Binding characteristics of [3H]ucb 30889 to levetiracetam binding sites in rat brain

Eur J Pharmacol. 2003 Sep 30;478(1):1-9. doi: 10.1016/j.ejphar.2003.08.032.


Levetiracetam (2S-(2-oxo-1-pyrrolidinyl)butanamide, KEPPRA, a novel antiepileptic drug, has been shown to bind to a specific binding site located in brain (levetiracetam binding site [Eur. J. Pharmacol. 286 (1995) 137]). However, [3H]levetiracetam displayed only micromolar affinity for these sites making it an unsuitable probe for further characterization. The present study describes the binding properties of an analogue of levetiracetam: [3H]ucb 30889, (2S)-2-[4-(3-azidophenyl)-2-oxopyrrolidin-1-yl]butanamide. [3H]ucb 30889 binds reversibly to specific binding sites in rat brain. Kinetics at 4 degrees C were biphasic with half-times of association and dissociation of, respectively, 3 and 4 min for the fast component and 47 and 61 min for the slow component. [3H]ucb 30889 saturation binding curves were compatible with the labelling of a homogenous population of binding sites having a B(max) of 4496+/-790 fmol/mg protein (mean+/-S.D., n=5) and a K(d) of 62+/-20 nM (mean+/-S.D., n=5), a 20-fold increase in affinity compared to [3H]levetiracetam. Competition binding curves with ligands known to interact with levetiracetam binding sites and tissue distribution restricted to the brain indicated that [3H]ucb 30889 and [3H]levetiracetam bind to the same site. Although levetiracetam binding sites and GABA(A) (gamma-aminobutyric acid) receptors share some ligands such as pentobarbital and pentylenetetrazol, experiments performed with [35S]TBPS (tert-butyl-bicyclo[2.2.2]phosporothionate), a probe for the GABA(A) Cl(-) channel do not support the hypothesis that levetiracetam binding sites are part of the GABA(A) receptor complex. Preliminary autoradiography studies in rat brain revealed that [3H]ucb 30889 labels specific sites in all brain regions and that this binding is concentration-dependently displaced by levetiracetam.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Anticonvulsants / chemistry
  • Anticonvulsants / metabolism*
  • Azides / chemistry
  • Azides / metabolism*
  • Binding, Competitive / drug effects
  • Binding, Competitive / physiology
  • Brain / drug effects
  • Brain / metabolism*
  • Dose-Response Relationship, Drug
  • Levetiracetam
  • Male
  • Piracetam / analogs & derivatives
  • Piracetam / chemistry
  • Piracetam / metabolism*
  • Pyrrolidines / chemistry
  • Pyrrolidines / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Tissue Distribution / drug effects
  • Tissue Distribution / physiology
  • Tritium
  • gamma-Aminobutyric Acid / pharmacology


  • (2S)-2-(4-(3-azidophenyl)-2-oxopyrrolidin-1-yl)butanamide
  • Anticonvulsants
  • Azides
  • Pyrrolidines
  • Tritium
  • Levetiracetam
  • gamma-Aminobutyric Acid
  • Piracetam