Endocrine-Disruptive Effects of Adenylate Cyclase Activator Forskolin: In Vitro and In Vivo Evidence

Forskolin (FSK) is a potent adenylate cyclase activator and may display endocrine-disruptive effects via the disruption of steroidogenesis. Here, we tested this hypothesis by use of the in vitro H295R steroidogenesis assay and the in vivo long-term medaka (<i>Oryzias latipes</i>) exposure assay. The results from the H295R assay demonstrated that the transcriptional levels of a series of genes involved in steroidogenesis, including <i>HSD3B2</i>, <i>CYP11A</i>, <i>CYP11B2</i>, <i>CYP17</i>, <i>CYP19</i>, and <i>CYP21</i>, were remarkably up-regulated. Meanwhile, the productions of estrogens (17β-estradiol (17β-E₂) and estrone (E₁)) and progestins (progesterone (PGT) and 17-hydroxyprogesterone (17-HPT)) were significantly increased, and those of androgens (androstenedione (ADD) and testosterone (TTR)) were significantly inhibited. After waterborne exposure of medaka to FSK for 100 days, the gene expressions of <i>HMGR</i>, <i>HSD17B1</i>, <i>CYP17B</i>, <i>CYP19A</i>, and <i>CYP21A</i> were significantly enhanced in the gonads of male medaka. 17β-E2 was remarkably induced, although without statistical significance. In addition, the biomarker genes for estrogenicity, including <i>VTG-I</i>, <i>VTG-II</i>, <i>CHG-H</i>, and <i>CHG-L</i>, were significantly induced in male medaka livers. Pathological damage to their gonads was further identified. Therefore, the results demonstrated that FSK modulates the transcriptions of steroidogenesis genes and alters hormone levels in vitro and in vivo, which is a mark of endocrine disruption in organisms.