Search

Aim: To examine the effects of pancreatic rest, stimulation and rest/stimulation on the natural course of recovery after acute pancreatitis., Methods: Acute hemorrhagic pancreatitis (AP) was induced in male rats by intraductal infusion of 40 μL/100 g body weight of 3% sodium taurocholate. All rats took food ad libitum. At 24 h after induction of AP, rats were divided into four groups: control (AP-C), pancreas rest (AP-R), stimulation (AP-S), and rest/stimulation (AP-R/S). Rats in the AP-C, AP-R and AP-S groups received oral administration of 2 mL/kg body weight saline, cholecystokinin (CCK)-1 receptor antagonist, and endogenous CCK release stimulant, respectively, twice daily for 10 d, while those in the AP-R/S group received twice daily CCK-1 receptor antagonist for the first 5 d followed by twice daily CCK release stimulant for 5 d. Rats without any treatment were used as control group (Control). Biochemical and histological changes in the pancreas, and secretory function were evaluated on day 12 at 24 h after the last treatment., Results: Feeding ad libitum (AP-C) delayed biochemical, histological and functional recovery from AP. In AP-C rats, bombesin-stimulated pancreatic secretory function and HOMA-β-cell score were significantly lower than those in other groups of rats. In AP-R rats, protein per DNA ratio and pancreatic exocrine secretory function were significantly low compared with those in Control rats. In AP-S and AP-R/S rats, the above parameters recovered to the Control levels. Bombesin-stimulated pancreatic exocrine response in AP-R/S rats was higher than in AP-S rats and almost returned to control levels. In the pancreas of AP-C rats, destruction of pancreatic acini, marked infiltration of inflammatory cells, and strong expression of α-smooth muscle actin, tumor necrosis factor-α and interleukin-1β were seen. Pancreatic rest reversed these histological alterations, but not atrophy of pancreatic acini and mild infiltration of inflammatory cells. In AP-S and AP-R/S rats, the pancreas showed almost normal architecture., Conclusion: The favorable treatment strategy for AP is to keep the pancreas at rest during an early stage followed by pancreatic stimulation by promoting endogenous CCK release.

Recent studies demonstrated that cholecystokinin (CCK) at physiological levels stimulates pancreatic enzyme secretion via a capsaicin-sensitive afferent vagal pathway. This study examined whether chemical ablation of afferent vagal fibers influences pancreatic growth and secretion in rats. Bilateral subdiaphragmatic vagal trunks were exposed, and capsaicin solution was applied. Pancreatic wet weight and pancreatic secretion and growth in response to endogenous and exogenous CCK were examined 7 days after capsaicin treatment. Perivagal application of capsaicin increased plasma CCK levels and significantly increased pancreatic wet weight compared with those in the control rats. Oral administration of CCK-1 receptor antagonist loxiglumide prevented the increase in pancreatic wet weight after capsaicin treatment. In addition, continuous intraduodenal infusion of trypsin prevented the increase in plasma CCK levels and pancreatic wet weight after capsaicin treatment. There were no significant differences in the expression levels of CCK-1 receptor mRNA and protein in the pancreas in capsaicin-treated and control rats. Intraduodenal administration of camostat or intravenous infusion of CCK-8 stimulated pancreatic secretion in control rats but not in capsaicin-treated rats. In contrast, repeated oral administrations of camostat or intraperitoneal injections of CCK-8 significantly increased pancreatic wet weight in both capsaicin-treated and control rats. Present results suggest that perivagal application of capsaicin stimulates pancreatic growth via an increase in endogenous CCK and that exogenous and endogenous CCK stimulate pancreatic growth not via vagal afferent fibers but directly in rats.

Presents information on a study which examined the effect of troglitazone treatment on pancreatic growth in the cholecystokinin-A receptor-deficient subject. Methodology; Results of the study; Discussion.

Abstract Cholecystokinin (CCK) is a major gastrointestinal hormone that plays an important role in stimulation of pancreatic secretion and gall-bladder contraction, regulation of gastrointestinal motility and induction of satiety. Ingestion of fat and protein induces significant increases in plasma CCK. Intraluminal mediators of CCK secretion, luminal CCK releasing factor and diazepam-binding inhibitor, were purified from rat intestinal secretion. These CCK-releasing factors (RF) are secreted tonically by the small intestine and stimulate CCK release. Another kind of CCK-RF named ‘monitor peptide’ was purified from the rat pancreatic juice that stimulates CCK secretion when introduced into rat intestine. Bile exclusion from the duodenum causes an increase in basal CCK and enhances stimulated plasma CCK release, and bile salt replacement reverses these effects. Thus, the CCK-RF are spontaneously secreted into the intestinal lumen in humans, while the CCK-producing cells are under constant suppression by intraduodenal bile acids. In acute pancreatitis, plasma CCK levels are high in patients with gallstone pancreatitis, but not in patients with pancreatitis from other causes, such as alcoholic and idiopathic pancreatitis. A transient disturbance of bile flow into the duodenum by stones or oedema of the pancreas together with impairment of pancreatic exocrine function might cause the increase in plasma CCK release in gallstone pancreatitis. Patients with chronic pancreatitis with mild to moderate impairment of exocrine function and abdominal pain, had significantly higher plasma CCK concentrations, whereas patients with pancreatic insufficiency had a significantly lower plasma CCK response to a test meal than the healthy subjects. The increased CCK may further aggravate pancreatitis and worsen the prognosis of pancreatitis by stimulating the injured pancreas, resulting in the vicious circle via endogenous CCK release. The CCK-A receptor antagonist might be therapeutically useful in acute pancreatitis by stopping the vicious circle. [ABSTRACT FROM AUTHOR]

Recent studies in genetically obese and diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats suggest defects of cholecystokinin (CCK)-A receptor gene expression and CCK-A receptor-mediated biological functions such as pancreatic juice, protein, and gastric acid secretion. The present studies were undertaken to further examine CCK-A receptor gene expression and CCK-A receptor-mediated biological functions in the pancreas, stomach, and brain of OLETF rats. Expression of the CCK-A receptor gene could not be detected in the stomach, pancreas and brain by the reverse-transcription polymerase chain reaction (RT-PCR) method and Southern blotting of the PCR products. Southern blot analysis of genomic DNA from OLETF and control Long-Evans Tokushima Otsuka (LETO) rats with CCK-A receptor fragment as a probe revealed different restriction bands. Expression of the CCK-B receptor gene was observed in the stomach, pancreas, and brain in both OLETF and LETO rats by the RT-PCR method, with expression of the CCK-B receptor gene markedly enhanced in OLETF rats compared with that in LETO rats. Consistent with the defect of CCK-A receptor gene expression, CCK-A receptor-mediated biological functions were not observed in these organs. Perfused exocrine and endocrine pancreas of OLETF rats were insensitive to CCK stimulation but not to carbamylcholine stimulation. Basal gastric acid and pepsinogen secretions in OLETF rats were higher than in LETO rats. OLETF rats showed a significantly higher average daily food intake, gained body weight faster, and were heavier than LETO rats. The present study confirmed that OLETF rats have CCK-A receptor gene anomalies and demonstrated deficient CCK-A receptor-mediated biological function in the pancreas, stomach, and brain. [ABSTRACT FROM AUTHOR]

Discusses the loss of sensitivity to cholecystokinin (CCK) stimulation of isolated pancreatic acini from genetically diabetic rats. Responsiveness to fluoride; Selective defect in the binding of CCK to its receptors on the acinar cell surface; Enzyme activities in serum and pancreas; Response to secretagogues.

Editorial. Provides details on the interaction among fat, lipase, cholecystokinin (CCK) and gastric emptying. Stimulator of CCK release; Feedback system made possible by the interaction of CCK and gastric emptying; Effect of triglycerides on plasma CCK levels and gastric emptying in young and elderly subjects in the presence or absence of lipase.

Abstract: Background/aim: The renin–angiotensin system (RAS) exists in the pancreas, but the role of RAS in the regulation of pancreatic exocrine secretion under physiological conditions has been little known. The present study addressed the RAS''s effect on the pancreatic secretion by using valsartan, a specific angiotensin II receptor blocker, in conscious rats. Method: Male Wistar rats prepared with pancreatic, biliary, duodenal and jugular vein cannulas were used. To examine the role of RAS in the pancreatic secretion, valsartan at 1, 5, or 25mg/kg was administered into the duodenum via cannula, and volume of pancreatic juice and protein concentration were determined. In addition, to examine the role of RAS in hormone-stimulated pancreatic hypersecretion, pancreatic secretion was examined in response to stimulation of secretin or cholecystokinin after intraduodenal infusion of valsartan at 25mg/kg. Furthermore, to examine the mechanism of action of RAS on pancreatic secretion, intravenous infusion of atropine or perivagal application of capsaicin was conducted and then the pancreatic secretion was examined following intraduodenal infusion of valsartan at 25mg/kg. Results: Volume of pancreatic juice, but not protein output, significantly decreased after administration of valsartan. However, administration of valsartan did not exert significant effects on secretin- or cholesystokinin-stimulated pancreatic secretion. Treatment with atropine and perivagal application of capsaicin completely abolished the suppressive effect of valsartan on pancreatic juice secretion. Conclusion: Present results suggest that RAS plays a stimulatory role in pancreatic juice secretion via cholinergic afferent pathway without affecting protein secretion and hormonally stimulated pancreatic secretion under physiological conditions. [Copyright &y& Elsevier]