Effects of Finasteride on Steroid Production and Gene Expression in Male Fathead Minnow and Medaka

The study investigated the effects of Finasteride (FIN) on male fathead minnow and medaka, focusing on steroid production and gene expression. Fish were exposed to 1 mg/L of FIN for up to 21 days, with measurements taken at various intervals. Results showed a significant reduction in plasma DHT concentration in fathead minnows and upregulation of testes srd5a2 expression in both species, indicating that DHT plays a crucial role in fish similar to mammals. The study highlights the conserved molecular targets in the androgen biosynthesis pathway across species. Internal plasma concentrations of FIN were higher than water concentrations, emphasizing the need to understand internal exposure for assessing pharmacological effects in fish. The findings suggest potential read across between humans and fish through 5αR inhibition.