Original Article

Multidrug resistance-associated protein 1 decreases the concentrations of antiepileptic drugs in cortical extracellular fluid in amygdale kindling rats

Ying-hui Chen, Cui-cui Wang, Xia Xiao, Li Wei, Guoxiong Xu
DOI: 10.1038/aps.2012.183


Ying-hui CHEN1, 2, *, Cui-cui WANG1, 2, Xia XIAO1, 2, Li WEI1, 2, Guoxiong XU3, *
1Department of Neurology, Jinshan Hospital, Fudan University, Shanghai 201508, China; 2Department of Neurology, Shanghai Medical College, Fudan University, Shanghai 200032, China; 3Center Laboratory, Jinshan Hospital, Fudan University, Shanghai 201508, China

Aim: To investigate whether multidrug resistance-associated protein 1 (MRP1) was responsible for drug resistence in refractory epilepsy in amygdale kindling rats.
Methods: Rat amygdale kindling was used as a model of refractory epilepsy. The expression of MRP1 mRNA and protein in the brains was examined using RT-PCR and Western blot. MRP1-positive cells in the cortex and hippocampus were studied with immunohistochemical staining. The rats were intraperitoneally injected with phenytoin (50 mg/kg) or carbamazepine (20 mg/kg), and their concentrations in the cortical extracellular fluid were measured using microdialysis and HPLC. Probenecid, a MRP1 inhibitor (40 mmol/L, 50 μL) was administered through an inflow tube into the cortex 30 min before injection of the antiepileptic drugs.

Results: The expression of MRP1 mRNA and protein was significantly up-regulated in the cortex and hippocampus in amygdale kindling rats compared with the control group. Furthermore, the number of MRP1-positive cells in the cortex and hippocampus was also significantly increased in amygdale kindling rats. Microdialysis studies showed that the concentrations of phenytoin and carbamazepine in the cortical extracellular fluid were significantly decreased in amygdale kindling rats. Pre-administration of probenecid could restore the concentrations back to their control levels.

Conclusion: Up-regulation of MRP1 is responsible for the resistance of brain cells to antiepileptic drugs in the amygdale kindling rats.

Keywords: multidrug resistance-associated protein 1; refractory epilepsy; amygdale kindling; antiepileptic drug; phenytoin; carbamazepine; cortex; hippocampus; microdialysis

This work was supported by grants from the Natural Science Foundation of Shanghai (09ZR1405500) and the Shanghai Municipal Health Bureau (2008-08) to Yin-hui CHEN and a start-up fund of research from the Jinshan Hospital of Fudan University to Guoxiong XU (2012-2).
* To whom correspondence should be addressed.
E-mail cyh1973131@163.com (Ying-hui CHEN); guoxiong.xu@fudan.edu.cn (Guoxiong XU)
Received 2012-09-25 Accepted 2012-12-05

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