Chronic ethanol administration decreases rat pancreatic GP2 content.
Postulated mechanisms of alcoholic pancreatitis include (i) zymogen granule fragility facilitating intracellular activation of digestive enzymes and (ii) ductular obstruction by protein plugs. GP2, a pancreatic glycoprotein, stabilizes zymogen granule membranes and is an important constituent of pancreatic protein plugs. Therefore, this study examined the pancreatic content and messenger RNA levels of GP2 after chronic ethanol administration. Rats were fed liquid diets with or without ethanol, for four weeks. GP2 levels in pancreatic homogenates, crude zymogen granules and zymogen granule membrane fractions were assessed by immunoblotting. Messenger RNA levels for GP2 were measured by Northern and dot blotting of pancreatic RNA. Pancreatic GP2 levels were lower in ethanol-fed rats than in controls (GP2 levels expressed as % of control: 38.75 +/- 5.8, p < 0.001 in homogenate; 31.28 +/- 3.5, p < 0.0005 in crude zymogen granules and 22.89 +/- 5.4, p < 0.0005 in zymogen granule membranes). Messenger RNA levels for GP2 were unchanged after ethanol feeding. Chronic ethanol consumption decreases GP2 content of pancreatic homogenate and zymogen granules. This decrease could (i) result from an increased release into pancreatic juice thereby favouring protein plug formation and (ii) impair zymogen granule stability. Both these mechanisms could potentiate pancreatic damage.
Apte
M V
MV
Gastrointestinal Unit, Prince of Wales Hospital and University of New South Wales, Sydney, Australia.
Norton
I D
ID
Haber
P S
PS
Korsten
M A
MA
McCaughan
G W
GW
Pirola
R C
RC
Wilson
J S
JS
D000818:Animals; D015152:Blotting, Northern; D000431:Ethanol / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D010179:Pancreas / Q000187:drug effects* / Q000201:enzymology; D006005:Phosphorylases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D012333:RNA, Messenger; D000431:Ethanol; D006005:Phosphorylases; C105247:glycogen phosphorylase 2 protein, Dictyostelium discoideum