Chronic stress sensitizes rats to pancreatitis induced by cerulein: Role of TNF-α

Figure 1 Tumor necrosis factor-α disorganizes the actin cytoskeleton and reduces submaximal cholecystokinin-stimulated amylase secretion. A: Amylase secretion from pancreatic acini. Isolated pancreatic acini were stimulated with either the indicated concentrations of tumor necrosis factor-α (TNF-α) for 2 h, or 50 pmol/L cholecystokinin (CCK) for 1 h, or the indicated concentrations of TNF-α for 1 h followed by the indicated concentrations of TNF-α plus 50 pmol/L CCK for 1 h, or Krebs-Ringer-HEPES (KRH) (vehicle-control) for 2 h. Amylase secreted into the media was determined and expressed as a percentage of the total cellular amylase of the respective sample. Results correspond to the mean ± SE from four independent experiments, with samples performed in triplicate. ^aP < 0.05 vs KRH; ^cP < 0.05 vs CCK alone; B-F: Filamentous actin distribution; B-E: Confocal images of filamentous actin localization in pancreatic acinar cells. Isolated pancreatic acini were treated with either KRH for 2 h (B), or 10 ng/mL TNF-α for 2 h (C), or 50 pmol/L CCK for 1 h (D), or 10 ng/mL TNF-α for 1 h followed by 10 ng/mL TNF-α plus 50 pmol/L CCK for 1 h (E). Fixed and permeabilized acini were stained with Alexa Fluor 488-phalloidin. Arrows show apical lumens, and arrowheads show basolateral membranes. These are representative images selected from three independent experiments, with samples performed in triplicate; F: Quantification of filamentous actin distribution. Areas of the apical and basolateral membranes in acinar cells treated as in B-E were delineated and the fluorescence intensity was determined. Sixty cells from three independent experiments were analyzed per condition. Values correspond to the intensity in the basolateral area vs the apical area, and are expressed as the mean ± SE. ^aP < 0.05 vs KRH; ^cP < 0.05 vs TNF-α alone.