| The health state was significantly influenced and performance was decreased by oxidative stress in piglets.However,there is little research about the effect of metabolism and the characteristic of requirement on nutrients in pigs.This research was conducted to study the effects of oxidative stress induced by diquat on arginine metabolism and requirement of piglets.We will try to find out the metabolism and requirement of arginine under oxidative stress and the effect of anti-oxidative stress by arginine in piglets.It will accumulate the data of arginine nutrition of piglets and provide the information for relieving the harm by oxidative stress and using arginine rationally.The main results were listed as following:Exp.1 Effects of oxidative stress induced by diquat on arginine metabolism of pigletsA total of 24 crossbred postweaning pigs with 10.63±0.21 kg BW were individually penned and assigned to three treatments to investigate the influences of diquat-induced oxidative stress on performance and arginine metabolism.Pigs of oxidative stress group were intraperitoneally injected with 10mg/kg BW of diquat and fed ad libitum,those of control group were injected with isotonic saline and fed ad libitum,and those of pair-fed group were injected with isotonic saline and fed the same amount of feed as stress group.The experiment lasted for 7 days.Results indicated that compared to control treatment,oxidative stress induced by diquat significantly decreased average daily gain,feed intake and efficiency of feed utilization,decreased activities of antioxidant enzymes,increased concentration of malondialdehyde in serum,increased cationic amino acid transporter-1 m RNA level and activities of ornithine aminotransferase and concentrations of arginine and citrulline in jejunum,decreased the concentrations of arginine in serum and kidney,decreased induced nitric oxide synthase m RNA level.It is concluded that oxidative stress induced by diquat can reduce performance,influence absorption and metabolism of arginine and consequently modify the requirement of arginine in postweaning pigs.Exp.2 Effects of oxidative stress induced by diquat on arginine requirement of pigletsThis study evaluated whether arginine(Arg)supplementation could attenuate oxidative stress induced by diquat in piglets.A total of 36 PIC postweaning pigs were individually penned and assigned to three treatments including:(1)Arg=1.19%(2)Arg=1.99%(3)Arg=2.79%.On day 8,pigs in each treatment were divided into two to intraperitoneally injected with diquat or sterile saline.At 96 h post-injection,pigs were killed for evaluation of performance,the activities of antioxidant enzymes and TAOC and malondialdehyde in plasma and liver,the concentrations of amid acid in plasma and tissue.The results indicated:(1)Oxidative stress induced by diquat significantly decreased average daily gain(P?0.001),feed intake(P?0.001)and efficiency of feed utilization(P?0.05).Supplementation of arginine(Arg=2.79%)significantly increased average daily gain(P?0.05).(2)Supplementation of arginine(Arg=2.79%)significantly increased activities of antioxidant enzymes and TAOC,decreased concentration of malondialdehyde in liver.(3)Oxidative stress induced by diquat significantly decreased the concentrations of arginine,glutamic acid,lysine,methionine,threonine and tyrosine in plasma,increased the concentrations of isoleucine and valine in plasma.Supplementation of arginine significantly increased the concentration of lysine under oxidative stress.(4)Oxidative stress induced by diquat significantly decreased the concentrations of arginine and citrulline in jejunum,decreased the concentrations of citrulline in kidney,increased the concentrations of arginine in kidney.Supplementation of arginine have no significantly effect on the concentrations of arginine and citrulline in tissue.It is concluded that arginine can alleviate the growth depression and stress response induced by oxidative stress to some degree through depress the decreasing of food intake,increasing the ability of anti-oxidative stress,improving amino acid level in circulation in piglets.It illustrated that the requirement of arginine was increased under oxidative stress in piglets.Exp.3 The possible mechanism of arginine for anti-oxidative stress of pigletsThis study evaluated the mechanism of arginine(Arg)supplementation attenuate oxidative stress induced by diquat in piglets.A total of 36 PIC postweaning pigs were individually penned and assigned to three treatments including:(1)Arg=1.19%(2)Arg=1.99%(3)Arg=2.79%.On day 8,pigs in each treatment were divided into two to intraperitoneally injected with diquat or sterile saline.At 96 h post-injection,pigs were killed for evaluation of intestinal morphology,arginine metabolism,endocrine secretion,the gene relatively expression of growth factors and inflammatory cytokines.The results indicated:(1)Within 96 h of oxidative stress,oxidative stress induced by diquat significantly decreased villus width,membrane propria thickness and crypt depth in jejunum.Supplementation of arginine significantly mitigated jejunum morphology impairment(e.g.lower villus width and membrana propria thickness).(2)Oxidative stress induced by diquat significantly increased cationic amino acid transporter-1,2,3 m RNA level.Supplementation of arginine significantly suppressed the m RNA level of CAT-1 and CAT-2 induced by oxidative stress.(3)Oxidative stress induced by diquat significantly decreased m RNA level of ENOS and INOS in liver and INOS in jejunum,increased m RNA level of INOS in kidney.Supplementation of arginine significantly suppress the elevation of the m RNA level of INOS in kidney induced by oxidative stress,significantly increased the m RNA level of ENOS in jejunum and kidney suppressed by oxidative stress.(4)Oxidative stress induced by diquat significantly decreased activities of ENOS and INOS and the production of NO in liver,significantly increased activities of INOS in plasma at 24 h and 48 h.Supplementation of arginine significantly increased activities of TNOS in liver.(5)Oxidative stress induced by diquat significantly increased concentrations of cortisol in plasma at 48 h,96h.Oxidative stress significantly decreased concentrations of insulin and IGF-1 in plasma.Supplementation of arginine significantly prevented the elevation of plasma cortisol induced by oxidative stress.Arginine significantly increased plasma insulin and IGF-1 suppressed by oxidative stress.(6)Supplementation of arginine significantly increased the m RNA level of IGF-1 and IGFBP3 in liver.Supplementation of arginine significantly increased the m RNA level of IGF-1,IGF-1R and IGFBP3 in muscle suppressed by oxidative stress.(7)Supplementation of arginine significantly suppressed the m RNA level of TNF-? in jejunum.These results indicate that Arg supplementation has beneficial effects in piglets induced by oxidative stress through keeping morphous of intestine,regulating endocrine section,increasing the availability of arginine,maintaining endogenous stability of arginine,promoting protein synthesis in muscle,depressing inflammatory cytokines.ConclusionsThese results indicate that oxidative stress induced by diquat can reduce performance,influence absorption and metabolism of arginine and consequently modify the requirement of arginine for postweaning pigs.Arginine can alleviate the growth depression and stress response induced by oxidative stress to some degree through depress the decreasing of food intake,increasing the ability of anti-oxidative stress,improving amino acid level in circulation in piglets.Arg supplementation has beneficial effects in piglets induced by oxidative stress through keeping morphous of intestine,regulating endocrine section,increasing the availability of arginine,maintaining endogenous stability of arginine,promoting protein synthesis in muscle,depressing inflammatory cytokines. |
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