Zinc supplementation prevents the development of thymic involution induced by tumor growth in mice

Abstract

Aim. The aim of this study was to investigate the influence of zinc supplementation on the development of thymic involution during the growth of transplantable tumor in mice. Materials and methods. Inbred C3HA mice after subcutaneous syngeneic hepatoma 22a inoculation received zinc sulfate with drinking water. After 3 weeks of tumor growth animals were killed, and evaluated for zinc content in serum blood samples, thymus status and parameters of tumor growth. Results. At the 21 day of tumor 22a growth weight and cellular content of the thymus were decreased by 3 times and endogenous zinc content in samples of blood serum was decreased by 1,9 times. Oral zinc sulfate supplementation at concentration of 22 mkg/ml in drinking water during 3 weeks, started from the first day after tumor inoculation, increased thymus weight and cellularity as well as serum zinc content. At the same time, it did not influence tumor size and survival rate of mice with hepatoma 22a. As a possible mechanism of zinc action, we studied the influence of zinc supplementation on the activity of two anti-oxidative defense enzymes: Cu,Zn-superoxide dismutase and catalase in the thymus. Zinc supplementation had no influence on these parameters, both remained at a higher level in tumor-bearing mice. Conclusion. Oral zinc supplementation in hepatoma 22a bearing mice induced retards the development of thymic involution with no influence on the tumor growth per se. The study allows to suggest that oral zinc administration may be considered as a prospective strategy for thymus reconstitution in oncology patients.