Yeast cultures alleviate gossypol induced inflammatory response in liver tissue of Ussuri catfish (Pseudobagrus ussuriensis)

Abstract

The present study explored the mechanisms of gossypol induced inflammatory response in liver tissue of Ussuri catfish (Pseudobagrus ussuriensis), and investigated whether the yeast culture could relieve the inflammatory response of fish. For this purpose, Ussuri catfish were fed two diets with or without yeast culture for 8 weeks, and then fish were treated with 300 mg gossypol/kg body weight by intragastric administration for 15 days. Fish pre-fed diet without yeast culture supplementation and treated with gossypol oral administration (Gos group) had higher interleukin-1β (IL-1β) and interleukin 8 (IL-8) mRNA levels compared with fish pre-fed diet without yeast culture supplementation and treated with sodium carboxymethylcellulose solution oral administration (control group) and pre-fed yeast culture diet and treated with gossypol oral administration (Gos/YC group), but had lower interleukin 10 mRNA level than the control group (P < .05). Simultaneously, hepatic toll-like receptor 2 (TLR2), myeloid differentiation factor 88 (MyD88) and nuclear transcription factor kappa B p65 (NF-κB p65) mRNA levels of fish in Gos group were also up-regulated. However, dietary yeast culture supplementation remarkably prevented the increase of IL-1β and IL-8 mRNA levels and the decrease of IL-10 mRNA level by inhibiting the excessive activation of TLR2-MyD88-NF-κB signaling pathway through down-regulating TLR2, NF-κB p65 (P < .05) and MyD88 (P > .05) mRNA levels. Besides, the lowest serum lysozyme and alkaline phosphatase activities were observed in fish of Gos group. There was an increased trend in immunoglobulin M content among the groups. Fish in Gos group had significantly lower hepatic catalase, superoxide dismutase and total antioxidant capacity compared with those fish in the control group (P < .05). Higher occurrences of the dilatation in sinusoids, karyolysis, hydropic degenerations and nuclei shifting to the cellular periphery were detected in Gos group compared with those in the control group, coupled with increased serum aspartate aminotransferase activity. Lower occurrences of these histopathological symptoms were observed in the Gos/YC group compared with those of fish in the Gos group. Overall, the results mentioned above indicated that gossypol could result in immune and oxidative damage, liver injury and inflammatory response and dietary yeast culture supplementation could alleviate these negative responses for Ussuri catfish.