Ontogeny of insulin binding in different regions of the rat brain.

Insulin binding was measured on crude mitochondrial or plasma membranes prepared from different rat brain regions during postnatal development. In the cerebral cortex and brainstem, insulin binding decreased 60-70% between birth and the adult period. In the cerebellum, insulin binding doubled in the first 10 postnatal days and then decreased 40% in the adult, while in the olfactory bulb, insulin binding changed little during postnatal development. Postnatal reductions of insulin binding in cerebral cortex and brainstem were from a loss of binding sites and not from a change in binding affinity. Of the major postnatal developmental processes, maximal insulin binding was most closely associated with neuronogenesis, less closely with gliogenesis and not with synaptogenesis, neural process formation or myelination.