Merck Sharp & Dohme Research Laboratories, The Neuroscience Research Centre, Terlings Park, Eastwick Road, Harlow, Essex CM20 2QR, UK. mark_chambers@merck.com
Nonselective inverse agonists at the benzodiazepine binding site on the GABA-A chloride ion channel enhance cognitive performance in animals but cannot be used in the treatment of cognitive disorders because of anxiogenic and convulsant side effects. We have identified a novel series of GABA-A alpha5 receptor ligands during our search for alpha5 receptor inverse agonists as potential cognition enhancers. In particular, 6,6-dimethyl-3-(2-hydroxyethyl)thio-1-(thiazol-2-yl)-6,7-dihydro-2-benzothiophen-4(5H)-one (26) has been identified as a functionally selective GABA-A alpha5 inverse agonist.