The present study was undertaken to investigate the mechanism by which 1α, 25-dihydroxy-cholecalciferol [1α,25-(OH)2-VD3] modulates the differentiation of mouse 3T3-L1 preadipocytes into mature adipocytes. Treatment with 1α,25-(OH)2-VD3 in the presence of insulin, dexamethasone and 3-isobutyl-1-methyl-xanthine significantly inhibited the triacylglycerol accumulation, and mRNA expressions of adipocytokines (adiponectin and tumor necrosis factor-α) and plasminogen activator inhibitor-1 in the pico-nanomolar concentration range, indicating that 1α,25-(OH)2-VD3 under physiological conditions inhibits the differentiation of 3T3-L1 cells. 1α,25-(OH)2-VD3 potently reduced the mRNA and/or protein expressions of CCAAT-enhancer binding protein α (C/EBPα) and peroxisome proliferator-activated receptor γ (PPARγ), and the nuclear translocation of PPARγ. Furthermore, it inhibited the mRNA expression and phosphorylation of extracellular signal-regulated kinase (ERK), one of mitogen-activated protein kinases. These results indicate that 1α,25-(OH)2-VD3 can be an inhibitor of adipocyte differentiation, and suggest, in addition to C/EBPα and PPARγ, an important role of ERK in mediating 1α,25-(OH)2-VD3-induced alteration in adipocyte differentiation.
Cinnamaldehyde (CNA), a pungent compound in cinnamon or dried bark of cassia, is a TRPA1 agonist. The effect of 0.1-1.0% CNA on pair-fed mice with high fat and high sucrose (HFS) diet for 1 mo was investigated. The total food intake was similar in the mice fed control and CNA diets, but the body weight showed a tendency to be lower in CNA-fed mice than in control mice. By adding CNA at 0.1, 0.5, and 1.0% concentrations, the weight of the mesenteric adipose tissue decreased significantly, and there was a tendency foward lower perirenal and epididymal adipose tissue weights compared to the control. No differences were found in any blood component measured. UCP1 protein levels in the interscapular brown adipose tissue were higher in the 0.5 and 1.0% CNA groups than in the HSF group, as shown by Western blotting. Collectively, these data show that the addition of CNA diminishes visceral fat deposition in HFS diet-fed mice, in part by stimulating interscapular brown adipose tissue.
Porphyran (POR) from the red alga Porphyra yezoensis is a water soluble dietary fiber. In this study, we investigated the effect of dietary POR on glucose metabolism in KK-Ay mice (a model for type 2 diabetes). Mice were divided into 4 groups and fed a diet containing 5% cellulose (control), POR, POR Arg or POR K. After 3 wk of feeding, plasma insulin levels and the calculated homeostasis model assessment-insulin resistance (HOMA-IR) index were significantly lower in the POR group than in the control group. Compared with the control group, plasma adiponectin levels were significantly increased in the POR, POR Arg and POR K groups. These results suggest that dietary POR should improve glucose metabolism in diabetes via up-regulation of adiponectin levels. In addition, the amount of propionic acid in the cecum of the POR group was significantly higher than in the control group and the profile of bacterial flora was changed by dietary POR. In the cecum of the POR, POR Arg and POR K groups, Bacteroides was significantly increased and Clostridium coccoides was significantly decreased compared with in the control group. The effects of dietary POR on the hindgut environment might contribute to the improvement of glucose metabolism.
The effects of dietary supplementation with folate (20 mg/kg diet), 2.5% serine, or both on choline deprivation-induced hyperhomocysteinemia were investigated in rats fed a 10% casein diet (10C) or 25% soybean protein diet (25S) to determine whether folate supplementation with or without serine can suppress choline deficiency-induced hyperhomocysteinemia. Choline deprivation-induced enhancement of plasma homocysteine concentration was significantly suppressed by supplementation with folate, serine, or both, but the effects of these supplements were partial or limited in the rats fed both 10C and 25S. The extents of suppression of plasma homocysteine increments by folate, serine, or both were 29.6, 37.8, and 46.2%, respectively, in rats fed 10C and 27.2, 36.6, and 42.8%, respectively, in rats fed 25S. There was no significant additive effect between folate and serine, a source of C1 units. Folate supplementation with or without serine significantly increased or tended to increase hepatic 5-methyltetrahydrofolate concentration together with methionine synthase (MS) and cystathionine β-synthase (CBS) activities and MS mRNA level in both rats fed 10C and rats fed 25S. Hepatic betaine-homocysteine S-methyltransferase activity was unaffected by folate with or without serine. Supplementation with serine alone significantly increased hepatic serine concentration and increased or tended to increase CBS activity slightly. It is thought that the suppressive effect of folate on choline deficiency-induced hyperhomocysteinemia was due to increased metabolism of homocysteine via the MS pathway and that the suppressive effect of serine was due to increased metabolism of homocysteine via cystathionine formation. One of the reasons for the insufficient effect of folate alone or in combination with serine is thought to be that the capacity of the MS pathway for homocysteine metabolism is less enhanced by supplementation with folate and serine.
Dietary energy density (DED) might be associated with the quality of the consumed diet. Therefore, this study was conducted to report the relationship between dietary energy density and diet quality index in Iranian youths. In this cross-sectional study we enrolled 410 female young adults in Isfahan-Iran who were selected according to the stratified random sampling method from among students of Isfahan University of Medical Sciences. A validated semi quantitative food frequency questionnaire was used to assess the usual dietary intakes. Dietary energy density was calculated as each individual's reported daily energy intake (kcal/d) into total weight of foods (excluding beverages) consumed (g/d). Diet quality was assessed by healthy eating index (HEI), nutrient adequacy ratio (NAR), and mean adequacy ratio (MAR). For calculating the NAR the ratio of daily individual intakes to standard recommended amounts for the subject's sex and age category was used. MAR was calculated as the sum of NARs divided by the number of nutrients (n=10). Mean dietary energy density was 1.5±0.2 kcal/g and mean HEI was 57.5±16.0. Those in the highest quartile of DED had the lowest value for HEI, MAR, and NAR of zinc, calcium, vitamin C, vitamin B12 and vitamin B2 (p<0.05). Those in the highest quartile of DED had the highest prevalence of calcium, zinc, vitamin B2, vitamin B12, and vitamin C deficiency (p<0.05). Dietary energy density was inversely associated with the diet quality indices among Iranian young women adults.
Ultra-marathon running is supposed to increase the parameters of skeletal muscle damage and impair renal function. The purpose of this study was to investigate the effect of branched-chain amino acid supplementation on skeletal muscle damage and renal function during a 100-km ultra-marathon. Twenty-eight athletes were randomly divided into two groups, one group using branched-chain amino acid supplementation (BCAA) and a control group (CON). The athletes in the BCAA group were supplemented with a total of 50 g of an amino acid concentrate including 20 g of BCAA. The intake of energy, antioxidants and parameters of both skeletal muscle damage and renal function were determined. Race time was not different between BCAA and CON when controlled for the personal best time in a 100-km ultra-marathon. Neither the intake of energy and antioxidants nor the parameters of skeletal muscle damage and renal function were different between BCAA and CON. We concluded that BCAA-supplementation before and during a 100-km ultra-marathon had no effect on performance, skeletal muscle damage or renal function.
This study was carried out to elucidate the structural advantage of a gallated form of tea catechin on modulating bioavailability of dietary starch in rats. Animal studies demonstrated that the addition of 0.5% (w/w) (−)-epigallocatechin gallate (EGCG) to the diet brought about a significant increase in the starch content in the feces collected for 2 d at the fourth week of feeding over that with the control diet. Of the gross starch that the rats consumed from their respective diets during the fecal collection period, 0.1% (for control diet) and 1.9% (for EGCG diet) were estimated to be excreted in the feces. However, such a significant increase in the fecal excretion of starch by the EGCG diet was lost by undergoing hydrolysis of EGCG to (−)-epigallocatechin (EGC) and gallic acid (GA). In vitro investigation also showed that EGCG inhibited porcine pancreatic α-amylase activity in a concentration-dependent fashion, whereas the hydrolyzed preparation (the mixture of EGC and GA) exhibited a lack of the inhibitory activity for α-amylase. The modification of dietary starch digestion by inhibiting intestinal α-amylase activity with EGCG may be responsible at least in part for increasing fecal output of starch in rats. Thus, the attachment of a galloyl moiety to the tea flavan-3-ol skeleton may be of key importance for reducing intestinal digestion of dietary starch in rats.
Vitamin B12 content of an edible cyanobacterium, Nostochopsis sp. was determined to be 140.6±16.2 μg/100 g dry weight by a microbiological method. To evaluate whether the Nostochopsis cells contain vitamin B12 or inactive corrinoid compounds, corrinoid compounds were purified from the cells and then identified as pseudovitamin B12 (97.4±11.8 μg/100 g dry weight) and vitamin B12 (43.2±6.0 μg/100 g dry weight) on the basis of silica gel 60 TLC bioautograms and LC/ESI-MS/MS chromatograms. Vitamin B12 content was significantly increased in the Nostochopsis cells (254.8±17.6 μg/100 g dry weight) grown in the vitamin B12-supplemented medium.
It is thought that the contents of water-soluble vitamins in the body are generally low in diabetic patients because large amounts of vitamins are excreted into urine. However, this hypothesis has not been confirmed. To investigate this hypothesis, diabetes was induced in male Wistar rats (6 wk old) by streptozotocin treatment, and they were then given diets containing low, medium or sufficient vitamins for 70 d. The contents of 6 kinds of B-group vitamins, namely vitamin B1, vitamin B2, vitamin B6, vitamin B12, folate and biotin, were determined in the urine, blood and liver. No basic differences among the dietary vitamin contents were observed. The urinary excretion of vitamins was higher in diabetic rats than in control rats. The blood concentrations of vitamin B12 and folate were lowered by diabetes, while, those of vitamin B1, vitamin B2, vitamin B6, and biotin were not. All liver concentrations of vitamins were increased in diabetic rats above those in control rats. These results showed that streptozotocin-induced diabetes increased urinary excretion of water-soluble vitamins, though their blood and liver concentrations were essentially maintained in the rats.
A limited number of studies have been available to compare blood folate concentrations by the microbiological assay (MA) method with those using the chemiluminescent immunoassay (CLIA) method. We compared folate concentrations measured by Lactobacillus rhamnosus MA with those measured by CLIA (Access Immunoassay Systems) in human plasma/serum and erythrocytes pairs (n=35). The mean plasma folate by MA was significantly higher than that by CLIA (p<0.0001), whereas the mean erythrocyte folate by MA was significantly lower than that by the CLIA method (p<0.001). Plasma folate by MA significantly correlated with serum folate by CLIA (r=0.85, p<0.001). Similarly, the correlation between erythrocyte folate measured by MA and CLIA methods was significant (r=0.87, p<0.001). We conclude that folate concentrations obtained by CLIA are different from those obtained by MA, suggesting that it is undesirable for inter-laboratory comparisons when folate values are obtained by different methods. Although we evaluated only one CLIA method, we recommend careful evaluation of folate assay by each CLIA method before the use in clinical and research settings.
While the industrial value of fruits has long been recognized, only recently have the leaves of fruit trees been considered to have immense and mostly-untapped potential. In the present study, the physiological effects of apple leaf extract in mice were investigated. In addition, we sought to elucidate the active principle(s) and examined its potential for application. Apple leaf extract suppressed postprandial elevation of the blood glucose level and increased the residual amount of glucose in the small intestine in glucose-loaded mice compared with those in control mice. Bioassay-guided fractionation led to an active component that was identified as phloridzin, a known SGLT inhibitor, based on an analysis of its spectral data. With regard to an anti-hyperglycemic effect, extraction with ethanol from leaves of apple tree gave the best results. These effects decreased with heating during the extraction procedure. Since bolus ingestion of the extract did not affect blood glucose levels in normal mice with or without an overnight fast, the inhibitory effects on glucose absorption were not considered to be associated with unspecific gastrointestinal impairment and the extract did not cause hypoglycemia at a normally effective dose. Therefore, the leaf parts of apple tree may be a promising candidate as an industrial resource for maintaining good health in the future.