engleski

Oxidative stress after partial hepatectomy in tumor bearing animals

There is an increasing body of evidence that oxidative stress is involved in pathogenesis of many types of liver injury, not only ischemia-reperfusion injury, but especially in the damage induced by toxic substances. As an organ where xenobiotics are mainly metabolized, liver has extraordinary ability to regenerate after injury and recover its effective mass. Liver regeneration is dynamic process well controlled by systemic mechanisms of combined cellular and humoral type, which are not sufficiently understood yet. It seems that unspecific inflammatory response may be involved in both in liver damage caused by trauma or toxic compounds and in consequential liver regeneration. During liver regeneration, some hepatocytes contain catalase-negative peroxisomes. This phenotype diminishes after complete restoration of the liver mass, indicating that oxidative stress is present not only in pathological conditions but also as physiological factor during regeneration. Healthy, female Wistar rats were used for the experiment. Animals were injected with W256 tumor in hind right limb. After 3 days 40% partial hepatectomy was performed. Animals were sacrificed 24 and 72 hours after partial hepatectomy, and blood was collected from the heart. Measurement of malondialdehyde (MDA) was done on HPLC, and antioxidative capacity of the plasma was measured. Also, full blood chemiluminiscence was performed to monitor activation of the granulocytes. Tumor presence in organism did not change significantly its antioxidative capacity and MDA level in plasma in observed time points. Antioxidative capacity was increased in animals 24 hours after partial hepatectomy in comparison to healthy controls and to tumor bearing controls, but it was back to control level 72 hours after partial hepatectomy. Analysis of MDA level in plasma has shown an increase 72 hours after partial hepatectomy, when antioxidative capacity normalized after initial increase. Tumor bearing animals had increased chemiluminescence during tumor growth. Also, partial hepatectomy additionally increased chemiluminiscence compared to control tumor bearing animals. So, granulocytes are more activated in tumor presence and partial hepatectomy causes additional activation. These results indicate that trauma, like partial hepatectomy mobilize antioxidative defense in the organism. Both, partial hepatectomy and tumor growth disturbed balance between oxidants and antioxidants in organism. Also, activation of granulocytes presented unspecific inflammatory response of the organism to tumor presence. Further, additional activation of granulocytes caused by surgical procedure represented immunological stress response and could play certain role in control of tumor growth.

oxidative stress; partial hepatectomy

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