Effect of secretin on pancreatic juice proteins in caerulein-induced acute pancreatitis in the rat

Administration of encapsulated L-tryptophan improves duodenal starch digestion and increases gastrointestinal hormones secretions in beef cattle

Objective

This study investigated the effects of oral administration of rumen-protected L-tryptophan (RPL-T) on duodenal starch digestion and gastrointestinal hormones (GIH) secretions using Hanwoo beef steers as the animal models.

Methods

Four steers (423±24 kg) fitted with ruminal and duodenal cannulas were employed in a crossover design replicated twice. Treatments were control (basal diet) and RPL-T (basal diet+191.1 mg/kg body weight [BW]) group. Blood and duodenal samples were collected to measure serum GIH levels and pancreatic α-amylase activity at day 0, 1, 3, and 5 (−30, 30, 90, 150, and 210 min) of the study. Samples from each segment of the gastrointestinal tract were collected via ruminal and duodenal cannulas and were used to determine soluble protein and the starch digestion rate at days 6 (−30, 180, 360, and 540 min) and 8 (−30, 90, 270, and 450 min) of the experiment.

Results

No significant difference in ruminal pH, NH₃-N, and total volatile fatty acid including the levels of acetate, propionate, butyrate, isobutyrate, valerate, isovalerate, and the acetate-to-propionate ratio was observed between groups (p>0.05). Crude protein uptake was higher and feces starch content was lower in RPL-T group than the control group (p<0.05). The D-glucose contents of feces in RPL-T group decreased at day 5 compared to those in the control group (p<0.05), however, no change was found at day 0, 1, or 3 compared to the control group (p>0.05). Serum cholecystokinin (CCK), melatonin, duodenal pancreatic α-amylase activity, and starch digestion were significantly higher in RPL-T group than the control group (p<0.05).

Conclusion

Taken together, oral administration of RPL-T at the rate of 191.1 mg/kg BW consistently increased CCK concentration, pancreatic α-amylase activity in duodenal fluids, and starch digestion rate in the small intestine and thus found to be beneficial.

Effect of Oral Administration of Intact Casein on Gastrointestinal Hormone Secretion and Pancreatic α-Amylase Activity in Korean Native Steer

Three Korean native steers (779±24 kg) fitted with duodenal cannulas were used in a 3×3 Latin square design to investigate the influence of oral administration of soluble proteins, intact casein (IC) and acid hydrolyzed casein (AHC), on gastrointestinal hormone (GIH) secretion in the blood and pancreatic α-amylase activity in the duodenum. Oral treatment consisted of a basic diet (control), IC (C+100% protein), or AHC (C+80% amino acid, 20% peptide) for 21 d. Blood and duodenum samples were collected for measurement of serum GI hormones, and pancreatic α-amylase activity was determined at 900, 1030, 1330, 1630, and 1930 h after feeding on d 21 of treatment. The levels of serum cholecystokinin (CCK) and secretin in the IC treatment group were higher compared to the other treatment groups (p<0.05). In addition to the changes in CCK and secretin levels upon IC treatment, the pancreatic α-amylase activity in the duodenum was higher in the IC group compared to the control diet group (p<0.05). The response of serum ghrelin to IC and AHC treatment was in accordance with the response of serum secretin. The level of peptide fragments flowing in the duodenum was higher in the IC treatment group than the other treatment groups (p<0.05). In conclusion, this study demonstrated that an increase in duodenal CCK and secretin upon IC oral administration increased pancreatic α-amylase secretion. In addition, ghrelin may be associated with GI hormone secretion in Korean native steers.

Effects of the cholecystokinin receptor antagonist L-364,718 on pancreatitis induced by a deficient in choline and supplemented with ethionine (CDE) diet in the rat

The role of cholecystokinin (CCK) in the development of a necrotizing acute pancreatitis induced by a diet deficient in choline and supplemented with ethionine (CDE) has been evaluated in the rat by using a potent CCK receptor antagonist L-364,718. Acute pancreatitis was induced by administration of CDE diet for 14 days. L-364,718 administration was carried out by subcutaneous injections at dose of 0.1 mg/kg/day. Pancreatic exocrine secretion (flow, protein, amylase and trypsin outputs) in resting and under infusion of 1.25 microgram/kg/h of CCK-8 were used to evaluate the pancreatic functionality. Others parameters (serum amylase, percentage fluid in pancreas, haematocrit and mortality) evaluated the severity of pancreatitis. L-364,718 slightly reduced the mortality and the increases of percentage of fluid accumulated in pancreas in CDE diet acute pancreatitis. Basal and CCK stimulated pancreatic secretion was significantly depressed 36 hours after L-364,718 treatment. A slight response to CCK was observed. Nevertheless it was lower than usually observed in control rats. Our results demonstrate that in the rat, chronic L-364,718 treatment did not completely restore pancreatic activity in acute pancreatitis induced by CDE diet. Hence CCK cannot be considered as the main factor involved in the development of this pancreatitis model.

Cerulein-induced acute pancreatitis in the rat. Study of pancreatic secretion and plasma VIP and secretin levels

A study was made with different doses of cerulein (2, 4, 10 and 20 micrograms/kg) administered subcutaneously to rats by four injections at intervals of 1 hr; the aim of this work was to study exocrine pancreatic secretion of the rat under cerulein-induced acute pancreatitis, analyzing enzyme and hydroelectrolyte secretion of pancreatic juice. A further aim was to study the relationship between the dose of cerulein and the plasma levels of peptides controlling hydroelectrolyte secretion of the pancreas, like secretin and vasoactive intestinal peptide (VIP). At the lowest dose schedule, the amounts of total protein and enzymes (amylase and trypsin) in pancreatic juice decreased significantly, plasma amylase increased, and the pancreas became edematous. Higher doses magnified these effects. By contrast, ductular function (flow and HCO3-) was well preserved in cerulein-treated rats, and this was probably due to the significant increase in plasma levels of immunoreactive secretin whereas VIP levels were unchanged. The secretin released by treatment with cerulein is able to palliate the lack of flow from acinar origin that is affected in the process of acute pancreatitis, being a beneficial response to the cerulein treatment.

Glucocorticoids effects on exocrine pancreatic secretion in caerulein-induced acute pancreatitis in the rat

The present work reports on exocrine pancreatic secretion in control rats, adrenalectomized rats and hydrocortisone-treated (10 mg/Kg/d) rats during 7 days, under normal conditions and after induction of acute pancreatitis with caerulein (20 micrograms/Kg) by 4 subcutaneous injections at hourly intervals. Pancreatic secretion was seen to be affected by the procedure of adrenalectomy, which led to a marked reduction in the secretion of proteins and amylase with respect to control values. This was probably due to the decrease occurring in the zymogen granules in the acinar cells of the exocrine pancreas, a phenomenon which also led to a decrease in pancreatic weight observed in these animals. Treatment with hydrocortisone induced a decrease in the secretion of proteins and amylase, as well as an increase in pancreatic weight. This agrees with the accepted hypothesis that large amounts glucocorticoids stimulate the synthesis and storage of proteins in the exocrine pancreas, reducing the secretory phase. The administration of high doses of caerulein under these conditions led to acute pancreatitis in the three groups of animals. This was paralleled by a dramatic decrease in protein and amylase secretion and by severe interstitial edema of the pancreas and by increases in serum amylase values. In the case of the animals treated previously with hydrocortisone, the latter were tripled with respect to the control animals. The conclusion is offered that since the storage of enzyme proteins is governed by glucocorticoids, which furthermore increase the sensitivity of the acinar cells to stimulation by secretagogues, the administration of these substances during the development of pancreatic lesions such as acute pancreatitis is highly compromising to the organism.

Caerulein-induced acute pancreatitis in the rat. Pancreatic secretory response to cholecystokinin

The response of pancreatic exocrine secretion to cholecystokinin (CCK), has been studied in experimental acute pancreatitis induced in rats by supramaximal doses of caerulein. Several doses of caerulein were used (4, 20 and 40 micrograms/Kg) and each one was administered by four subcutaneous injections over 3 h at hourly intervals. Pancreatic juice was collected 9 h after the first injection. The caerulein-treated animals showed a statistically significant increase in serum amylase levels. Secretory activity of ductular cells remained unchanged in all the caerulein-treated animals, but total protein and amylase secretion decreased significantly at all the caerulein doses used, both in resting conditions and under stimulation with CCK (1.25 micrograms/Kg/h). Despite this the acinar cells of rats treated with the lowest dose of caerulein retained a certain degree of secretory function since amylase activity in pancreatic juice was greater than in other groups of rats treated with higher doses of caerulein. Moreover, the percentage of increase observed in total protein and amylase in response to CCK respect to basal secretion is similar to that of the untreated animals. At higher doses (20 and 40 micrograms/Kg) the secretory capacity in response to CCK was inhibited. Therefore CCK administration in slight acute pancreatitis could be used as a therapy since it favours the secretion of pancreatic enzymes at percentual levels similar to those of the controls.