Effects of secretin and caerulein on enzymes of cultured pancreatic acinar cells

Co-operative effects of angiotensin II and caerulein in NFκB activation in pancreatic acinar cells in vitro

Angiotensin II is a vasoactive peptide that controls blood pressure and homeostasis. Emerging evidence shows that locally generated angiotensin II plays a crucial role in normal physiology, as well as pathophysiological conditions such as pancreatitis. We recently reported that angiotensin II activates pancreatic NFκB in obstructive pancreatitis. However, the specific cell type responsible for this activation remains unclear. In this study, we investigated whether pancreatic acinar cells respond to angiotensin II. These cells are the most abundant pancreatic cells and the most vulnerable to pancreatitis. Pancreatic acinar AR42J cells were used as an in vitro model of pancreatic inflammation. Our results demonstrated that treatment with caerulein, a cholecystokinin receptor agonist, induced hypersecretion and NFκB activation, as demonstrated by elevated amylase secretion and degradation of inhibitor of NFκB (IκBβ). Angiotensin II, either alone or in combination with caerulein, augmented IκBβ degradation. Pre-treatment with losartan, an antagonist of the angiotensin type I (AT₁) receptor, abolished NFκB activation by angiotensin II and caerulein in a dose-dependent manner. Treatment with PD123319, a blocker of the angiotensin type II (AT₂) receptor, enhanced the activation of NFκB by angiotensin II and caerulein. Preliminary data further demonstrated that angiotensin II could extend caerulein-induced ERK1/2 activation in acinar cells. These results indicated that inflammation triggered by hyperstimulation of pancreatic acinar cells is enhanced by angiotensin II, via the AT₁ receptor. In contrast, stimulation of the AT₂ receptor protects against caerulein-induced NFκB activation. The differential roles of the AT₁ and AT₂ receptors might be useful in developing potential therapies for pancreatic inflammation.

Defatted bovine colostrum-supplemented diet around weaning improves exocrine pancreatic secretion by means of volume, digestive enzymes, and antibacterial activity

OBJECTIVES

Exocrine pancreatic secretion contributes to limit pathogenic bacteria-associated diarrhea. Bovine colostrum, used in the treatment of diarrhea, reduces symptoms originating from gut pathogenic bacteria overgrowth. We hypothesized that bovine colostrum may stimulate the exocrine pancreatic secretion.

METHODS

Eighteen piglets fitted with 2 permanent catheters (for pancreatic juice collection and reintroduction) were allocated to 1 of the following 2 dietary treatments for 5 days: a control diet or a diet supplemented with defatted bovine colostrum. Pancreatic juice was collected daily, and digestive enzyme activities and antibacterial activity were determined.

RESULTS

The prandial pancreatic juice outflow, the basal and prandial lipase output, and the basal secretion of the antibacterial activity were, respectively, 60% (P = 0.08), 154% (P = 0.08), 92% (P = 0.06), and 72% (P < 0.05) higher in piglets fed a diet supplemented with defatted bovine colostrum.

CONCLUSIONS

With defatted bovine colostrum, the increased antibacterial activity secretion against Escherichia coli may limit pathogenic bacteria overgrowth of the gut and reduce diarrheal episodes. The role of secretin in the increased pancreatic juice flow and lipase secretion was considered.

Preservation studies using acinar cell cultures of the pancreas: stimulation of amylase/lipase release before and after hypoxic stress

In clinical pancreas transplantation, postischemic (i. e. postpreservation) transplant pancreatitis is a major problem in some cases but also an interesting model of pancreatitis. In this study, the effect of simulated organ preservation of isolated acinar cells was evaluated as regards enzyme release (basic and cerulein-stimulated), using common preservation solutions as the incubation media. Primary pancreas acinar cell cultures were isolated from the pancreas of male Wistar rats using the modified method of Amsterdam and Jamieson. After resting the cells in culture flasks for 1 week, monolayer cultures were obtained. The basic enzyme release of amylase and lipase was measured as well as the effect of stimulation with cerulein (10(-8) M) and the effect of replacing the medium (without changing the consistence or temperature of the medium). In a second step, the cultures were incubated under conditions of cold hypoxia for 6 h (4 degrees C, P O2 < 0.1 mm Hg) using Krebs-Henseleit solution (KH), Euro-Collins solution (EC), HTK solution of Bretschneider (HTK) or University of Wisconsin solution (UW) as the incubation solution. After 6 h, the media were changed to warm normoxic KH, and a second stimulation test with cerulein was performed. The native microstructure of the cultures was observed as well. Enzyme release was elevated by a factor of 5 by stimulating the acinar cells with cerulein as well as by changing the medium in the experiments prior to the hypoxic incubation. After hypoxic incubation and change to KH, the morphology of the cultures was excellent, while the basic enzyme release was on a very low level, no matter which preservation solution was used during cold hypoxia. Stimulation with cerulein caused only minimal elevation of enzyme release during an observation period of 60 min. These observations show that cold storage in preservation solution provides maintenance of the cell morphology and sufficient down-regulation of enzyme release of pancreatic acinar cells. Thus, acinar cells alone do not seem to be the pacemaker of pancreatitis after organ preservation. The presented experimental model will be the subject of extended evaluation in the future.