Distribution of insulin-like growth factor II receptor immunoreactivity in rat tissues

Antibodies specific for the insulin-like growth factor II (IGF-II) receptor were used to study its distribution in a number of rat tissues and cell lines in order to determine which cells might be responsive to local or circulating IGF-II. In cultured 18-54.SF and B104 neuroblastoma cells, plasma membrane and cytoplasmic staining corresponding to Golgi apparatus could be seen, consistent with the glycoprotein nature of this receptor. Antibody binding was also seen in the central nervous system, confined primarily to the choroid plexus, and the vascular and ependymal elements. Some staining was seen in the parenchyma of the brain, in addition to binding around nerve sheaths and axon bundles. There were high levels of immunoreactivity in all three lobes of the pituitary, including vascular and cellular elements. In liver, highest levels of immunoreactivity occurred in the sinusoidal cells. In lung, IGF-II receptor immunostaining was seen in the alveoli and around the bronchioles. Staining in kidney was observed in glomeruli, tubules, and Bowman’s capsules. Lower levels of immunostaining were seen in skeletal muscle, located primarily around the muscle sheaths. Localization of IGF-II receptor to cells of known function in different tissues will help elucidate the role of this ligandreceptor system in regulating growth and metabolism.