Mechanisms in endocrinology: Ghrelin: the differences between acyl- and des-acyl ghrelin.

Des-acyl ghrelin (DAG) is one of the three preproghrelin gene-encoded peptides. Compared with ghrelin and obestatin, it has not received the attention it deserves. DAG has long been considered an inert degradation product of acyl ghrelin (AG). Recent evidence, however, indicates that DAG behaves like a separate hormone. DAG can act together with AG, can antagonize AG, and seems to have AG-independent effects. Therefore, it is believed that DAG must activate its own receptor and that it may also interact with AG at this receptor. Of potential clinical importance is that an increasing number of studies suggest that DAG might be a functional inhibitor of ghrelin and that DAG can suppress ghrelin levels in humans. Therefore, DAG or DAG analogs might be good candidates for future treatment of metabolic disorders or other conditions in which antagonism of AG actions could be beneficial, such as diabetes, obesity, and Prader-Willi syndrome.