Environmental estrogens and progestins disturb testis and brood pouch development with modifying transcriptomes in male-pregnancy lined seahorse Hippocampus erectus.

Exposure to environmental estrogens and progestins has contributed to adverse effects on the reproduction of many aquatic wildlife species. However, few reports have paid attention to fish species with specialized reproductive strategies, such as male-pregnancy seahorses. In this study, the potential effects on the behavior, gonad and brood pouch development, and transcriptomic profiles of lined seahorse Hippocampus erectus exposed to environmentally relevant concentrations of 17α-ethynyl estradiol (EE2, 5 ng/L, 50 ng/L, 10 ng/L, 100 ng/L) or progesterone (P4) for 60 days were examined. Both EE2 and P4 significantly inhibited male brood pouch development by disrupting the extracellular matrix and basement membrane pathways. In addition, both EE2 and P4 impaired the expression of genes associated with spermatogenesis in the testis, and even caused male feminization. We suggest that seahorses be regarded as a sensitive indicator for evaluating the potential effects of endocrine disrupting chemical (EDC) pollution on aquatic biotic communities.