Redox balance is increasingly identified as a major player in cellular signaling. A fundamentally simple reaction of oxidation and reduction of cysteine residues in cellular proteins is the central concept in this complex mode of protein function regulation. Oxidation of key cysteine residues occurs at the physiological levels of reactive oxygen species (ROS) but are reduced by a supply of thiol antioxidant molecules including glutathione, glutaredoxin and thioredoxin. While these molecules show complex compensatory roles in experimental conditions, transgenic animal models provide a comprehensive picture to pinpoint the role of each antioxidant. In this review we have specifically focused on the available literature on Thioredoxin-1 system transgenic models that includes Thioredoxin and Thioredoxin reductase proteins. As identification of Thioredoxin protein targets is technically challenging the true contribution of this system in maintaining cellular balance remains unidentified, including the role of this system in the brain.