Ghrelin and obestatin are both neuropeptides of the brain-gut axis, and the products of the same preproghrelin precursor gene, which have been isolated first from the GI tract. Ghrelin was shown to have multiple functions in appetite regulation, energy homeostasis, anxiety, depression and addictive behaviors. Obestatin is a 23 amino-acid peptide, originally described to antagonize the orexigenic effects of ghrelin. Later, it has also been shown to influence the function of endocrine pancreas and that of the adipose tissue, as well as thirst, sleep, thermoregulation and neurogenesis. However, there are only a few available data on behavioral effects of obestatin. The primary aim of our studies is therofore to investigate the effects of this peptide on anxiety and depression as well as to elucidate the delicate correlation between behavior and feeding.