Novel 5-HT1 autoreceptor ligands based on the N-4-aryl-piperazinyl-N′-ethyl-5, 6, 7, 8- tetrahydropyrido [4′, 3′: 4, 5] thieno [2, 3-d] pyrimidin-4 (3H)-one core are described. Aiming at antidepressants with a novel mode of action our objective was to identify potent antagonists showing balanced affinities and high selectivity for the 5-HT1A and 5-HT1B receptors. Strategies for the development of dual 5-HT1A and 5-HT1B antagonists based ...