[Somatostatin - an important inhibitor of neuronal activity]

Many neuropeptides are involved in the processing of painful stimuli but a peptide of particular interest is somatostatin ("somatotropin release-inhibiting factor", SRIF). The physiological effects of SRIF are mediated by five SRIF receptors (sst receptors) which belong to the family of G protein-coupled receptors. All sst receptors inhibit the adenylate cyclase and open K(+)-channels, which leads to a decrease of neuronal excitability and decreases the secretion of neuropeptides or hormones. Many animal experimental data show that activation of sst receptors leads to a reduction of pain behaviour. Because SRIF also reduces important immune functions its effects on chronic inflammatory diseases, for example rheumatoid arthritis, have been extensively examined. Because SRIF only has a very short half-life, many SRIF analogues were synthesized. The first clinical study which documents an effectiveness of octreotide in the therapy of rheumatoid arthritis showed that this peptide has a significant therapeutic potential and opens new possibilities for the reduction of pain and inflammation.