Endogenous systems which regulate the stress response are interesting targets for the development of novel treatments for stress-related disorders. In this PhD research we focus on the neuromedin U (NMU) system. Our running hypothesis is that reducing the central activity of NMU could be beneficial for the treatment of stress-related disorders. Peptidergic NMU-analogs are synthesized in a first part of the project. Secondly, these novel ligands will be screened in vitro for their affinity and activity on both NMU-receptors. Finally, the most optimal peptides will be evaluated in in vivo mouse models for stress-related disorders.