Alcohol feeding and lipopolysaccharide injection modulate apoptotic effectors in the rat pancreas in vivo

The purpose of this study was to determine if alcohol consumption and endotoxin injection change the rate of apoptosis in the pancreas. Rats were fed a Lieber-DeCarli diet for 14 weeks. At 14 weeks, the animals were injected with lipopolysaccharide (LPS) or saline and killed. The pancreata were resected and snap frozen. Apoptosis was detected by TUNEL assay. Caspase-3 activity, Bcl-2 (protein), and Fas ligand (mRNA) were assayed in pancreas extracts and oc-amylase in plasma. Alcohol feeding significantly decreased oc-amylase and caspase-3 activity, and significantly increased Bcl-2. LPS injection increased caspase-3 activity and decreased Bcl-2. Fas ligand mRNA was increased only in alcohol-fed, LPS-injected rats. TUNEL labeling was significantly increased only in alcohol-fed, LPS-injected rats. These data show that (a) long-term alcohol feeding suppresses apoptosis in the pancreas; (b) LPS increases the rate of apoptosis in the pancreas; (c) caspase-3 activity and Bcl-2 expression change in opposite directions; (d) TUNEL positivity and Fas ligand expression are increased, and Bcl-2 is decreased in ethanol-fed + LPS-injected rats. These results suggest that prolonged alcohol consumption may sensitize acinar cells to endotoxin-induced injury and raise the possibility that a similar mechanism may cause pancreatitis in human alcoholics.