Interaction between nicotine and MPTP/MPP+ in rat brain endothelial cells

Area of Science:

• Neuroscience
• Pharmacology
• Cell Biology

Background:

• The blood-brain barrier (BBB) tightly regulates the passage of substances into the brain.
• MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) and its metabolite MPP+ (1-methyl-4-phenylpyridinium) are neurotoxins implicated in Parkinson's disease.
• Nicotine's potential neuroprotective effects warrant investigation into its interaction with BBB transport mechanisms.

Purpose of the Study:

• To investigate the interaction between nicotine and MPTP/MPP+ transport across the BBB.
• To determine the role of organic cation transporter 1 (OCT1) in this interaction.
• To evaluate the in vivo effect of nicotine on brain extracellular levels of MPTP and MPP+.

Main Methods:

• Utilized an adult rat brain microvascular endothelial cell line (ARBEC) to study cellular uptake kinetics of MPTP, MPP+, and nicotine.
• Employed RT-PCR to detect OCT1 mRNA expression in ARBEC.
• Conducted in vivo microdialysis in rats to measure brain extracellular levels of MPTP and MPP+ after MPTP administration and nicotine pre-treatment.

Main Results:

• Uptake of MPTP, MPP+, and nicotine in ARBEC cells was partially mediated by a carrier system sensitive to the OCT inhibitor decynium22.
• OCT1 mRNA was detected in ARBEC cells.
• Nicotine competitively inhibited the uptake of both MPTP and MPP+ in vitro.
• In vivo, nicotine pre-treatment significantly reduced brain extracellular MPTP levels within 30 minutes but did not affect MPP+ levels.

Conclusions:

• Nicotine inhibits both in vitro cellular uptake and in vivo transfer of MPTP across the BBB.
• These effects are mediated by multiple pathways, including OCT1.
• Nicotine's modulation of MPTP transport across the BBB may have implications for understanding neurotoxin exposure and potential therapeutic strategies.