Intracellular activation of trypsinogen in rat pancreatic acini after supramaximal secretagogue stimulation: cysteine protease and serine protease activity.
OBJECTIVE
The aim of the study was to explore the mechanism by which trypsinogen becomes activated during acute pancreatitis.


METHODS
Given the ability of cholecystokinin (CCK) to induce pancreatitis in vivo, the effects of high-dose CCK on preparations of isolated pancreatic acini were examined using immunofluorescence techniques for the detection of trypsinogen activation. Acini were pretreated with weak base or serine or cysteine protease inhibitors before CCK hyperstimulation.


RESULTS
CCK was found to stimulate the generation of trypsinogen activation peptide (TAP), a marker for trypsinogen processing. The generation of TAP was inhibited by pretreatment with a weak base, chloroquine (40 micromol/L). TAP generation was also inhibited by pretreatment with serine protease inhibitor FUT-175 (1 micromol/L) but not cysteine protease inhibitor E64 (0.1 mmol/L) or E64-d (0.1 mmol/L). Although treatment with a high dose of E64-d (1 mmol/L) reduced activation, it also caused cell injury.


CONCLUSIONS
High-dose CCK stimulated the intracellular activation of trypsinogen within isolated pancreatic acini. This event appears to require an acidic subcellular compartment and serine protease activity. The role for thiol proteases in this model remains unclear.
Department of Surgery, University of Tokyo, Tokyo, Japan.
Akira
A
Matsukura
Taiichi
T
Otani
Takeshi
T
Takamoto
Hiroshi
H
Usui
Yuka
Y
Goto
Masatoshi
M
Makuuchi
D000818:Animals; D002766:Cholecystokinin / Q000494:pharmacology*; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004789:Enzyme Activation; D008297:Male; D010179:Pancreas / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D051381:Rats; D017208:Rats, Wistar; D012697:Serine Endopeptidases / Q000378:metabolism*; D014362:Trypsinogen / Q000378:metabolism*
D014362:Trypsinogen; D002766:Cholecystokinin; D012697:Serine Endopeptidases; D003546:Cysteine Endopeptidases