L-Theanine from Green Tea May Calm Brain Excitation by Targeting Key Signaling Pathway

A recent study published in Current Molecular Pharmacology highlights how L-theanine—a calming component found in green tea—can mitigate brain overexcitation induced by NMDA, a compound known to stimulate neuronal activity. The research, led by Nobuyuki Kuramoto and his team at Setsunan University, demonstrates that L-theanine specifically suppresses the mTOR-p70S6K signaling pathway, which is associated with neuroexcitatory and potentially toxic effects.

Using mouse models, the team observed that L-theanine not only reached the brain rapidly after administration but also remained there for hours. When NMDA was given, it increased the expression of c-Fos, a marker of neuronal excitation, and boosted phosphorylation of the S6 protein. However, pretreatment with L-theanine significantly reduced these effects.

“Our data suggest that L-theanine helps normalize the disrupted signaling caused by excessive calcium influx,” said Nobuyuki Kuramoto, corresponding author of the study. “It appears to selectively inhibit the p70S6K pathway, which may explain its sedative and neuroprotective properties.”

Interestingly, L-theanine did not affect another related kinase, p90RSK, indicating a targeted mechanism. The researchers propose that by calming overactive mTOR-p70S6K signaling, L-theanine could potentially protect against excitotoxicity seen in conditions like stress, anxiety, and neurodegenerative diseases.

The study opens new avenues for using L-theanine as a dietary supplement or supportive agent in managing brain overexcitation and related disorders.