Effects of selenium deficiency on the formation and detoxification of endogenous electrophiles in rats

Selenium deficiency could be expected to lead to enhanced lipid peroxidatio n through loss of selenium-dependent glutathione peroxidase activity. Such a relation has, however, been difficult to verify. In the present study, th e influence of selenium deficiency in rats on in vivo doses of some endogen ously occurring low-molecular mass aldehydes and epoxides was determined. I n vivo doses were measured by mass-spectrometric analysis according the N-a lkyl Edman method of reaction products (adducts) with N-terminal valines in hemoglobin. Despite variations between experiments, the adduct levels of a cetaldehyde and malonaldehyde were shown to be significantly higher in rats fed a selenium-deficient diet than in controls fed a selenium-adequate die t. No significant effect was found for the other aldehydes measured. In con trast, the in vivo doses of endogenous ethylene oxide and propylene oxide w ere lowered in selenium-deficient rats, indicating a 1.7-times faster detox ification rate. This was verified by the lower adduct levels in selenium-de ficient rats following intraperitoneal administration of these epoxides at moderate doses. In conclusion, the results seem to reflect the complex chan ges of induced and reduced enzyme activities in response to selenium defici ency. Measurement of reactive compounds through their adducts to hemoglobin has shown its ability to elucidate the effects of selenium deficiency per se. (J. Nutr. Biochem. 11:425-430, 2000) (C) Elseiver Science Inc. 2000. Al l rights reserved.