Adrenal maturation, nutritional status, and mucosal immunity in Bolivian youth.

OBJECTIVES Humans-and several other apes-exhibit a unique pattern of post-natal adrenal maturation; however, the causes and consequences of variation in adrenal development are not well understood. In this study, we examine developmental and age-related maturation of the adrenal gland (measured via dehydroepiandrosterone-sulfate [DHEA-S]) for potential life-history associations with growth and mucosal immunity in a rural population of immune-challenged Bolivian juveniles and adolescents. METHODS Salivary DHEA-S, anthropometrics, and salivary mucosal immunity (secretory IgA [sIgA]) were measured in 171 males and females, aged 8-23. RESULTS Males with greater energy (i.e. fat) stores showed higher DHEA-S levels. Controlling for age and energetic condition (to control for phenotypic correlation), higher DHEA-S was associated with higher mucosal immunity (sIgA) among both males and females. Higher DHEA-S levels were positively associated with growth (i.e. height and strength) in males. CONCLUSIONS In accordance with predictions derived from life-history theory, males with higher energy stores secrete more adrenal androgens. This suggests that adrenal maturation is costly and subject to constraints; that is, only males with sufficient reserves will invest in accelerated adrenal maturation. Further, DHEA-S appears to have a measureable influence on immunocompetence in adolescent males and females; therefore, deficits in DHEA-S may have important consequences for health and maturation during this period. Adrenal maturation is an important, but understudied component of human growth and development.