氮乙酰半胱氨酸对家蚕辛硫磷农药中毒的预防作用

Effect of N-acetyl-cysteine on Preventing Bombyx mori Larvae from Toxification Caused by Phoxim

氮乙酰半胱氨酸(NAC)是谷胱甘肽的前体物质,能脱乙酰基生成半胱氨酸并具有很强的抗氧化作用。给家蚕5龄起蚕连续24 h添食200μg/mL NAC后,再连续24 h添食0.5倍半致死浓度(4μg/mL)的辛硫磷药液,检测家蚕体内蛋白质、碳水化合物含量和相关解毒酶活性以及还原型谷胱甘肽(GSH)代谢的变化,探究NAC对家蚕辛硫磷农药中毒的预防效果。试验结果表明:预添食NAC能显著提高辛硫磷中毒5龄幼虫的体质量和存活率(P<0.05);能显著提高辛硫磷中毒家蚕产茧的全茧量、茧层量、茧层率和上茧率(P<0.05);能有效缓解辛硫磷中毒家蚕血液蛋白质和碳水化合物含量的下降,能使超氧化物歧化酶(SOD)活性在更短时间内被激发,羧酸酯酶(ESTs)的活性上升至仅用辛硫磷处理组家蚕的1.64倍,并且能有效缓解辛硫磷对过氧化物酶(POD)活性的抑制作用;能促进家蚕体内的GSH代谢,激发谷胱甘肽合成酶(GSTs)的活性等。依据试验结果初步认为,NAC通过促进家蚕体内相关生化代谢活动,激发相关解毒酶的活性,从而提高蚕体对亚致死剂量辛硫磷毒性的抵抗能力。

N-acetyl-cysteine（ NAC） is the precursor of glutathione（ GSH）,which is able to form cysteine after release of acetyl group and has strong antioxidant effect. To explore whether NAC has an effect on preventing silkworm（ Bombyx mori） from toxification caused by phoxim,we fed the newly exuviated larvae of the 5th silkworm instar with 200 μg / mL NAC for 24 h,then with 0. 5 LC50phoxim（ 4 μg / mL） for 24 h,and assayed the contents of proteins and carbohydrates and the activity of related detoxification enzymes and reduced GSH metabolism. The results showed that addition of NAC could improve body weight and survival rate of phoxim poisoned silkworm larvae significantly（ P 0. 05） and increase cocoon weight,cocoon shell weight,cocoon shell rate and reelable cocoon rate of phoxim poisoned silkworm larvae significantly（ P 0. 05）. Furthermore,NAC treatment could effectively slow the decrease of protein and carbohydrate contents in hemolymph of phoxim poisoned silkworm larvae. NAC treatment could stimulate activity of superoxide dismutase（ SOD） in much shorter time. Activity of carboxylesterase（ ESTs） in silkworm larvae with NAC treatment was 1. 64 folds to that in silkworm larvae without NAC treatment. NAC treatment could effectively alleviate inhibition of phoxim on activity of peroxidase（ POD）,enhance GSH anabolism and induce activity of glutathione synthetase（ GSTs）. Based these data,it is concluded that NAC can enhance the resistance of silkworm larvae against phoxim of sub-lethal concentration through promoting related biochemical metabolisms and stimulating activity of detoxification related enzymes.