Cerulein-induced in vitro activation of trypsinogen in rat pancreatic acini is mediated by cathepsin B.
OBJECTIVE
One of the central, unresolved issues in the pathogenesis of acute pancreatitis is the uncertainty regarding the mechanisms responsible for the premature intrapancreatic activation of digestive enzyme zymogens. The aim of the current study was to develop and characterize an in vitro system that might mimic the events leading to trypsinogen activation within the pancreas during pancreatitis.


METHODS
Activation of trypsinogen in response to stimulation with cerulein was quantitated in isolated rat pancreatic acini.


RESULTS
Activation of trypsinogen was detected within 10 minutes of exposing isolated rat pancreatic acini, in Ca2+-containing buffer, to a supramaximally stimulating concentration of cerulein in vitro. Complete inhibition of pancreatic cathepsin B activity with E-64d, a specific, potent and irreversible cathepsin B inhibitor, prevents cerulein-induced in vitro trypsinogen activation.


CONCLUSIONS
In vitro activation of trypsinogen can be detected when pancreatic acini are exposed to a supramaximally stimulating dose of cerulein. The results using this in vitro system support the hypothesis that the appearance of active trypsin within the pancreas during the early stages of cerulein-induced pancreatitis reflects activation of trypsinogen by the lysosomal hydrolase cathepsin B.
Saluja
A K
AK
Department of Surgery, Beth Israel Hospital and Harvard Medical School, Boston, Massachusetts 02215, USA.
Donovan
E A
EA
Yamanaka
K
K
Yamaguchi
Y
Y
Hofbauer
B
B
Steer
M L
ML
D000681:Amylases / Q000378:metabolism; D000818:Animals; D002401:Cathepsin B / Q000037:antagonists & inhibitors / Q000502:physiology*; D002108:Ceruletide / Q000494:pharmacology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005765:Gastrointestinal Agents / Q000494:pharmacology*; D066298:In Vitro Techniques; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D010179:Pancreas / Q000187:drug effects / Q000201:enzymology*; D051381:Rats; D017208:Rats, Wistar; D013268:Stimulation, Chemical; D013997:Time Factors; D014357:Trypsin / Q000378:metabolism; D014362:Trypsinogen / Q000378:metabolism*
D015853:Cysteine Proteinase Inhibitors; D005765:Gastrointestinal Agents; D002108:Ceruletide; D014362:Trypsinogen; D000681:Amylases; D014357:Trypsin; D002401:Cathepsin B; D007930:Leucine; C024974:E 64