Oxidative stress in hypopituitary dwarf mice and in transgenic mice overexpressing human and bovine GH

Growth hormone (GH) stimulates metabolic activity. The purpose of this study was to examine whether it is involved in the aging process by increasing oxidative stress. Inorganic peroxides and lipid peroxides were measured in kidney and liver samples in dwarf mice that are deficient in GH, prolactin and thyrotropin and in transgenic mice that produce high levels of GH. In normal male mice, there was an increase in inorganic peroxides in the kidney with age. Levels were lower in old male dwarfs when compared with normal male mice of similar age. Unexpectedly, concentrations of inorganic peroxides were frequently lower in transgenic male and female mice expressing extra copies of GH than in normal controls. Lipid peroxide concentrations were more variable. Transgenic animals expressing bovine GH had the highest levels of lipid peroxides. In dwarfs, kidney levels were similar to those of normal mice but concentrations in the liver were more variable. This study does not indicate that the decrease in life span in transgenic mice producing high levels of GH is due to an increase of oxidative stress. Rather, it suggests that expression of extra copies of the GH gene may lead to a compensatory increase in antioxidant protection.