Exocrine Pancreatic Function In Rats Research Articles

Variation in exocrine pancreatic secretion in rats due to different commercial diets

The diet fed to laboratory animals is one of many variables that can confound research results. The authors investigated the effect of the composition of commercial standard rodent diets on exocrine pancreatic function in rats. They compared two widely used commercial animal diets and found that diet composition greatly influences pancreatic secretion. Their results indicate that commercial diets should conform to the recommended composition requirements to avoid alterations in physiological functions that would eventually affect the results of biomedical research and that investigators should be keenly aware of the composition of the diets being fed to their animals.

Exocrine pancreatic function in rats after acute pancreatitis.

The present studies were performed to evaluate pancreatic exocrine function in rats during the early stage of acute pancreatitis in two models: one is edematous pancreatitis induced by four subcutaneous injections of 20 micrograms/kg body weight of cerulein at hourly intervals and the other is hemorrhagic pancreatitis induced by retrograde infusion of 0.4 ml/kg body weight of 3% sodium taurocholate (NaTc) into the pancreatic duct. Secretory studies were performed in vivo under urethane anesthesia at various times after induction of acute pancreatitis. Basal pancreatic fluid secretion was significantly elevated after induction of acute pancreatitis in both the cerulein and the NaTc models, reaching the peak level on postpancreatitic days 1 and 3, respectively. In both models of rats, a stepwise increasing dose of cerulein was unable to cause a further increase in fluid secretion above the basal level, whereas it caused a dose-dependent increase in protein output in both models, although the responsiveness and the sensitivity were markedly reduced compared with the controls. In contrast to cerulein, secretin caused a dose-dependent increase in fluid secretion in both models of pancreatitis. In cerulein-induced postpancreatitic rats, secretin also caused a dose-dependent increase in protein output and bicarbonate concentration, but it had only a small effect at certain doses in NaTc-induced postpancreatitic rats. These results indicate that basal pancreatic fluid secretion was greatly increased but the secretory response to cerulein stimulation was reduced in acute pancreatitis early after the onset but was not reduced to secretin stimulation and that protein output and bicarbonate concentration were reduced depending on the severity of pancreatitis (NaTc-pancreatitis > cerulein-pancreatitis.

Altered exocrine pancreatic function in rats treated with nicotine

The present study investigates the effects of nicotine treatment on exocrine pancreatic function. Adult male, Sprague-Dawley rats received nicotine via a time-release pellet, at a rate of 1.65 μg/min for 3 weeks. At the end of the experimental period, it was observed that although nicotine did not affect final body or pancreatic weight, the activities of amylase, trypsin, and chymotrypsin in pancreatic homogenates from nicotine-treated rats were 51, 29, and 35% higher, respectively, than in controls. Levels of immunoreactive cationic trypsin(ogen) were significantly higher in pancreatic homogenates and serum from nicotine-treated rats as compared with controls. In addition, concentrations of mRNA, encoding for pancreatic amylase, were higher in pancreatic homogenates from the nicotine-treated rats than in controls. In dispersed pancreatic acini isolated from nicotine-treated rats, basal secretion of amylase, trypsinogen, and chymotrypsinogen was 50% higher than controls and enzyme release following CCK-8 (100 p m), secretin (1 μ m), and carbachol (7.5 μ m) stimulation was also significantly higher. These dat indicate that nicotine treatment, at levels comparable to those expected in moderate cigarette smokers, increases the content of digestive enzymes in rat pancreas, as well as their basal and secretagogue-induced release.

Exocrine pancreatic function in rats after acute trypsin inhibitor treatment.

A single oral dose of synthetic trypsin inhibitor (TI, 20 mg/100 g) was given to rats by orogastric tube 6, 12, 18, or 24 hr before the removal of the pancreas and the preparation of isolated perfused pancreas. TI treatment induced no significant changes in body weight and total amount of DNA content in the pancreas, but pancreatic wet weight, total pancreatic protein and amylase, and the concentration of total protein and amylase relative to DNA were significantly decreased at 6 or 12 hr posttreatment, with a partial return toward control values at 18-24 hr after TI treatment. In isolated perfused pancreas, basal amylase output was similar in the control and in all 4 groups of TI-pretreated rats, while basal rate of flow of pancreatic juice was significantly increased at 12-24 hr posttreatment. Caerulein (0.1 ng/ml; 64 pM) stimulated pancreatic juice flow was greatly increased in rats pretreated with TI 12-24 hr earlier. In contrast, caerulein-stimulated amylase output was significantly lower in TI-pretreated groups compared with the control. However, when amylase output was related to the total content in the pancreas, the secretory responsiveness for amylase release was significantly higher in rats at 6-18 hr posttreatment compared with the control. The present study indicates that a single oral administration of TI modulates biological response to caerulein in the isolated perfused pancreas. The enhanced responsiveness of amylase release to subsequent stimulation is seen in early periods, while that of pancreatic juice flow is observed in late periods.