Antiepileptic activity of total triterpenes isolated from Poria cocos is mediated by suppression of aspartic and glutamic acids in the brain

Context: Triterpenes from Poria cocos Wolf (Polyporaceae) have been used to treat various diseases in traditional Chinese medicine. However, the antiepileptic effects and mechanism are not fully understood.

Objective: The objective of this study is to investigate the antiepileptic properties of total triterpenes (TTP) from the whole P. cocos.

Materials and methods: The ethanol extract TTP was identified by HPLC fingerprint analysis. Male ICR mice were gavaged (i.g.) with TTP (5, 20, 80 or 160?mg/kg) or reference drugs twice a day for 7 d. Antiepileptic activities of TTP were evaluated by maximal electroshock (MES)- and pentylenetetrazole (PTZ)-induced seizures in mice for 30 and 60?min, respectively. Locomotor activity and Rota-rod tests were performed for 60?min and 5?min, respectively. The levels of glutamic acid (Glu), aspartic acid (Asp), γ-aminobutyric acid (GABA) and glycine (Gly) in convulsive mice were estimated. The chronic epileptic model of Wistar rats was built to measure expressions of glutamate decarboxylase 65 (GAD65) and GABA_A in rat brain after TTP treatment.

Results: The LC₅₀ of TTP (i.g.) was above 6?g/kg. TTP (5–160?mg/kg) protected mice against MES- and PTZ-induced convulsions at 65.0% and 62.5%, respectively, but have no effect on rota-rod treadmill; TTP (20–160?mg/kg) significantly reduced the locomotor activities, shortened the onset of pentobarbital sodium-induced sleep; TTP decreased Glu and Asp levels in convulsive mice, but increased the GAD65 and GABA_A expressions in chronic epileptic rats at doses usage.

Discussion and conclusion: TTP extracted from P. cocos possessed potential antiepileptic properties and is a candidate for further antiepileptic drug development.