ENZYME ACTIVITY OF CARBOHYDRATE AND AMINOACID METABOLISM, LIPID PEROXIDATION IN CARP TISSUES UNDER THE EFFECT OF 19-NORTESTOSTERONE

Abstract

The aim of the study was to investigate the activity of a number of enzymes of carbohydrate metabolism, individual amino acids, creatine phosphate, inorganic phosphorus and lipid peroxidation (LPO) in the hepatopancreas and blood plasma of carp (Cyprinus carpio L.) under the influence of the synthetic steroid 19-norethisterone. The experiments were conducted on two-year-old carps, which were kept for 24 hours in aquariums with different concentrations of 19-nortestosterone in water at optimal temperature, oxygen content and pH. The activity of lactate dehydrogenase (LDH), alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatine phosphokinase (CPK) in the supernatant fraction of hepatopancreatic homogenate was monitored by UV-kinetic and colourimetric methods. The activity of isocitrate dehydrogenase (ICDH) was determined spectrophotometrically by the accumulation of NADPH, and lactate dehydrogenase (LDH), glucose-6-phosphate dehydrogenase (Gl-6-PDH) and glucose-6-phosphatase (Gl-6-Phase) - by the accumulation of NADH in the reactions of conversion of the corresponding substrates. Conventional biochemical methods were used to determine the concentration of diene conjugates, malondialdehyde (MDA), lipid hydroperoxides, catalase (CAT) and superoxide dismutase (SOD) activity in blood plasma and supernatant fraction of hepatopancreatic homogenate. Conventional biochemical methods were used to determine the concentration of diene conjugates, malondialdehyde (MDA), lipid hydroperoxides, catalase (CAT) and superoxide dismutase (SOD) activity in blood plasma and the supernatant fraction of hepatopancreatic homogenate. It was found that fish exposed to water with a concentration of synthetic steroid 19-nortestosterone of 50 µg/dm3 for 24 hours had higher levels of MDA and diene conjugates, increased activity of CAT and SOD in blood plasma, increased activity of ALP, ALT, AST, CK, CAT and SOD in the hepatopancreatic supernatant fraction, and LDH remained unchanged, as well as the level of lipid hydroperoxides in blood plasma. Under the influence of 19-nortestosterone, the activity of Gl-6-FDG and IDDG in the mitochondrial fraction of carp hepatopancreas increases, and that of Gl-6-phase in the supernatant. At a concentration of 19-nortestosterone in water of 200 μg/dm3, the content of lipid hydroperoxides in the blood plasma of carp increases, and in the hepatopancreatic supernatant fraction - diene conjugates and SOD activity, while ALP and CPK decrease relative to their values in fish with a low level of xenobiotic in water. The content of MDA, diene conjugates, as well as the activity of CAT, SOD, ALP, CPK and LDH in blood plasma, IDH and Gl-6-PDH in the mitochondrial fraction and Gl-6-Phase and LDH in the hepatopancreatic supernatant did not change, but remained higher than in the control. It was concluded that 19-nortestosterone stimulates carbohydrate metabolism, amino acids alanine and aspartate transamination, creatine phosphate conversion, antioxidant enzyme activity and lipid peroxidation in the hepatopancreas of two-year-old carp. The obtained results deepen the understanding of the mechanism of action of synthetic steroids in bony fish, and the differences in enzyme activity and lipid peroxidation can be important criteria for ecotoxicological assessment of water bodies contaminated with hormonal compounds.