Study data from Environmental Protection Agency provide new insights into hormones.(Report)

According to recent research published in the journal Environmental Health Perspectives, "Several chemicals in the environment have the potential to inhibit aromatase, an enzyme critical to estrogen synthesis. The objective of this study was to provide a detailed characterization of molecular and biochemical responses of female fathead minnows to a model aromatase inhibitor, fadrozole (FAD)."

"Fish here exposed via water to 0, 3, or 30 mu g FAD/L for 8 days and then held in clean water for 8 days, with samples collected at four time points during each 8-day period. We quantified ex vivo steroid production, plasma steroids, and plasma vitellogenin (Vtg) concentrations and analyzed relative transcript abundance of 10 key regulatory genes in ovaries and 3 in pituitary tissue by real-time polymerase chain reaction. Ex vivo 17 beta-estradiol (E-2) production and plasma E-2 and Vtg concentrations were significantly reduced after a single day of exposure to 3 mu g or 30 mu g FAD/L. However, plasma E-2 concentrations recovered by the eighth day of exposure in the 3-mu g/L group and within 1 day of cessation of exposure in the 30-mu g/L group, indicating concentration- and time-dependent physiologic compensation and recovery. Concentration-dependent increases in transcripts coding for aromatase (A isoform), cytochrome P450 side-chain cleavage, steroidogenic acute regulator), protein, and follicle-stimulating hormone receptor all coincided with increased E-2 production and recovery of plasma E-2 concentrations," wrote D.L. Villeneuve and colleagues, Environmental ...