| To evaluate the anti-immunological stress effects of Astragalus polysaccharide (APS), achyranthes bidentata polysaccharide (ABPS) and their interaction, an immunological stress model was established through intraperitoneal injecting with E. coli lipopolysaccharide (LPS). A total of 48 crossbred weaned pigs (Duroc×Large White×Landrace, average initial BW of 8.45±0.14 kg) were used in a 2×2×2 factorial design. The main factors consisted of dietary addition of APS (0 or 500 mg/kg), dietary addition of ABPS (0 or 500 mg/kg) and immunological challenge (with LPS or saline). Pigs were randomly allotted to eight treatments by initial BW (6 replicates per treatment and one pig per replicate). On d 14 and 21, pigs were given an intraperitoneal injection with either 100μg/kg BW of LPS or an equivalent amount of sterile saline. Blood samples were obtained for analysis of inflammatory parameters, endocrine hormones, blood biochemical index and white blood cell differential counts at 3 h post-injection and at 2 d post-injection for analysis of peripheral blood lymphocyte proliferation (PBLP). The results showed that LPS challenge decreased average daily gain (ADG) and average daily feed intake (ADFI) from 14~21, 21~28 and 0~28 d, whereas ABPS increased ADG (P < 0.05) and ADFI (P = 0.124) from d 21~28. APS did not affect growth performance in the whole trial. On d 14 and 21, LPS challenge significantly increased (P < 0.001) the concentration of plasma tumor necrosis factor-α(TNF-α), cortisol and prostaglandin E2 (PGE2) and decreased (P < 0.001) the level of plasma insulin-like growth factor (IGF)-I. An interaction between ABPS and LPS challenge was observed for all these plasma indices, which is to say the concentration of plasma TNF-α(P < 0.05), PGE2 (P < 0.10) and cortisol (P < 0.10) was lower, and the level of IGF-I was higher (P < 0.05) in pigs receiving the ABPS diet than the LPS-treated pigs fed the control diet, but there was no difference for these indices response in the saline-injected pigs. On d 14, there was a LPS challenge×APS interaction for plasma insulin (P < 0.10) and glucose (P < 0.05), which suggested APS attenuated the decline of plasma insulin and glucose in LPS-treated pigs but not affected them in saline-injected pigs. On d 14, LPS significantly decreased (P < 0.001) the number of white blood cells (WBC), lymphocytes, monocytes, neutrophils and the percentage of monocytes, whereas ABPS increased the number of WBC (P < 0.10) and neutrophils (P < 0.05), as well as the percentage of neurtrophils (P < 0.05). On d 21, LPS significantly decreased (P < 0.001) the number of WBC, lymphocytes and the percentage of neutrophils, but ABPS increased the number of WBC (P < 0.05) and neutrophils (P < 0.05), as well as the percentage of neurtrophils (P < 0.10). It suggested that ABPS could play an anti-inflammatory role. APS did not affect leukocyte differential counts. LPS significantly increased PBLP (P < 0.01) when these cells were incubated with LPS during both the challenge periods, which suggested LPS activated the cellular immune response. An interaction (P < 0.05) between APS and LPS challenge was observed for PBLP when these cells were incubated Concanavalin A during the first challenge period, which suggested APS mitigated the excessive activation of cellular immune response to some extend. The results suggest that there is no interection between APS and ABPS. There is no amelioration observed dued to APS supplementation, but ABPS attenuates the negative effect induced by immunological stress to some extent through playing an anti-inflammatory role. |
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