Efectos del porcentaje y fuente de proteína, del entrenamiento de fuerza y de la administración de esteroides anabolizantes sobre marcadores metabólicos, hepáticos, renales y óseos en ratas

Resumen

ABSTRACT In the last years, diets based on high protein intakes have won in popularity. Furthermore, resistance trainers sometimes combine such whey or soy protein based diets with the administration of anabolic androgenic steroids. The overall objective of this Thesis has been to analyze the metabolic, hepatic, renal and bone effects of high-protein diets, the protein source (whey vs. soy), resistance training and anabolic androgenic steroids in rats. The main findings from this Thesis suggest that: a) Plasma and urinary markers showed higher metabolic acidity after a high whey or soy protein diet consumption, which could explain the heavier kidney and liver observed in those groups and could increase the risk of kidney stones. Despite of this acidosis, bone mineral content was not affected. b) Resistance training was effective at enhancing bone mineral content, as measured by femur ashes weight. The effects of training were generally observed at the second and third month, suggesting a mid-long term effect. c) Resistance training had a protective action against hepatic and renal inflammation promoted by the high protein diet. d) Among all the interventions tested, anabolic androgenic steroids administration was the factor that most negatively affected plasma and hepatic lipid profile, whereas high-protein diets and hypertrophy resistance training could induce, in general, a better lipid profile, especially when combined. Any consistent benefits on body weight loss, hepatic and plasma lipid profile have been observed derived from soy protein instead to whey-protein consumption. e) The increase of acid and urinary calcium excretion due to the whey-protein diet can constitute a favorable environment for kidney stones and renal diseases. However, any significant renal morphological effects attending to the protein source have been observed. f) High-protein diets and anabolic androgenic steroids increased kidney weight and glomerular area, especially when combined. Hypertrophy resistance training reduced the higher kidney weight observed in those groups and the glomerular area, but with the parallel increase of renal and tubular fibrosis. The high intensity of the training protocol performed under our experimental design might be on the basis of this worse morphological renal status. The results of the present Thesis highlight the usefulness of resistance training among all the interventions tested (high-protein diets, whey or soy protein source, exercise and anabolic androgenic steroids) on promoting weight loss and improving plasma and hepatic lipid profile, but the present hypertrophy resistance training protocol performed under our experimental conditions induced a less favorable renal morphology.