CHARACTERIZATION OF GABA(B) LIGANDS IN-VIVO

1. While GABA(B) antagonists have been examined in vitro, very few hav e been tested in vivo. A range of GABA(B) antagonists were tested agai nst baclofen-induced muscle relaxation and hypothermia. 2. The GABA(B) antagonists exhibited a range of in vivo activity profiles. 3. CGP 35 348 showed clear antagonist effects, while BPBA and 4-ABPA appeared to have agonist properties. 4. Phaclofen, 2-hydroxysaclofen, 3-APPA and 9G seemed to have little effect in this system at the doses tested. 5. Differences between in vivo and in vitro activity could be explained by differences in blood-brain barrier permeability, or possible differ ences in affinities for the sub-classes of GABA(B) receptors.