Somatostatin analogs inhibit somatostatin release

Area of Science:

• Endocrinology
• Pancreatic Physiology

Background:

• Somatostatin regulates various pancreatic functions, including hormone secretion.
• The potential for somatostatin to inhibit its own secretion (autoinhibition) is not fully understood.

Purpose of the Study:

• To investigate whether somatostatin inhibits its own secretion from the pancreas, similar to insulin.
• To explore the direct effects of somatostatin analogs on somatostatin-like immunoreactivity (SLI) release.

Main Methods:

• Utilized a nonrecirculating perfusion system in an isolated dog pancreaticoduodenal preparation.
• Administered nonimmunoreactive somatostatin analogs ([D-Trp8-D-Cys14]somatostatin and des Asn5-[D-Trp8]somatostatin) at varying concentrations.
• Measured somatostatin-like immunoreactivity (SLI), insulin, and glucagon levels in response to stimuli and analog perfusion.

Main Results:

• [D-Trp8-D-Cys14]somatostatin blocked SLI responses to cholecystokinin and arginine, with SLI increasing upon analog removal.
• Des Asn5-[D-Trp8]somatostatin (0.1 ng/ml) reduced SLI without significantly affecting glucagon.
• Des Asn5-[D-Trp8]somatostatin (1 ng/ml) significantly inhibited SLI, insulin, and glucagon release.
• Glucagon perfusion did not overcome the inhibitory effects of des Asn5-[D-Trp8]somatostatin on SLI and insulin release.

Conclusions:

• Somatostatin analogs exert a direct inhibitory effect on SLI release.
• The findings support the hypothesis that native somatostatin may possess a self-inhibiting action on its pancreatic secretion.