Endogenous somatostatin inhibits interaction of insulin and cholecystokinin on exocrine secretion of isolated, perfused rat pancreas.
BACKGROUND
Although somatostatin inhibits pancreatic exocrine secretion, the inhibitory mechanism of endogenous somatostatin is not clearly understood.


OBJECTIVE
To investigate the effect of endogenous somatostatin on the interaction between endogenous insulin and exogenous cholecystokinin (CCK) in exocrine secretion of the totally isolated, perfused rat pancreas.


METHODS
Endogenous releases of somatostatin and insulin were induced by 18 mM glucose. Streptozotocin (75 mg/kg) or cysteamine (300 mg/kg) was injected into rats 24 hours before the experiment to deplete insulin or somatostatin in the pancreas.


RESULTS
Glucose (18 mM) enhanced CCK (10 pM)-stimulated secretions of fluid and amylase in the normal pancreas, which was further elevated by a somatostatin antagonist. Exogenous insulin (100 nM) also enhanced CCK-stimulated secretions in the streptozotocin-treated pancreas, which was also markedly increased by the somatostatin antagonist. The glucose (18 mM)-enhanced CCK-stimulated secretions were much higher in the cysteamine-treated pancreas than in the normal pancreas, which was dose-dependently reduced by exogenous somatostatin (30, 100 pM). However, endogenous or exogenous somatostatin did not modify the pancreatic responses to CCK alone.


CONCLUSIONS
Endogenous somatostatin inhibits the interaction of endogenous insulin and CCK on pancreatic exocrine secretion in the rat rather than reducing the action of CCK alone or endogenous release of insulin.
Park
Hyung Seo
HS
Department of Physiology, College of Medicine, Konyang University, Nonsan, Chungnam-Do, Korea.
Yoon
Hyo Seop
HS
Park
Yong Deuk
YD
Cui
Zheng Yun
ZY
Lee
Yun Lyul
YL
Park
Hyoung Jin
HJ
D000818:Animals; D002766:Cholecystokinin / Q000494:pharmacology*; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D004347:Drug Interactions; D005947:Glucose / Q000494:pharmacology; D006727:Hormone Antagonists / Q000494:pharmacology; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology*; D008297:Male; D010179:Pancreas / Q000378:metabolism*; D010477:Perfusion; D051381:Rats; D017207:Rats, Sprague-Dawley; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology
D006727:Hormone Antagonists; D007004:Hypoglycemic Agents; D007328:Insulin; D013004:Somatostatin; C043820:cyclo(7-aminoheptanoylphenylalanyl-tryptophyl-lysyl-benzylthreonyl); D002766:Cholecystokinin; D005947:Glucose