[Curcumin attenuated the lipid peroxidation and apoptotic liver injury in copper-overloaded rats]

Hepatolenticular degeneration (Wilson disease, WD) is an autosomal recessive disorder of copper metabolism. The clinical manifestations are dominated by the neuropsychiatric and hepatic symptoms due to copper deposition. Investigation of mechanism of copper injury should be helpful for elucidating the pathogenesis and treatment of WD. Curcumin, a plant-derived polyphenol, exhibits the properties of anti-oxidant, anti-inflammation and has no evident side effects, therefore, today curcumin is studied by more and more researchers in pharmacologic action and clinical application especially for its protective effect on liver diseases. The present study was designed to investigate the lipid peroxidation and apoptotic liver injury in copper-overloaded rats, and to explore the protective effects of curcumin.

Wistar rats, male, were randomly divided by copper-overloaded groups and curcumin treatment groups and control group. Copper-overloaded rat model was established by feeding with forage containing 1 g/kg copper sulfate and water with 0.185% copper sulfate for 8 weeks or 12 weeks. In the treatment groups, curcumin was administered orally either 50 mg/kg or 200 mg/kg for 2 weeks and 4 weeks and 8 weeks and fed with copper sulfate at the same time until the 12th week. Malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH) in liver homogenates were measured to reflect the copper induced lipid peroxidation. The apoptosis of liver cell was detected by electron microscope (EM) and TUNEL assay. The expressions of TNF-alpha mRNA and IL-8 mRNA were observed by RT-PCR. Contents of TNF-alpha and IL-8 in liver homogenates were measured by ELISA.

The MDA concentrations were significantly increased and the GSH and SOD levels were decreased in the copper-overloaded rats. The apoptosis index displayed from (2.2 +/- 1.2)% in control rats to (16.7 +/- 2.5)% in the copper treated animals. Expression of TNF-alpha mRNA and IL-8 mRNA were enhanced in the copper-overloaded rats. Curcumin significantly attenuated the increase of MDA concentrations and recovered the GSH and SOD levels. The apoptosis index decreased to (10.4 +/- 1.2)% in the copper-overloaded rats with curcumin treatment. Curcumin down-regulated the expressions of TNF-alpha mRNA and IL-8 mRNA and content of TNF-alpha and IL-8. Histological changes induced by copper in liver, such as mitochondrial swelling and endoplasmic reticulum distention and increased lysosomal granules in the model rats, were also improved significantly by curcumin treatment as evidenced by EM examination.

Copper-overloading caused lipid peroxidatic injury and induced significant apoptosis in liver. TNF-alpha and IL-8 might be involved in liver injury in this model. Curcumin exhibited protective effects and possibly acted through its antioxidant and anti-apoptotic properties.