Department of Internal Medicine, Endocrine-Metabolic Sciences and Biochemistry, University of Siena, Siena, Italy.
Adv Clin Chem. 2011;54:129-64. doi: 10.1016/b978-0-12-387025-4.00006-6.
Aromatase is a specific component of the cytochrome P450 enzyme system that is responsible for the transformation of C19 androgen precursors into C18 estrogenic compounds. This enzyme is encoded by the CYP19A1 gene located at chromosome 15q21.2, that is expressed in ovary and testis not only but also in many extraglandular sites such as the placenta, brain, adipose tissue, and bone. The regulation of the level and activity of aromatase determines the levels of estrogens that have endocrine, paracrine, and autocrine effects on target issues including bone. Importantly, extraglandular aromatization of circulating androgen precursors is the major source of estrogen not only in men (since only 15% of circulating estradiol is released directly by the testis) but also in women after the menopause. Several lines of clinical and experimental evidence now clearly indicate that aromatase activity and estrogen production are necessary for longitudinal bone growth, attainment of peak bone mass, the pubertal growth spurt, epiphyseal closure, and normal bone remodeling in young individuals. Moreover, with aging, individual differences in aromatase activity and thus in estrogen levels may significantly affect bone loss and fracture risk in both genders.
芳香化酶是细胞色素 P450 酶系统的特定组成部分，负责将 C19 雄激素前体转化为 C18 雌激素化合物。这种酶由位于 15q21.2 染色体上的 CYP19A1 基因编码，不仅在卵巢和睾丸中表达，而且在许多 外分泌组织如胎盘、脑、脂肪组织和骨中表达。芳香化酶的水平和活性的调节决定了雌激素的水平，雌激素对包括骨在内的靶组织具有内分泌、旁分泌和自分泌作用。重要的是，循环雄激素前体的 外分泌芳香化作用不仅是男性（因为只有 15%的循环雌二醇是由睾丸直接释放的），而且是绝经后女性雌激素的主要来源。现在有几条临床和实验证据清楚地表明，芳香化酶活性和雌激素产生对于纵向骨生长、达到峰值骨量、青春期生长突增、骺板闭合和年轻人的正常骨重塑是必要的。此外，随着年龄的增长，芳香化酶活性和雌激素水平的个体差异可能会显著影响两性的骨丢失和骨折风险。
