA elevated liver and lung retinyl esters (RE) on d 9 (P < 0.0001), and prevented the fall in plasma retinol to <1 micromol/L by 9 wk of age, when the diet was vitamin A-deficient, lung RE fell to 28% of the concentration present in the lungs of rats fed the vitamin A-adequate diet (P < 0.0001). We infer that the lungs depend, at least in part, on the uptake of dietary vitamin A, probably from chylomicrons, to develop RE stores in the postweaning growth period.
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Affiliation(s)
- A Catharine Ross
- Department of Nutritional Sciences, Pennsylvania State University, University Park, PA 16802, USA.
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Ramalho A, Paes CA, Souza GG, Libera BD, Chaves GV, Lento DF. Vitamin A liver store: a case-control study. Int J Food Sci Nutr 2007; 59:202-10. [PMID: 17852482 DOI: 10.1080/09637480701497311] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The present study aims to assess the vitamin A liver store in individuals who died of several causes and to compare them with those who died of violent causes. A case-control study was performed with 60 individuals, where 30 died of violent causes (control) and 30 of other causes (cardiovascular diseases, infections, other chronic degenerative diseases, several causes). According to the cause of death, the mean retinol from liver stores was 281.5 +/- 63.50 mg/g for individuals who died of violent causes--a significantly higher amount (P < 0.05) than those observed in the other group (105.4 +/- 87.54 mg/g by cardiovascular diseases, 88.1 +/-78.03 mg/g by infections, 162.4 +/- 119.19 mg/g by other chronic degenerative diseases and 205.5 + 126.63 mg/g by several causes). The highest prevalence of low vitamin A was observed in individuals who died of infections and cardiovascular diseases, which emphasizes the role of vitamin A in these pathological processes.
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Affiliation(s)
- Andréa Ramalho
- Vitamin A Research Group, Instituto de Nutrição Josué de Castro/Universidade Federal do Rio de Janeiro (GPVA/INJC/UFRJ), Rio de Janeiro, Brazil.
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Clark RM, Balakrishnan A, Waters D, Aggarwal D, Owen KQ, Koo SI. l-Carnitine increases liver α-tocopherol and lowers liver and plasma triglycerides in aging ovariectomized rats. J Nutr Biochem 2007; 18:623-8. [PMID: 17368883 DOI: 10.1016/j.jnutbio.2006.11.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2006] [Revised: 10/30/2006] [Accepted: 11/01/2006] [Indexed: 10/23/2022]
Abstract
The objective of this study was to determine whether dietary L-carnitine can influence the status of alpha-tocopherol, retinol and selected lipid parameters in aging ovariectomized rats, an animal model for the menopausal state. Fourteen Fisher-344 female rats 18 months old were acclimated for 4 weeks and ovarectomized. Seven rats per treatment were assigned to either a control group fed ad libitum AIN-93M diet or a carnitine group fed the same diet supplemented with L-carnitine. After an 8-week feeding period, blood and selected tissues were taken for analyses. No differences were noted in food intake, body weight, or organ weights due to L-carnitine. Dietary carnitine significantly increased liver alpha-tocopherol and tended to increase plasma alpha-tocopherol (P<.09). No changes in alpha-tocopherol were observed in other tissues including the brain, lungs and retroperitoneal fat. Retinol levels in plasma and tissues were not affected by supplemental L-carnitine. Significant decreases in liver and plasma triglyceride (TG) levels were noted, suggesting increased utilization of fatty acids. No differences were observed in the fatty acid profile of tissues. The results provide evidence that dietary supplementation of L-carnitine enhances the alpha-tocopherol status and improves the utilization of fat leading to lowering of the liver and plasma levels of TG in aging ovariectomized rats. Whether supplemental L-carnitine may be of benefit to postmenopausal women in lowering plasma TG and improving the antioxidant status remains to be studied.
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Affiliation(s)
- Richard M Clark
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269-4017, USA.
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Paula TPD, Peres WAF, Ramalho RA, Coelho HSM. Vitamin A metabolic aspects and alcoholic liver disease. REV NUTR 2006. [DOI: 10.1590/s1415-52732006000500008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The liver is a strategic organ in the metabolism of macro and micronutrients; when its functioning is compromised, it may cause some change in the nutritional status of vitamin A. The purpose of this article is to review scientific evidence in literature on the liver metabolism of vitamin A, the role of ethanol and retinol interactions on hepatic morphology, besides the alterations in the metabolism of this vitamin in alcoholic liver disease. Data were collected from Medline database. The liver is the main organ responsible for the storage, metabolism and distribution of vitamin A to peripheral tissues. This organ uses retinol for its normal functioning such as cell proliferation and differentiation. This way, vitamin A deficiency seems to alter liver morphology. Patients with alcoholic liver disease have been found to have low hepatic levels of retinol in all stages of their disease. In alcoholic liver disease, vitamin A deficiency may result from decreased ingestion or absorption, reduction in retinoic acid synthesis or increased degradation. Long-term alcohol intake results in reduced levels of retinoic acid, which may promote the development of liver tumor. So, in chronic alcoholic subjects, vitamin A status needs to be closely monitored to avoid its deficiency and clinical effects, however its supplementation must be done with caution since the usual dose may be toxic for those who consume ethanol.
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Ross AC, Zolfaghari R. Regulation of hepatic retinol metabolism: perspectives from studies on vitamin A status. J Nutr 2004; 134:269S-275S. [PMID: 14704332 DOI: 10.1093/jn/134.1.269s] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Liver vitamin A (retinol) is obtained from several sources and is subject to multiple fates. Lecithin:retinol acyltransferase (LRAT), a microsomal enzyme present in liver and several other retinol-metabolizing tissues, esterifies retinol that is associated with a cellular retinol-binding protein, CRBP or CRBP-II. Recent research has shown that LRAT mRNA expression and enzyme activity are regulated in a tissue-specific manner. In vitamin A-deficient liver, both LRAT mRNA and activity are significantly down-regulated as well as rapidly induced after the administration of vitamin A or its principal hormonal metabolite, retinoic acid (RA). In long-term feeding studies and the metabolic steady state, liver LRAT is expressed dose-dependently across a wide range of dietary vitamin A. Additionally, an RA-inducible cytochrome P450, P450RAI or CYP26, is down-regulated in liver during vitamin A deficiency and up-regulated dose-dependently by dietary vitamin A and exogenous RA. Based on these results, we propose that LRAT and CYP26 serve as two molecular mechanisms, coordinately regulated by all-trans-RA, to control the availability of retinol and RA, respectively. The LRAT reaction, besides providing a readily retrievable storage form of vitamin A, may regulate the availability of retinol to other pathways, while the CYP26 reaction may serve to prevent a detrimental "overshoot" of RA concentration. Moreover, retinoid metabolism in the liver is likely to be closely integrated with that in peripheral tissues through the rapid interorgan transfer and recycling of retinoids, affecting the whole-body economy of vitamin A.
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Affiliation(s)
- A Catharine Ross
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA 16802, USA.
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16
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van der Loo B, Labugger R, Aebischer CP, Bachschmid M, Spitzer V, Kilo J, Altwegg L, Ullrich V, Lüscher TF. Age-Related Changes of Vitamin A Status. J Cardiovasc Pharmacol 2004; 43:26-30. [PMID: 14668564 DOI: 10.1097/00005344-200401000-00005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Ageing is an independent risk factor for the development of cardiovascular disease. The ageing process is known to be associated with increased oxidative stress and an increased risk for cardiovascular and other diseases, such as cancer. To delay this process, therapeutic strategies involving the use of naturally occurring antioxidants, such as vitamin A, have gained considerable interest. Therefore, we wanted to investigate in a model of mammalian ageing whether changes in tissue and plasma levels of vitamin A occur with increasing age. This would constitute a prime rationale for its dietary supplementation. Experiments were performed in three different age groups (4-6 months old, 19 months old, 32-35 months old) of F1 (F344 x BN) healthy male rats that were fed a normal diet without any additional supplementation. Vitamin A and carotenoids in plasma and major organs were measured by reverse-phase high-performance liquid chromatography. In 3-year-old rats, vitamin A levels were found to be decreased in plasma (P < 0.0001) as compared with young and middle-aged animals. However, they were markedly increased in the main storage organ (ie, the liver) (P < 0.01-0.0001), and also in the aortic vessel wall. They were undetectable in the heart, irrespective of age. Increased tissue levels of vitamin A, especially in the vasculature, may be part of an age-associated self-regulatory process of adaptation, possibly as a counter-regulation against oxidative tissue damage. Based upon the assumption that in elderly humans, as in our animal model, a similar demand-regulated mechanism may work independently of additional dietary vitamin A supplementation, one may question the strategy of large clinical interventional trials using vitamin A or its derivatives beyond normal dietary intake.
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Affiliation(s)
- Bernd van der Loo
- Division of Cardiology, Cardiovascular Centre, University Hospital Zurich, Switzerland
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17
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Hoegberg P, Schmidt CK, Nau H, Ross AC, Zolfaghari R, Fletcher N, Trossvik C, Nilsson CB, Håkansson H. 2,3,7,8-tetrachlorodibenzo-p-dioxin induces lecithin: retinol acyltransferase transcription in the rat kidney. Chem Biol Interact 2003; 145:1-16. [PMID: 12606150 DOI: 10.1016/s0009-2797(02)00157-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Vitamin A (retinoids) has an essential role in development and throughout life of humans and animals. Consequently, effects of the environmental pollutant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on retinoid metabolism may be contributory to its toxicity. This study was performed to clarify the mechanism behind dioxin-induced retinyl ester formation in the rat kidney. In addition we investigated the possible role of CYP1A1 in dioxin-induced all-trans-retinoic acid (atRA) formation. Male Sprague-Dawley rats were exposed to a single oral dose of TCDD in a combined dose-response and time-course study, with doses ranging from 0.1 to 100 microg/kg bw and time points from 1 to 28 days. Levels of atRA and the expression of two potentially retinoic acid (RA)-controlled proteins critically involved in retinoid storage regulation, lecithin: retinol acyltransferase (LRAT) and cellular retinol binding protein I (CRBP I), were analyzed in liver and kidney. The expression and activity of cytochrome P4501A1 (assayed as ethoxyresorufin-O-deethylase activity) was assessed to gain insight into its potential role in RA synthesis. There was a significant increase in LRAT mRNA expression in the kidney, whereas no such increase could be observed in the liver, despite significantly increased atRA levels in both tissues. This suggests a tissue-specific regulation of LRAT by TCDD that may be dependent on other factors than atRA. Neither CRBP I mRNA nor protein levels were altered by TCDD. The time-course relationship between CYP1A1 activity and atRA levels in liver and kidney does not exclude a role of CYP1A1 in TCDD-induced RA synthesis. The observed altered regulation of the retinoid-metabolizing enzyme LRAT, together with the low doses and short time required by TCDD to change tissue RA levels, suggest that enzymes involved in retinoid metabolism are specific and/or direct targets of TCDD.
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Affiliation(s)
- Pi Hoegberg
- Institute of Environmental Medicine, Karolinska Institutet, P.O Box 210, S-17177 Stockholm, Sweden
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18
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Ross AC. Retinoid production and catabolism: role of diet in regulating retinol esterification and retinoic Acid oxidation. J Nutr 2003; 133:291S-296S. [PMID: 12514312 DOI: 10.1093/jn/133.1.291s] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Retinoic acid (RA), a transcriptionally active metabolite of vitamin A (retinol), activates two families of nuclear retinoid receptors that have the potential to regulate the expression of a large number of genes. Although it may be presumed that the concentration of RA is closely regulated, the mechanisms underlying such regulation are not well understood. Our research has examined the expression and function of two enzymes, lecithin:retinol acyltransferase (LRAT) and a cytochrome P450, CYP26, in the liver and lung of rats and mice, over a wide range of vitamin A status or after treatment of vitamin A-deficient animals with exogenous RA. LRAT expression at both the mRNA and protein activity levels and CYP26 mRNA are regulated by dietary vitamin A in a steady-state model and are acutely regulated by RA in an acute repletion model. In the liver, the level of expression of LRAT and CYP26 is as follows: vitamin A deficient < vitamin A marginal < vitamin A adequate < vitamin A supplemented < RA treated. The regulation of LRAT shows strong tissue specificity (highly regulated in liver and lung but not in small intestine), whereas CYP26 is strongly regulated in the liver, lung, testis and intestine. RA may function as a signal of the body's vitamin A adequacy. The regulated expression of LRAT, CYP26 and other genes by RA may provide a sensitive response mechanism that overall serves to adjust the metabolism of vitamin A to maintain retinoid homeostasis and prevent retinoid excess.
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Affiliation(s)
- A Catharine Ross
- Department of Nutritional Sciences, The Pennsylvania State University, University Park 16802, USA.
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19
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Abstract
Excessive intake of vitamin A has been associated with an increased risk of hip fracture in humans. This finding has raised the question of whether long-term intake of relatively moderate doses ("subclinical" hypervitaminosis A) contributes to fracture risk. Although it has been known for more than half a century that toxic doses of vitamin A lead to spontaneous fractures in rats, the lowest intake that induces adverse effects is not known, and the result of exposure to excessive doses that do not cause general toxicity has been rarely investigated. In this study, mature female rats were fed a standard diet with 12 IU vitamin A/g pellet (control, C), or standard diet supplemented with either 120 IU ("10 x C") or 600 IU ("50 x C") vitamin A/g pellet for 12 weeks. Fifteen animals were included in each group. The supplemented diets correspond to a vitamin A intake of approximately 1800 IU/day and 9000 IU/day, respectively. The latter dose is about one third of that previously reported to cause skeletal lesions. At the end of the study, serum retinyl esters were elevated 4- (p < 0.01) and 20-fold (p < 0.001) and the total amount of liver retinoid had increased 3- (p < 0.001) and 7-fold (p < 0.001) in the 10 x C and 50 x C group, respectively. The animals showed no clinical signs of general toxicity, and there were no significant bone changes in the 10 x C group. However, in the 50 x C group, a characteristic thinning of the cortex (cortical area -6.5% [p < 0.001]) and reduction of the diameter of the long bones were evident (bone cross-sectional area -7.2% [p < 0.01] at the midshaft and -11.0% [p < 0.01] at the metaphysis), as measured by peripheral quantitative computed tomography. In agreement with these data and a decreased polar strength strain index (-14.0%, p < 0.01), the three-point bending breaking force of the femur was reduced by 10.3% (p < 0.01) in the 50 x C group. These data indicate that the negative skeletal effects appear at a subchronic vitamin A intake of somewhere between 10 and 50 times the standard diet. This level is considerably lower than previously reported. Our results suggest that long-term ingestion of modest excesses of vitamin A may contribute to fracture risk.
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Affiliation(s)
- S Johansson
- Department of Medical Sciences, Uppsala University, Uppsala, Sweden
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20
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Abstract
This review summarizes the available data on the effects of dioxins on retinoid levels, retinoid-related enzyme activities, and toxicological endpoints that have been correlated to retinoid effects. Similarities between dioxin toxicity and retinoid deficiency as well as retinoid excess are pointed out. Several possible levels of interaction between the dioxin and the retinoid signaling pathways are discussed, including the involvement of the Ah receptor, altered retinoic acid homeostasis, and an altered set point for retinoid storage. A hypothesis for the effect of dioxins on retinoids is suggested. In this hypothesis, comprising two cascades of effects on the molecular level, the effect of dioxins on retinoic acid levels is central.
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Affiliation(s)
- Charlotte B Nilsson
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
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McGowan SE, Smith J, Holmes AJ, Smith LA, Businga TR, Madsen MT, Kopp UC, Kline JN. Vitamin A deficiency promotes bronchial hyperreactivity in rats by altering muscarinic M(2) receptor function. Am J Physiol Lung Cell Mol Physiol 2002; 282:L1031-9. [PMID: 11943668 DOI: 10.1152/ajplung.00319.2001] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Vitamin A deficiency (VAD) remains an important health problem among children in developing countries. Children living in these areas have a higher mortality from respiratory infections, which likely results in part from suboptimal nutrition, including VAD. Bronchial hyperreactivity can follow viral respiratory infections and may complicate the recovery. To investigate whether VAD promotes bronchial hyperreactivity, we have assessed methacholine-induced bronchoconstriction in VAD and vitamin A-sufficient rats. Bronchial constriction developed at lower concentrations of inhaled methacholine in VAD than in vitamin A-sufficient rats. This did not result from an increase in the bronchial wall thickness or the clearance of a small molecule (with a size similar to methacholine) from the air space. The function and abundance of the muscarinic M(2) receptors in bronchial tissue were reduced in VAD rats, suggesting that this receptor may contribute to these animals' diminished ability to limit cholinergic-mediated bronchoconstriction. A similar reduction in muscarinic M(2) receptor function has been observed in asthma. Vitamin A (retinol) and its congeners (retinoids) may be required to regulate bronchial responsiveness in addition to maintaining a normal bronchial epithelium.
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Affiliation(s)
- Stephen E McGowan
- Department of Veterans Affairs Research Service, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA.
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22
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Kelleher SL, Lönnerdal B. Long-term marginal intakes of zinc and retinol affect retinol homeostasis without compromising circulating levels during lactation in rats. J Nutr 2001; 131:3237-42. [PMID: 11739873 DOI: 10.1093/jn/131.12.3237] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Marginal zinc or vitamin A intake is more common than previously thought in industrialized and developing countries, with pregnant and lactating women believed to be particularly at risk. However, the lack of sensitive indicators of zinc and vitamin A status precludes accurate assessment of marginal nutriture. Concurrent deficiencies in zinc and vitamin A intake often coexist, and the interaction between zinc deficiency and vitamin A metabolism may confound results from epidemiologic or intervention studies. To investigate effects of a maternal diet chronically restricted in zinc or vitamin A intake on indices of vitamin A metabolism, we fed rats a control diet (C) or a diet marginal in zinc (ZD), marginal in vitamin A (AD), marginal in both (DD) or pair-fed to DD (PF), preconception through lactation. Plasma retinol (ROH) was greater and retinol binding protein (RBP) was lower in rats fed ZD, AD and DD compared with those fed C. Hepatic cellular retinol binding protein (CRBP) expression was greater than controls in rats fed ZD and AD and lower in those fed DD, whereas RBP expression was greater in the DD- and PF-fed groups compared with rats C. Mammary gland CRBP and RBP expression were not affected by the diets. Milk ROH was lower in rats fed AD, and milk RBP was lower in those fed ZD and DD compared with rats fed C. In summary, chronic, marginal intake of zinc or vitamin A resulted in alterations in tissue retinol metabolism and milk retinol levels without decreasing plasma zinc, retinol or ROH:RBP during lactation. These observations are of concern because these parameters, which are commonly used to assess zinc and vitamin A status, may lead to misassessment of marginal zinc or vitamin A nutriture in some human populations.
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Affiliation(s)
- S L Kelleher
- Department of Nutrition, University of California Davis, Davis, CA, USA
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Fortuna VA, Trugo LC, Borojevic R. Acyl-CoA: retinol acyltransferase (ARAT) and lecithin:retinol acyltransferase (LRAT) activation during the lipocyte phenotype induction in hepatic stellate cells. J Nutr Biochem 2001; 12:610-621. [PMID: 12031254 DOI: 10.1016/s0955-2863(01)00179-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We have examined retinol esterification in the established GRX cell line, representative of hepatic stellate cells, and in primary cultures of ex vivo purified murine hepatic stellate cells. The metabolism of [3H]retinol was compared in cells expressing the myofibroblast or the lipocyte phenotype, under the physiological retinol concentrations. Retinyl esters were the major metabolites, whose production was dependent upon both acyl-CoA:retinol acyltransferase (ARAT) and lecithin:retinol acyltransferase (LRAT). Lipocytes had a significantly higher esterification capacity than myofibroblasts. In order to distinguish the intrinsic enzyme activity from modulation of retinol uptake and CRBP-retinol content of the cytosol in the studied cells, we monitored enzyme kinetics in the purified microsomal fraction. We found that both LRAT and ARAT activities were induced during the conversion of myofibroblasts to lipocytes. LRAT induction was dependent upon retinoic acid, while that of ARAT was dependent upon the overall induction of the fat storing phenotype. The fatty acid composition of retinyl-esters suggested a preferential inclusion of exogenous fatty acids into retinyl esters. We conclude that both LRAT and ARAT participate in retinol esterification in hepatic stellate cells: LRAT's activity correlates with the vitamin A status, while ARAT depends upon the availability of fatty acyl-CoA and the overall lipid metabolism in hepatic stellate cells.
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Affiliation(s)
- Vitor A. Fortuna
- Departamento de Histologia e Embriologia, Instituto de Ciências Biomédicas, Rio de Janeiro, Brazil
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Ross AC, Zolfaghari R, Weisz J. Vitamin A: recent advances in the biotransformation, transport, and metabolism of retinoids. Curr Opin Gastroenterol 2001; 17:184-192. [PMID: 11224677 DOI: 10.1097/00001574-200103000-00015] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Advances in vitamin A research in 1999 and 2000 have improved the understanding the molecular processes through which beta-carotene and other provitamin A carotenoids are converted to vitamin A, the roles of cellular retinoid-binding proteins that serve as retinoid chaperones during metabolism, the regulation of retinoid transport, and the nature and regulation of several enzymes required for the absorption, storage, activation, and inactivation or degradation of retinoids. Not only has a clearer picture emerged of specific molecular processes, but it is also becoming evident that whole-body retinoid homeostasis is facilitated by close communication among organs due to the rapid interorgan recirculation of retinoids, and by the "autoregulation" by retinoic acid of several enzymes and retinoid-binding proteins that mediate retinoid homeostasis.
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Affiliation(s)
- A. Catharine Ross
- Department of Nutrition, The Pennsylvania State University, University Park, Pennsylvania; Department of Obstetrics and Gynecology, The Milton S. Hershey Medical Center, Hershey, Pennsylvania, USA
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Lecithin:retinol acyltransferase from mouse and rat liver: cDNA cloning and liver-specific regulation by dietary vitamin A and retinoic acid. J Lipid Res 2000. [DOI: 10.1016/s0022-2275(20)32364-6] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Yamamoto Y, Zolfaghari R, Ross AC. Regulation of CYP26 (cytochrome P450RAI) mRNA expression and retinoic acid metabolism by retinoids and dietary vitamin A in liver of mice and rats. FASEB J 2000; 14:2119-27. [PMID: 11023996 DOI: 10.1096/fj.00-0061com] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Retinoic acid (RA), through nuclear retinoid receptors, regulates the expression of numerous genes. However, little is known of the biochemical mechanisms that regulate RA concentration in vivo. CYP26 (P450RAI), a novel cytochrome P450, is expressed during embryonic development, induced by all-trans RA, and capable of catalyzing the oxidation of [3H]RA to polar retinoids including 4-oxo-RA. Here we report that CYP26 expression in adult liver is regulated by all-trans RA and dietary vitamin A, and is correlated with the metabolism of all-trans RA to polar metabolites. In normal mouse and rat liver, CYP26 mRNA was barely detectable; however, after acute treatment with all-trans RA CYP26 mRNA and RA metabolism by liver microsomes were significantly induced. Aqueous-soluble RA metabolites were detected, but their formation was not induced. The expression of retinoid receptors, RAR-gamma and RXR-alpha, was not changed after RA treatment in vivo. In a model of chronic vitamin A ingestion during aging, CYP26 mRNA expression, determined by Northern blot and RT-PCR analysis, increased progressively with dietary vitamin A (P<0.0001; marginal < control < supplemented) and age (P<0.003). The relative expression of CYP26 mRNA was positively correlated with liver total retinol (log10), ranging from undetectable CYP26 expression at liver retinol concentrations below approximately 20 nmol/g to a three- to fourfold elevation at concentrations >10,000 nmol/g (r=0.90, P<0.0001). We conclude that CYP26 expression and RA metabolism are regulated in adult liver not only acutely by RA administration, as may be relevant to retinoid therapy, but under chronic dietary conditions relevant to vitamin A nutrition in humans.
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Affiliation(s)
- Y Yamamoto
- Department of Nutrition, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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