L-theanine intake increases threshold for limbic seizures but decreases threshold for generalized seizures

L-theanine, an ethylamide derivate of glutamate found peculiarly in green tea, has been shown to exert beneficial actions in animal models for several neurological disorders. We here studied for the first time the effect of L-theanine intake on seizure susceptibility, using an acute pilocarpine and pentylenetetrazol (PTZ) mouse model for studying respectively limbic seizures and primarily generalized seizures. Moreover, we studied the effect of L-theanine intake on extracellular hippocampal and cortical glutamate and GABA levels, using in vivo microdialysis. Feeding mice with 4% Ltheanine significantly decreased susceptibility for pilocarpine-induced seizures whereas susceptibility for PTZ-induced seizures was increased. The latter effect could be linked to decreased extracellular GABA concentrations in frontal cortex.