The depression of immune cell function that is typically observed after prolonged exercise is thought to be largely mediated by increased plasma concentrations of stress hormones and cytokines and possibly oxidative stress. The aims of this thesis were to determine the effects of acute and longer term oral antioxidant supplementation on immunoendocrine responses following prolonged exercise. In study 1 (Chapter 3) it was shown that vitamin C ingested acutely before and during prolonged exercise has little or no effect on immunoendocrine responses. Furthermore, the combined ingestion of vitamin C with carbohydrate provides no additional effects compared with carbohydrate alone. However, when vitamin C was supplemented acutely, 2 h prior to, and during prolonged exercise in addition to on the night before (14 h prior) exercise this limited the fall in neutrophil oxidative burst activity (study 2, Chapter 4). This was probably a result of reduced direct oxidative damage to neutrophils with vitamin C supplementation since there were no effects on the cortisol, interleukin-6, leukocytosis or neutrophilia responses. Longer periods of antioxidant supplementation (2 - 4 weeks) may be effective at blunting the cortisol, leukocytosis and neutrophilia responses to prolonged exercise (Chapters 5 and 6) but this had no effect on in vitro measures of neutrophil function. In study 5 (Chapter 7) it was shown that acute pre-exercise dark chocolate (which contains polyphenols) ingestion has some effects on plasma oxidative stress markers and circulating insulin and glucose responses but not the immunoendocrine responses to prolonged exercise.

No description available.

Prolonged strenuous exercise affects the circulating numbers and functions of immune cells. These effects are thought to be largely mediated by the actions of elevated circulating stress hormones and alterations in regulatory cytokines. Although the effects of a single acute bout of exercise on immune system function are quite well established, it is still not clear how time of day and repeated bouts of prolonged exercise on the same day influence immune function. It is of particular interest to understand the effects of nutritional supplementation on immunoendocrine responses. Therefore, the aims of the studies described in this thesis were to determine the effects of two bouts of prolonged cycling and carbohydrate supplementation on immunoendocrine responses. The saliva collection study showed that the use of a swab for collecting saliva is not an ideal method because it affects the results of saliva composition (Chapter 4). The comparison of the effects of exercise at different times of day on immunoendocrine responses showed that a single bout of prolonged exercise performed in the afternoon induces a larger perturbation in the redistribution of leukocytes into the circulation than an identical bout of morning exercise, which maybe due to higher hypothalamic-pituitaryadrenal (HP A) activation and. circadian rhythms. However, in terms of oral mucosal immunity, performing prolonged cycling at different times of day does not differently affect the salivary responses. The second compared with the first of two bouts of prolonged exercise on the same day induces a greater HP A activation, a larger leukocyte trafficking into the circulation, a decreased neutrophil degranulation response to lipopolysaccharide (LPS) on per cell basis and a lower saliva flow rate, but does not increase plasma interleukin-6 (IL-6), or change saliva immunoglobulin A (slgA) secretion rate (Chapter 5). Furthermore, carbohydrate (CHO) ingestion during any period of two bouts of prolonged exercise shows limited beneficial effect in blunting these higher responses in the second exercise bout compared with the first identical exercise bout on the same day (Chapter 6, 7 and 8). The determination of the effects of CHO ingestion on exercise-induced immunoendocrine responses showed that when two bouts of exercise are performed on the same day, the greater benefit in terms of circulating immunoendocrine responses is obtained by feeding CHO at the earliest opportunity (Chapter 6, 7 and 8). A 3-h interval is insufficient for recovery of leukocyte mobilisation and neutrophil function from the impact of previous exercise whether subjects consumed placebo or CHO during exercise or recovery (Chapter 5, 6, 7 and 8). However, an 18-h interval is sufficient for full recovery of all immunoendocrine variables that were measured in this thesis from the impact of two bouts of prolonged exercise (Chapter 8).

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The present work had as its objective to assess the oxidizing metabolism of neutrophils, the complete blood count (CBC) and the oxidizing profile of experimentally infected lambs with Haemonchus contortus and supplemented with selenium and vitamin E. 20 male lambs were used, of the Corriedale breed, distributed in four experimental groups with 5 animals: G1 larvae infected animals and supplemented with 0.2mg/kg living weight (PV) of selenite via intramuscular (IM); G2 larvae infected animals and supplemented with 0.2mg/kg PV of selenite IM and 2000 UI per animal of vitamin E IM; G3 larvae infected animals and supplemented with 2000 UI per animal of E IM; G4 larvae infected animals. For the CBC and the biochemical analysis blood collection on the day zero (T0) were carried out, 20 (T1), 40 (T2) and 60 (T3) through jugular venipuncture using vacutainer® tubes. The weighing and the egg determination by gram of animal feces occurred in the same experimental times. For the NBT tests heparinized blood samples were collected in the days zero, 30, 60. Smaller leukocyte values were detected in the supplemented group exclusively with selenium (G1) in relation to the control group (G4) in time 4. Concerning the lymphocytes it was observed a decrease in the G1 in relation to the supplemented only with vitamin E (G3) and G4 in time 3 (T3). For both the tests, NBT-NE and NBT-E there was a decrease in the dye reduction capacity at 60 days in relation to the other times in the groups treated with selenium (G1 and G2). The result of the oxidizing profile showed a significant elevation in the GSH-Px enzyme in the supplemented groups with selenium. Still, the correlation of Pearson revealed the existence of a negative correlation between the concentrations of GSH-Px and TBARS and between this enzyme and the OPG values. Increments were also observed for the catalase enzyme in animal which received the selenium supplementation or when this element was associated to the vitamin E. Smaller values of lipid peroxidation (TBARS) were detected in supplemented animals when these were compared to the control group. These results suggest that the reduced reserves of this antioxidant may exacerbate the generation of free radicals with an increase of the lipid peroxidation and the increase of the environment contamination by the eggs of Haemonchus contortus. Facing these results it is possible to conclude that the selenium supplementation provides a larger protection to the cell antioxidant and to the organism as a whole in lambs experimentally infected by Haemonchus contortus. / O presente trabalho teve como objetivo avaliar o metabolismo oxidativo dos neutrófilos, o hemograma e o perfil oxidativo de cordeiros experimentalmente infectados com Haemonchus contortus e suplementados com selênio e vitamina E. Foram utilizados 20 cordeiros machos, da raça Corriedale, distribuídos em quatro grupos experimentais com 5 animais: G1- animais infectados com larvas e suplementados com 0,2mg/kg de peso vivo (PV) de selenito de sódio por via intramuscular (IM); G2- animais infectados com larvas e suplementados com 0,2mg/kg PV de selenito de sódio IM e 2000 UI por animal de Vitamina E IM; G3- animais infectados com larvas e suplementados com 2000 UI por animal de Vitamina E IM; G4-animais infectados com larvas. Todos os grupos foram infectados, pela via oral, com 500 larvas L3 de Haemonchus contortus por animal a cada dois dias, pelo período de vinte dias a partir do dia zero. Para o hemograma e as análises bioquímicas foram realizadas coletas de sangue nos dias zero (T0), 20 (T1), 40 (T2) e 60 (T3) por venopunção da jugular utilizando-se tubos vacutainer®. As pesagens e a determinação dos ovos por grama de fezes dos animais ocorreram nesses mesmos tempos experimentais. Para as provas de NBT foram coletadas amostras de sangue heparinizadas nos dias zero, 30 e 60. Menores valores de leucócitos totais foram detectados no grupo suplementado exclusivamente com selênio (G1) em relação ao grupo controle (G4) no tempo 4. Em relação aos linfócitos observou-se diminuição no G1 em relação ao suplementado somente com vitamina E (G3) e G4 no tempo 3 (T3). Para ambos os testes, NBT-NE e NBT-E houve uma diminuição da capacidade de redução do corante aos 60 dias em relação aos demais tempos nos grupos tratados com selênio (G1 e G2).Os resultados do perfil oxidativo demonstraram significativa elevação da atividade da enzima GSH-Px nos grupos suplementados com selênio. Ainda, a correlação de Pearson revelou a existência de correlação negativa entre as concentrações de GSH-Px e TBARS e entre esta enzima e os valores de OPG. Incrementos também foram observados para a enzima catalase nos animais que receberam suplementação com selênio ou quando este elemento foi associado a vitamina E. Menores valores de lipoperoxidação lipídica (TBARS) foram detectados nos animais suplementados quando estes foram comparados ao grupo controle. Esses resultados sugerem que as reservas diminutas deste antioxidante podem exacerbar a geração de radicais livres com um aumento da peroxidação lipídica e o aumento da contaminação ambiental pelos ovos de Haemonchus contortus. Diante dos resultados é possível concluir que a suplementação com selênio proporciona uma maior proteção antioxidante celular e ao organismo como um todo de cordeiros experimentalmente infectados pelo Haemonchus contortus.