High-Dose Porcine Galanin Infusion and Effect on Intravenous Glucose Tolerance in Humans

The neuropeptide galanin inhibits glucose-stimulated insulin release in dogs and rodents and has been proposed as having a role in the control of insulin release in humans. The effect of infused galanin on intravenous glucose tolerance in humans was investigated by giving an intravenous glucose tolerance test (0.5 g glucose/kg body wt) alone and with infusions of synthetic porcine galanin at high-dose levels (80 and 160 pmol · kg⁻¹ · min⁻¹) to seven healthy male volunteers. The results showed no effect of galanin infusion on plasma glucose or serum insulin, although a rise in serum growth hormone even in the face of the intravenous glucose load confirmed the potent growth hormone-stimulating effect of galanin. These results suggest that caution should be exercised in extrapolating a physiological role for galanin in humans from the results of animal studies.