Effects of MSG supplementation on free amino acids in plasma of growing-finishing Pigs

Glutamate is extensively metabolized in small intestine epithelial cells during its transcellular transfer from the lumen to bloodstream and after its uptake from the bloodstream. In order to study the effect of monosodium glutamate (MSG) supplementation given either by the parenteral route or by the enteral route on the circulating amino acid concentrations in growing-finishing pigs, animals received MSG at a dose equal to 0.25 g/kg body weight by intraperitoneal injection or by injection into the stomach. Up to 255 min, arterial and portal venous blood was collected and amino acid concentrations were measured. The results show that the glutamate concentrations in venous and arterial plasma increase rapidly after injection of MSG in stomach. However, glutamate concentration in both venous and arterial plasma was much higher after peritoneal than stomach injection. Aspartate and alanine concentrations in both venous and arterial plasma were higher after stomach than peritoneal injection. The results obtained are compatible with the view that i) a large part of glutamate in MSG is metabolized by the intestine in pigs; ii) at the dose used. MSG is, however, not entirely metabolized by the intestine and iii) glutamate metabolism in pig intestine leads to aspartate and alanine production.