Thiamine deficiency affects glucose transport and ß-oxidation in rats.

Thiamine is recognized as a cofactor for many enzymes involved in intermediary metabolism responsible for energy production. Animal model of thiamine deficiency (TD) included direct evaluation of glucose uptake by estimation of 3 H-deoxyglucose transport across red blood cells membranes and ß-oxidation of fatty acids in isolated leucocytes. Feeding of animals with the thiamine-deficient diet (0.018 mg/kg diet) for 30 days resulted in disturbances in energy production. The thiamine intake was limited not only by vitamin B1 deficiency in the diet, but also by time-dependent drop of feed consumption by rats fed this diet. At the end of experiment, diet consumption in this group of rats was 52% lower than in the control group. This was accompanied by low glucose uptake by erythrocytes of rats suffering vitamin B1 deficiency for longer time. At the end of experimental period, glucose uptake was over 2 times lower in TD erythrocytes than in control RBC. Such drop of energy production was not compensated by delivery of energy from fatty acid degradation. In leucocytes from TD rats, the ß-oxidation was also suppressed. Observed significant decrease of serum insulin from 2.25 ± 0.25 ng/ml (day 0) to 1.94 ± 0.17 ng/ml (day 30) might have significant impact on observed energy production disorders. The results from this study indicate that the thiamine deficiency significantly reduces feed intake and causes modest abnormalities in glucose and fatty acid utilization.

Effects of genistein on insulin pathway-related genes in mouse differentiated myoblast C2C12 cell line: evidence for two independent modes of action.

INTRODUCTION: Genistein (plant isoflavone) is a well-known anti-cancer drug with estrogenic-like properties. Genistein also regulates sugar and lipid metabolism; thus, it has anti-diabetic properties. The aim of the study was to evaluate in vitro effects of genistein on glucose transport, fatty acids oxidation, activation of PKB, and expression of genes related to insulin pathway in differentiated myoblast C2C12 mouse cell line. MATERIAL AND METHODS: Differentiated myoblast C2C12 mouse cell line was used to assess the effects of different genistein concentrations on glucose transport and fatty acids oxidation measured by radioactivity technique, activation of PKB, and expression of selected genes related to insulin signaling pathway (IR-a, IR-b, IRS-1, PKB, GLUT-4, PP2A, SH-PTP2) at the mRNA and protein levels. Cells were incubated with various concentrations of genistein under standard conditions for 0-48 hours. RESULTS: Genistein in low concentrations (0.1-1 µM) significantly increased glucose transport and decreased fatty acids oxidation in C2C12 cells after 48 h of incubation. High concentration of genistein (50 µM) had the opposite effect. Genistein stimulated PKB phosphorylation during the first 5-10 minutes of incubation. There was no significant impact on the protein expression of selected genes (IR-a, IR-b, IRS-1, PKB, GLUT-4, PP2A-Ca, ER-a and ER-b) after 48 h treatment. We observed inverse correlation between genistein concentration and the expression of SH-PTP2 protein. Genistein affected the expression pattern of mRNAs for genes related to the insulin pathway, however, not the expression of the encoded proteins. CONCLUSIONS: The results of this study showed that depending on the concentration and time of incubation genistein significantly affects glucose and lipid metabolism and at low concentration modifies expression pattern of a few genes in C2C12 cells.

Mechanism of insulin-like effect of chromium(III) ions on glucose uptake in C2C12 mouse myotubes involves ROS formation.

Chromium is considered a trace element which improves glucose tolerance, but mechanism accounting for this insulin-like action is not recognized. The main purpose of this study was to examine the role of reactive oxygen species (ROS) in chromium and insulin stimulated glucose transport using antioxidants. Effect of chromium ions on phosphatases, enzymes involved in inhibition of insulin signaling was also investigated. Experiments were performed in vitro on C2C12 mouse myotubes. ROS level was measured with the use of confocal microscope and 2',7' dichlorodihydrofluorescein diacetate (DCFH-DA). Glucose metabolism was assayed by the measurement of 2-[3H]-deoxyglucose uptake. Cr3+ ions and insulin treatment caused significant increase of ROS formation and also stimulated glucose uptake in C2C12 cells in concentration dependent manner. Antioxidants (L-ascorbic acid and N-acetyl cysteine 100µM) and DPI (diphenyleneiodonium-NADPH oxidase inhibitor, 10µM) abolished insulin- and Cr-inducted glucose transport. Our results confirm the hypothesis that the ROS are integral part of insulin signaling pathway and that the insulin mimetic effect of Cr3+ ions depends on the antioxidant status of the cells. Surprisingly, chromium treatment resulted in increased activity of membrane phosphatases.

Influence of protein deficient diet, vitamin B[sub]2[/sub] supplementation and physical training on serum composition of polyunsaturated fatty acids (PUFAs) in rats.

[b]Introduction[/b]. Prolonged shortages of protein in the diet significantly alter the composition and content of polyunsaturated fatty acids (PUFA) in tissues and body fluids. One of nutritional factors which may reduce negative effects of protein malnutrition might be vitamin B[sub]2[/sub] due to its influence on lipids metabolism. [b]Objective. [/b]The aim of the study was to investigate the influence of low protein (LP) diet enriched with vitamin B[sub]2[/sub] on the content and composition of PUFA in the blood serum of rats treated with dosed physical exercise. [b]Materials and method. [/b]The experiment was carried out for 3 months on 72 growing male Wistar rats divided into 5 groups. Animals were fed ad libitum on a diet with an energy value of 350 kcal/100 g, in which 4.5% of the energy was provided by protein. In the control diet, 20% of the energy was provided by protein. Two groups were fed the diet enriched with vitamin B2. The two groups of tested animals were trained for 5 days a week. [b]Results.[/b] LP diet caused a decrease in α-linolenic acid (ALA) after 30 days, and a decrease in docosahexaenoic acid (DHA) after 60 days of experiment, compared with rats fed the control diet. After 60 and 90 days of the experiment, a significant decrease was noted in arachidonic acid (AA) in serum of trained rats, compared with sedentary rats fed the LP diet. Physical activity increased LA (mainly on day 30), EPA (on day 90) and reduced AA content (on day 90) in serum of rats fed the LP diet. B2 supplementation in the trained LP group did not change the EPA and AA dependence; however, there was a decrease in LA content in comparison to the non-supplemented trained group. [b]Conclusions. [/b] Results of this study suggest that all investigated factors (protein deficiency, physical exercise and supplementation of vitamin B2) have significant impact on PUFA composition of serum in rats.

Effect of Pregnancy and Stage of Lactation on Energy Processes in Isolated Blood Cells of Dairy Cows.

INTRODUCTION: The transition period is the most challenging time for dairy cattle, which is characterised not only by negative energy balance but also by fatty tissue mobilisation. MATERIAL AND METHODS: The efficiency of energy pathways, ß-oxidation in WBC and glycolysis in RBC (based on deoxyglucose transmembrane transport) were estimated. Insulin in blood plasma was determined using ELISA. RESULTS: After calving and up to one month after delivery, a significant drop in blood plasma level was noticed, simultaneously with a rise in ß-oxidation from 18.93 ±3.64 to 30.32 ±5.28 pmol/min/mg protein in WBC. A strong negative correlation between these two indices (r = -0.68) was found. During the period of transition to lactation an increase in glucose cross-membrane transportation from 41.44 ±4.92 to 50.49 ±6.41 µmol/h/g Hb was observed. A strong positive correlation between glucose transportation in RBC and ß-oxidation in WBC (r = 0.71) was noticed. These data are in agreement with results of studies on dairy cows using liver slices from dairy cows in late pregnancy and different stages of lactation, in which changes in gene expression were analysed. CONCLUSION: It seems that measuring fatty acids oxidation and glycolysis using isolated blood cells may be an adequate and relatively simple method for energy state analysis to estimate the state of dairy cow metabolism and animal health.

Alpha-Tocopherol May Protect Hepatocytes Against Oxidative Damage Induced by Endurance Training in Growing Organisms.

BACKGROUND: Training-induced oxidative stress can be reduced by α-tocopherol. Adequate intake of α-tocopherol could have health benefits for previously untrained young subjects. OBJECTIVES: The aim of this study was to determine the effects of training and different doses of α-tocopherol on exercise-induced oxidative stress in rat livers. MATERIAL AND METHODS: Young male Wistar rats (n = 40) were randomly divided into eight groups (undergoing training and not undergoing training, given orally administered α-tocopherol doses of 0, 0.5, 1.0 and 4.0 mg). Every day for 10 consecutive days, the rats in the training groups ran for 15 min on a treadmill at 20 m/min to induce oxidative stress. Hepatic oxidative stress was evaluated based on the liver concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and thiobarbituric acid reactive substances (TBARS). RESULTS: The liver concentrations of α-tocopherol were significantly influenced by α-tocopherol doses (p < 0.001) and physical exercise (p < 0.001). The liver concentrations of α-tocopherol increased in response to the highest dose (4 mg/d) of α-tocopherol in the non-training groups. In the training groups, the liver concentrations of α-tocopherol were independent of the dose. The levels of TBARS, a marker of lipid peroxidation, were lowest in the training and non-training rats administered 4.0 mg of α-tocopherol. Physical exercise and α-tocopherol doses significantly influenced TBARS concentrations (p = 0.004, p < 0.05). CONCLUSIONS: The results of this study indicate that running training causes lipids peroxidation and reduces α-tocopherol levels in the liver, but it does not contribute to DNA damage. Increased liver concentrations of α-tocopherol were found to exert a protective effect against oxidative damage induced by endurance training. An adequate intake of α-tocopherol is important for previously untrained young subjects.

Short communication: Streptococcus canis is able to establish a persistent udder infection in a dairy herd.

Bovine mastitis caused by Streptococcus canis is relatively rare. Consequently, many epidemiologic aspects of the infection, including factors that mediate crossing of host species barriers by the pathogen, infectiousness of the microorganism to the mammary gland, and the course of the disease within a herd, are still not elucidated. Therefore, the aim of the present study was to describe results of a 15-mo observation of subclinical Strep. canis mastitis on a dairy farm housing 76 lactating Holstein-Friesian cows. Upon 3 visits to the farm during a period between April 2013 and June 2014, Strep. canis was cultured from milk samples of 17 (22.4% of the herd), 7 (9.6%), and 8 (11.3%) cows, respectively. The isolates obtained were characterized phenotypically by means of the API Strep identification kit (bioMérieux, Marcy l'Etoile, France), as well as genetically by using random amplified polymorphic DNA and macrorestriction analysis of the chromosomal DNA by pulsed-field gel electrophoresis. All strains displayed the same biochemical features, and the molecular methods revealed that the isolates belonged to a single clone or were very closely related. Results of the study indicate that Strep. canis is capable of causing intramammary infections of long duration, behaving in a contagious manner. Because a persistently infected cow may serve as the source of Strep. canis infection for other animals, effective control of this type of udder infection within a herd may require similar measures to those adopted in Streptococcus agalactiae eradication programs.

The role of Chromium III in the organism and its possible use in diabetes and obesity treatment.

INTRODUCTION: Diabetes and obesity are diseases characterized by their increasing incidence every year. When comparing with healthy subjects, the serum levels of chromium (Cr) are lowered in these two diseases. Several studies conducted in laboratory animals with experimentally- induced diabetes demonstrated that supplementation with chromium ions (III) decreased glucose concentration in the blood, reduced the probability of atherosclerosis and heart attack, lowered the levels of cholesterol and low density lipoprotein (LDL). The Importance of chromium is actually challenged due to lack of clear manifestations of Cr deficiency in humans and animals. OBJECTIVE: The aim of this review was to present current knowledge about Cr its role in the organism and possible mechanisms of its action also in metabolic disorders such as diabetes or obesity. STATE OF KNOWLEDGE: In the last decade, Cr was established to be rather a beneficial than essential trace element in mammals, and has gained popularity as a nutritional supplement and a component of many multivitamin/mineral formulations, fortified food and energy drinks. Cr supplements are widespread for diabetes and obesity treatment, despite conflicting reports on its efficacy. It was suggested that Cr shows a beneficial influence upon glucose and lipid disturbances. CONCLUSIONS: The recent clinical trials provided evidence both in favor and against the importance of Cr in healthy and ill organisms. Unfortunately, also the molecular mechanism by which chromium affects glucose and lipid metabolism is still unclear. Beneficial effects of diet supplementation with different sources of Cr³âº can be potentially explained by rather pharmacological than nutritional effects.

The effect of microelements supplementation on beta-oxidation activity in healthy and type 1 diabetic rats.

Diabetes mellitus type 1 disease changes the activity of fatty acid degradation as compared to healthy animals. Supplementation in vitro with microelements chromium Cr3+ and selenium Se4+ and Se2- in non-toxic ([96.15 pmol (5 ppm) for chromium and 6.33 micromol (0.5 ppm) for selenium] concentrations strongly stimulates the activity of this process in diabetic rats. In healthy animals only chromium Cr3+ in concentration of 96.15 micromol (5 ppm) stimulated beta-oxidation activity in lymphocytes. It may indicate the beneficial effect of supplementation of the diet with microelements, chromium Cr3 and selenium Se4+ or Se2- at concentrations as low as 100 micromol for chromium and 6 micromol for selenium, respectively.

Chromium(III) propionate and dietary fructans supplementation stimulate erythrocyte glucose uptake and beta-oxidation in lymphocytes of rats.

The study describes the effects of 10-wk dietary supplementation with fructans (inulin and oligofructose, 5% and 10%, respectively) as well as the biomimetic Cr(III) propionate complex (0.5 and 5 mg Cr/kg diet) on blood glucose, insulin, glucose transmembrane transport, and beta-oxidation of fatty acids in healthy male rats. No significant differences in blood serum glucose concentrations were found. Rats fed diets supplemented with the biomimetic complex (5 mg Cr/kg diet) had markedly decreased serum insulin level by 15%, whereas the red blood cells (RBCs) glucose transmembrane transport and beta-oxidation of fatty acids in white blood cells (WBCs) were elevated by 9% and 77%, respectively. These effects were accompanied by a slight decrease of the insulin-resistance index. Oligofructose and the high-fructan diet (10%) were more effective in increasing the RBCs glucose transmembrane transport vs inulin and low-fructan diet (5%). Also, beta-oxidation of fatty acids in WBCs was increased by 37.5% in groups fed the high-fructan diet (10%). The results suggest that dietary fructans and the biomimetic Cr(III) complex exerted beneficial effects on glucose and lipid metabolism, increasing the efficiency of their utilization.

Polyunsaturated fatty acid (PUFA) changes in serum and liver of undernourished rats given dietary vitamin B6 supplementation.

The influence of vitamin B6 on linoleic (LA), alpha-linolenic (ALA), arachidonic (AA), eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid content in serum and liver of rats fed with protein-energy deficient diets for 90 d, was studied. To estimate the effect of dietary supplementation with vitamin B6 on the composition and level of fatty acids in the serum and liver of rats, two experiments were performed. In these experiments control rats were fed ad libitum semisynthetic isocaloric diets of 1,466.5 kJ/100 g (350 kcal/100 g) throughout 90 d while the examined rats were offered 50% and 30% of the previously determined daily intake of the diet consumed in the control group. The experimental diet was supplemented with vitamin B6 to the level 4-times higher than in the control diet. A reduction to the half consumption of a standard diet supplemented with vitamin B6 caused a significant decrease of LA and ALA in blood serum at 30 and 60 d. At 90 d of the experiment the value of LA was lower and the content of AA was higher in comparison to the control group. After 30 d of consumption of vitamin B6 enriched diet in rats subjected to feed restriction to only 30% of the control intake, an increase of ALA and a decrease of AA, EPA and DHA were noticed in serum. At 60 d an increase of DHA was observed. Ninety days of feeding this diet caused a significant increase of AA level. Feeding animals for 90 d with a vitamin B6 enriched diet, with limited consumption to 50%, caused a significant increase of ALA content in liver. Further limitation of this diet consumption to 30%, caused a significant decrease of LA and ALA and an increase of EPA content.

Chromium-yeast supplementation of chicken broilers in an industrial farming system.

The experiment was performed on ISA broilers at big farm conditions. One day old chickens were randomly assigned to two poultry-houses with the capacity of 10600 birds each. Chromium was provided in the form of chromium enriched yeast (1.0 g Cr/kg yeast) given in doses of 0.2 mg Cr/kg diet. No significant differences in growth rate and only a slight decrease of feed conversion ratio was found in broilers receiving chromium-yeast supplement. However, these birds had a lower mortality rate comparied with the rate observed in the controls. Moreover, dietary chromium led also to an improvement of carcass composition. Organic chromium supplementation increased the weight of pectoral muscles and meat of these broilers contained less amounts of fat and cholesterol. These effects were accompanied by an insignificant increase of chromium concentration in the pectoral muscles of birds fed chromium supplemented diets, from 40 to 52 microg/kg wet tissue.

Dietary selenium supplementation prolongs pentobarbital induced hypnosis.

The present studies characterized the influence of dietary selenium (Na2SeO3) on the duration of pentobarbital (PB) induced hypnosis (sleep) in the rat. Rats were fed semipurified diets varying from 0.01 to 2.0 mg Se/kg for up to 4 weeks. Consumption of diets containing 1.0 and 2.0 mg Se/kg significantly prolonged PB induced hypnosis. Hepatic selenium, but not hepatic glutathione peroxidase activity, correlated with the length of PB induced hypnosis. The prolongation of hypnosis caused by diets containing 1.0 mg Se/kg was substantially reduced or eliminated by repeated exposure to PB. Although single exposure to increasing quantities of PB (60-100 mg/kg body weight) led to a progressive increase in sleep duration, the proportional increase caused by supplemental selenium (2.0 vs 0.1 microg Se/g) remained relatively constant (approximately 25%). Increasing maturity was inversely related to the duration of PB induced hypnosis, regardless of dietary selenium provided. Consumption of the 2.0 mg Se/kg diet prolonged PB induced hypnosis to a greater degree in immature than in mature rats (P < 0.05). Consumption of the selenium enriched diet (2 microg Se/g) resulted in an increase in cytochrome 2B, but had no effect on cytochrome 1A compared to controls (0.1 microg Se/g). Pretreatment of rats with P450 enzymes activators (i.e., PB, Aroclor 1254, or 3-methylcholanthrene) shortened the duration of PB induced sleep and masked the effects of dietary selenium. The current studies document that dietary selenium can influence the response to pentobarbital induced hypnosis and likely relates to changes in drug detoxification enzymes.

Influence of vitamin B6 supplementation on polyunsaturated fatty acids concentration in serum and liver of rats fed a diet restricted in protein.

The influence of vitamin B6 on fatty acids content in serum and liver of rats receiving low protein diets was studied. Addition of B6 decreased linoleic acid (LA) and increased alpha-linolenic acid (ALA) and docosahexaenoic acid (DHA) in serum of rats fed a protein-deficient diet (9% energy from proteins) for 3 months. Further restriction of dietary protein (4.5% of energy from protein) caused an increase of the DHA concentration and sum of polyunsaturated fatty acids (PUFAs). In the liver of undernourished rats significant changes of PUFA composition were noticed, although without any significant influence of vitamin B6.

Effect of restricted feed intake and addition of vitamins B2 and B6 and folic Acid on the liver concentration of zinc and copper in rats.

The aim of the present study was to investigate the influence of nutritional deficiency and dietary addition of vitamins (B2, B6, and folate) on hepatic concentration of zinc and copper in rats. The experiment was performed on 260 growing male Wistar rats divided into 13 groups. Animals of 11 groups were fed isocaloric diets (14.7 MJ/kg) in which the 20% of energy was derived from protein. Another two groups of rats were offered diets with 9% or 4.5% of energy originating from protein. Animals of both mentioned groups and of the control group (20% of energy from protein) were offered diets ad libitum. The other 10 groups were offered 50% and 30% of the amount consumed in the control group. Eight groups, from those 10 restricted ones, were differentiated by dietary addition of vitamins B2 and B6 and folate (300% addition). Restricted feed intake did not affect the liver zinc concentration but significantly increased the copper concentration. The addition of vitamin B6 decreased the liver Zn concentration. The highest liver Cu concentration was noted in rats offered restricted diets to only 30% of intake in the control group and high in vitamin B2 and in rats supplemented with all of studied vitamins together. It suggests that vitamin B2 had the strongest impact on liver Cu concentration in rats fed restricted diets.

Content of polyunsaturated fatty acids (PUFAs) in serum and liver of rats fed restricted diets supplemented with vitamins B2, B6 and folic acid.

The aim of study was to investigate an influence of nutritional deficiency and dietary addition of vit. B(2), B(6) and folic acid on PUFAs content in rats' serum and liver. Limitation of consumption full value diet to 50% of its previously determined daily consumption, enriched with m/a vitamins, significant decreased of linoleic (LA) and alpha-linolenic (ALA) acids as well as distinctly increased arachidonic (AA) and docosahexaenoic (DHA) acids content in serum in 30th day. In 60th day lower content of AA and DHA fatty acids was found. Nutrition with such diet, lasting 90 days caused decrease of LA content and increase of AA. Diet limitation to its 30% of daily consumption decreased of eicosapentaenoic acid (EPA) and DHA in the 30th day, while AA and DHA content was increased in the 60th day. Distinct decrease of AA content and increase of EPA content were found in the 90th day of experiment. Use of diets, with limited consumption to 50% caused increase of LA and ALA acids content while AA and DHA acids content were significantly decreased in the liver, in 90th day. Limited consumption supplemented diet to 30% caused in liver significant decrease of LA and increase of EPA acids content.