过量锰暴露对雄性大鼠血清胆碱酯酶活力的时间毒性研究

Chronotoxicity of over exposure of manganese to serum cholinesterase activity in male rats

目的研究不同授时时间(zeitgeber time,ZT)过量锰暴露对雄性大鼠血清乙酰胆碱酯酶(ChE)活力的影响。方法将96只健康成年SPF级雄性SD大鼠在严格控制光照/黑暗(12 h/12 h)条件下适应性喂养7 d后,随机分为4个对照(蒸馏水)组与4个锰暴露(30 mg/kg氯化锰)组,每组12只。分别于ZT2(9:00)、ZT8(15:00)、ZT14(21:00)与ZT20(3:00)授时时间点进行腹腔注射染毒,染毒容量为2.5 ml/kg,每天1次,连续染毒21 d。第22天时,检测大鼠血清乙酰胆碱酯酶的活力并进行统计学余弦分析。结果与对照组比较,ZT2、ZT20授时时间点锰暴露组雄性大鼠血清ChE的活力较低,差异均有统计学意义(P<0.05);而ZT8、ZT14授时时间点锰暴露组大鼠血清ChE的活力略低,差异均无统计学意义(P>0.05)。锰暴露组雄性大鼠血清ChE的活力日均值下降,振幅增加,峰值时间延迟;对照组与锰暴露组雄性大鼠血清ChE的活力均无昼夜节律。结论过量锰暴露可抑制雄性大鼠血清胆碱酯酶活力,但可能具暴露时间依赖性。

Objective To explore the chronotoxicity of the over exposure of manganese(Mn) to serum cholinesterase(ChE)activity in male rats. Methods Ninety-six healthy male SD rats of SPF grade were accustomed in 12 h/12 h light-dark photoperiod for one week and then were divided into four Mn-exposure groups and four control groups. Mn-exposure groups were exposed to Mn(30 mg/kg MnCl2) by intraperitoneal injection(i.p.) and the control groups were administered with distilled water of equal volume,respectively at zeitgeber time of ZT2,ZT8,ZT14 and ZT20 for consecutive 21 days. The serum cholinesterase activity was measured by ELISA method and the data were analyzed by Cosinor analysis. Results Compared with the corresponding control groups,Mn-exposure groups showed reduced ChE activity at ZT2 and ZT20 by 12.69% and 15.65%, respectively. The average levels of cholinesterase activity in Mn-exposure groups declined,with increased amplitude and delayed peak time. No circadian rhythmicity of cholinesterase activity in the control groups and Mn-exposure groups were observed. Conclusion Over exposure of Mn can inhibit the serum ChE activity in male rats,which maybe presents exposure time dependence.