Vitamin E requirement of the growing rat during selenium deficiency with special reference to selenium dependent--and selenium independent glutathione peroxidase

A comparative transcriptomic study of vitamin E and an algae-based antioxidant as antioxidative agents: investigation of replacing vitamin E with the algae-based antioxidant in broiler diets

Previous study indicated that inclusion of an algae-based antioxidant as an antioxidative agent [EconomasE, Alltech, Nicholasville, KY; EcoE] significantly reduced the amount of vitamin E (VE) required in broiler diets without compromising performance and meat quality. To assess the mechanisms related to the VE-saving activity of EcoE, as well as other potential functions related to EcoE and VE supplementation, we analyzed gene expression profiles of breast muscle from broilers fed a control diet, the control diet + 50 IU of VE/kg, the control diet + 100 IU of VE/kg, or the control diet + 200 g of EcoE/ton. Evaluation of the serum antioxidant capacity indicated that dietary supplementation of either a high level of VE (50 or 100 IU of VE/kg) or EcoE significantly improved bird antioxidant status. Analysis of gene expression profiles indicated that expression of 542 genes of the breast muscle were altered (P < 0.05, fold change >1.2) by dietary treatments, of which a significant part were commonly regulated by EcoE and VE (especially the control diet + 50 IU of VE/kg). In addition to the process of cellular oxidation, gene ontology analysis indicated the involvement of EcoE and VE on cell morphology, skeletal and muscular system development and function, immune response, and multiple metabolic processes, including lipid, carbohydrate, and drug metabolism. Results of this experiment indicate that the biological roles of high VE, including its activity as an antioxidant, can be greatly mimicked at the transcriptional level by EcoE, and they suggest a relationship of functional redundancy between VE and EcoE in the broiler diets.

Sesamin (a compound from sesame oil) increases tocopherol levels in rats fed ad libitum

Six groups of rats were fed diets low, but adequate, in alpha-tocopherol but high in gamma-tocopherol. The six diets differed only in their contents (0, 0.25, 0.5, 1.0, 2.0, and 4.0 g/kg, respectively) of sesamin, a lignan from sesame oil. After four weeks of ad libitum feeding, the rats were sacrificed and the concentrations of alpha- and gamma-tocopherols were measured in the plasma, livers, and lungs. Sesamin-feeding increased gamma-tocopherol and gamma-/alpha-tocopherol ratios in the plasma (P < 0.05), liver (P < 0.001), and lungs (P < 0.001). The increase was non-significant for alpha-tocopherol. Thus, sesamin appears to spare gamma-tocopherol in rat plasma and tissues, and this effect persists in the presence of alpha-tocopherol, a known competitor to gamma-tocopherol. This suggests that the bioavailability of gamma-tocopherol is enhanced in phenol-containing diets as compared with purified diets.

[Hematological parameters, selenium concentration and glutathione peroxidase activities in serum and the liver of rats at different selenium and vitamin E levels]

The aim of the both experiments was to determine whether selenium or selenium/vitamin E supply of rats significantly influences the most important hematological criteria. With experiment 1 the influence of Se deficiency should be determined at two different times of growing. So 36 weaned rats were divided into 2 groups of 18 animals each, the half of them being decapitated at day 22, the rest on day 45. In experiment 2 with the aim to investigate a combination of deficient, adequate and excessive Se and vitamin E supply 90 weaned rats in 9 groups were decapitated at day 44. The basic diet contained 0.04 mg Se and 8 mg vitamin E per kg dry matter and was supplemented in exp. 1 with 0 mg or 0.2 mg Se and 30 mg vitamin E and in exp. 2 with 0 mg, 0.2 mg or 1.0 mg Se and 0 mg, 30 mg or 200 mg vitamin E. With Se deficiency Se concentration and GSH-Px activity in serum and liver were significantly reduced. With excessive Se supply Se concentration in serum was higher; there was no effect on GSH-Px activity. Vitamin E supply had no influence neither on Se content nor on GSH-Px activity in serum or in liver. In exp. 1 Se deficiency caused no clear changes of the analysed hematological criteria although the increase of MCV (+3%) and hematocrit (+7%) on day 22 and the increase of leucocytes (+43%) and the decrease of MCH (-3%) and MCHC (-6%) on day 45 were statistically significant. In exp. 2 these results could not be repeated. The vitamin E supply was without significant effects on the examined hematological parameters.

Histopathological and biochemical changes associated with selenium and vitamin E deficiency in chicks

One day old unsexed White Leghorn chicks obtained either from commercial hens fed adequate levels of selenium (Se) and vitamin E (VE) (Comm. chicks), or from hens depleted in both nutrients (Depl. chicks), were fed a low Se-VE semi-synthetic basal diet. The dietary Se content was kept constantly low, while graded levels of VE as dl-alpha-tocopheryl acetate (dl-alpha Ta), (0, 5, 10 or 15 mg VE/kg diet) were fed for six weeks. An efficient carry-over of Se and VE from hens to their progeny was observed by a significant increase in their muscle Se, liver Se-glutathione peroxidase (Se-GSH-Px), and VE content at hatching. In the Depl. chicks, signs of Se-VE deficiency, i.e. exudative diathesis (ED) were observed at hatching, indicating that the deficiency lesions had developed during the embryonic period, whereas these signs were not observed in Comm. chicks on the depletion diets until they were 2 weeks old. The VE supplemental level of 15 mg/kg was not adequate to provide a complete protection against ED. Exudative diathesis was associated with low levels of muscle Se, liver Se-GSH-Px and VE and was also accompanied by a simultaneous increase in the liver non-Se-GSH-Px. Autopsy findings and histopathological lesions were observed only in subcutaneous tissue and skeletal muscle. The subcutaneous tissue was edematous with hyaline vascular lesions and hemorrhages. The thigh muscles were more susceptible to deficiency lesions than were the breast muscles, and showed in acute stages degenerative processes of the muscle fibers including calcium deposits, vascular lesions and hemorrhages. In subacute and chronic cases, reparative changes and muscle damage may develop independently of the hyaline vasculosis. To prevent ED, adequate Se and VE in chick diet is essential after hatching, irrespective of their tissue reserves of both nutrients at 1 day of age.

Response of whole blood, erythrocyte and plasma vitamin E content to dietary vitamin E intake in the chick

Whole blood, red blood cells (RBC), and plasma vitamin E (VE) levels in chicks fed dietary VE (dl-alpha-tocopheryl acetate, dl-alpha Ta) supplementation in steps of 0.0, 5.0, 10.0, 15.0, 20.0 and 30.0 mg/Kg were determined to examine their usefulness as an index of VE status. The increase in VE level was significant and linear in whole blood (r = 0.90), RBC (r = 0.89) and plasma (r = 0.93) in response to dietary VE intake. There was a close correlation between VE in plasma vs whole blood (r = 0.90), plasma vs RBC (r = 0.91) and whole blood vs RBC (r = 0.95). The plasma VE content was 1.2-1.8 times greater than that of whole blood, and 6.6-12.5 times greater than that of RBC. The plasma total lipids content was not affected by the dietary VE intake, whereas the level of VE in the plasma total lipids was significantly increased with increasing supplementation. Alpha tocopherol was the major isomer (ca 92%) of VE in whole blood, RBC and plasma at hatching. The small proportions of beta-tocopherol (ca 2%), gamma-tocopherol (ca 5%) and alpha-tocotrienol (ca 1%) observed at 1 day of age had decreased or totally disappeared by 7 days of age after feeding the VE-free basal diet. The data showed that in the chick, the whole blood and RBC levels of VE were as sensitive and reliable indexes of dietary VE status as was that of the plasma.