Protective Effects and Mechanisms of Glycyrrhizin and Oleanolic Acid Against Cadmium induced Hepatic Injury in Rats

To examine the hepatoprotecive effects of Gly cyr rhizin(GL) and Oleanolic acid(OA)against Cadmium(Cd)-induced liver injury in rats and the mechanisms of protection,SD rats were injected ip with CdCl₂(0.8mg/kg Cd²⁺/kg body weight,five times a week).Two cadmium-challenged groups were concomitantly injected sc with GL(20mg/kg,three times a week)and OA(60mg/kg,five times a week)respectively.Serum activities of alanine aminotransferase(ALT)and aspartate aminotr ansferase(AST)indicative of hepatic injury were measured,and livers were examined mor phologically and analyzed for cadmium and metallothio nein (MT).Bo th GLand OA delayed and attenuated the elevation of serum ALT and AST activities,ameliorated hepatic parenchymal swelling and necrosis produced by cadmium.Electron microscopy showed the pathological changes of hepatocellular mitochondr ia and smooth endo plasmic reticulum were less severe in Cd-GL,CdOA-cotreated rats compared with Cd-treated ones.In the early stage of cadmium exposure,GLnd OA also decreased hepatic cadmium accumulation and increased hepatic MT induction,which in turn elevated MT amount available to every cadmium unit.It show s that both GLand OA can protect rats against Cd-induced hepatotoxicity in subchronic Cd exposure.The protection may be in partrelated to decrease of cadmium accumulation and additional increase of MT induction in the target or gan.