Thomas Damgaard Sandahl

Tumor necrosis factor-alpha acutely up-regulates urea synthesis in vivo in rats - a hepatic component of inflammatory catabolism?

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  • The Department of Hepatology and Gastroenterology V
  • The Department of Endocrinology and Diabetes
Abstract Background. Catabolism is a serious problem in patients with active inflammation. The tissue nitrogen (N) depletion is related to increased hepatic capacity for elimination of N via conversion of amino-N into urea-N. This is caused by the inflammatory process, but the mediators responsible are unknown. Tumor necrosis factor-alpha (TNF-alpha) plays a key role in inflammation, and we hypothesized that TNF-alpha up-regulates urea synthesis. Methods. We examined the in vivo capacity of urea-N synthesis (CUNS) and mRNA levels of urea cycle enzyme genes 3 h after TNF-alpha injection in rats. Circulating concentrations of glucagon, corticosterone, insulin, glucose, cytokines and acute phase proteins and their liver tissue gene expressions were measured. Results. TNF-alpha increased CUNS by 40% (p=0.03) despite decreased urea-cycle enzyme gene expression. TNF-alpha increased interleukin 6 (IL-6) (p < 0.001); circulating acute phase proteins were unchanged. Conclusion. TNF-alpha in rats caused an acute up-regulation of the in vivo capacity of urea synthesis which may promote loss of nitrogen from the body and catabolism. The results indicate that TNF-alpha has a post-transcriptional effect on regulation of urea synthesis that is independent of the acute phase protein synthesis. Effects of IL-6 may be involved.
Original languageEnglish
Book seriesScandinavian Journal of Clinical and Laboratory Investigation. Supplement
Volume70
Issue3
Pages (from-to)151-7
Number of pages7
ISSN0085-591X
DOIs
Publication statusPublished - 2010

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