The protective effects of tea polyphenols and schisandrin B on nephrotoxicity of mercury

Mercury (Hg) is an occupational and environmental contaminant that is a well-recognized health hazard. To approach the concrete mechanisms of mercury nephrotoxicity and find out a new way to prevent it, the rats were subcutaneously injected with different dosages of mercuric chloride (HgCl(2))--0, 2.2, 4.4, and 8.8 μmol/kg. The levels of Hg, blood urea nitrogen (BUN), urine protein, glutathione (GSH), malondialdehyde (MDA) and activities of N-acetyl-beta-D-glucosaminidase (NAG), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) were investigated, and the levels of reactive oxygen species (ROS) and apoptosis and the pathological changes were also observed. In addition, the effects of 1 mmol/kg tea polyphenols (TP) and 0.04 mmol/kg schisandrin B (Sch B) were studied at 8.8 μmol/kg HgCl(2). It was observed that the levels of Hg, BUN, urine protein, GSH, and MDA and activities of NAG, ALP, and LDH increased significantly; the activities of SOD and GSH-Px decreased significantly; the levels of ROS and apoptosis increased obviously; and many pathological changes occurred dose-dependently in the HgCl(2) injection groups. Further investigation indicated that pretreatment with TP and Sch B significantly reversed the toxic effects of HgCl(2). These results suggested that TP and Sch B might antagonize the nephrotoxicity caused by HgCl(2) exposure.