Portal de Periódicos da CAPES

Somatostatin Analogues: Mechanisms of Action

1993; Springer Science+Business Media; Linguagem: Inglês

10.1007/978-3-642-84956-5_1

2197-6767

H. Parmar, Rachel Phillips, Stafford L. Lightman,

Pancreatic function and diabetes

The structure of somatostatin was elucidated by Brazeau et al. in 1973 [13], and scientific work prior to and following the discovery of the structure of the peptide has accelerated at an ever-increasing pace. It has been noted that it can act as an almost universal chalone (a secretion that depresses and inhibits the activity of various intracellular processes). For many years the concept of the existence of an inhibitory hormone for the gastrointestinal tract had been established, and this had been recognised and discussed many times even prior to the discovery of somatostatin. Further research has established that there are several related peptides which make up a family that includes the originally identified 14 amino acid peptide designated somatostatin 14 (SS14) [10], Somatostatin 28 (SS28) [34, 41], several species-specific variants, and even larger pro-hormone forms which are secreted in different parts of the body. Therefore, the singular name “somatostatin” is inappropriate, but is widely used and accepted to include all the variants. These peptides are widely distributed beyond the confines of the growth hormone (GH) regulatory system and are found in the gut, in various exocrine and endocrine glands throughout the body, and in most organs. They display highly selective and sometimes specific functions depending upon the anatomical site of localisation and the local physiological environment. For example, SS28 is found among other sites in the central nervous system and has a more potent neuromodulator action than SS14. Furthermore, it has been demonstrated that SS28 has a greater suppressive effect on insulin secretion than SS14 in the pancreas [68]. This differential response seems to depend on the actual size of the peptide, the specific binding of the peptide to the different high-capacity and low-capacity somatostatin receptors discovered, and the latent potency of the peptide.