Schisandrin B stimulates a cytoprotective response in rat liver exposed to mercuric chloride

Mercury represents an ubiquitous environmental toxic metal. Heat shock proteins (HSP) and metallothioneins (MTs) help to protect cells against metal toxicity. Schisandrin B (Sch B), a lignoid from Schisandra chinensis, has been successfully used to treat hepatitis, but its effect against mercury hepatotoxicity remains unknown. We analyzed whether Sch B could protect rat liver against mercuric chloride (HgCl2) intake by analyzing stress proteins and histopathological changes. Wistar rats were administered Sch B (10mg/kg/day by gavage) or vehicle (olive oil) for 10 days. A subset of each group also received low-dose HgCl2 (0.1mg/kg/day) for 3 days on days 8-10. Another group received Sch B for 10 days with a single high dose of HgCl2 (1mg/kg intraperitoneally) on day 10. In rats treated with Sch B and HgCl2, HSP72, HSP25 and MTs were overexpressed in liver zones 1 and 3 irrespective of HgCl2 dosing schedules. Furthermore Sch B alone induced perinuclear rough endoplasmic reticulum alignment and if associated to HgCl2, increased mitochondrial density and dense bodies, all signs of intense detoxification machinery. Taking together these data suggest that dietary Sch B counteracts HgCl2 hepatotoxicity in the rat by stimulating chaperones responsible for anabolic activity.