Effect of medical herbs in Tian-Dong-Tang-Gan powder on the oxidative stress induced by ammonia and nitrite in Litopenaeus vannamei

In order to evaluate the effect of different doses of Tian-Dong-Tang-Gan powder (TDTGP) on the immune function of Litopenaeus vannamei, and the molecular mechanism of anti-ammonia stress and anti-nitrite stress, and screening for the best dose, a 35-day feeding experiment and a 72-h ammonia stress or nitrite stress experiment were carried out. The results showed that when compared with the blank control group, the different doses of TDTGP could increase the body weight (BW), percent weight gain (PWG), body length (BL) and percent body length growth (PBLG), and the activities of acid phosphatase (ACP), phenol oxidase (PO), inducible nitric oxide synthase (i-NOS) and the total antioxidant capacity (T-AOC) in the hemolymph of L. vannamei during the feeding experiment, and the effect of TDTGP-4 treatment group was the best. When exposed ammonia or nitrite stress for 72 h, the PO activity was decreased in the hemolymphs, and the mRNA expression of PPO, MT, GSH-Px, Mn-SOD, HSP70 and HIF-1α in the hepatopancreas of L. vannamei. However, different TDTGP doses were fed to the shrimp followed by the application of ammonia and nitrite stresses. The activities of ACP, PO, i-NOS and T-AOC in the hemolymphs remained stable, and the mRNA expression of PPO, ACP, metallothionein (MT), glutathione peroxidase (GSH-Px), superoxide dismutase (Mn-SOD), heat shock protein 70 (HSP70), Hypoxia inducible factor 1α (HIF-1α) and other factors in the hepatopancreas could be maintained or improved to varying degrees in comparison with the blank control group and positive group. These results indicated that the TDTGP can improve growth performance and non-specific immune response of L. vannamei, and by maintaining the mRNA expression of the antioxidative stress factor, such as MT, GSH-PX, Mn-SOD, HSP70, HIF-1α and PPO and ACP in the hepatopancreas, acting against the damage of hepatopancreas caused by ammonia and nitrite stress in L. vannamei. The changes in BW, WG, activities of PO and ACP, and mRNA expression levels of PO, Mn-SOD and ACP indicated that the optimum supplement of dietary TDTGP should be 4 g per·kg.