鸡肾脏对微囊藻毒素-LR氧化胁迫的响应

Oxidative Stress Responses in Kidney of Chicken Exposed to Microcystin-LR

天然蓝藻中蛋白质含量高达40%,与大豆的蛋白质含量相当,是优质饲料蛋白的潜在来源。然而,天然蓝藻中主要含有一种称为微囊藻毒素(Microcystins,MCs)的生物毒素,对动物和人体的健康具有潜在威胁,且关于MCs对家禽氧化胁迫的研究几乎是一片空白。因此,急需开展蓝藻饲料化利用对家禽氧化胁迫的研究,为蓝藻饲料化利用提供理论依据。该文通过腹腔注射的方式研究了崇仁麻鸡肾脏对微囊藻毒素-LR(MC-LR)氧化胁迫的响应。试验设置了5μg·kg^-1 MC-LR(低剂量组)、10μg·kg^-1 MC-LR(中剂量组)和20μg·kg^-1 MC-LR(高剂量组)3个染毒组,同时腹腔注射生理盐水作为对照组。在腹腔注射后的1、3、12、24、48 h检测了鸡肾脏中谷胱甘肽(GSH)含量以及谷胱甘肽转移酶(GST)、谷胱甘肽过氧化物酶(GPX)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性变化以及肾体比变化。结果表明:在MC-LR的作用下,鸡肾脏抗氧化酶(GST、SOD、CAT和GPX)和GSH含量均存在不同程度的变化,但除了3 h时中和高剂量染毒组肾脏中CAT酶活性(值分别为(96.66±1.13)和(74.01±11.20)U·mg^-1)显著低于对照组(123.58±11.33)U·mg^-1(t=4.253;P=0.024和t=4.432;P=0.022)外,其它染毒组的各类抗氧化酶和GSH指标与对照组之间均无显著性差异(P>0.05);鸡肾脏系数从1h就开始呈现毒素处理组高于对照组,并在12、24和48 h时,毒素处理组肾脏系数(0.79%-0.87%)显著高于对照组(0.58%-0.70%)的趋势(t=-6.687--3.495;P=0.018-0.036)。上述结果表明,在MC-LR作用下,鸡肾脏产生了氧化应激现象,但是其抗氧化酶系统可能难以抵御MC-LR危害,MC-LR对鸡肾脏的毒性较大。

It is well known that cyanobacteria contains much high content of nutritive substance,such as protein,vitamin,and so on.The natural cyanobacteria(dried cyanobacteria)contains about 40% protein,which is equivalent to that in soybean.Thus,cyanobacteria can be used a potential protein source for animals.Unfortunately,some species of cyanobacteria are able to produce a wide range of bioactive compounds(mainly microcystins(MCs))that pose potential risks to human health and living animals.However,studies on oxidative stress induced by MCs in poultry are scare.Hence,it is necessary to examine the toxicity of MCs to poultry,to provide theoretical evidence for the utilizations of cyanobacteria as feed products.In the present study,four experimental groups were set up:control group,low-dose(LD)microcystin-LR(MC-LR)group,middle-dose(MD)MC-LR group and high-dose(HD)MC-LR group.Chicken in the LD,MD,and HD MC-LR groups were intraperitoneally injected with pure MC-LR at various single doses of 5,10,and 20 μg·kg^-1 body mass(bm),respectively.Chicken in the control group were injected with the same amount of stroke-physiological saline solution.Glutathione(GSH)content,glutathione S-transferase(GST),glutathione peroxide(GPX),superoxide dismutase(SOD),catalase(CAT)activity,and kidney body weight index were determined at 1,3,12,24,and 48 h after i.p.injection.Various changes of GSH content,GST,GPX,SOD,and CAT activity in kidney of chicken were observed in the present study,while no significant differences in GSH content and activity of oxidative enzyme between MC-LR treatment and control group(P>0.05)during the whole experimental periods,excluding the significant decrease of CAT activity in middle and high dose groups(96.66±1.13 and 74.01±11.20 U·mg^-1,respectively)at 3 h post-injection when compared with control group(123.58±11.33)U·mg^-1(t=4.253;P=0.024 and t=4.432;P=0.022,respectively).The kidney body weight index increased at the initial 1 h post-injection in all the three MC-LR treatment groups,and these indexes in all treatment groups(0.79%-0.87%)were significant higher than that in control group(0.58%-0.70%)at 12,24 and 48 h post-injection(t=-6.687--3.495;P=0.018-0.036).The above results suggested that MC-LR should induce oxidative stress in kidney of chicken,however,the oxidative stress induced by MC-LR might not be overwhelmed by antioxidant systems in kidney.