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Insulin secretion is inhibited by subtype five somatostatin receptor in the mouse
S P Fagan1, A Azizzadeh, S Moldovan
1Department of Surgery, Baylor College of Medicine, Houston, Texas, USA.
Background:
Recently five somatostatin receptor subtypes (SSTRs) were cloned, allowing the development of highly specific agonists to these SSTRs. Previous studies have shown a species specificity phenomenon with respect to the inhibition of insulin secretion by these selective agonists. This study was undertaken to determine which SSTR (2 or 5) is responsible for the inhibitory effect of somatostatin on glucose-stimulated mouse insulin secretion.
Methods:
Intact mouse islets (n = 10) were stimulated with D-glucose in the presence or absence of receptor-specific somatostatin agonists.
Results:
D-glucose (16.7 mmol/L) augmented insulin secretion by 158% above that seen with 3.9 mmol/L D-glucose. In the presence of DC 32-92 (SSTR5) selective agonist, D-glucose (16.7 mmol/L) augmented insulin secretion by 64% above that seen with 3.9 mmol/L D-glucose. The presence of SSTR 5 selective agonist resulted in a significant (P < .05) inhibition of glucose-stimulated insulin secretion. The identification of SSTR5 within the mouse pancreas was established by reverse transcriptase polymerase chain reaction and confirmed by Southern blot analysis.
Conclusions:
These results suggest that the inhibitory effect of somatostatin on insulin secretion is mediated through the subtype 5 receptor within the mouse islet.