MDR1 gene expression in brain of patients with medically intractable epilepsy

D. M. Tishler, K. I. Weinberg, D. R. Hinton, Nicholas Barbaro, G. M. Annett, C. Raffel

Research output: Contribution to journalArticle

415 Citations (Scopus)

Abstract

Why some patients with seizures are successfully treated with antiepileptic drugs (AEDs) and others prove medically intractable is not known. Inadequate intraparenchymal drug concentration is a possible mechanism of resistance to AEDs. The multiple drug resistance gene (MDR1) encodes P- glycoprotein, an energy-dependent efflux pump that exports planar hydrophobic molecules from the cell. If P-glycoprotein is expressed in brain of some patients with intractable epilepsy and AEDs are exported by P-glycoprotein, lower intraparenchymal drug concentrations could contribute to lack of drug response in such patients. Eleven of 19 brain specimens removed from patients during operation for intractable epilepsy had MDR1 mRNA levels >10 times greater than those in normal brain, as determined by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) method. Immunohistochemistry for P-glycoprotein from 14 of the patients showed increased staining in capillary endothelium in samples from epileptic patients as compared with staining in normal brain samples. In epileptic brain specimens with high MDR1 mRNA levels, expression of P-glycoprotein in astrocytes also was identified. Last, steady-state intracellular phenytoin (PHT) concentrations in MDR1 expressing neuroectodermal cells was one fourth that in MDR1-negative cells. MDR1 expression is increased in brain of some patients with medically intractable epilepsy, suggesting that the patients' lack of response to medication may be caused by inadequate accumulation of AED in brain.

Original languageEnglish
Pages (from-to)1-6
Number of pages6
JournalEpilepsia
Volume36
Issue number1
DOIs
StatePublished - 1995
Externally publishedYes

Fingerprint

P-Glycoprotein
Gene Expression
Brain
Anticonvulsants
Pharmaceutical Preparations
Staining and Labeling
Messenger RNA
Drug Resistant Epilepsy
Vascular Endothelium
Phenytoin
Multiple Drug Resistance
Reverse Transcriptase Polymerase Chain Reaction
Astrocytes
Seizures
Immunohistochemistry
Genes

Keywords

  • Antiepileptic drug levels
  • Brain
  • Medically intractable epilepsy
  • Multiple drug resistance
  • P-Glycoprotein

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)

Cite this

Tishler, D. M., Weinberg, K. I., Hinton, D. R., Barbaro, N., Annett, G. M., & Raffel, C. (1995). MDR1 gene expression in brain of patients with medically intractable epilepsy. Epilepsia, 36(1), 1-6. https://doi.org/10.1111/j.1528-1157.1995.tb01657.x

MDR1 gene expression in brain of patients with medically intractable epilepsy. / Tishler, D. M.; Weinberg, K. I.; Hinton, D. R.; Barbaro, Nicholas; Annett, G. M.; Raffel, C.

In: Epilepsia, Vol. 36, No. 1, 1995, p. 1-6.

Research output: Contribution to journalArticle

Tishler, DM, Weinberg, KI, Hinton, DR, Barbaro, N, Annett, GM & Raffel, C 1995, 'MDR1 gene expression in brain of patients with medically intractable epilepsy', Epilepsia, vol. 36, no. 1, pp. 1-6. https://doi.org/10.1111/j.1528-1157.1995.tb01657.x
Tishler, D. M. ; Weinberg, K. I. ; Hinton, D. R. ; Barbaro, Nicholas ; Annett, G. M. ; Raffel, C. / MDR1 gene expression in brain of patients with medically intractable epilepsy. In: Epilepsia. 1995 ; Vol. 36, No. 1. pp. 1-6.
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