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Quantification of Neurovascular Protection Following Repetitive Hypoxic Preconditioning and Transient Middle Cerebral Artery Occlusion in Mice
Published on: May 4, 2015
Repetitive/temporal hypoxia increased P-glycoprotein expression in cultured rat brain microvascular endothelial cells
Liu Xiao-Dong1, Yang Zhi-Hong, Yang Hui-Wen
1Key Lab of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009, China. xdliu@cpu.edu.cn
Abstract:
The aim of the study was to investigate whether repetitive/temporal hypoxia up-regulated P-glycoprotein (P-gp) in cultured rat brain microvascular endothelial cells (rBMECs). Cultured rBMECs were used as in vitro blood brain barrier (BBB) model. Cells reached confluence were subjected to temporal hypoxic exposure. Under free-glucose cultured medium, the cells were covered by sterile paraffin oil for 15 min, inducing temporal hypoxic exposure. The hypoxic-exposure was carried out once every day up to 8 days, leading to the repetitive/temporal hypoxia in rBMECs. The cell viability was tested using CCK-8 kit, function and levels of P-gp in the cells were measured using rhodamine 123 uptake and western blot, respectively. It was found that 8-temporal hypoxic exposure induced 1.6-fold increase of P-gp level in cells, accompanied by decrease of cellular accumulation of rhodamine 123. Cellular accumulation of phenobarbital was also decreased. These findings indicated that repetitive/temporal hypoxia may be one of the factors resulting in P-gp overexpression in refractory epilepsy.
Insights
Repetitive temporal hypoxia increases P-glycoprotein (P-gp) levels in rat brain endothelial cells. This suggests hypoxia may cause P-gp overexpression, potentially contributing to drug resistance in epilepsy.
Area of Science:
- Neuroscience
- Cell Biology
- Pharmacology
Background:
- The blood-brain barrier (BBB) regulates substance entry into the brain.
- P-glycoprotein (P-gp) is a key efflux transporter at the BBB.
- Understanding factors affecting P-gp is crucial for treating brain disorders.
Purpose of the Study:
- To investigate the effect of repetitive/temporal hypoxia on P-glycoprotein (P-gp) expression and function in cultured rat brain microvascular endothelial cells (rBMECs).
- To explore the potential role of hypoxia-induced P-gp changes in conditions like refractory epilepsy.
Main Methods:
- Primary rat brain microvascular endothelial cells (rBMECs) were cultured to form an in vitro BBB model.
- Cells were subjected to daily repetitive/temporal hypoxic exposure for up to 8 days.
- P-gp levels were assessed using Western blot, and P-gp function was evaluated by measuring rhodamine 123 and phenobarbital uptake.
Main Results:
- Eight days of repetitive/temporal hypoxia significantly increased P-gp levels by 1.6-fold in rBMECs.
- Hypoxia led to decreased cellular accumulation of rhodamine 123, indicating reduced P-gp function.
- The uptake of phenobarbital, another substrate of P-gp, was also decreased.
Conclusions:
- Repetitive/temporal hypoxia up-regulates P-glycoprotein expression and function in brain microvascular endothelial cells.
- Hypoxia-induced P-gp overexpression may be a contributing factor to the development of P-gp-mediated drug resistance in refractory epilepsy.
- This study highlights hypoxia as a potential therapeutic target for improving drug delivery across the BBB in neurological disorders.
