Anti-TNF treatment does not reverse the abnormalities in lipid metabolism of the obese Zucker rat

Because obesity, insulin resistance, and hyperlipidemia are often associated, and recent evidence suggests that the cytokine tumor necrosis factor-alpha (TNF) may influence the activity of insulin in various target tissues, the present study was designed to see whether TNF was also associated with the changes in lipid metabolism that lead to hyperlipidemia in the obese model of the Zucker rat. A polyclonal goat anti-rat TNF antibody was subcutaneously administered to Zucker rats for 4 days to block TNF actions. The results indicate that none of the alterations in lipid metabolism seen in the obese animals were reversed by the anti-TNF treatment. This was the case for the lipogenic rate in liver and adipose tissue, the disposal of an exogenous [C-14]triolein load, adipose tissue lipoprotein lipase activity, and the hypertriglyceridemia. Measurements of lipolysis in adipose tissue slices from the anti-TNF-treated animals also did not show any significant effect of the treatment. In conclusion, TNF does not seem to be involved in the abnormalities of lipid metabolism observed in the obese Zucker rat.