Effect of Dietary Lactobacillus casei on Physiometabolic Responses and Liver Histopathology in Common Carp (Cyprinus carpio) After Exposure to Iron Oxide Nanoparticles.

A 60-day feeding trial was performed to assess the dietary effect of Lactobacillus casei as a probiotic supplement on some serum biochemical parameters and liver histopathology in common carp fry after exposure to iron oxide nanoparticles (IoNPs). Six treatments were prepared as follows: control (no IoNP exposure and no dietary probiotic), P6: 106 CFU/g probiotic diet, P7: 107 CFU/g probiotic diet, NPs: 0.15 mg/l IoNPs, NPs + P6: 0.15 mg/l IoNPs with 106 CFU/g probiotic diet, and NPs + P7: 0.15 mg/l IoNPs with 107 CFU/gprobiotic diet. Based on the results, serum aspartate aminotransferase and alanine aminotransferase levels were significantly increased in 0.15 mg/l IoNPs, P7, and NPs + P6 treatments compared to the control group. In addition, the examination of antioxidant enzymes showed a significant increase in the levels of cortisol and glutathione S-transferase as well as malondialdehyde level. IoNPs also caused significant histopathological changes in the fish liver during the experiment such as hyperemia in sinusoidal spaces, hepatocytes vacuolation and necrosis, pyknosis, and disruption of hepatic lobules and atrophy. Results revealed the protective effects of dietary L. casei to mitigate the adverse impacts of IoNPs on the physiological processes of common carp.