Effect of tumor weight and tube feeding on TNF-α and IL-1β mRNA expression in the brain of mice

Background: Previous studies have shown that cytokine mRNA expression is elevated in the brains of anorectic, tumor-bearing rats. The objectives of the current study were as follows: (1) to determine whether a small tumor would result in up-regulation of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 beta mRNA expression in the brain and other tissues of tumor-bearing mice; and (2) to determine whether hyperalimentation by tube feeding would prevent up-regulation of cytokine mRNA expression in the brain and other tissues of tumor-bearing mice. Methods: Male C57BL/6 mice were divided into 4 groups: (1) control mice fed ad libitum (Control); (2) tumor-bearing mice fed ad libitum (TB); (3) control mice receiving tube feeding (CTF); and (4) tumor-bearing mice receiving tube feeding (TBTF). Results: TNF-alpha and IL-1 beta mRNA expression was elevated in the brains of mice with a 1% body weight tumor, relative to the control and CTF groups, without any detectable changes in the other organs. On the other hand, TNF-alpha and IL-1 beta mRNA expression was elevated in all organs of mice with an 8% body weight tumor, relative to the control and CTF groups. Tube feeding did not change TNF-alpha and IL-1 beta mRNA expression in mice burdened with either a 1% or 8% body weight tumor. Conclusions: Up-regulation of cytokine mRNA synthesis occurs earlier in the brain than in other organs, and hyperalimentation does not change cytokine mRNA expression in tumor-bearing mice.