AUTHOR=Liang Hualiang , Ji Ke , Ge Xianping , Xi Bingwen , Ren Mingchun , Zhang Lu , Chen Xiaoru 

TITLE=Tributyrin Plays an Important Role in Regulating the Growth and Health Status of Juvenile Blunt Snout Bream (Megalobrama amblycephala), as Evidenced by Pathological Examination

JOURNAL=Frontiers in Immunology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2021.652294

DOI=10.3389/fimmu.2021.652294

ISSN=1664-3224

ABSTRACT=<p>The present study aimed to assess the role of tributyrin (TB) in regulating the growth and health status of juvenile blunt snout bream (<italic>Megalobrama amblycephala</italic>) through an 8-week feeding experiment. Six groups were fed experimental diets with added TB percentages of 0% (control group), 0.03%, 0.06%, 0.09%, 0.12% and 0.15%. The present results showed that TB supplementation in feed had some positive impacts on FW, WG, FCR and SGR, and the best results were found in the 0.06% TB group (<italic>P&lt;0.05</italic>). However, TB supplementation in feed had no significant effects on SR, CF, VSI or whole-body composition (<italic>P&gt;0.05</italic>). TB supplementation in feed increased antioxidant capacity and immunological capacity and attenuated the inflammatory response by increasing the activity of T-SOD, GPx, CAT and the levels of anti-inflammatory cytokines (IL-10 and TGF-β) and decreasing the levels of MDA and anti-inflammatory cytokines (TNF-α) (<italic>P&lt;0.05</italic>). Furthermore, TB supplementation improved immunity by increasing the levels of immunoglobulins (IgM and IgG), C3 and IFN-γ (<italic>P&lt;0.05</italic>). Surprisingly, 0.06%-0.12% TB supplementation significantly increased the content of IL-1β (<italic>P&lt;0.05</italic>). However, TB supplementation in feed had no significant effects on the plasma content of GSH, HSP70, IL-8 and the activity of T-AOC (<italic>P&gt;0.05</italic>). The possible mechanism was that TB activated PI3K/Akt/Nrf2 and inhibits the NF-κB signaling pathway, further regulating the mRNA levels of key genes with antioxidant capacity and the inflammatory response; for example, it increased the mRNA levels of Nrf2, Cu/Zn-SOD, HO-1, CAT, Akt, PI3K, GPx, IL-10, and TGF-β and decreased the mRNA levels of NF-κB and TNF-α (<italic>P&lt;0.05</italic>). In addition, 0.06%-0.15% TB supplementation significantly increased the mRNA levels of IL-1β (<italic>P&lt;0.05</italic>). TB supplementation in feed had no significant effects on the mRNA levels of HSP70, Mn-SOD and IL-8 (<italic>P&gt;0.05</italic>). Evidence was presented that TB supplementation decreased the mortality rate caused by <italic>Aeromonas hydrophila</italic> challenge. In pathological examination, TB supplementation prevented hepatic and intestinal damage. Generally, TB supplementation improved the growth performance of juvenile blunt snout bream. Furthermore, TB supplementation activated PI3K/Akt/Nrf2 and inhibited the NF-κB signaling pathway, regulating health status and preventing hepatic and intestinal damage.</p>