Resveratrol Attenuates Heat-Stress-Impaired Immune and Inflammatory Responses of Broilers by Modulating Toll-Like Receptor-4 Signaling Pathway

This study investigated the effect of resveratrol on the immune and inflammatory responses and the mRNA levels of splenic toll-like receptor (TLR)-4 signaling pathway-related genes of broilers under heat stress (HS). One hundred and sixty-two birds were allocated to three groups, each with 6 replicates, for 21 continuous days. The three treatments were as follows: the control group (22 ± 1 °C), the HS (33 ± 1 °C for 10 h d -1 and 22 ± 1 °C for the remaining time) group and the HS + resveratrol (400 mg kg -1 ) group. At the end of the trial, one bird per replicate close to the average body weight (BW) was selected, exsanguinated, and slaughtered. Compared with the control group, the HS treatment decreased ( p <0.05) final BW, average daily gain (ADG), average daily feed intake (ADFI), relative weight of bursa of Fabricius and spleen, serum immunoglobulin (Ig) Y, IgA and interleukin (IL)-10 contents, and splenic IL-10 mRNA level, while it increased ( p <0.05) feed/gain, mRNA levels of splenic tumor necrosis factor-α (TNF-α ), TLR-4, nuclear factor-kappa-B (NF-κ B), IL-1 β , and IL-6. Compared to the HS group, the HS+resveratrol group exhibited increased ( p <0.05) final BW, ADG, relative weight of bursa of Fabricius and spleen, serum IgY, IgA and IL-10 contents, and splenic IL-10 mRNA level, while it exhibited lower ( p <0.05) TNF-α , IL-1 β and IL-6 contents in serum, and splenic TLR4, TNF-α , IL-1 β , and NF-κ B mRNA levels. In conclusion, resveratrol prevented a HS-impairment of the immune function of broilers by blocking the abnormal activation of the TLR4 signaling pathway.