New nephron development in goldfish (Carassius auratus) kidneys following repeated gentamicin-induced nephrotoxicosis

Renal development in mammalian kidneys can only be studied in embryonic ani mals. Hence, research in this area is hampered by the need to maintain preg nant animals and by the small size of the embryonic kidney. Here, we descri be a goldfish (Carassius auratus) model for studying renal repair and nephr on development in an adult animal. Previous studies have indicated that che mically induced nephrotoxicosis in goldfish is followed by new nephron deve lopment. We tested the hypothesis that new nephron development is not a one -time only event and, thus, will occur after repeated nephrotoxic events. W e used repeated injections of gentamicin (50 mg/kg of body weight), a nephr otoxic antibiotic, which has been used as a model nephrotoxicant to study r enal repair. Fish were allowed either a recovery period of 9 or 24 weeks be tween injections. In both experiments, new nephrons developed after each in jection of gentamicin, supporting our hypothesis. Nephron development occur ring after a 9-week recovery period was similar to development observed aft er a 24-week recovery period; therefore, the shorter experimental paradigm appears sufficient and can save time and money. Future research using this fish nephrogenesis model may identify the genes responsible for nephron neo genesis, Such information is a prerequisite for developing alternative rena l replacement therapies based on the induction of de novo nephrogenesis in diseased kidneys.