Insulin receptors in the peripheral nervous system: a structural and functional analysis.

Although the brain is known to contain specific insulin receptors, there is no information on whether these receptors are also present in the peripheral nervous system (PNS). The present studies sought to provide this information by characterizing insulin binding in bovine autonomic (superior cervical) and sensory (trigeminal) ganglia. It was found that both ganglia contain specific, high-affinity receptors for insulin. Like insulin receptors in other tissue, these receptors could be solubilized and purified on wheat germ agarose columns and were found to have tyrosine-specific kinase activity. SDS-PAGE and autoradiography revealed that the apparent molecular weight (Mr) of the PNS insulin receptor was approximately 133 kDa which is similar to the Mr of hepatic receptors, but is approximately 10 kDa larger than the insulin receptor found in the brain. Because the vasculature of autonomic and sensory ganglia is fenestrated, it is possible that PNS insulin receptors are exposed to blood-borne insulin.