[Development of sigma-receptor ligands and clinical trials]

There are at least two classes of sigma-receptors, termed sigma 1 and sigma 2. Recently, the sigma 1-receptor has been completely sequenced in different species. The amino acid sequences of the different purified proteins are highly homologous, but it shares no homology to know mammalian proteins. These results suggest that the sigma 1 receptor is a distinct entity from any often known receptors. sigma-Receptors are involved in many physiological functions. Therefore, sigma-ligands show many different pharmacological effects such as glucose utilization, neuroprotective, antipsychotic, antidepressive, anxiolytic, nootropic, antiepileptic, antiabuse, antitussive, antidiarrhea, anti-inflammatory, tear protein releasing stimulant and central anti-micturition reflex actions. These results suggest that sigma-receptors are very promising targets for the development of new drugs that have new mechanisms of action.