Protective Effect of L-Theanine on Haloperidol-Induced Orofacial

Tardive dyskinesia (TD) is a severe side effect of chronic neuroleptic treatment consisting of abnormal involuntary movements, characterized by orofacial dyskinesia (OD). Haloperidol (HAL)-induced OD has been widely used as an animal model to study the neuropathophysiology of human TD with its pathophysiology strongly associated with striatal oxidative stress. (L)-Theanine (LT), one of the major amino acid components in green tea, has potent antioxidative effects and is able to protect against various oxidative injuries. In this study, we examined the potential protective effects of LT on HAL-induced behavioral and neurochemical dysfunction in rats. HAL treatment (1 mg/kg i.p. for 21 days) induced significant increases (P < 0.001) in the frequency of vacuous chewing movement (VCM) and tongue protrusion (TP) as well as the duration of facial twitching (FT). LT treatment (100, 300 mg/kg orally for 35 days, starting 14 days before HAL injection) was able to prevent most of the HAL-induced OD. LT treatment was also able to reduce the lipid peroxidation (LPO) production, and enhance the antioxidation power in striatum from rats with HAL treatment. The above results indicate that LT has a protective role against HAL-induced OD, probably via its powerful antioxidative properties. Thus, LT may have a clinically relevant therapeutic effect in delaying or treating TD.