Distribution of epidermal growth factor binding sites in the adult rat adrenal gland by light microscope autoradiography.

The distribution of epidermal growth factor (EGF) receptors was studied in the adrenal gland using light microscope autoradiography which was carried out 2 min after intravenous (iv) injection of [125I]EGF into adult rat. At the light microscope level, the labelling was found over the cells of the capsule and adrenal medullary chromaffin cells. No specific labelling of the steroid-secreting cells was observed. Control experiments indicated that the autoradiography reaction was due to specific interaction of [125I]EGF with its receptor. These results clearly indicate that EGF receptors are present in the majority of the adrenal medulla cells. They suggest that EGF may exert a physiological role in the regulation of rat adrenal medulla.