褪黑素对AFB1所致大鼠心肌损伤作用及机制

ROLE AND MECHANISM OF MELATONIN IN RATS WITH MYOCARDIAL INJURY INDUCED BY AFLATOXIN B1

目的研究褪黑素(MT)对黄曲霉毒素B1(AFB1)诱导大鼠心肌损伤的作用及其相关机制。方法将成年雄性健康SD大鼠随机分为对照组、AFB1组和AFB1+MT组。对照组大鼠给予溶媒溶液灌胃,AFB1组和AFB1+MT组大鼠连续6周每天给予AFB1溶液(0.3 mg/kg)灌胃制备大鼠心肌损伤模型,AFB1+MT组大鼠在每天AFB1灌胃前半小时给予MT溶液(5 mg/kg)灌胃。连续灌胃6周后,腹主动脉取血制备血清,比较3组大鼠血清中乳酸脱氢酶(LDH)、肌酸激酶-MB(CK-MB)的水平;取大鼠心脏组织,应用酶标仪检测超氧化物歧化酶(SOD)、过氧化氢酶(CAT)的活性和丙二醛(MDA)的含量,采用Western blot法检测半胱氨酸天冬氨酸蛋白酶3(caspase-3)蛋白的表达;大鼠心脏组织切片后行TUNEL染色标记凋亡的心肌细胞。结果与对照组比较,AFB1组大鼠的血清LDH和CK-MB水平及心脏组织MDA含量均升高,抗氧化酶SOD、CAT活性降低;AFB1+MT组大鼠的血清CK-MB、LDH水平及心脏组织MDA含量低于AFB1组,SOD、CAT活性得到恢复,差异均有显著意义(F=5.63~17.75,P<0.05)。Western blot和TUNEL染色结果显示,MT预处理可下调caspase-3蛋白的表达,降低AFB1诱导的心肌细胞凋亡(F=8.98~11.94,P<0.05)。结论 MT可能通过减轻氧化应激、下调caspase-3的表达、抑制细胞凋亡改善AFB1诱导的心肌损伤。

Objective To investigate the role and mechanism of melatonin(MT)on aflatoxin B1(AFB1)-induced myocardial injury in rats.Methods Healthy adult male Sprague-Dawley rats were randomly divided into control group,AFB1 group,and AFB1+MT group.The rats in the control group were given solvent solution by gavage,and those in the AFB1 group and the AFB1+MT group were given AFB1 solution at a dose of 0.3 mg/(kg·d)by gavage for 6 consecutive weeks to establish a rat model of myocardial injury;in addition,the rats in the AFB1+MT group were given MT solution(5 mg/kg)by gavage half an hour before the administration of AFB1.After 6 consecutive weeks of intragastric administration,blood was collected from the abdominal aorta to prepare the serum,and the three groups were compared in terms of the serum levels of lactate dehydrogenase(LDH)and creatine kinase-MB(CK-MB);heart tissue was collected,and a microplate reader was used to measure the activities of superoxide dismutase(SOD)and catalase(CAT)and the content of malondialdehyde(MDA);Western blot was used to measure the protein expression of caspase-3;heart tissue sections were prepared and TUNEL staining was used to observe apoptotic cells.Results Compared with the control group,the AFB1 group had significant increases in the serum levels of LDH and CK-MB and the content of MDA in heart tissue,as well as significant reductions in the activities of SOD and CAT;compared with the AFB1 group,the AFB1+MT group had significantly lower serum levels of CK-MB and LDH and content of MDA in heart tissue,as well as significant recovery of the activities of SOD and CAT(F=5.63-17.75,P<0.05).Western blot and TUNEL staining showed that MT pretreatment downregulated the protein expression of caspase-3 and reduced cardiomyocyte apoptosis induced by AFB1(F=8.98-11.94,P<0.05).Conclusion MT can significantly improve myocardial injury induced by AFB1,possibly by redu-cing oxidative stress,downregulating the expression of caspase-3,and inhibiting apoptosis.