B6-deficient Diet Research Articles

Does Vitamin B6 Act as an Exercise Mimetic in Skeletal Muscle?

Marginal vitamin B6 (B6) deficiency is common in various segments worldwide. In a super-aged society, sarcopenia is a major concern and has gained significant research attention focused on healthy aging. To date, the primary interventions for sarcopenia have been physical exercise therapy. Recent evidence suggests that inadequate B6 status is associated with an increased risk of sarcopenia and mortality among older adults. Our previous study showed that B6 supplementation to a marginal B6-deficient diet up-regulated the expression of various exercise-induced genes in the skeletal muscle of rodents. Notably, a supplemental B6-to-B6-deficient diet stimulates satellite cell-mediated myogenesis in rodents, mirroring the effects of physical exercise. These findings suggest the potential role of B6 as an exercise-mimetic nutrient in skeletal muscle. To test this hypothesis, we reviewed relevant literature and compared the roles of B6 and exercise in muscles. Here, we provide several pieces of evidence supporting this hypothesis and discuss the potential mechanisms behind the similarities between the effects of B6 and exercise on muscle. This research, for the first time, provides insight into the exercise-mimetic roles of B6 in skeletal muscle.

Cross-Talk between miRNAs from the Dlk1-Dio3 Locus and Histone Methylation to Protect Male Cerebellum from Methyl Donor Deficiency.

Disruption of the one carbon metabolism during development, i.e., following a gestational vitamin B9 and B12 deficiencies, is involved in birth defects and brain development delay. Using a rat nutritional model, consisting of pups born to dams fed a vitamin B9 and B12 deficient diet (MDD), the study previously reports molecular and cellular alterations in the brain, in a sex dependent manner, with females being more affected than males. The study hypothesizes that epigenetic modifications could participate in the sex differences is observed. The study investigates lysine methylation of histones and expression of microRNAs in the cerebellum of MDD male and female pups. The study reports a differential regulation of H3K36Me2 and H4K20Me3 between males and females, in response to MDD. Moreover, distinct regulation of Kmt5b and Kdm2a expression by miR-134-5p and miR-369-5p from the Dlk1-Dio3 locus, contributes to the maintenance of expression of genes involved in synaptic plasticity. These results could explain the neuroprotection to MDD that male pups display. The work will contribute to the understanding of the consequences of vitamin starvation on brain development, as well as how the epigenome is affected by one carbon metabolism disruption.

Effect of Roselle Flower Extract (Hibiscus sabdariffa Linn.) on Reducing Steatosis and Steatohepatitis in Vitamin B12 Deficiency Rat Model.

Background and Objectives: Non-alcoholic Fatty Liver Disease (NAFLD) can occur as a result of micronutrient deficiencies. Hibiscus sabdarifa, a plant used in traditional medicine, contains ingredients that can help prevent this process. This study looked at the potency of Hibiscus sabdariffa Ethanol Extract (HSE) to prevent homocysteine-induced liver damage in animals that were deficient in vitamin B12. Materials and Methods: A comparative study of the effects of roselle extract is presented in an experimental design. Thirty Sprague-Dawley rats were divided into six groups using randomization. To demonstrate the absence of liver damage in the experimental animals under normal conditions, a control group was fed a normal diet without HSE. For the induction of liver damage in the experimental animals, the vitamin B12-restricted group was administered a vitamin B12-restricted diet. To test the effect of HSE on liver damage, the treatment group was given HSE along with a vitamin B12-restricted diet. Each group was given two treatment periods of eight and sixteen weeks. These results were compared with the results of the parameter examination between the vitamin B12 restriction group, with and without HSE, using an ANOVA statistic. The data were analyzed with licensed SPSS 20.0 software. Results: HSE significantly increased the blood levels of vitamin B12 while lowering homocysteine levels. The administration of HSE reduced liver damage based on the activity of liver function enzymes in the plasma due to a limitation of vitamin B12. HSE decreased Sterol Regulatory Element-Binding Protein-1c (SREBP1c) and Nuclear Factor Kappa B (NFkB) protein expressions in the liver tissue, but did not decrease Glucose-Regulated Protein 78 (GRP78) protein expression. Significantly, the levels of Tumor Necrosis Factor alpha (TNF-a) and IL-6 in the liver tissue were lower, while the levels of IL-10 and Nuclear factor-erythroid-2 Related Factor 2 (NRF2) were higher with HSE administration. HSE produced a better histopathological profile of the Hematoxylin and Eosin (H&E)-Masson tricrome for inflammation, fat and fibrosis in the liver. Conclusions: In this study, HSE was found to slow the development of liver damage in experimental animals that were given a vitamin B12-deficient diet.

Dietary vitamin B12 deficiency impairs motor function and changes neuronal survival and choline metabolism after ischemic stroke in middle-aged male and female mice

ABSTRACT Nutrition is a modifiable risk factor for ischemic stroke. As people age their ability to absorb some nutrients decreases, a primary example is vitamin B12. Older individuals with a vitamin B12 deficiency are at a higher risk for ischemic stroke and have worse stroke outcome. However, the mechanisms through which these occur remain unknown. The aim of the study was to investigate the role of vitamin B12 deficiency in ischemic stroke outcome and mechanistic changes in a mouse model. Ten-month-old male and female mice were put on control or vitamin B12 deficient diets for 4 weeks prior to and after ischemic stroke to the sensorimotor cortex. Motor function was measured, and tissues were collected to assess potential mechanisms. All deficient mice had increased levels of total homocysteine in plasma and liver tissues. After ischemic stroke, deficient mice had impaired motor function compared to control mice. There was no difference between groups in ischemic damage volume. However, within the ischemic damage region, there was an increase in total apoptosis of male deficient mice compared to controls. Furthermore, there was an increase in neuronal survival in ischemic brain tissue of the vitamin B12 deficient mice compared to controls. Additionally, there were changes in choline metabolites in ischemic brain tissue because of a vitamin B12 deficiency. The data presented in this study confirms that a vitamin B12 deficiency worsens stroke outcome in male and female mice. The mechanisms driving this change may be a result of neuronal survival and compensation in choline metabolism within the damaged brain tissue.

Vitamin B12 deficiency induces glucose intolerance, delays peak insulin levels and promotes ketogenesis in female rats.

Vitamin B12 (B12) deficiency is common among individuals with diabetes mellitus, but it is unknown if B12 deficiency contributes to impaired glucose homeostasis in this disorder. Female Sprague-Dawley rats were assigned to a control or B12-deficient diet for 4 weeks. Intraperitoneal glucose tolerance tests were performed after 25 days, and blood and liver samples were collected for metabolic profiling. B12 deficiency resulted in a prediabetic-like phenotype characterised by glucose intolerance, a delayed peak in plasma insulin levels following a glucose challenge and increased ketogenesis. We attributed increased ketogenesis to reduced liver anaplerosis, which limited the availability of the TCA cycle intermediates citrate, succinate and succinyl-CoA. This was associated with increased Mut mRNA levels and citrate synthase activity in the liver. One-carbon metabolite levels were altered in plasma and the liver, which was linked to reduced methylation capacity, altered amino acid levels and elevated Slc7a5 mRNA expression. Plasma folate and biotin levels were reduced, as were the majority of B vitamins in the liver. Changes in these B12-dependent processes and reduced B vitamin amounts likely contributed to deficits in glucose handling. Our findings highlight that B12 deficiency may promote the development of metabolic disorders like diabetes mellitus and emphasise the importance of adequate B12 intake for metabolic health.

CONSUMPTION OF Hibiscus sabdariffa DRIED CALYX ETHANOL EXTRACT IMPROVED REDOX IMBALANCE AND GLUCOSE PLASMA IN VITAMIN B12 RESTRICTION DIET IN RATS

This study aimed to evaluate the effect of Hibiscus sabdariffa L. dried calyx ethanolic (HSE) extract on the redox imbalance and glucose plasma of vitamin B12 restriction Sprague-Dawley rats. The rat was fed a Vitamin B12 Restriction Diet for 16 weeks and treated with HSE as the treatment group. One group was fed a restriction diet not treated with HSE as a positive control group, and another was fed a control chow diet not treated with HSE as a negative control group. Vitamin B12, MDA, SOD activity enzyme, and glucose levels were evaluated in this study. The extract had a significant antioxidant capacity in terms of reducing the production of free radical scavenging activity. The HSE can repair the skewed redox imbalance and oxidative damage generated by a vitamin B12-deficient diet in the rat liver. The result of fasting glucose plasma levels, in 16 weeks showed both significantly different in all groups. In Sprague-Dawley rats with vitamin B12 restriction treated with HSE, a decrease in the glucose plasma in week sixteen was observed, together with a reduction of hepatic redox imbalance. Treatment with HSE protected hepatocytes from oxidative damage caused by vitamin B12 deficiency.

Gambaran Hematologi pada Defisiensi Vitamin B12

Background and Aims. Anemia is a condition when the number of red blood cells or hemoglobin is lower than the normal number. The main cause of anemia is a lack of factors for the formation and maturation of red blood cells. Vitamin B12 plays a role in the synthesis and maturation of red blood cells, a lack of this vitamin will cause the formation and maturation of red blood cells to be disrupted.
 Method. This was an experimental animal study with twelve rats with frederer's family. The rat was fed a Vitamin B12 Deficient Diet for 16 weeks as the treatment group and standard diet as the control group. Vitamin B12 in the liver was analyzed in rats for 16 weeks. Hemoglobin and MCV were analyzed in plasma for 16 weeks. Results are expressed as means of control, and test animals were established by ANOVA using SPSS 20.0 software
 Results. In the present study, we found that liver vitamin B12 level was decreased in treatments groups compares to the positive control group at sixteen weeks (p<0.01). Hemoglobin was decreased in the treatment group compare positive control group at sixteen weeks (p<0.001). Mean Corpuscular Volume (MCV) was increased in the treatment group's compare positive control group at sixteen weeks (p<0.01)
 Conclusions. Our findings demonstrate that vitamin B12 deficiency decreased hemoglobin and increased MCV.

A Dietary Vitamin B12 Deficiency Impairs Balance and Coordination After Ischemic Injury to the Sensorimotor Cortex in Adult Male and Female Mice

ObjectivesThe majority of the world’s population is growing older, in 2000, 10% of the total population of the world was over 60 years old and is projected to increase to 21% by 2050. Brain vasculature is unique, and its aging has been scarcely investigated at the cellular, and molecular levels, as well as in the context of age-related comorbidities. Nutrition is a modifiable risk factor for stroke, as people age their ability to absorb some nutrients decreases. A primary example is vitamin B12, the majority of older adults are deficient in vitamin B12 because of changes in breakdown and absorption of the vitamin. Furthermore, a vitamin B12 deficiency results in elevated levels of homocysteine which is a risk factor for cardiovascular diseases, such as stroke. Using a mouse model system, the aim of this study was to understand the role of vitamin B12 deficiency in ischemic stroke outcome and investigate mechanistic changes in the brain. MethodsAt 10-weeks of age male and female C57Bl/6J mice were put on control (0.025 mg/kg of vitamin B12) or vitamin B12 deficient (0 mg/kg of vitamin B12) diets for 4-weeks prior to ischemic damage. At 14 weeks of age we induced ischemic stroke in the sensorimotor cortex using the photothrombosis model, all animals received damage. Animals continued on diets for 4 weeks after damage. At 18 weeks of age we assessed stroke outcome using the accelerating rotarod and forepaw placement task. After the collection of behavioral data, we euthanized animals and collected brain, blood, and liver tissue to assess histological and biochemical measurements. Plasma was used to measure total homocysteine and methylmalonic acid. ResultsAll animals maintained on the vitamin B12 deficient diet had increased levels of total homocysteine in plasma and liver tissue. Male and female mice maintained on a vitamin B12 deficient diet had impairments in balance and coordination on the accelerating rotarod compared to animals maintained on a control diet. ConclusionsVitamin B12 deficiency impacts motor function in older adult male and female mice. We are investigating damage volume and potential mechanisms within the damage brain tissue. Funding SourcesMidwestern University Start-Up Funds.

Abstract P807: Vitamin B12 Deficiency Impairs Balance and Coordination After Photothrombotic Damage to the Sensorimotor Cortex in Adult Male and Female Mice After Ischemic Stroke

Introduction: The majority of the world’s population is growing older, in 2000, 10% of the total population of the world was over 60 years old and is projected to increase to 21% by 2050. Brain vasculature is unique, and its aging has been scarcely investigated at the cellular, and molecular levels, as well as in the context of age-related comorbidities. Nutrition is a modifiable risk factor for stroke, as people age their ability to absorb some nutrients decreases. A primary example is vitamin B12, the majority of older adults are deficient in vitamin B12 because of changes in breakdown and absorption of the vitamin. Furthermore, a vitamin B12 deficiency results in elevated levels of homocysteine which is a risk factor for cardiovascular diseases, such as stroke. Using a mouse model system, the aim of this study was to understand the role of vitamin B12 deficiency in ischemic stroke outcome and investigate mechanistic changes in the brain. Hypothesis: Vitamin B12 deficient mice will exhibit worse stroke outcome compared to control diet mice through increased apoptosis. Methods: At 10-weeks of age male and female C57Bl/6J mice were put on control (0.025 mg/kg of vitamin B12) or vitamin B12 deficient (0 mg/kg of vitamin B12) diets for 4-weeks prior to ischemic damage. At 14 weeks of age we induced ischemic stroke in the sensorimotor cortex using the photothrombosis model, all animals received damage. Animals continued on diets for 4 weeks after damage. At 18 weeks of age we assessed stroke outcome using the accelerating rotarod and forepaw placement task. After the collection of behavioral data, we euthanized animals and collected brain and liver tissue to assess histological and biochemical measurements. Plasma was used to measure total homocysteine and methylmalonic acid. Results: All animals maintained on the vitamin B12 deficient diet had increased levels of total homocysteine in plasma and liver tissue. Male and female mice maintained on a vitamin B12 deficient diet had impairments in balance and coordination on the accelerating rotarod compared to animals maintained on a control diet. Conclusions: Vitamin B12 deficiency impacts motor function in older adult male and female mice. We are investigating damage volume and potential mechanisms within the damage brain tissue.

Is There a Carcinogenic Risk Attached to Vitamin B12 Deficient Diets and What Should We Do About It? Reviewing the Facts.

The number of individuals partaking in veganism has increased sharply in the last decade. Therefore, it is critical to look at the implications of vegan diets for public health. Although there are multiple health benefits of a vegan diet, studies have also linked the diet with deficiencies in various micronutrients. This study focuses on vitamin B12, because of its critical role in DNA synthesis and methylation. In light of these connections, a critical review of recent scientific literature is conducted to understand the effects of a B12 deficient diet on the genome and epigenome, and whether it can give rise to cancer. It is observed that a B12 deficiency leads to increased uracil misincorporation, leading to impaired DNA synthesis and genomic instability. The deficiency also leads to global hypomethylation of DNA, a hallmark of early carcinogenesis. The findings of this study highlight the need for increased awareness among vegans to ensure adequate B12 intake through supplementation or consumption of fortified products as a preventative measure. Additionally, the biofortification of staple crops and an improved version of fermented products with increased B12 content can be developed when inadequate intake seems otherwise inevitable.

Vitamin B12 Deficiency Alters the Gut Microbiota in a Murine Model of Colitis.

Purpose: Inflammatory bowel disease (IBD) refers to a spectrum of autoimmune diseases, which result in chronic intestinal inflammation. Previous findings suggest a role for diet, nutrition and dysbiosis of the gut microbiota in both the development and progression of the condition. Vitamin B12 is a key cofactor of methionine synthase and is produced solely by microbes. Previous work links increased levels of homocysteine, a substrate of methionine synthase, MetH, to IBD indicating a potential role for vitamin B12 deficiency in intestinal injury and inflammation. This study assessed the role of vitamin B12 in shaping the gut microbiota and determining responses to intestinal injury using a reproducible murine model of colitis.Methods: The effects of vitamin B12 supplementation and deficiency were assessed in vivo; 3-week-old post-weanling C57Bl/6 mice were divided into three dietary treatment groups: (1) sufficient vitamin B12 (50 mg/Kg), (2) deficient vitamin B12 (0 mg/Kg) and (3) supplemented vitamin B12 (200 mg/Kg) for a period of 4 weeks. Intestinal injury was induced with 2% dextran sodium sulphate (DSS) via drinking water for 5 days. The impact of varying levels of dietary vitamin B12 on gut microbiota composition was assessed using 16S rRNA gene sequencing from fecal samples collected at day 0 and day 28 of the dietary intervention, and 7 days following induction of colitis on day 38, when blood and colonic tissues were also collected.Results: No significant alterations were found in the gut microbiota composition of disease-free animals in response to dietary interventions. By contrast, after DSS-induced colitis, >30 genera were significantly altered in vitamin B12 deficient mice. Altered B12 levels produced no significant effect on composite disease-activity scores; however, administration of a B12 deficient diet resulted in reduced DSS-induced epithelial tissue damage.Conclusions: Vitamin B12 supplementation does not alter the gut microbiota composition under healthy conditions, but does contribute to differential microbial responses and intestinal dysbiosis following the induction of experimental colitis.

Vitamin B6 Regulates Muscle Satellite Cell Function: A Novel Possible Role of Vitamin B6 in Muscle Regeneration

Abstract Objectives So far, there is scarce information on potential roles of vitamin B6 (B6) in muscle regeneration. Thus, we examined if B6 has any effects on satellite cells (SCs), the muscle stem cells crucial for muscle regeneration. Methods Male ICR mice were divided into two groups receiving a B6 deficient level diet (1 mg pyridoxine (PN) HCl/kg diet) or a B6 supplement level diet (35 mg PN HCl) for 6 weeks (n = 6/group). Single fibers were isolated from EDL muscles and cultured in plating medium at 37°C, for 0 or 48 hr. Then, fixed fibers were co-immunostained for Pax7 and MyoD. Without culturing (0 hr), SCs are in quiescent state and stained positive with Pax7 +. Following 48 hr of culture, SCs will be activated and enter cell cycle for proliferation (stained positive with MyoD + Pax7+), commitment to differentiation (stained positive with MyoD+), or self-renew (stained positive with Pax7+). Results Without culturing (0 hr), the number of SCs on single fibers isolated from the muscles of the B6-deficient mice was lower than that in the B6-supplement mice (4.0 vs. 7.2 Pax7 + nuclei/fiber, P < 0.01), suggesting that B6 deficiency possibly induced a decline in the quiescent population of SCs. At 48 hr of culture, as compared to the B6-supplement mice, the B6-deficient mice showed the lower number of MyoD + Pax7 + clusters (3.7 vs. 8.1 clusters/fiber, P < 0.01) and the lower number of Pax7 + nuclei (P < 0.01), but no effects on the number of MyoD + nuclei. This suggested that B6 deficiency might affect the self-renewal function of SCs, while had less effects on proliferation and differentiation. Next, we hypothesized that the adverse effects of B6 deficiency on SCs is reversible, since the plating medium contained normal levels of B6. To test this hypothesis, single fibers isolated from the muscles of the B6-deficient mice were cultured in the medium contained with or without B6. As a result, the number of MyoD + Pax7 + clusters on single fibers in the culture without B6 was lower than that with B6 (2.6 vs. 3.7 clusters/fiber, P < 0.05), indicating that SCs cultured without B6 barely proliferated and possibly underwent apoptosis. Conclusions B6 may play a role in proliferation and apoptosis prevention of SCs. This study is the first to show the effects of B6 on SC function and will pave the way for new research on the role of B6 in muscle regeneration in the future. Funding Sources None.

Effects of altered maternal folate and vitamin B12 on neurobehavioral outcomes in F1 male mice

Maternal folate and vitamin B12 status during pregnancy may influence development of central nervous system (CNS) in the offspring. Very little attention has been paid to understand the combined effects of both the vitamins during pregnancy. The present study was designed to evaluate the biochemical and behavioral outcomes following alterations in folate and vitamin B12 levels in C57BL/6 mice. The female mice were fed with different combinations of folate and vitamin B12 whereas; males were fed with normal diet for 4 weeks. The mice were mated and the pregnant mice received the same diets as before pregnancy. The F1 male mice were further continued on maternal diet for 6 weeks following neurobehavioral and biochemical assessment. The body weight of the F1 male mice was significantly decreased in the mice that received folate and vitamin B12 deficient diet. Altered cognitive functions were observed in the folate and B12 deficient F1 male mice as assessed by Morris water maze and novel object recognition tests. Spontaneous locomotor activity was decreased in F1 male mice fed with folate and B12 deficient diets. Elevated homocysteine levels and decreased hydrogen sulfide levels were also observed in the brain of F1 male mice on folate and B12 deficient diets. However, GSH and GSSG levels were increased in the brain of the animals supplemented with folate deficient diet with different combinations of B12. The study suggests that exposure of female mice to folate and vitamin B12 deficiency during pregnancy effects in-utero development of fetus, which further leads to behavioral anomalies in adult life and is sufficient to cause impaired cognitive behavior in the subsequent generation. Thus, elucidating the role and importance of maternal dietary folate and B12 ratio during pregnancy.

Accumulation of Liver Lipids Induced by Vitamin B6 Deficiency Was Effectively Ameliorated by Choline and, to a Lesser Extent, Betaine.

Despite previous studies suggesting that choline and betaine ameliorate lipid accumulation in rat livers, the relative effectiveness of the two nutrients is unclear. We examined the efficacy of dietary supplementation with choline or betaine in ameliorating lipid accumulation induced by vitamin B6 (B6) deficiency in the rat liver. Male Wistar rats were fed control, B6-deficient, choline-supplemented B6-deficient, betaine-supplemented B6-deficient, or both choline and betaine-supplemented B6-deficient diets (all containing 9 g of l-methionine (Met)/kg) for 35 d. Two experiments were performed, i.e., one using 17 mmol/kg diet choline bitartrate, betaine anhydrous, and the combination and another using 8.5 mmol/kg diet. Rats fed a B6-deficient diet developed lipid accumulation in the liver with a reduction of plasma lipids induced by the disruption of Met metabolism. However, the addition of 17 mmol/kg diet choline or betaine was sufficient to ameliorate the disruptions of lipid and Met metabolism. Additionally, 8.5 mmol/kg diet choline ameliorated liver lipid deposition, while the same amount of betaine had no significant effects on liver or plasma lipid profiles. Supplementation with choline resulted in a higher liver betaine than that found using the same amount of betaine alone, although the overall liver betaine content was reduced in B6-deficient rats. Our findings indicate that choline is more effective than betaine in ameliorating B6 deficiency-related disruptions in Met metabolism and liver lipid accumulation by increasing liver betaine levels.

Adequate or elevated dietary folate does not ameliorate the reduced antioxidant capacity induced by vitamin B12 deficiency in aged rats.

Folate could have an antioxidant role but also may be detrimental under vitamin B12 deficiency. The aim was to investigate the effect of different dietary folic acid (FA) levels, on oxidative stress in B12 induced deficient aged rats. Thirty-five male aged Sprague-Dawley rats, were fed either a vitamin B12 deficient (n=27) or a control diet (n=8) during eight weeks. Then, animals were divided into four groups: B12 and FA deficient diet (DBDF), B12 deficient diet and FA control diet (DBCF), B12 deficient diet and FA supplemented diet (DBSF), and control diet (CBCF) for a 30 days period. Methionine metabolism and antioxidant status were evaluated. Both vitamins deficiencies elevated serum homocysteine (Hcy) (7.7 vs. 4.3μmol/L, p<0.05) and reduced S-adenosylmethionine hepatic content (283.7 vs. 581.9μg/g protein, p<0.05), the total antioxidant capacity (155.7 vs. 189.3μmol/L, p<0.05), glutathione (GSH) (120.5 vs. 419.9μg/mg protein, p<0.05) and oxidized glutathione (0.9 vs. 2.6μg/mg protein, p<0.05) compared to control. Activities of glutathione peroxidase and glutathione reductase enzymes or damage to macromolecules were unaffected. Adequate or elevated dietary FA in B12 deficiency rats decreased Hcy (5.7 and 6.3μmol/L, respectively) and increased total antioxidant capacity (189.8 and 192.6μmol/L, respectively) to values similar to control group, whereas GSH concentration was significantly lower than control (209.1 and 208.0μg/mg protein respectively, p<0.05). In conclusion, in a vitamin B12 deficiency status, adequate or elevated FA prevented impairment in one-carbon metabolism, but does not fully reverse the decrease in antioxidant capacity.

Mice lacking the transcobalamin-vitamin B12 receptor, CD320, suffer from anemia and reproductive deficits when fed vitamin B12-deficient diet.

In humans, poor nutrition, malabsorption and variation in cobalamin (vitamin B12) metabolic genes are associated with hematological, neurological and developmental pathologies. Cobalamin is transported from blood into tissues via the transcobalamin (TC) receptor encoded by the CD320 gene. We created mice carrying a targeted deletion of the mouse ortholog, Cd320. Knockout (KO) mice lacking this TC receptor have elevated levels of plasma methylmalonic acid and homocysteine but are otherwise healthy, viable, fertile and not anemic. To challenge the Cd320 KO mice we maintained them on a vitamin B12-deficient diet. After 5 weeks on this diet, reproductive failure develops in Cd320 KO females but not males. In vitro, homozygous Cd320 KO embryos from cobalamin-deficient Cd320 KO dams develop normally to embryonic day (E) 3.5, while in vivo, few uterine decidual implantation sites are observed at E7.5, suggesting that embryos perish around the time of implantation. Dietary restriction of vitamin B12 induces a severe macrocytic anemia in Cd320 KO mice after 10-12 months while control mice on this diet are anemia-free up to 2 years. Despite the severe anemia, cobalamin-deficient KO mice do not exhibit obvious neurological symptoms. Our results with Cd320 KO mice suggest that an alternative mechanism exists for mice to transport cobalamin independent of the Cd320 encoded receptor. Our findings with deficient diet are consistent with historical and epidemiological data suggesting that low vitamin B12 levels in humans are associated with infertility and developmental abnormalities. Our Cd320 KO mouse model is an ideal model system for studying vitamin B12 deficiency.

Rapid induction of vitamin B12 deficiency in Caenorhabditis elegans cultured in axenic medium

Animal models of B12 deficiency have proven to be difficult due to storage of substantial amounts in the liver and the length of time required to maintain animals on a B12 deficient diet to induce deficiency. Caenorhabditis elegans (C. elegans), due to its short lifespan, has recently emerged as an alternate model to investigate vitamin B12 (B12) deficiency. However, when C. elegans are maintained on bacterial diet, five generations of B12 deficient diet is required before the worms show signs of deficiency. Here we show that C. elegans grown in chemically defined axenic medium without added B12 exhibit signs of deficiency within one generation. Worms grown in deficient media had lower cobalt concentration, retarded growth, reduced fertility, increased motility, reduced quiescence and a shortened lifespan. In conclusion, C. elegans cultured in a defined axenic medium is a suitable and rapid model for studies on B12 deficiency.

Choline and betaine ameliorate liver lipid accumulation induced by vitamin B6 deficiency in rats.

We investigated the efficacy of supplementing the diet with choline or betaine in ameliorating lipid accumulation induced by vitamin B6 (B6) deficiency in rat liver. Male Wistar rats were fed a control, B6-deficient, choline-supplemented (2, 4, or 6g choline bitartrate/kg diet) B6-deficient diet or betaine-supplemented (1, 2, or 4g betaine anhydrous/kg diet) B6-deficient diet for 35 d; all diets contained 9g L-methionine (Met)/kg diet. Choline or betaine supplementation attenuated liver lipid deposition and restored plasma lipid profiles to control levels. These treatments restored the disruptions in Met metabolism and the phosphatidylcholine (PC)/phosphatidylethanolamine (PE) ratio induced by B6 deficiency in liver microsomes. These results suggest that choline and betaine ameliorated liver lipid accumulation induced by B6 deficiency via recovery of Met metabolism and very low-density lipoprotein secretion by restoring the supply of PC derived from PE.

Biochemistry, function, and deficiency of vitamin B12 in Caenorhabditis elegans.

Caenorhabditis elegans is a nematode that has been widely used as an animal for investigation of diverse biological phenomena. Vitamin B12 is essential for the growth of this worm, which contains two cobalamin-dependent enzymes, methylmalonyl-CoA mutase and methionine synthase. A full complement of gene homologs encoding the enzymes associated with the mammalian intercellular metabolic processes of vitamin B12 is identified in the genome of C elegans However, this worm has no orthologs of the vitamin B12-binders that participate in human intestinal absorption and blood circulation. When the worm is treated with a vitamin B12-deficient diet for five generations (15 days), it readily develops vitamin B12 deficiency, which induces worm phenotypes (infertility, delayed growth, and shorter lifespan) that resemble the symptoms of mammalian vitamin B12 deficiency. Such phenotypes associated with vitamin B12 deficiency were readily induced in the worm.

Metabolic network rewiring of propionate flux compensates vitamin B12 deficiency in C. elegans

Metabolic network rewiring is the rerouting of metabolism through the use of alternate enzymes to adjust pathway flux and accomplish specific anabolic or catabolic objectives. Here, we report the first characterization of two parallel pathways for the breakdown of the short chain fatty acid propionate in Caenorhabditis elegans. Using genetic interaction mapping, gene co-expression analysis, pathway intermediate quantification and carbon tracing, we uncover a vitamin B12-independent propionate breakdown shunt that is transcriptionally activated on vitamin B12 deficient diets, or under genetic conditions mimicking the human diseases propionic- and methylmalonic acidemia, in which the canonical B12-dependent propionate breakdown pathway is blocked. Our study presents the first example of transcriptional vitamin-directed metabolic network rewiring to promote survival under vitamin deficiency. The ability to reroute propionate breakdown according to B12 availability may provide C. elegans with metabolic plasticity and thus a selective advantage on different diets in the wild.DOI: http://dx.doi.org/10.7554/eLife.17670.001