The binding of insulin to cerebral capillaries and astrocytes of the rat.

The binding [125I]insulin and its displacement by the unlabeled hormone was measured in vitro in the isolated cerebral capillaries and astroglia cell-enriched fraction as well as in the particulate fraction of cerebral homogenate and liver plasma membrane preparation. The results indicate the specificity and affinity of the hormone binding to astrocytes to be similar to that to cerebral homogenate and liver fractions and markedly higher than to cerebral blood vessels. The possible functional significance of the insulin receptors on astrocytes is discussed.