Effects of 17 α-methyltestosterone on the transcriptome, gonadal histology and sex steroid hormones in Pseudorasbora parva.

In recent years, the increasing use of environmental endocrine disruptors has caused serious environmental pollution and hurt aquatic organisms. It is still risky for aquatic species and humans exposed to 17α-methyltestosterone (MT), however, the harmful effect of MT on fish is still poorly understood. The main purpose of this study is to evaluate the influence of MT on Pseudorasbora parva at multi-levels. We analyzed gonadal histology, the sex steroid hormones, steroidogenic genes expression, and transcriptome profiling of gonads in response to MT in adult P. parva. Through this study, we found MT could inhibit the gonadal development of P. parva, and the growth and development of fish could be delayed by exposure to MT at 200 ng/L. MT could produce disruption effects on fish from multiple pathways, while its interference to the HPGL axis happens primarily through the steroidogenic pathway, e.g., disturbing the expression of crucial genes and sex steroids synthesis. Besides, we constructed 4 RNAseq libraries and obtained 7758 and 11,543 DEGs in females and males, respectively. Interestingly, we found MT had more obvious disruption effects on males than the females, mainly reflected in the immune system. Interestingly, we found three common pathways in both sexes after MT exposure, i.e., cell adhesion molecules, cytokine-cytokine receptor interaction, and neuroactive ligand-receptor interaction. These results confirm the suitability of P. parva as a model fish for aquatic toxicological study and provide us a multidimensional sight for the disruption effects of MT on fish.