Effects of Sex Steroid Hormone for Vitamin K Levels

Abstract

Castrated immature male and female rats were injected subcutaneously with sex hormones either estrogen or testosterone, and the concentration of vitamin K2 (menaquinone-4, MK-4) in the liver was compared. The level of liver MK-4 increased after injection of estrogen, but decreased after injection of testosterone regardless of the sexes of castrated rats. Although the amounts of estrogen given the animals were the same, the increase in the liver MK-4 was more distinct in males than in females, reflecting a sex-dependent sensitivity of the liver MK-4 to the level of estrogen (means: 9.68ng/g in females: 12.54ng/g in males at 6 weeks of age). When these animals were fed with vitamin K-deficient foods, females showed greater decreases in the liver MK-4 than males (means: from 13.62 to 1.86ng/g in females: 3.97 to 2.47ng/g in males). The female rats thus appear to be far more sensitive to vitamin K-deficiency for maintaining the level of liver MK-4. Although there still exists the species barrier regarding the level of liver MK-4, the data altogether seem to be relevant to the clinical consequence of osteoporosis as occures more frequently in postmenopausal women manifesting a rapid decrease in the estrogen level than in men at the same ages.