Site-Specific Localization of Protein Kinase C Isoforms in Rat Pancreas

Background: Protein kinase C (PKC), a major signal-transducing enzyme, is recognized to play an important role in the regulation of pancreatic exocrine and endocrine secretion, and yet the distribution of PKC isoforms in rat pancreas has remained unclarified. Aim of the Study: We examined the precise localization of PKC iso-forms to elucidate the role of PKC in the normal rat pancreas. Methods: Male Sprague-Dawley rats were used throughout the experiment. For Western blot analysis, the islet of Langerhans and the acinar tissue were separated by the collagenase digestion method. Also, the whole pancreas was taken out and immunohistochemistry performed. Results: According to Western blot analysis, PKC-α, -γ, -δ, -ε, -ζ, and -λ were detected in both acinar and islet cells while PKC-βII were observed exclusively in the islet. PKC-βI was not observed. On immunohis-tochemistry, the immunoreactivities of PKC isoforms were observed as follows: PKC-α, weakly in some endocrine cells and ductal epithelium; PKC-βII, mainly in the islet center; PKC-γ, in the islet, intrapancreatic ganglia and ductal epithelium; PKC-δ, in the islet periphery, weakly in some acinar cells and ductal epithelium; PKC-ε, strongly in the islet, acinar cell and ductal epithelium; PKC-ζ, in the islet, acinar cell and ductal epithelium; PKC-λ in some endocrine cells and ductal epithelium. Conclusion: These results suggest that the intrapancreatic site-specific existence of PKC isoforms may regulate pancreatic exocrine and endocrine functions via a PKC-mediated signal transduction.