Liver fibrosis is considered as a dynamic and highly integrated cellular response to chronic liver injury. The present study was designed to determine the possible protective effect of silymarin on hepatic fibrosis induced by carbon tetrachloride (CCl4) injections in rats. Seventy male Sprague-Dawely rats were divided into 3 groups; group I (control n=10), rats of group II (n= 30) were injected with CCl4 intra-peritoneally in a dose of 1.0 ml/kg BW for three doses weekly, each other, for 12 weeks and rats of group III (n= 30) were injected with CCl4 as in group II and treated with silymarin in a daily oral dose of 50 mg/kg BW for 12 weeks. Rats were sacrificed after 4, 8 and 12 weeks and liver was quickly dissected out. Liver specimens were subjected to routine H &E stain and immunohistochemical stain of proliferating cell nuclear antigen (PCNA). The histopathological results showed that CCl4 revealed necrotic and vacuolated hepatocytes as well as dilation and congestion in both sinusoids and in the branches of the portal vein. These alterations were marked in addition to portal fibrosis after 12 weeks. Silymarin treatment reduced the impaired hepatic changes induced by CCl4 as evidenced in hepatocytes regeneration and decreased inflammation and congestion. Immunohistochemical results showed time-dependant increase in PCNA expression in CCl4 injected group and it was more significant in CCl4- silymarin treated group. It was concluded that silymarin has a hepatoprotective effect in rats with liver injury induced by CCl4 where it improved hepatic structure through the stimulation of liver regeneration and alleviated liver fibrosis by its anti-fibrotic role.
Key words: CCl4, Silymarin, Rats, Liver, Histopathology, PCNA