Abstract
Theanine (L-N-ethylglutamine, a constituent of Japanese green tea), L-glutamine or caffeine did not affect adenosine 3', 5'-monophosphate (cAMP) formation in cerebral cortex slices from rats. In addition, theanine and L-glutamine did not show any effect on cAMP formation in the presence of caffeine. Theanine did show an inhibitory effect on norepinephrine-stimulated cAMP formation in the presence or absence of caffeine. Theanine also showed an inhibitory effect on histamine-stimulated cAMP formation in the absence of caffeine, but not in the presence of caffeine. It appears that theanine does not antagonize caffeine in cAMP metabolism, but does inhibit the stimulation of cAMP formation by norepinephrine.
