Adult-level insulin binding is present in term fetal rat CNS membranes.

Insulin binding was measured using partially-purified membranes prepared from the brains of term fetal and adult rats as the source of receptors. The membranes from the fetal rat brains bound at least as much insulin as did those from the adult rats at all concentrations of insulin used. This finding supports our hypothesis that insulin contributes to the postnatal growth of the rat brain.