When hemolyzates from erythrocytes of selenium-deficient rats were incubated in vitro in the presence of ascorbate or H(2)O(2), added glutathione failed to protect the hemoglobin from oxidative damage. This occurred because the erythrocytes were practically devoid of glutathione-peroxidase activity. Extensively purified preparations of glutathione peroxidase contained a large part of the (75)Se of erythrocytes labeled in vivo. Many of the nutritional effects of selenium can be explained by its role in glutathione peroxidase.

https://science.sciencemag.org/content/sci/179/4073/588.full.pdf

Selenium: Biochemical Role as a Component of Glutathione Peroxidase

Publisher Summary Glutathione (GSH) is the most important nonprotein thiol in living systems and is of widespread occurrence in the intracellular milieu of animals, plants, and microorganisms GSH was isolated and named by the English biochemist Frederick Gowland Hopkins This chapter discusses GSH status, the biologically relevant chemistry of GSH, the forms in which GSH can be present within the cell, along with the GSH content of cells and the methods for analysis of this substance GSH-related biochemical reactions and the biological roles of GSH are discussed in the chapter The use of perturbations in GSH status as a means for investigating GSH-related phenomena and an analysis of the consequences of perturbation are presented A short summary of genetic lesions related to GSH is also included Like chemically induced perturbations in GSH status, genetic lesions provide valuable insights into the role of GSH in normal functions and processes in cells The chapter concludes with some brief comments about the future of the relationship of GSH status to cellular processes

The Glutathione Status of Cells

Experiments were conducted with male rats to quantitate the relation ship between dietary selenium (Se) intake and the amount of the enzyme glutathione peroxidase (GSH-Px) in erythrocytes and liver. Weanling male rats were fed torula yeast-based diets with 0, 0.05, 0.1, 0.5, 1.0, or 5.0 ppm Se supplemented as sodium selenite. Liver GSH-Px fell to undetectable levels (<1% of that found in the weanling rats) within 24 days in the O ppm Se group; feeding 0.1 ppm Se, or greater, caused liver GSH-Px to increase above that found in the weanling rats. The erythrocyte GSH-Px response to lack of dietary Se was somewhat smaller in magnitude and more gradual; however, only 21% of initial erythrocyte GSH-Px activity remained in the unsupplemented group after 66 days. Increased dietary Se resulted in corresponding increases of erythrocyte GSH-Px activity. Resupplementing with 0.1, 0.5, or 5.0 ppm Se elevated the depressed erythrocyte GSH-Px levels of the deficient rats. Increased dietary Se provided for both faster elevation, and higher maximal GSH-Px activity which in all cases was achieved 60 to 90 days after resupplementation. The results suggest that tissue GSH-Px can be used as an indicator of animal Se status, but other factors such as age, sex, and dietary vitamin E may have to be considered. Lack of GSH-Px in livers of Se-deficient rats may explain the liver necrosis observed when the diet is also deficient in vitamin E and sulfur-containing amino acids. J. Nutr. 104: 580-587,

Effect of dietary selenium on erythrocyte and liver glutathione peroxidase in the rat

Reactive oxygen species, such as superoxide and hydrogen peroxide, are generated in all cells by mitochondrial and enzymatic sources. Left unchecked, these reactive species can cause oxidative damage to DNA, proteins, and membrane lipids. Glutathione peroxidase-1 (GPx-1) is an intracellular antioxidant enzyme that enzymatically reduces hydrogen peroxide to water to limit its harmful effects. Certain reactive oxygen species, such as hydrogen peroxide, are also essential for growth factor-mediated signal transduction, mitochondrial function, and maintenance of normal thiol redox-balance. Thus, by limiting hydrogen peroxide accumulation, GPx-1 also modulates these processes. This review explores the molecular mechanisms involved in regulating the expression and function of GPx-1, with an emphasis on the role of GPx-1 in modulating cellular oxidant stress and redox-mediated responses. As a selenocysteine-containing enzyme, GPx-1 expression is subject to unique forms of regulation involving the trace ...

Glutathione Peroxidase-1 in Health and Disease: From Molecular Mechanisms to Therapeutic Opportunities

In many nonprimate mammalian species, cyclical regression of the corpus luteum (luteolysis) is caused by the episodic pulsatile secretion of uterine PGF2α, which acts either locally on the corpus l...

A. L. Pope

Papers

Prevention of oxidative damage to rat erythrocytes by dietary selenium.

Effect of Exogenous Progesterone on Estrous Cycle Length

Inequality in function of the right and left ovaries and uterine horns of the ewe.

Glutathione peroxidase response to selenium intake in lambs fed a Torula yeast-based, artificial milk.

Progesterone Levels in Corpora Lutea and Ovarian Effluent Blood of the Ewe