[Cellular biology of sex steroid and clinical implication]

Advances in molecular biology contribute to additional precise knowledge of sex steroid biology. Sex steroids, estrogens, androgens, and progesterone can exert their characteristic biological effects via cellular mechanism on their targets. Sex steroids are derived from the gonads and interact with SHBG or CBG, which is located in the serum, on the plasma-membrane and in the cytoplasm. They exert their known biological effects via interaction with cellular components such as the plasma membrane, the cytoplasmic component, the nuclear receptor, and the nuclear matrix. Estrogens and androgens are detected in the serum of both sexes, which shows the necessity of both steroids for the expression of either sex characteristics. Sex steroids and their metabolites can demonstrate individually different biological effects, suggesting the presence of the individual receptors. The presence of cooperative effects among each steroid induces complexity in the evaluation of each steroid effect. As to the imbalance of the effects of sex steroids, the predominance of estrogens induces female dimorphism of autoimmune diseases and the protective effects on psychoneurological diseases, and that of androgens does the reverse. The continuous exposure to estrogens (and androgens) may induce benign and malignant tumors in their target organs. Various mutations mainly in sex steroid receptor genes, and other unknown abnormalities cause sex steroid resistance, e.g. male pseudohermaphroditism and uterine dysfunction. Finally, climacteric disorders are derived from estrogen-deficiency and can be managed by estrogens under the milieu of an expanded lifespan.