Sub‐chronic exposure to ammonia inhibits the growth of juvenile Wuchang bream (Megalobrama amblycephala) mainly by downregulation of growth hormone/insulin‐like growth factor axis

In this study, healthy Wuchang bream (Megalobrama amblycephala) juveniles were exposed to 0, 5, 10, 20 and 30 mg/L total ammonia nitrogen for 30 days to elucidate toxic effects and mechanisms of ammonia on growth performance involved with the regulation of growth hormone/insulin‐like growth factor (GH/IGF) and hypothalamic–pituitary‐thyroid (HPT) axes. Our results showed that the increasing total ammonia nitrogen concentrations caused dose‐depend decreases in the weight gain and specific growth rate but increases in the food conversion ratio and mortality in juvenile bream, indicating growth inhibitory effects induced by ammonia. Concurrently, GH, IGF‐1 at protein and mRNA levels were significantly decreased in ammonia exposure groups (p