硒对镉致脂质过氧化与金属硫蛋白诱导合成的影响

Effects of sodium selenite and selenomethionine on cadmium-induced lipid peroxi dation and the ability of cadmium to induce metallothionein in rats

目的 比较亚硒酸钠 (Na2 SeO3 )与硒代蛋氨酸 (SeMet)对镉 (Cd)毒性的拮抗效应 ,探讨脂质过氧化及金属硫蛋白 (MT)的诱导合成在硒 (Se)拮抗Cd毒性作用中的意义 ,为镉中毒的防护提供依据。方法 健康雄性Wistar大鼠 36只 ,随机分 6组。Ⅰ组为正常对照组 ,Ⅱ组为Cd中毒组 ,Ⅲ组为Na2 SeO3 组 ,Ⅳ组为SeMet组 ,Ⅴ组为Cd +Na2 SeO3 组 ,Ⅵ组为Cd +SeMet组。Cd按 1 0 0 μmol kg体重 ,Se(Na2 SeO3 及SeMet)按 1 0 μmol kg体重的剂量隔日 1次经口灌胃 ,其中Ⅴ组和Ⅵ组按先Se后Cd交替灌胃。Se、Cd均灌胃 1 5次。实验时间为 30d。结果 单独给Cd组大鼠肝脏和肾脏MT水平升高 ,而血清MT出现降低 ;2种Se化合物均使大鼠肾脏和肝脏MT含量轻度增高 ,但 2个Se加Cd组与单独给Cd组比较 ,MT水平差异不显著 ;染Cd大鼠仅见血清脂质过氧化产物丙二醛 (MDA)含量明显升高 ,而 2种Se化合物对其没有明显影响 ;无论是单独给Se组 (Ⅲ、Ⅳ ) ,还是Se加Cd组 (Ⅴ、Ⅵ ) ,大鼠全血、肝脏及肾脏GSH PX 活力均明显增高。结论 Se能在一定程度上诱导机体合成MT ,但在Se拮抗Cd毒性作用中MT的诱导合成可能不起主要作用 ;Se能提高机体的抗氧化能力。对拮抗Cd毒性具有一定的作用 ;SeMet与Na2 SeO3 对诱导MT的合成及提高GSH PX 的活力 。

Objective To compare the effects of sodium seleni te(Na 2SeO 3) and selenomethionine(SeMet)on cadmium-induced lipid peroxidat ion and the ability of cadmium to induce metallothionein,and to assess the prote ctive effects of two selenium compounds on cadmium-induced poisoning in rats.Methods 36 adult Male Wistar rats were allotted at random to 6 groups of 6 each.Rats were given selenium as Na 2SeO 3 or SeMet (10μmol/kg) and cadmium(Cd)as cadmium chloride(100 μmol/kg)every other day by oral gavage. The 6 groups of rats were used as follow,Group Ⅰ:control,group Ⅱ:Cd;group Ⅲ:N a 2SeO 3,group Ⅳ:SeMet,group Ⅴ:Cd+Na 2SeO 3,and group Ⅵ:Cd+SeMet,After 3 0 days,blood,liver,kidneys and testes were collected.Malondialdehyde(MDA),glutat hione peroxidase(GSH-P X) and metallothionein(MT)in all samples were determine d.Results Over 30d period the content of MT was obviously increas ed by Cd in liver and kidneys,but not in testes.However,MT in serum was decrease d by Cd treatment.Although the synthesis of MT was stimulated slightly by Na 2 SeO 3 and SeMet in rat kidneys,the induction of renal MT by Cd was not modifie d by selenium including Na 2SeO 3 and SeMet.The content of MDA was significant ly increased in serum of Cd-treated rats,but not in liver,kidneys and testes.Bo th Na 2SeO 3 and SeMet did not alter the increase of MDA in serum by Cd.Na 2S eO 3 and SeMet increased the activity of GSH-P X in blood,liver and kidneys, bu t not in testes.The activity of GSH-P X in blood,liver and kidneys of rats wit h selenium was higher than that from rats treated only by Cd.Conclusion It appears that stimulation of MT is not a main factor i n the acquired tolerance to Cd-induced toxicity by selenium.Selenium possesses a certain protective effect against the toxicity of Cd on lipid peroxidation.Na 2SeO 3 shows similar effects with SeMet on activity of GSH-P X and MT conte nt by Cd.The elucidation of a definitive mechanism in selenium-induced tolerance to Cd toxicity and the different effects of Na 2SeO 3 and SeMet on Cd toxicity will require further research.