No Effect of Insulin on Glucose Blood-Brain Barrier Transport and Cerebral Metabolism in Humans

摘要

The effect of hyperinsulinemia on glucose blood-brain barrier (BBB) transport and cerebral metabolism (CMR_glc) was studied using the intraenous double- indicator method and positron emission tomography using [18~F] fluorodeoxyglucose as tracer (PET-FDG). Sixteen normal healthy control subjects (25±4 years Old) were studied twice during a euglycemic and a Euglycemic-hyperinsulinemic condition. Our hypothe- Sis was that high physiologic levels of insulin did not Affect the BBB transport or net metabolism of glucose. During insulin infusion , arterial plasma insulin levels Increased from 48.5 to 499.4 pmol/l. The permeability- Surface areas products for glucose and FDG BBB trans- Port obtained with the double-indicator method Remained constant during hyperinsulinemia. Similarly Using PET-FDG, no changes were observed in the uni- Directional clearance of FDG from blood to brain.