Somatostatin receptor type 2 antagonism improves glucagon and corticosterone counterregulatory responses to hypoglycemia in streptozotocin-induced diabetic rats

Diabetes. 2012 Jan;61(1):197-207. doi: 10.2337/db11-0690. Epub 2011 Nov 21.

Abstract

Diminished responsiveness to hypoglycemia contributes to defective counterregulation in diabetes. Pancreatic and/or circulating somatostatin are elevated in diabetes, which may inhibit counterregulatory hormone release during hypoglycemia. Thus, a selective somatostatin receptor type 2 antagonist (SSTR2a) should improve hormone counterregulation to hypoglycemia. Nondiabetic (N) and streptozotocin-induced diabetic (D) rats underwent 4-h infusion of saline or SSTR2a with insulin-induced hypoglycemia clamped at 2.5 ± 0.5 mmol/L. To evaluate the effect of the SSTR2a in the absence of hypoglycemia, rats underwent a 4-h infusion of saline (Ctrl:N, Ctrl:D) or SSTR2a (Ctrl:D+SSTR2a) only. The attenuated glucagon response to hypoglycemia in D (P < 0.0002) was fully restored by SSTR2a (P < 0.0001). Furthermore, the attenuated corticosterone response in D (P < 0.002) was also enhanced by SSTR2a (P < 0.05). In the absence of hypoglycemia, SSTR2a did not alter basal blood glucose levels. D exhibited 62% more pancreatic somatostatin than N after hypoglycemia. In N rats, SSTR2a did not augment the glucagon or corticosterone response to hypoglycemia. Thus, somatostatin may contribute to impaired glucagon responsiveness to hypoglycemia in diabetes. We demonstrate that SSTR2 antagonism enhances hypoglycemia-stimulated glucagon and corticosterone release in D but not in N rats. SSTR2 antagonism does not affect basal glycemia in D rats.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blood Glucose / drug effects
  • Blood Glucose / metabolism
  • Corticosterone / blood
  • Corticosterone / metabolism*
  • Cytoprotection / drug effects*
  • Cytoprotection / physiology
  • Diabetes Mellitus, Experimental / blood
  • Diabetes Mellitus, Experimental / chemically induced
  • Diabetes Mellitus, Experimental / complications
  • Diabetes Mellitus, Experimental / metabolism*
  • Glucagon / blood
  • Glucagon / metabolism*
  • Glucose / administration & dosage
  • Glucose / pharmacology
  • Hormone Antagonists / pharmacology*
  • Hypoglycemia / blood
  • Hypoglycemia / complications
  • Hypoglycemia / metabolism*
  • Male
  • Peptides, Cyclic / pharmacology
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Somatostatin / antagonists & inhibitors*
  • Streptozocin
  • Time Factors

Substances

  • Blood Glucose
  • Hormone Antagonists
  • PRL 2903
  • Peptides, Cyclic
  • Receptors, Somatostatin
  • Sstr2 protein, rat
  • Streptozocin
  • Glucagon
  • Glucose
  • Corticosterone