Cephalic-phase insulin release induced by taste stimulus of monosodium glutamate (umami taste).

In order to confirm the effect of umami taste stimulation on visceral functions, blood insulin and glucose assays and an electrophysiological study were performed on the rat. Blood insulin and glucose assays were carried out in conscious and free-moving rats. When the oral cavity was infused by MSG solution, a transient increase in blood insulin level was recognized at 3 min after this oral stimulation. The electrophysiological study revealed that applications of monosodium glutamate (MSG) glucose to the tongue in the anesthetized rat caused an increase in efferent activity of the pancreatic branch of the vagus nerve. These observations support the conclusion that taste stimulation of MSG induces cephalic-phase insulin secretion.