Glutamine is the most abundant free
amino acid of the human body. Besides its role as a constituent of
proteins and its importance in
amino acid transamination,
glutamine has regulatory capacity in immune and cell modulation.
Glutamine deprivation reduces proliferation of lymphocytes, influences expression of surface activation markers on lymphocytes and monocytes, affects the production of
cytokines, and stimulates apoptosis. Moreover,
glutamine administration seems to have a positive effect on
glucose metabolism in the state of
insulin resistance.
Glutamine influences a variety of different molecular pathways.
Glutamine stimulates the formation of
heat shock protein 70 in monocytes by enhancing the stability of
mRNA, influences the redox potential of the cell by enhancing the formation of
glutathione, induces cellular
anabolic effects by increasing the cell volume, activates
mitogen-activated protein kinases, and interacts with particular aminoacyl-
transfer RNA synthetases in specific
glutamine-sensing metabolism.
Glutamine is applied under clinical conditions as an oral, parenteral, or enteral supplement either as the single
amino acid or in the form of
glutamine-containing
dipeptides for preventing
mucositis/
stomatitis and for preventing
glutamine-deficiency in
critically ill patients. Because of the high turnover rate of
glutamine, even high amounts of
glutamine up to a daily administration of 30 g can be given without any important side effects.