Effects of taste stimulation on the behavior of serum amino acid concentrations and amylase and trypsin activities in easting rats

The effect of taste stimulation on serum free-amino acid concentrations and amylase and trypsin activities in fasting rats was studied. Following an a cclimation period of 5d, male Sprague-Dawley rats were fasted for 4d and sa crificed after taste stimulation with a palatable sodium saccharin or unpal atable quinine sulfate flavored diet. Blood was collected from the portal v ein and inferior vena cava at 0, 5, 10, 20 and 30 min after taste stimulati on. Intestinal contents were also collected at the same time intervals as t he blood collections. Total amino acid concentrations in the saccharin stim ulated group increased significantly at 5 and 20 min following taste stimul ation in comparison with the control of 0 time in the portal vein, and a si gnificant difference between the saccharin and quinine stimulated groups wa s also observed at 5 min. No difference was found in the inferior vena cava . A high level of alanine and low level of glutamine were depicted in the p ortal vein as compared to that of the inferior vena cava. The elevation of alanine that is gluconeogenic amino acid was remarkable in the saccharin gr oup at 20 min in the portal vein. Moreover, amylase and trypsin activities in the saccharin group reached peak values promptly and kept constant throu ghout the experiment as compared to the quinine group. The results suggest that taste stimulation originates changes in the cephalic phase amino acid concentrations in the portal vein and that taste information, overcoming a hunger, plays an important role in amino acid metabolism and digestive enzy me activities. Therefore, eating with gusto is significant for the maintena nce of body functions even under starvation conditions.