Protective effect of zinc against cadmium hepatotoxicity depends on this bioelement intake and level of cadmium exposure: A study in a rat model

• Published in: Chemico-biological interactions 2011-09, Vol.193 (3), p.191-203
• Main Authors: Rogalska, Joanna, Pilat-Marcinkiewicz, Barbara, Brzóska, Malgorzata M.
• Format: Article
• Language: English
• Subjects: Alanine transaminase; Alanine Transaminase - blood; Animal models; Animals; Apoptosis; Apoptosis - drug effects; Aspartate Aminotransferases - blood; Aspartate transaminase; blood serum; Cadmium; Cadmium - toxicity; Chemical and Drug Induced Liver Injury - metabolism; Chemical and Drug Induced Liver Injury - pathology; Chemical and Drug Induced Liver Injury - prevention & control; Cytokines; Enzymes; Hepatotoxicity; humans; Inflammation; Injuries; Ions; Liver; Liver - metabolism; Liver - pathology; Liver function; Liver morphology; Male; Models, Animal; necrosis; Necrosis - pathology; Protection; Protective Agents - therapeutic use; protective effect; Rats; Rats, Wistar; Structure-function relationships; Supplementation; Tumor necrosis factor- alpha; Tumor Necrosis Factor-alpha - blood; Zinc; Zinc - therapeutic use
• ISSN: 0009-2797; 1872-7786
• DOI: 10.1016/j.cbi.2011.05.008

► Zn supplementation can protect against Cd-induced damage to the structure and function of the liver. ► Hepatoprotective effect of Zn under moderate and relatively high exposure to Cd depends on its intake. ► Excessive Zn intake at relatively high exposure to Cd may intensify liver injury. It was estimated, in a rat model of moderate and relatively high chronic human exposure to cadmium (Cd), whether enhanced zinc (Zn) consumption may prevent Cd-induced liver injury and if the possible protective effect of this bioelement depends on its intake. For this purpose, the structure and function of the liver of the rats that received Zn (30 and 60 mg/l) or/and Cd (5 and 50 mg/l) for 6 months were evaluated. The treatment with Cd led to, dependent on the exposure level, pathological changes in the liver, including enhanced apoptosis and induction of inflammatory and necrotic processes. Moreover, the serum activities of hepatic marker enzymes (alanine transaminase and aspartate transaminase) and the concentration of proinflammatory cytokine – tumor necrosis factor α were increased. The supplementation with 30 and 60 mg Zn/l (enhancing daily Zn intake by 79% and 151%, respectively) partially or totally prevented from some of the Cd-induced changes in the liver structure and function; however, it provided no protection from necrosis, and the administration of 60 mg Zn/l during the higher Cd exposure even intensified this process. At both levels of Cd treatment, the use of 30 mg Zn/l was more effective in preventing liver injury than that of 60 mg Zn/l. The hepatoprotective impact of Zn may be explained, at least partly, by its antioxidative, antiapoptotic and anti-inflammatory action, ability to stimulate regenerative processes in the liver tissue, and indirect action resulting in a decrease in the liver pool of the non-metallothionein-bound Cd 2+ ions able to exert toxic action. The results provide strong evidence that enhanced Zn consumption may be beneficial in protection from Cd hepatotoxicity; however, its excessive intake at relatively high exposure to Cd may intensify liver injury.