Hypoxia/reoxygenation stress signals an increase in organic anion transporting polypeptide 1a4 (Oatp1a4) at the blood-brain barrier: relevance to CNS drug delivery

J Cereb Blood Flow Metab. 2014 Apr;34(4):699-707. doi: 10.1038/jcbfm.2014.4. Epub 2014 Jan 29.

Abstract

Cerebral hypoxia and subsequent reoxygenation stress (H/R) is a component of several diseases. One approach that may enable neural tissue rescue after H/R is central nervous system (CNS) delivery of drugs with brain protective effects such as 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (i.e., statins). Our present in vivo data show that atorvastatin, a commonly prescribed statin, attenuates poly (ADP-ribose) polymerase (PARP) cleavage in the brain after H/R, suggesting neuroprotective efficacy. However, atorvastatin use as a CNS therapeutic is limited by poor blood-brain barrier (BBB) penetration. Therefore, we examined regulation and functional expression of the known statin transporter organic anion transporting polypeptide 1a4 (Oatp1a4) at the BBB under H/R conditions. In rat brain microvessels, H/R (6% O2, 60 minutes followed by 21% O2, 10 minutes) increased Oatp1a4 expression. Brain uptake of taurocholate (i.e., Oap1a4 probe substrate) and atorvastatin were reduced by Oatp inhibitors (i.e., estrone-3-sulfate and fexofenadine), suggesting involvement of Oatp1a4 in brain drug delivery. Pharmacological inhibition of transforming growth factor-β (TGF-β)/activin receptor-like kinase 5 (ALK5) signaling with the selective inhibitor SB431542 increased Oatp1a4 functional expression, suggesting a role for TGF-β/ALK5 signaling in Oatp1a4 regulation. Taken together, our novel data show that targeting an endogenous BBB drug uptake transporter (i.e., Oatp1a4) may be a viable approach for optimizing CNS drug delivery for treatment of diseases with an H/R component.

MeSH terms

  • Animals
  • Atorvastatin
  • Biological Transport
  • Blood Gas Analysis
  • Blood-Brain Barrier / drug effects
  • Blood-Brain Barrier / metabolism*
  • Blotting, Western
  • Carbon Dioxide / blood
  • Drug Delivery Systems*
  • Electrolytes / blood
  • Female
  • Heptanoic Acids / administration & dosage
  • Heptanoic Acids / pharmacokinetics
  • Heptanoic Acids / therapeutic use
  • Hypoxia, Brain / complications
  • Hypoxia, Brain / drug therapy
  • Hypoxia, Brain / metabolism*
  • Microvessels / metabolism
  • Neuroprotective Agents / administration & dosage
  • Neuroprotective Agents / pharmacokinetics
  • Neuroprotective Agents / therapeutic use
  • Organic Anion Transporters / metabolism*
  • Oxygen / blood
  • Pyrroles / administration & dosage
  • Pyrroles / pharmacokinetics
  • Pyrroles / therapeutic use
  • Rats
  • Rats, Sprague-Dawley
  • Reperfusion Injury / drug therapy
  • Reperfusion Injury / etiology
  • Reperfusion Injury / metabolism*

Substances

  • Electrolytes
  • Heptanoic Acids
  • Neuroprotective Agents
  • Organic Anion Transporters
  • Pyrroles
  • Slco1a4 protein, rat
  • Carbon Dioxide
  • Atorvastatin
  • Oxygen