Whole Body Radioautographic Analysis of the In Vivo Distribution of Glucagon Receptors in Mice

In the present study, the histologic distribution of glucagon receptors in the mouse was studied by in vivo whole body radioautography. Male mice were injected intravenously with 125l-labeled glucagon in the absence of and, in the presence of, excess unlabeled glucagon. Three, 6, 15 and 30 min after injection, the animals were perfused and subjected to radioautographic procedures. The results demonstrated that only the liver had a very high level of specific glucagon binding. Low level of specific glucagon binding was observed in the stomach, small intestine, heart, kidney cortex, adipose tissue and spleen. These quantitative results from in vivo whole body radioautography did not always correspond to those from the quantification of mRNA expression. This seems to support a suggestion that glucagon receptor expression is modulated at a step after mRNA formation. High level of non-specific glucagon binding was observed in the kidney, thyroid, sublingual and submandibular glands and seminal vesicle.