Physiologically Unique Insulin Receptors on Neuronal Cells

Abstract

Neuronal cells in primary culture from the brain have been utilized in the present study to determine the physiological and biochemical roles of neuronal insulin receptors. Kinetic characteristics of ¹²⁵I-insulin binding to neuronal cells were similar to those for glial and peripheral cells although the a and β subunits of the neuronal receptor were significantly smaller in size. Insulin inhibited [³H]norepinephrine uptake and stimulated [³H]-serotonin uptake in neuronal cells, the effect most likely mediated by insulin receptors. In addition, insulin upregulated, while tunicamycin failed to exert any effects on, neuronal insulin receptors. These observations indicate that the neuronal insulin receptor is physiologically distinct from the glial and peripheral receptors and suggest that insulin may have a neuromodulatory role in the brain function.