Inhibitory effect of somatostatin on cholecystokinin release is independent of luminal cholecystokinin-releasing factor content in conscious rats.
BACKGROUND
Exclusion of bile-pancreatic juice from the intestine increases pancreatic secretion via cholecystokinin (CCK) release in conscious rats. Luminal CCK-releasing factor (LCRF), purified from rat intestinal secretions, is an intraluminal regulator of CCK secretion during bile-pancreatic juice diversion.


OBJECTIVE
Because somatostatin is a potent inhibitor of CCK release and pancreatic secretion, the inhibitory effect of somatostatin on LCRF was examined.


METHODS
Rats were prepared with bile and pancreatic cannulae and two duodenal cannulae and with an external jugular vein cannula. The experiments were conducted without anesthesia. After 1.5-hour basal collection of pancreatic juice with bile-pancreatic juice return, bile-pancreatic juice was diverted for 2 hours, during which time somatostatin (2, 10 nmol/kg/h) was infused intravenously. The rats were killed before and 1 and 2 hours after bile-pancreatic juice diversion. To examine the effect of luminal somatostatin, 50 or 200 nmol/kg/h of somatostatin was infused into the duodenum. The plasma CCK and luminal content of LCRF were measured by specific radioimmunoassays.


RESULTS
Bile-pancreatic juice diversion significantly increased pancreatic secretion, plasma CCK, and LCRF levels. Intravenous infusion of somatostatin inhibited CCK release and pancreatic secretion, but not LCRF content. Luminal administration of somatostatin did not show any effect.


CONCLUSIONS
Inhibitory effect of circulating somatostatin on CCK release and pancreatic secretion is independent of LCRF content.
Miyasaka
K
K
Department of Clinical Physiology, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashiku, Tokyo-173-0015, Japan. miyasaka@tmig.or.jp
Masuda
M
M
Kanai
S
S
Ohta
M
M
Suzuki
S
S
Tateishi
K
K
Funakoshi
A
A
D000818:Animals; D001646:Bile / Q000502:physiology; D015904:Biliopancreatic Diversion; D002766:Cholecystokinin / Q000097:blood / Q000378:metabolism*; D004386:Duodenum / Q000187:drug effects; D006133:Growth Substances / Q000032:analysis / Q000378:metabolism; D007262:Infusions, Intravenous; D036341:Intercellular Signaling Peptides and Proteins; D007422:Intestines / Q000737:chemistry; D008297:Male; D010179:Pancreas / Q000378:metabolism; D010189:Pancreatic Juice / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D013004:Somatostatin / Q000008:administration & dosage / Q000032:analysis / Q000494:pharmacology*; D014359:Trypsin Inhibitor, Kazal Pancreatic
D006133:Growth Substances; D036341:Intercellular Signaling Peptides and Proteins; C504705:Spink1 protein, rat; D014359:Trypsin Inhibitor, Kazal Pancreatic; D013004:Somatostatin; D002766:Cholecystokinin