GENTAMICIN-INDUCED NEPHROTOXICITY AND NEPHRONEOGENESIS IN OREOCHROMIS-NILOTICA, A TILAPIAN FISH

The renal response to 2 doses of gentamicin (low dose of 5 mg kg(-1) o f body weight and high dose of 25 mg kg(-1) of body weight) was examin ed in the tilapian fish Oreochromis nilotica. Gentamicin exposure indu ced acute tubular necrosis that peaked in severity at 2 d following in traperitoneal injection of the high dose and at 4 to 7 d following inj ection of the low dose. Necrosis following high dose exposure was more severe than that following low dose exposure. Histochemical staining for gamma glutamyl transpeptidase showed the site of injury to be loca lized in the proximal tubules. Immunohistochemical staining with 5-bro mo-2'-deoxyuridine was used to mark cell proliferation during regenera tion and nephroneogenesis. Regeneration of epithelial cells along the basement membrane of damaged tubules and development of new nephrons w ere both documented following nephrotoxic injury. Although the overall pattern of renal response to gentamicin exposure was similar to that which has been previously documented in other freshwater fish species, the commercially important tilapian fish was significantly more sensi tive than other fishes.