Glutamate up-regulates P-glycoprotein expression in rat brain microvessel endothelial cells by an NMDA receptor-mediated mechanism

Life Sci. 2004 Jul 30;75(11):1313-22. doi: 10.1016/j.lfs.2004.02.027.

Abstract

The accumulation of glutamate in the extracellular space in the central nervous system (CNS) plays a major part in ischemic and anoxic damage. In this study, we examined the effect of glutamate on the expression and activity of P-glycoprotein (P-gp) in rat brain microvessel endothelial cells (RBMECs) making up the blood-brain barrier (BBB). The level of P-gp expression significantly increased in RBMECs after the treatment of 100 microM glutamate. At this concentration, glutamate also enhanced rat mdr1a and mdr1b mRNA levels determined by RT-PCR analysis. Flow cytometry was used to study P-gp activity by analysis of intracellular rhodamine123 (Rh123) accumulation. Overexpression of P-gp resulted in a decreased intracellular accumulation of Rh123 in RBMECs. Glutamate-induced increase of intracellular reactive oxygen species (ROS) was observed by using the 2',7'-dichlorofluorescein (2',7'-DCF) assay. MK-801, a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist, and ROS scavenger N-acetylcysteine obviously blocked ROS generation and attenuated the changes of both expression and activity of P-gp induced by glutamate in RBMECs. These data suggested that glutamate up-regulated P-gp expression in RBMECs by an NMDA receptor-mediated mechanism and that glutamate-induced generation of ROS was linked to the regulation of P-gp expression. Therefore, transport of P-gp substrates in BBB appears to be affected during ischemic and anoxic injury.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B / genetics
  • ATP Binding Cassette Transporter, Subfamily B / metabolism
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / genetics
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism*
  • ATP-Binding Cassette Transporters / genetics
  • ATP-Binding Cassette Transporters / metabolism
  • Animals
  • Blood-Brain Barrier / drug effects*
  • Blood-Brain Barrier / metabolism
  • Cell Survival / drug effects
  • Cells, Cultured
  • Cerebral Cortex / blood supply
  • Dizocilpine Maleate / pharmacology
  • Dose-Response Relationship, Drug
  • Endothelium, Vascular / drug effects*
  • Endothelium, Vascular / metabolism
  • Glutamic Acid / pharmacology*
  • Microcirculation / drug effects
  • Microcirculation / metabolism
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Rats
  • Reactive Oxygen Species / antagonists & inhibitors
  • Reactive Oxygen Species / metabolism
  • Receptors, N-Methyl-D-Aspartate / antagonists & inhibitors
  • Receptors, N-Methyl-D-Aspartate / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Up-Regulation

Substances

  • ATP Binding Cassette Transporter, Subfamily B
  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • ATP-Binding Cassette Transporters
  • P-glycoprotein 2
  • RNA, Messenger
  • Reactive Oxygen Species
  • Receptors, N-Methyl-D-Aspartate
  • Glutamic Acid
  • Dizocilpine Maleate
  • multidrug resistance protein 3