The mRNA content of both TNF-α and its receptors (TNFR1 and TNFR2) in skeletal muscle and adipose tissue from cachectic rats has been assessed. The implantation of the Yoshida AH-130 ascites hepatoma resulted in substantial decrease in skeletal muscle TNF-α expression as early as at day 2 following tumour implantation. However, the mRNA content for the two receptors followed a different pattern, being significantly increased at day 7. In adipose tissue the expression of the TNF-α gene was significantly increased at all the time points studied, whereas TNF-α receptors expression followed a similar pattern to that observed in skeletal muscle. Western blot analysis indicated that the TNFR1 protein followed an identical pattern to that observed in the mRNA content both in muscle and adipose tissue. It is concluded that, during experimental cancer cachexia, the contribution of muscle-produced TNF-α is decreased; however, significant changes were observed in relation with TNF-α receptors at the skeletal muscle level that could possibly be related to the muscle wasting process associated with tumour growth.

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