The Distribution of Tissue Insulin Receptors in the Mouse by Whole – Body Autoradiography

Abstract

The distribution of insulin binding sites in the mouse was investigated by in vivo whole-body autoradiography. Male mice were injected intravenously with 125I-insulin in the absence of and, in the presence of, excess unlabeled insulin. Three, 6, 15, 30 and 60 minutes after injection, the animals were perfused and subjected to autoradiographic procedures. Specific insulin binding was observed in the choroid plexus, liver, gastrointestinal tract, spleen, pancreas, deferent duct, and Harderian gland. In the liver and spleen, the distribution of binding sites was heterogeneous. In the liver, the density of the binding was higher around the branches of the portal vein than around the central vein. In the spleen, the marginal zone exhibited a higher density than the white and red pulp. The kidney cortex, and the thyroid gland showed a high degree of insulin binding, but the binding was nonspecific. The binding of insulin to other tissues and organs, including the skeletal muscle and fat, was weak, and most of the binding was nonspecific.

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

“…These results differed substantially from those on the insulin receptor [41]. The relatively high level of specific insulin bindings was observed in a number of tissues including the choroid plexus, stomach, large and small intestines, spleen, pancreas, deferent duct, and Harderian gland [41].…”

Histologic distribution of insulin and glucagon receptors

“…are used. With the 125 I-plastic standards the sensitivity of the film to 125 I should be determined (62). To obtain appropriate absorbance values for the radioautographs, it is necessary to know the relationship between isotope concentrations and film blackings at various exposure times.…”

Use of in vivo Whole-Body Autoradiography to Identify the Distribution of Epidermal Growth Factor Binding Sites under Normal Conditions in the Mouse Digestive System.

“…Structural (71) and metabolic (33,38,47) heterogeneity of cells within the hepatic lobule is well known and it is referred to as "metabolic zonation" (47,48). Such a gradient has been observed for the uptake of plasma-derived protein insulin (6,25,83). The EGF taken up by the hepatocytes is internalized, degraded, and secreted into bile, but a small percentage of endocytosed EGF is also secreted into the bile as intact EGF (11).…”

“…The region incised for perfusion was covered with 3% carboxymethylcellulose frozen with powdered dry ice, and the entire body of the animal was frozen in a mixture of dry ice and acetone. Whole-body autoradiographs of cryosections 20 pm thick were prepared by the methods reported in a previous paper (83). In the present study, we used tritium-sensitive film (Konica Macroautoradiograph Film, 3H type, Konica Co., Tokyo, Japan).…”

“…The response of the film to the 125I used in this experiment has approximate linearity with the radioactivities under OD 2.5 (83). Because the maximum OD value was under 2.5, ODs were used to compare the densities of EGF binding sites without any corrections.…”