-transparent.png){kind=logo}
Somatostatin increases absorption of electrolytes and inhibits diarrhea in patients with endocrine tumors and short bowel syndrome. In an attempt to develop a gut-specific somatostatin analog, each amino acid in the somatostatin molecule was replaced with L-alanine, deleted, or substituted with its D-isomer. The potency of each analog to stimulate ion transport in the rabbit ileum was then determined using the modified Ussing chamber technique. The results were compared to the ability of each analog to inhibit the stimulated release of growth hormone from cultured rat anterior pituitary cells and to inhibit the arginine-stimulated release of insulin and glucagon in the rat in vivo. Analogs that showed gut selectivity were then tested for their ion transport properties in the rat colon. RESULTS (a) Substitution with L-alanine or deletion of the amino acid at position 6, 7, 8, or 9 and deletion of Threonine(10)-produced analogs with significantly reduced ion transport properties to <4% of somatostatin's action. The substitution also markedly reduced the ability of the compounds to inhibit the release of growth hormone, insulin, and glucagon. (b) Selectivity of intestinal ion transport was achieved by any one of the following alterations: L-alanine substitution at Phenylalanine(11), deletion of Phenylalanine(11), substitution with D-lysine at Lysine(4), or substitution with L-alanine at Lysine(4). These compounds had intestinal ion transport properties of 52, 34, 139, and 94%, respectively, while demonstrating little or no inhibition of growth hormone, insulin or glucagon release. CONCLUSIONS (a) Phenylalanine(6), Phenylalanine(7), Tryptophan(8), and Lysine(9) are required for the ion transport and other biologic actions of somatostatin, whereas Threonine(10) serves as an essential spacer. (b) Alteration at Phenylalanine(11) or Lysine(4) yields analogs that are selective for ion transport in the rabbit ileum and rat colon. These findings should be taken into consideration when developing a gut-specific somatostatin analog that can be useful in the treatment of diarrhea.
L E Rosenthal, and
D J Yamashiro, and
J Rivier, and
W Vale, and
M Brown, and
K Dharmsathaphorn
January 1984,
Gastroenterology,
L E Rosenthal, and
D J Yamashiro, and
J Rivier, and
W Vale, and
M Brown, and
K Dharmsathaphorn
January 1988,
Hormone research,
L E Rosenthal, and
D J Yamashiro, and
J Rivier, and
W Vale, and
M Brown, and
K Dharmsathaphorn
November 2013,
Molecules (Basel, Switzerland),
L E Rosenthal, and
D J Yamashiro, and
J Rivier, and
W Vale, and
M Brown, and
K Dharmsathaphorn
January 1987,
Journal of cardiovascular pharmacology,
L E Rosenthal, and
D J Yamashiro, and
J Rivier, and
W Vale, and
M Brown, and
K Dharmsathaphorn
May 1988,
Brain research,
L E Rosenthal, and
D J Yamashiro, and
J Rivier, and
W Vale, and
M Brown, and
K Dharmsathaphorn
June 1991,
The Journal of antibiotics,
L E Rosenthal, and
D J Yamashiro, and
J Rivier, and
W Vale, and
M Brown, and
K Dharmsathaphorn
January 1976,
Pharmacology & therapeutics. Part B: General & systematic pharmacology,
L E Rosenthal, and
D J Yamashiro, and
J Rivier, and
W Vale, and
M Brown, and
K Dharmsathaphorn
September 1976,
The Journal of antibiotics,
L E Rosenthal, and
D J Yamashiro, and
J Rivier, and
W Vale, and
M Brown, and
K Dharmsathaphorn
January 2001,
Journal of enzyme inhibition,
L E Rosenthal, and
D J Yamashiro, and
J Rivier, and
W Vale, and
M Brown, and
K Dharmsathaphorn
January 1987,
NIDA research monograph,
