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This Article Full Text Full Text (PDF) All Versions of this Article: 93/10/1091    most recent expphysiol.2008.043141v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Binker, M. G. Articles by Cosen-Binker, L. I. PubMed PubMed Citation Articles by Binker, M. G. Articles by Cosen-Binker, L. I. Related Collections GI & Epithelial

¹ CBRHC Research Center, Buenos Aires, Argentina ² Departments of Medicine and Physiology, University of Toronto, Toronto, Ontario, Canada

Pancreatitis is a disease with high morbidity and mortality. In vitro experiments on pancreatic acini showed that supramaximal but not submaximal cholecystokinin (CCK) stimulation induces effects in the acinar cell that can be correlated with acinar morphological changes observed in the in vivo experimental model of cerulein-induced pancreatitis. The GTPase Rac1 was previously reported to be involved in CCK-evoked amylase release from pancreatic acinar cells. Here, we demonstrate that pretreatment with the Rac1 inhibitor NSC23766 (100 µM, 2 h) effectively blocked Rac1 translocation and activation in CCK-stimulated pancreatic acini, without affecting activation of its closely related GTPase, RhoA. This specific Rac1 inhibition decreased supramaximal (10 nM) CCK-stimulated acinar amylase release (27.% reduction), which seems to be connected to the reduction observed in serum amylase (46.6% reduction) and lipase levels (46.1% reduction) from cerulein-treated mice receiving NSC23766 (100 nmol h^–1). The lack of Rac1 activation also reduced formation of reactive oxygen species (ROS; 20.8% reduction) and lactate dehydrogenase release (LDH; 24.3% reduction), but did not alter calcium signaling or trypsinogen activation in 10 nM CCK-stimulated acini. In the in vivo model, the cerulein-treated mice receiving NSC23766 also presented a decrease in both pancreatic and lung histopathological scores (reduction in oedema, 32.4 and 66.4%; haemorrhage, 48.3 and 60.2%; and leukocyte infiltrate, 53.5 and 43.6%, respectively; reduction in pancreatic necrosis, 65.6%) and inflammatory parameters [reduction in myeloperoxidase, 52.2 and 38.9%; nuclear factor B (p65), 61.3 and 48.6%; and nuclear factor B (p50), 46.9 and 44.9%, respectively], together with lower serum levels for inflammatory (TNF-, 40.4% reduction) and cellular damage metabolites (LDH, 52.7% reduction). Collectively, these results suggest that pharmacological Rac1 inhibition ameliorates the severity of pancreatitis and pancreatitis-associated lung injury through the reduction of pancreatic acinar damage induced by pathological digestive enzyme secretion and overproduction of ROS.

(Received 24 April 2008; accepted after revision 9 June 2008; first published online 20 June 2008)
Corresponding author L. I. Cosen-Binker: CBRHC Research Center, Arribenos 1697, P.1, Buenos Aires, 1426, Argentina.  Email: licb{at}cbrhc.org