去甲肾上腺素转运体和多巴胺转运体在甲基苯丙胺成瘾致大鼠心肌损伤中的作用及机制

Effect and mechanism of norepinephrine transporter and dopamine transporter in myocardial injury induced by methamphetamine addiction in rats

目的探讨去甲肾上腺素转运体(NET)和多巴胺转运体(DAT)在甲基苯丙胺(MA)成瘾致大鼠心肌损伤中的作用及机制。方法将17只雄性8周龄Sprague Dawley大鼠随机分为对照组(n=7)和MA组(n=10)。MA组大鼠分别于实验第5、7、9、11、13、15、17天腹腔注射5 g·L^(-1)MA溶液(1 mL·kg^(-1)),第6、8、10、12、14、16、18天腹腔注射生理盐水(1 mL·kg^(-1));对照组大鼠每日腹腔注射生理盐水(1 mL·kg^(-1))。实验第19天,对2组大鼠进行条件性位置偏爱测试,记录大鼠在白箱中停留时间和活动轨迹,分析活动轨迹曲线密度。2组大鼠用体积分数2%的戊巴比妥钠进行麻醉,依次用200 mL生理盐水和200 mL多聚甲醛溶液(4 g·L^(-1))行心脏灌流,然后取左心室制作组织切片,采用苏木精-伊红染色观察2组大鼠左心室心肌组织形态学变化,免疫组织化学法检测2组大鼠心肌组织中NET及DAT表达。结果实验第19天,对照组和MA组大鼠白箱中停留时间分别为(404.478±87.512)、(165.433±27.323)s,MA组大鼠白箱中停留时间显著长于对照组(P<0.05);MA组大鼠白箱活动轨迹曲线密度明显高于前测期,对照组大鼠白箱活动轨迹曲线密度无明显变化。对照组大鼠左心室心肌细胞排列整齐,未见心肌损伤表现;MA组大鼠左心室心肌细胞排列紊乱,可见心肌组织出血、心肌细胞波纹样改变,心肌内炎症细胞聚集。对照组和MA组大鼠心肌组织中均有NET及DAT表达,MA组大鼠心肌组织中NET及DAT相对表达量显著低于对照组(P<0.05)。结论MA成瘾可对大鼠心肌产生毒性作用,其机制可能是通过降低心肌组织中NET和DAT表达水平来增加突触后儿茶酚胺水平,从而导致心肌损伤。

Objective To investigate the effect and mechanism of norepinephrine transporter(NET)and dopamine transporter(DAT)in methamphetamine(MA)addiction-induced myocardial injury in rats.Methods Seventeen male 8-week-old Sprague Dawley rats were randomly divided into control group(n=7)and MA group(n=10).The rats in the MA group were injected intraperitoneally with 5 g·L^(-1) MA solution(1 mL·kg^(-1))on the 5^(th),7^(th),9^(th),11^(th),13^(th),15^(th),17^(th) day,and saline(1 mL·kg^(-1))on the 6^(th),8^(th),10^(th),12^(th),14^(th),16^(th) and 18^(th) day;the rats in the control group were injected intraperitoneally with saline(1 mL·kg^(-1))daily.On the 19^(th) day of the experiment,the conditioned place preference test were performed in the rats of the two groups,and the residence time and activity track of rats in the white box were recorded,the curve density of movement track was analyzed.The rats in the two groups were anesthetized with volume fraction of 2%sodium pentobarbital,the heart was perfused with 200 mL normal saline and 200 mL paraformaldehyde solution(4 g·L^(-1))successively,and then the left ventricle was taken out and made into tissue sections;the morphological changes of left ventricle of rats in the two groups were observed by hematoxylin eosin staining,and the expressions of NET and DAT in the myocardial tissue of rats in the two groups were detected by immunohistochemistry.Results On the 19^(th) day of the experiment,the residence time in the white box of rats in the control group and MA group was(404.478±87.512)s and(165.433±27.323)s,respectively;the residence time in the white box of rats in the MA group was significantly longer than that in the control group(P<0.05).The curve density of movement track in the white box of rats in the MA group after administration was significantly higher than that in the pre-test period,while there was no significant change in curve density of movement track in the white box of rats in the control group.In the control group,the myocardial cells in the left ventricle were neatly arranged and no myocardial injury was observed;in the MA group,the myocardial cells in the left ventricle of rats were disordered,and the myocardial tissue hemorrhage,ripple-like changes in myocardial cells and inflammatory cell aggregation were observed.NET and DAT were expressed in the myocardial tissues of rats in the control group and MA group,while the relative expression levels of NET and DAT in the myocardial tissues of rats in the MA group were significantly lower than those in the control group(P<0.05).Conclusion MA addiction can produce toxic effects on myocardium of rat,and its mechanism may be to increase the level of postsynaptic catecholamine by reducing the expression levels of NET and DAT in myocardial tissue.