Molecular Mechanisms of Adrenarche

University Of Michigan At Ann Arbor, Ann Arbor MI

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Abstract

DESCRIPTION (provided by applicant): The adrenal gland is a significant contributor to the circulating androgen pool in women and pre- pubertal children. Unlike the zona glomerulosa (ZG) and zona fasciculata (ZF), the zona reticularis (ZR) is relatively inactive until around 6 years of age when the zone expands and significantly increases the production of DHEA-S. This event is termed adrenarche, and is associated with the initiation of pubic and axillary hair growth as well as development of pubertal body odor and acne. Premature adrenarche (PA) describes an early rise in adrenal androgen production associated with concomitant development of pubic hair. Numerous studies now indicate that children with PA are more likely to have adult onset diseases that include insulin resistance and polycystic ovary syndrome (PCOS). Because of the large number of adults affected by these diseases, a better understanding of PA as a potential cause or early indicator of future disease has a high degree of clinical significance. My laboratory has approached the study of adrenarche by focusing on the adrenal itself and the changes it undergoes during the process of adrenarche. During our past funding period, we demonstrated distinct intra-adrenal changes during adrenarche that would allow the adrenal to produce a novel set of bioactive androgens. Preliminary steroid metabolomic analysis of human adrenal vein samples identified a series of novel androgens, including 112-hydroxytestosterone (11OHT) and 11- ketotestosterone (11KT). 11OHT and 11KT represent novel adrenal-specific steroids because their synthesis requires CYP11B1 (112-hydroxylase), an enzyme expressed almost solely in the human adrenal cortex. Our proposed research will test the overall hypothesis that adrenarche is marked by the production of bioactive androgens that play key roles in the physiologic effects of normal and premature adrenarche. We will address this goal through three specific aims: Aim 1 will define the human adrenal bioactive androgen metabolome and the levels of these steroids during adrenarche. Aim 2 will define the adrenocortical biosynthetic pathway for 11OHT and 11KT. Aim 3 will determine the bioactive androgens that increase during premature adrenarche. Completion of the study goals will significantly increase our understanding of the adrenal products that cause the biochemical and phenotypic manifestations of adrenarche during the pre-pubertal years. Definition of this novel series of adrenal androgens will also provide new biomarkers of adrenal dysregulation that may have implications not only in PA but also in women with adrenal-related hyperandrogenism.