The effectiveness of the
antioxidant thiol,
N-acetylcysteine (NAC), in enhancing methylmercury (CH3HgCl) excretion and its utility as a possible
antidote in CH3HgCl
poisoning has been reported. NAC, however, has been reported to be ineffective in accelerating excretion of divalent toxic metals, including inorganic
mercury, Hg2+. In this study, we evaluated the possible protective effect of short-term pretreatment with NAC against
mercuric chloride (
HgCl2) toxicity in rat model. This is aimed at determining its chemopreventive or prophylactic benefit in situations of high risk exposure (occupational/industrial) to
mercury. Rats were divided into three treatment groups. Group I received saline (10 ml/kg) and served as control. Group II received
HgCl2 (5mg/kg) and group III received NAC (10mg/kg) plus (5mg/kg). All administration was via intraperitoneal (i.p.) injection. Saline and NAC were administered for 5days and
HgCl2 was administered to rats in groups II and III on the 5th day. Animals were sacrificed 24 hours after
HgCl2 injection and samples obtained for biochemical evaluation. Results revealed that single i.p. injection of
HgCl2 induced significant renal oxidative damage resulting in significant decrease in the activities of
superoxide dismutase (SOD),
catalase (CAT),
glutathione-s-transferase (GST), depletion of
reduced glutathione (GSH) and increase in
malondialdehyde (MDA) levels in these rats. The activities of
glucose-6-phosphatase (G6Pase) and
5'-nucleotidase (5'-NTD) (markers of microsomal damage) also decreased in these
HgCl2 treated rats. The oxidative damage induced by
HgCl2 led to significant alterations in renal histology and caused functional impairment (indicated by elevated blood
urea nitrogen (BUN) and serum
creatinine) in these rats. NAC was effective in attenuating the oxidative damage, functional impairments and histopathological changes that characterized
HgCl2 intoxication in this study. Renal
antioxidant defense system was re-enforced by NAC, leading to increase in the activities of SOD, CAT, GST and decreases in GSH depletion and MDA level. Our results therefore reveal the ameliorative effect of NAC pretreatment against
HgCl2 toxicity in vivo, thus, suggesting its usefulness as a possible chemoprophylactic agent during occupational or industrial exposure to inorganic
mercury.