Probenecid-induced accumulation of 5-hydroxyindoleacetic acid and homovanillic acid in rat brain

J Pharm Pharmacol. 1987 Sep;39(9):705-10. doi: 10.1111/j.2042-7158.1987.tb06973.x.


The accumulation of 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) in rat brain has been examined after probenecid infusion over 8 h. At plasma probenecid concentrations of 200-400 micrograms mL-1 a steady state level in the accumulation of 5-HIAA and HVA was achieved, the increase above the endogenous levels being 135% and 65%, respectively. When the plasma concentration of probenecid rose above 400 micrograms mL-1 there was further accumulation of both 5-HIAA and HVA probably induced by increased neuronal activity or toxicity due to probenecid. The explanation for the plateau of 5-HIAA and HVA obtained over the plasma probenecid concentration interval of 200-400 micrograms mL-1 could be that the levels were reached when there was complete inhibition of active transport, and when the rate of formation of the metabolites equalled the rate of elimination by alternative routes i.e. bulk flow and diffusion. Therefore when probenecid is used to inhibit the active transport of acid monoamine metabolites across the blood-brain barrier, its plasma concentration should be within the range of 200-400 micrograms mL-1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain Chemistry / drug effects*
  • Homovanillic Acid / metabolism*
  • Hydroxyindoleacetic Acid / metabolism*
  • Infusions, Intravenous
  • Male
  • Probenecid / administration & dosage
  • Probenecid / pharmacology*
  • Rats
  • Rats, Inbred Strains


  • Hydroxyindoleacetic Acid
  • Probenecid
  • Homovanillic Acid