Hormonal and nonhormonal cytoprotective effect by somatostatins

Beside its known hormonal activity, somatostatin exerts cytoprotective action. Thus, its favorable effect on the course of experimental pancreatitis, liver and lung lesions, and gastric ulcerations cannot be explained solely on the basis of hormone-mediated mechanisms. Cytoprotection is only observed when somatostatin is administered prior to toxin exposure or tissue damage, and the structure/activity of the substance is important in determining this effect. Thus, the non-hormonal biological effects of somatostatin can be summarized as follows: (a) Natural somatostatin-14 has been shown, in addition to its full endocrine effect, to block the uptake of toxic substances into liver cells. (b) Analogues with superactive cytoprotection may be devoid of endocrine activity. In turn, this effect is commonly found in the low-molecular derivatives. (c) Although the mechanism leading to tissue protection has not been clarified, stabilisation of cell membranes may play a role as well as changes in the aminoacid sequence.