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Zuotai and cinnabar(96%HgS) are contained in many traditional medicines. To examine their potential effects on drug metabolism genes, mice were orally given Zuotai or HgS at doses of 10, 30, 100, 300 mg•kg⁻¹ for 7 days. HgCl2(33.6 mg•kg⁻¹) was gavaged for control. Twenty-four hour later after the last administration, livers were collected, and expressions of genes related to metabolic enzymes and transporters were examined. Zuotai and HgS had no effects on major phase-1, phase-2 and transporter genes; HgCl2 increased the expressions of CYP2B10, CYP4A10, OATP1A4, UGT1A1, UGT2A3, SULT1A1, SULT2A1, MRP1, MRP3 and MRP4; expression of OATP1A1 was decreased by HgCl2, but not by Zuotai and HgS. Therefore, Zuotai and HgS have different adverse effects on drug-metabolizing genes from HgCl2.
Mercury sulfides are used in Ayurvedic medicines, Tibetan medicines, and Chinese medicines for thousands of years and are still used today. Cinnabar (α-HgS) and metacinnabar (β-HgS) are different from mercury chloride (HgCl2) and methylmercury (MeHg) in their disposition and toxicity. Whether such scenario applies to weanling and aged animals is not known. To address this question, weanling (21d) and aged (450d) rats were orally given Zuotai (54% β-HgS, 30mg/kg), HgS (α-HgS, 30mg/kg), HgCl2 (34.6mg/kg), or MeHg (MeHgCl, 3.2mg/kg) for 7days. Accumulation of Hg in kidney and liver, and the toxicity-sensitive gene expressions were examined. Animal body weight gain was decreased by HgCl2 and to a lesser extent by MeHg, but unaltered after Zuotai and HgS. HgCl2 and MeHg produced dramatic tissue Hg accumulation, increased kidney (kim-1 and Ngal) and liver (Ho-1) injury-sensitive gene expressions, but such changes are absent or mild after Zuotai and HgS. Aged rats were more susceptible than weanling rats to Hg toxicity. To examine roles of transporters in Hg accumulation, transporter gene expressions were examined. The expression of renal uptake transporters Oat1, Oct2, and Oatp4c1 and hepatic Oatp2 was decreased, while the expression of renal efflux transporter Mrp2, Mrp4 and Mdr1b was increased following HgCl2 and MeHg, but unaffected by Zuotai and HgS. Thus, Zuotai and HgS differ from HgCl2 and MeHg in producing tissue Hg accumulation and toxicity, and aged rats are more susceptible than weanling rats. Transporter expression could be adaptive means to reduce tissue Hg burden.