[3H](-)Baclofen: an improved ligand for GABAB sites

Neuropharmacology. 1985 Mar;24(3):207-10. doi: 10.1016/0028-3908(85)90075-9.


[3H](-)Baclofen, the radiolabelled form of the active isomer of baclofen, has been used as a ligand for GABAB (gamma-aminobutyric acid) receptors on synaptic membranes from whole brain of rat. The pharmacological profile for displacement of this ligand was observed to be identical with that for the racemic ligand [3H](+/-)baclofen and [3H]GABA under conditions where GABAB, but not GABAA sites, were labelled. The displaceable (specific) portion of membrane-bound [3H](-)baclofen was 47.5 +/- 2.3% of the total which was twice that obtained previously with [3H](+/-)baclofen. Two binding components were observed with affinities of 19 and 304 nM and binding capacities of 0.37 and 1.58 pmol/mg protein respectively. It is suggested that [3H](-)baclofen is an improvement over the labelled racemic form and binds to the same sites. It should provide a more reliable tool for studying GABAB receptors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Baclofen*
  • Binding, Competitive / drug effects
  • Brain / metabolism
  • In Vitro Techniques
  • Kinetics
  • Ligands
  • Rats
  • Receptors, GABA-A / drug effects*
  • Stereoisomerism
  • Synaptic Membranes / metabolism


  • Ligands
  • Receptors, GABA-A
  • Baclofen