Ginkgo biloba and vitamin E ameliorate haloperidol-induced vacuous chewingmovement and brain-derived neurotrophic factor expression in a rat tardive dyskinesia model

Neurodegeneration may be involved in the development of tardive dyskinesia (TD), and low levels of brain-derived neurotrophic factor (BDNF) may play a role. Ginkgo biloba (EGb761), a potent antioxidant, may have neuroprotective effects. We hypothesized that there would be decreased BDNF expression in TD, but that treatment with EGb761 would increase BDNF expression and reduce TD manifestations in a rat model. Forty rats were treated with haloperidol (2 mg/kg/day via intraperitoneal injections) for 5 weeks. EGb761 (50 mg/kg/day) and vitamin E (20 mg/kg/day) were then administered by oral gavage for another 5 weeks, and we compared the effects of treatment with EGb761 or vitamin E on haloperidol-induced vacuous chewing movements (VCMs) and BDNF expression in four brain regions: prefrontal cortex (PFC), striatum (ST), substantia nigra (SNR), and globus pallidus (GP). Our results showed that haloperidol administration led to a progressive increase in VCMs, but both EGb761 and vitamin E significantly decreased VCMs. Haloperidol also decreased BDNF expression in all four brain regions, but both EGb761 and vitamin E administration significantly increased BDNF expression. Our results showed that both EGb761 and VE treatments exerted similar positive effects in a rat model of TD and increased BDNF expression levels in the four tested brain regions, suggesting that both EGb761 and vitamin E improve TD symptoms, possibly by enhancing BDNF in the brain and/or via their free radical-scavenging actions.