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NADPH - and NADH - tetrazolium reductase activity in the liver of selenium and copper treated carp (Cyprinus carpio L.) (CROSBI ID 492715)

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Gorup, Margita ; Kralj-Klobučar, Nada NADPH - and NADH - tetrazolium reductase activity in the liver of selenium and copper treated carp (Cyprinus carpio L.) // Proceedings of the 6th Multinational Congress on Microscopy with European Extension (6.MCM.EE) / Milat, O., Ježek, D. (ur.). Zagreb: Hrvatsko društvo za elektronsku mikroskopiju, 2003. str. 312-313.-x

Podaci o odgovornosti

Gorup, Margita ; Kralj-Klobučar, Nada

engleski

NADPH - and NADH - tetrazolium reductase activity in the liver of selenium and copper treated carp (Cyprinus carpio L.)

NADPH- AND NADH-TETRAZOLIUM REDUCTASE ACTIVITY IN THE LIVER OF SELENIUM AND COPPER TREATED CARP (Cyprinus carpio L.) M. GORUP, N. KRALJ-KLOBUČAR Department of Biology, Faculty of Science, University of Zagreb NADPH- and NADH-tetrazolium reductase (NADPH- and NADH-TR) are enzymes, which have the property of transferring electrons to various electron acceptors. Electron transport systems, such as mitochondria, are involved in these transport processes. Therefore, changes in the activity of NADPH- and NADH-TR following intoxication with selenium or copper could serve as an indicator of the effects of these elements on mitochondria. This study was aimed at analysing the intracellular distribution of NADPH- and NADH-TR in conditions of chronic intoxication with low concentrations of selenium or copper. The second objective was to determine whether low concentrations of copper or selenium cause changes in mitochondrial populations in the liver. Carp (Cyprinus carpio L.) were kept for 52 days in aquariums with water containing 0.1 mg/L Se (Na2SeO3×5 H2O) or 0.1 mg/L Cu (CuSO4×5 H2O). The first four days, carp were sacrificed daily, and later at intervals of 2 or 7 days. Unfixed liver samples were cut on a cryostat at -20°C, and the sections were analysed for NADPH- and NADH-TR activity using the method described by Scarpelli et al1. The enzyme acts on its substrate (NADPH or NADH) and releases hydrogen. Hydrogen combines with tetrazolium salt, nitro blue tetrazolium, and this results in the deposition of a blue-purple formazan pigment at the site of enzyme activity. The sections were analysed under light microscopes and compared to control. Histochemical staining showed the intracellular granular distribution of NADPH- and NADH-TR activity. Activity of the NADH-tetrazolium reductase was diffusely distributed throughout the cytoplasm as well as in the granules. Selenium or copper treatment did not induce significant changes in NADPH-TR activity. In both treatments, enzyme activity was significantly reduced compared to control samples only on the 52nd day of treatment, along with simultaneous histomorphological changes that were evident in the presence of necrotized zones. The activity of NADH-TR in treated samples was in general, higher than that of NADPH-TR activity. During the first days of treatment with both elements an increase in NADH-tetrazolium reductase activity was noted. In the continuated treatment with selenium, intervals of slightly higher and lower activities were interchanged as compared to the control samples, while prolonged intoxication with copper induced increased enzyme activity in granules like in the diffuse activity in the cytoplasm. Treatment with copper and selenium after 52 days caused reductions in the activities of both enzymes. This study provided information regarding hepatocellular distribution of NADPH- and NADH-TR activity. The granules in which the activity of both enzymes was denoted represent mitochondria, which corresponds to the literature2, 3. The diffuse distribution of NADH-TR in the cytoplasm corresponds to the fact that NADH-TR activity, in addition to the mitochondria, is also represented in the ER4. It is well known that selenium and copper act prooxidatively, forming free oxygen radicals, which can damage cell structure. A result of such damage, compounds are formed, and NADH-TR is indirectly included in their detoxification, which explains the increased activity noted in the cytoplasm during treatment with selenium and copper. NADH-TR marks the activity of Complex I in the respiratory chain of the mitochondria. Short-term exposure to copper and selenium resulted in an increase in NADH-TR activity, which indicates increased oxidative metabolism and results in an increased generation of ATP. This ATP can be used in the cell defence mechanisms included in the detoxification of selenium and copper. Extended exposure to low concentrations of selenium and copper reduce the activity of both of these enzymes, which indicates reduced oxidative metabolism in hepatocytes. This agrees with the inhibition of mitochondrial respiration confirmed during long-term exposure to low concentrations of cadmium and lead 5. These results suggest the hepatotoxic effects of selenium and copper following chronic intoxication. These effects are evident in the reduction of enzymatic activity and histomorphological changes, including the necrosis of liver tissue. I acknowledge receiving the Student Grant which was partially supported by the FEICO company. References 1. Scarpeli D. G., Hess R., Pearse A. G. E. (1958) J. Biophys. Biochem. Cytol. 4: 747-751. 2. Rothe F., Huang P. L., Wolf G. (1999) Neurosci. 94: 193-201. 3. Khanna S., Porter D. (2001) Invest. Ophthalmol. Vis. Sci. 42: 1986-1992. 4. Malik S., Sudoyo H., Marzuki S. (2000) J. Inherit. Metab. Dis. 23: 730-744. 5. Meyer W., Kretschmer M., Hoffmann A., Harisch G. (1991) Ecotoxicol. Environ. Saf. 21: 137-156. mail: mgorup@zg.biol.pmf.hr

carp; selenium; copper; NADPH- and NADH-TR

nije evidentirano

nije evidentirano

nije evidentirano

nije evidentirano

nije evidentirano

nije evidentirano

Podaci o prilogu

312-313.-x.

2003.

objavljeno

Podaci o matičnoj publikaciji

Proceedings of the 6th Multinational Congress on Microscopy with European Extension (6.MCM.EE)

Milat, O., Ježek, D.

Zagreb: Hrvatsko društvo za elektronsku mikroskopiju

Podaci o skupu

6th Multinational Congress on Microscopy with European Extension (6.MCM.EE)

poster

01.06.2003-05.06.2003

Pula, Hrvatska

Povezanost rada

Biologija