Endocrine Abstracts

Puberty is the process of physical change that occurs between childhood and adulthood, during which adolescents reach sexual maturity and become capable of reproduction. The onset and course of puberty are under the control of the neuroendocrine system. Factors affecting the timing and regulation of the functions of this system may alter the onset and course of puberty. Recent studies have demonstrated a progressive decrease in the age of onset of puberty in children around the world. Although the exact reason for this shift is not completely understood, it is generally accepted to be the outcome of a complex interaction between genetic, epigenetic, endocrine, and environmental factors. It is also known that owing to the acceleration of industrialization throughout the world, a gradual but significant increase has occurred in the number and amount of environmental pollutants. Some of these environmental pollutants are natural or synthetic chemicals with considerable effects on the endocrine system. The chemicals that have negative effects on the endocrine system are called endocrine disrupting chemicals (EDCs). EDCs exert their effects through different mechanisms: by binding to the relevant hormone receptors; by direct action on cell signaling pathways or on the central nervous system and the neuroendocrine system. Several EDCs such as phytoestrogens, topical and natural estrogens, pesticides, industrial chemicals, and phthalates have been identified as possible agents affecting pubertal development in humans. These chemicals may exert their estrogenic effects either directly by binding to estrogen receptors, increasing aromatase activity, and increasing estrogen sensitivity, or indirectly by their effect on GnRH, leading to an increase in endogenous estrogen production. In this part of the panel, the roles of EDCs in precocious puberty will be discussed with examples from animal and human studies.