Insulin inhibits specific norepinephrine uptake in neuronal cultures from rat brain

Neuronal cells in primary culture have been demonstrated to possess specific insulin receptors (Boyd et al., J. Biol. Chem., 260 (1985) 15880-15884). Incubation of these cultures with insulin causes a dose-dependent inhibition of maprotiline-sensitive [3H]norepinephrine uptake. Maximum inhibition of 95% of maprotiline-sensitive norepinephrine uptake was observed at an insulin concentration of 167 nM with an ED50 of 30 nM. Competition-inhibition and Scatchard analysis of the insulin binding data suggested that maprotiline competed for high-affinity insulin receptors. These observations suggest that both insulin and maprotiline specifically inhibit neuronal norepinephrine uptake possibly involving insulin receptors.