GLUCAGON RECEPTOR MESSENGER-RNA DISTRIBUTION IN RAT-TISSUES

In addition to glucagon's role in regulating glucose production from t he liver, a number of extrahepatic effects of glucagon have been repor ted. We have therefore examined various rat tissues for glucagon recep tor mRNA expression. In liver, kidney, heart, adipose tissue, spleen, pancreatic islets, ovary, and thymus, glucagon receptor mRNA expressio n was found to be relatively abundant whereas lower levels were detect ed in stomach, small intestine, adrenal gland, thyroid, and skeletal m uscle. The presence of glucagon receptor mRNA in tissues known to be r esponsive to glucagon suggests that these effects are mediated by spec ific glucagon receptors. Furthermore, the finding of glucagon receptor mRNA in the spleen, thymus, thyroid, adrenal gland, ovary, and skelet al muscle, where glucagon is not generally considered to act, indicate s that there may be novel actions of glucagon that have yet to be dete rmined.