Gastrodia elata powder capsule enhances anti-epileptic effect of carbamazepine by decreasing P-gp expression

Abstract

Purpose: To investigate the influence of Gastrodia elata powder capsule (GC) or gastrodin (GTD) on the anti-epileptic effect of carbamazepine (CBZ) on penicillin (PG)-induced epilepsy in rats. Methods: A total 116 rats were used in this study. Rats in the control group (n = 8) were injected with normal saline (NS) in place PG. Epilepsy was induced in the remaining 108 rats on the first day via PG injection. The rats were then divided randomly into six groups (18 rats per group): PG group, CBZ group, CBZ + GC group, CBZ + GTD group, GC group, and GTD group, which were given (p.o.) NS, CBZ (100 mg/kg), CBZ (100 mg/kg.) + GC (350 mg/kg), CBZ (100 mg/kg) + GTD (100 mg/kg), GC (350 mg/kg), and GTD (100 mg/kg), respectively, once a day for 15 days. The behavioral characteristics of the rats were observed and used to assess the anti-epileptic effect of the test drugs. Real-time quantitative reverse transcription-PCR and Western blot assays were employed for the determination of the effect of CBZ, GC and GTD on the expression levels of P-gp. Results: CBZ significantly reduced the symptoms of epilepsy, while GC and GTD enhanced the antiepileptic effect of CBZ, and reversed the CBZ-induced increases in the protein expressions of mrd1a and P-gp (p < 0.05). Conclusion: GC reverses CBZ drug resistance, probably through downregulation of P-gp expression. This finding indicates that GC is a potential anti-epilepsy drug, but it merits further studies.