Tissue-Specific Increase Of Insulin-Like Growth Factor I Gene Expression In Human Adipose Tissue After Abdominal Surgery

Abstract

The growth hormone (GH)/insulin-like growth factor I (IGF-I) axis in catabolic conditions is believed to be severely altered, based on measurements of biochemical markers in plasma and clinical observations. To test the hypothesis that GH sensitivity may be differentially regulated in different tissues, we analysed GH receptor (GHR) and IGF-I gene expression in adipose tissue and skeletal muscle, before and after major surgery, and compared it with the corresponding gene products in plasma, IGF-I and GH-binding protein (GHBP). A significant increase (p<0.05) in IGF-I mRNA levels was found in adipose tissue after surgery whereas there were no changes in IGF-I mRNA levels in skeletal muscle or IGF-I concentrations in plasma. Furthermore, GHR mRNA levels did not change after surgery whereas GHBP in plasma decreased postoperatively (p<0.01). This study shows that catabolism induced by surgical trauma is associated with differential regulation of IGF-I gene expression in adipose tissue and skeletal muscle and that plasma measurements of IGF-I and GHBP may not accurately reflect changes in gene expression in different tissues. These observations may have implications in the planning and conduction of clinical studies in catabolic states. Ruth Wickelgren and Gunnel Hellgren contributed equally to this manuscript and should both be considered first