Reserpine (RES)-induced orofacial dyskinesia (OD) has been used as an animal model for human tardive dyskinesia (TD) for decades, due to its strong pathophysiological association with striatal oxidative stress and neural cytoarchitecture alteration. L-Theanine (LT), one of the major amino acid components in green tea, has potent antioxidative, anti-inflammatory, and neuroprotective effects. In this study, we examined the potential protective effects of LT on RES-induced behavioral and neurochemical dysfunction in rats. RES treatment (1 mg/kg s.c., 3 injections 1 day apart) induced significant increases (p < 0.001) in the frequency of vacuous chewing movements (VCM), tongue protrusion (TP), as well as the duration of facial twitching (FT). LT treatment (100, 300 mg/kg orally for 14 days, starting 10 days before RES injection) was able to prevent most of the RES-induced OD. Moreover, LT treatment reduced the RES-induced lipid peroxidation (LPO) production, increased the antioxidation power and catecholamines in the striatum, and significantly reduced the levels of neuroinflammatory and apoptotic markers. Our results indicated that LT was able to counteract the increased oxidative damage, neurotransmitter deficiency, neuroinflammation, and apoptosis induced by RES, and these results have demonstrated the possible neuroprotective effects of LT against RES-induced OD, including antioxidation, neurochemical deficiency prevention, antineuroinflammation, and antiapoptosis. These findings, therefore, suggest a potential role for LT to have a clinically relevant therapeutic effect in delaying or treating human TD.
Keywords: L-Theanine; Orofacial dyskinesia; Reserpine; Striatum.