title: Reversal of P-glycoprotein overexpression by Ginkgo biloba extract in the brains of pentylenetetrazole-kindled and phenytoin-treated mice.
abstract: The purpose of this study was to investigate the combined effects of Ginkgo biloba extract and phenytoin (PHT) sodium as a dose regimen simulating the clinical treatment of patients with epilepsy, on P-glycoprotein (P-GP) overexpression in a pentylenetetrazole-kindled mouse model of epilepsy. Epilepsy was induced by intraperitoneal administration of pentylenetetrazole (40 mg/kg) for 7 days followed by intragastric administration of PHT (40 mg/kg) for 14 days. Thirty mice that developed seizures were randomly divided into three groups and administered PHT as well as the following treatments: saline (negative control); verapamil (20 mg/kg, positive control); and G. biloba (30 mg/kg). Seizure severity was recorded 30 minutes after treatment on Day 4 of drug administration, after which the mice were euthanized, and their brains isolated. Western blots and immunohistochemistry were performed to analyze the expression of P-GP and caspase-3, respectively, in the brain tissue. High-performance liquid chromatography was used to measure the concentrations of PHT in the brains of the treated mice. After 4 consecutive days of treatment, the seizure severity in the mice in the G. biloba extract group was more significantly reduced than the seizure severity in the saline control group, and a significant difference was observed between the G. biloba extract and verapamil control groups (p < 0.05). P-GP expression in the brain more significantly decreased in the mice treated with G. biloba extract and verapamil than it did in the saline-treated control group (p < 0.05). Compared with the saline-treated control group, the mice treated with G. biloba extract and verapamil showed significantly increased brain PHT concentrations (p < 0.05). Furthermore, caspase-3 expression in the brain tissue of the G. biloba extract group was significantly lower than that in the vehicle control group (p < 0.05); this finding demonstrated the neuroprotective effects of G. biloba. Therefore, this study showed that treatment with G. biloba extract in combination with PHT prevented the upregulation of P-GP expression in mice. Moreover, G. biloba extract decreased seizure severity in pentylenetetrazole-kindled/PHT-treated mice through a mechanism that might be related to the reduction of P-GP expression in the brain.
authors.affiliation: Department of Pharmacy, The Second Affiliated Hospital of Dalian Medical University, Dalian, China. Electronic address: zhangce88@126.com.
authors.forename: Ce
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Pharmacy, The Second Affiliated Hospital of Dalian Medical University, Dalian, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Fan
authors.affiliation: Department of Neurology, The Second Affiliated Hospital of Dalian Medical University, Dalian, China.
authors.forename: Shu-Liang
authors.initials: SL
authors.lastname: Chen
authors.affiliation: Department of Pharmacy, The Second Affiliated Hospital of Dalian Medical University, Dalian, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Ma
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D053148:Caspase 3 / Q000378:metabolism; D004195:Disease Models, Animal; D020441:Ginkgo biloba / Q000737:chemistry*; D007696:Kindling, Neurologic; D008297:Male; D051379:Mice; D010433:Pentylenetetrazole; D010672:Phenytoin / Q000494:pharmacology / Q000627:therapeutic use*; D010936:Plant Extracts / Q000494:pharmacology* / Q000627:therapeutic use; D012640:Seizures / Q000139:chemically induced / Q000201:enzymology / Q000473:pathology; D014700:Verapamil / Q000494:pharmacology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D010936:Plant Extracts; D010672:Phenytoin; D014700:Verapamil; D053148:Caspase 3; D010433:Pentylenetetrazole
keywords: Caspase-3; Drug resistance; Ginkgo biloba; P-glycoprotein; Phenytoin