基于谷胱甘肽结合作用定量研究微囊藻毒素的解毒代谢机制

基于谷胱甘肽(GSH)解毒作用探讨了微囊藻毒素-RR(MCRR)在不同动物肝脏和肾脏合作下的代谢机制。通过人工合成MCRR的谷胱甘肽代谢物(MCRR-GSH),腹腔注射至鲫鱼和大鼠体内,利用液相色谱串联质谱技术(LC-MS/MS)定量检测MCRR-GSH及其下游半胱氨酸代谢物(MCRR-Cys)在组织内的代谢动力学变化。在72 h的暴露实验中,实验组鲫鱼和大鼠体内均定量检测到MCRR-GSH和MCRR-Cys。MCRR-GSH在肾脏中的浓度显著高于其他组织(P0.05),鲫鱼和大鼠体内累积浓度分别是(0.161±0.001)和(0.116±0.005)μg·g~(-1)DW。同样的,MCRR-Cys主要分布于鲫鱼和大鼠的肾脏组织。鲫鱼肾脏中MCRR-Cys的浓度出现明显的波动,而肝脏和胆汁内的MCRR-Cys浓度却呈现出上升的趋势;大鼠肾脏内MCRR-Cys的浓度呈缓慢下降的趋势,浓度范围为(8.899±0.817)μg·g~(-1)DW至(3.336±0.263)μg·g~(-1)DW。基于以上结果推测,微囊藻毒素在肝脏和肾脏合作下的解毒过程为:MC在肝脏内经GSH结合作用生成的代谢物MC-GSH随血液循环转运至肾脏,在肾脏内MCGSH快速地转化为下游代谢物MC-Cys以促进排泄。

Quantitative study in the Process of Glutathione Detoxification of Microcystin

To study the glutathione detoxification mechanism of microcystin-RR (MCRR), the synthetic microcys-tin-glutathione conjugates (MCRR-GSH) were i.p. injected into crucian carp or rat. The concentrations of MCRR-GSH and its metabolite, microcystin-cysteine conjugate (MCRR-Cys), in liver, kidney and bile were analyzed by liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS). In the 72 h experiment, contents of MCRR-GSH and MCRR-Cys were detected in all tissues of the MCRR-GSH-treated animals. The concentrations of MCRR-GSH in kidney were obviously higher than that in liver (P<0.05), and the values of MCRR-GSH concen-tration in crucian carp and rat were as high as (0.161±0.001) and (0.116±0.005)μg·g-1 DW, respectively. Similar-ly, MCRR-Cys was mainly distributed in kidney. In crucian carp, concentrations of MCRR-Cys in kidney showed significant up and down while concentrations of MCRR-Cys in liver and bile showed enhanced trend;the MCRR-Cys concentration in kidney of rat was decreased from (8.899±0.817) μg·g-1 DW to (3.336±0.263) μg·g-1 DW. Based on these results, the detoxification process of MC after the cooperation of liver and kidney was speculated:MC conjugates with GSH in liver to form the MC-GSH conjugate, which is transferred to kidney by blood circula-tion system. Subsequently MC-GSH is rapidly degraded to the cysteine conjugate for excretion.