Specific expressional pattern of HO-1 and HO-2 in rat pancreas: Role in experimentally induced diabetes mellitus

Abstract

The goal of this study was to elucidate expression of heme oxygenase inducible (HO-1) and constitutive (HO-2) isoforms in normal and diabetic pancreas and possible role of their catalytic product - carbon monoxide (CO) in this tissue. The male Mill Hill hybrid hooded rats were divided into two groups: diabetic and non-diabetic. The single dose of alloxan (120 mg/kg) was used for induction of insulin-dependent diabetes mellitus. Both groups were additionally separated in three subgroups: one, treated 12 days with L-arginine HCl (2.25%), another with Nω-nitro-L-arginine methyl ester (L-NAME HCl, 0.01%) and the third was control. HO isoforms were detected by immunohistochemistry. Strong HO-2 immunopositivity occurred in endocrine pancreas of non-diabetic control rats while weaker staining with HO-1 antibody was detected in this group. In diabetic control, as well as in non-diabetic and diabetic treated groups, isoforms specific changes of immunopositivity were observed. Regardless of group, strong immunoreactivity of one isoform was associated with weaker immunoreactivity of another. In conclusion, there is an inverse expressional pattern of HO-1 and HO-2 in normal as well as in diabetic pancreas, which enables maintaining of HO catalytic activity in this tissue. These results suggest that HO/CO pathway might be of importance for pancreatic function.Cilj ovog istraživanja bio je da se ispita ekspresija hem oksigenaze inducibilne (HO-1) i konstitutivne (HO-2) izoforme u normalnom i dijabetičnom pankreasu i moguća uloga njihovog katalitičkog produkta-ugljen monoksida (CO) u ovom tkivu. Mužjaci hibridnog Mill Hill soja pacova su podeljeni u dve grupe: bez dijabetesa i sa dijabetesom. Insulin zavisni diabetes mellitus indukovan je jednom dozom aloksana (120 mg/kg). Obe grupe su dodatno bile podeljene u tri podgrupe: jedna je tretirana 12 dana L-argininom HCl (2.25%) druga s Nω-nitro-L-arginin metil estar (L-NAME HCL, 0.01%) a treća je bila kontrola. HO izoforme su detektovane imunohistohemijski. Kod kontrolnih životinja bez dijabetesa je zabeležena jaka HO-2 imunopozitivnost u endokrinom pankreasu dok je imunoreakcija na HO-1 slabija. Imunopozitivnost HO-1 i HO-2 se menja u dijabetesu i pod dejstvom tretmana pri čemu se odgovor ove dve izoforme na njih međusobno razlikuje. Nezavisno od grupe, povećana imunoreakcija jedne izoforme je vezana sa smanjenom imunoreakcijom druge. Iz rezultata istraživanja proizilazi da postoji inverzan obrazac ekspresije HO-1 i HO-2 u normalnom kao i u dijabetičnom pankreasu što omogućava održanje katalitičke aktivnosti HO u ovom tkivu. Ovi rezultati ukazuju na to da HO/CO sistem može biti od posebnog značaja za funkcionisanje pankreasa.Projekat ministarstva br. 14305