dehydroascorbate pools and lipid peroxidation in tissues of streptozotocine diabetic rats

dehydroascorbate pools and lipid peroxidation in tissues of streptozotocine diabetic rats

s154 Poster Session I gestation on the sensitivity of fetal islet to ILlj3 was also investigated. After neoformation in culture, islets from fetuses...

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s154

Poster Session I

gestation on the sensitivity of fetal islet to ILlj3 was also investigated. After neoformation in culture, islets from fetuses of dams fed either LP (8% protein) or control (C, 20% protein) diet, supplemented or not with taurine, were incubated in the presence or not of taurine for 24 h. They were then exposed to 50 U/ml ILlb for 24 h in the same media. AR was quantified by confocal microscopy using TUNEL method. The basal AR was higher (~~0.05) in LP islets (3.0 f 0.2%) than in C islets (2.1 f 0.3%). Addition of ILlp induced a higher (p
P616

inhibits lipid peroxidation, thus prevens membrane damage and modification of low- density proteins. We have therefore investigated the level of lipid peroxidation products and levels of dehydroascorbic acid (DHA) and ascorbic acid (AA). We have used standard methods of measurement. We have shown the decrease of ascorbic acid level in plasma and cry throcytes and increase of DHA&A ratio in plasma (0,5 in comparizon to controle 0,26), in erythrocytes (from 1,7 by controle to 0.26 by diabetes), in liver (from by controle 0,82 to by diabetes 1,31). Markers of lipid peroxidation: thiobarbituric acid - reactive substances and lipid hydroperoxides were increased twice in all investigated tissues of untreated diabetic animals. The level of reduced glutathione (GSH) was decreased in plasma by 588, in erytrocytes by 69%, in liver by 64%, but increased in bone marrow by 12%. After nicotinamides’ injections during 14 days in dose 200mg per kg the AA level increased so the DHA/AA ratio decreased: in plasma to 0,34, in erythrocytes to 0.44, in liver to 0,14. The level of thiobarbituric acid reactive substances and lipid hydroperoxides normalized, the level of GSH increased in plasma and erytrocytes to normal level. Antioxidant effect of nicotinamide by streptozotocine induced diabetes is based on activation of NAD+ biosynthesis and corresponding alterations in the tedox state of free nicotinamide coenzymes.

Streptozotocin Increased Hydmxyl-Radicals in Pancreatic Islets of Mice In Vitm PATRICIA OHLY ‘, Lars Gille*, Sabine Schulte im Walde ‘, Hans Nohl*, Helga Gleichmann ’ . ’ German Diabetes Center, German Diabetes Research Institute, Duesseldorj Germany: 2 Institute of Pharmacology and Toxicology, Veterinary University Vienna, Vienna, Austria

P618 Studies of Mechanisms of Diabetogenic Action of Xanturenic Acid A. MEYRAMOVA, F. Abikenova, A. Kikimbaeva, K.D. Kohnert, G. Meyramov. Karaganda State University, Kazakhstan

Reactive oxygen species (ROS) participate in p-cell destruction induced by streptozotocin (STZ). We analyzed whether ROS and in particular hydroxyl-radicals (‘OH), the most toxic ones of ROS, are generated in islets after treatment with STZ in vitro. Therefore, isolated islets of C57BL/6 mice were treated with 3 or 6 mmol/l STZ or with the solvent of STZ for 30 min at 37°C. Electron spin resonance (ESR) spectroscopy, in combination with spin trapping by dimethyl-pyrroline-oxide(DMPG), and a fluorescent method with dichlorofluorescin-diacetate were performed to search for ‘OH and ROS, respectively. For the first time a constitutive level of ‘OH was detected in homogenates of mouse islets that was increased up to 25% after treatment with 6 mmol/l STZ. *OH were specifically detected by adding dimethylsulfoxide (DMSO) to the reaction mixture of islet homogenates and DMPO. The addition of catalase eliminated the ‘OH ESR signal. Furthermore, STZ significantly and dose-dependently increased the generation of ROS in islets, which was significantly reduced after addition of catalase and superoxiddismutase. In conclusion, the generation of ROS and *OH is increased in islets after treatment with STZ and may mediate STZ-induced B-cell destruction. It is planned to analyze whether diabetes induced with multiple low doses (MLD) of STZ is caused by augmented ‘OH-generation as mediator of /l-cell toxicity. Previously, H. Gleichmann and her coworkers reported on the protective effect of Zn2+ against STZ-mediated loss of B-cell function in vitro and against MLD-STZ-induced diabetes. It is speculated that metallothionein that was significantly induced by Zn 2+ in islets rescued B-cell function through scavenging of STZ-triggered *OH generation.

P617 Effect of Nicotinamide’s ‘D-eatment on AscorbaWDebydmascorbate Pools and Lipid Pemxidation in Tissues of Streptozotocine Diabetic Rats OLENA D. OLIYARNYK’, Nadiya V. Biront ‘, Tamara L. Vygnan’, Mykola M. Velyky ‘. ‘Department of Biochemistry, Ivan Franko National Lviv University Lviv, Ukraine; ‘Biochemical Laboratorium, Regional Hospital, Lviv, Ukraine An increase of oxidative stress may contribute to the development of diabetic complications. Vitamin C as the major chain breaking antioxidant

4,8-dihydroxyquinolin-2-carhoxylic acid (XA) is diabetogenic substance, derivative of 8-oxyquinolin (D80X), as product disturbance of Tryptophan metabolism is formed in human organism. More than 10 D80X in doses 40-60 mg/kg induced heavy diabetes due to ability to form a few minuts past injection toxic chelat complexes with Zn-ions in cytoplasm of B-cells which result selective destruction of B-cells 15-30 min. later. The diabetogenic action of XA was studied on models in viva and in vitro by histochemical methods and method of electron microscopy. The diabetes induced by endogene synthezed XA in organism of animals contained on diet enriched by fats, tryptophan, casein and yearst accompanied by hyperglycemia (9,8- 13.6 mmol/l), partial or total decreasing amount of deposited in B-cells insulin as by degenerative changes in B-cells. Thus diabetes induced by XA is not so heavy in the contrary to diabetes induced by other D80X perhaps as result of using evidently more less doses of XA which is synthezed daily in organism. On model of isolated islets we have used XA in doses 500 and 750 mcg/ml which are equivalent to injection of diabetogenie doses of other D80X. lh later we observed a complete degranulation and destruction of B-cells analogically to action of other D80X. As it was established previously diabetogenic D80X formed in cytoplasm of B-cells chelat complex 1: 1 with Zn-ions, the most toxic for cells chelat. Atom of Zn is fixing between active group in 8 position and 2 position of quinolin ring. XA formed same complex 1: 1 by fixing atom of Zn between active group in position 8 and carboxylic group in position 2. Extraction of active group from position 8 accompanied by complete disappearing of diabetogenic properties as of D80X as of XA. We supposed that diabetogenic action of XA determined by same mechanism as action of other D80X. Electron microscopy analysis showed that XA for first time induce in B-cells destruction of cover of B-granules which result destroying of granules and forming zones of destruction of cell’s matrix. Meanwhile all amount of Zn-ions in B-cells is located in B-granules. These result showed that starting of destruction of B-cells by destroying of B-granules may be determined by forming chelat of XA with Zn-ions in B-granules. Previous studies of mechanism of diabetogenic action as of other D80X as Dithizon demonstrated that destruction of B-cells induced by these chemicals started by destroying of B-granules which result forming of zones of destruction of cell’s matrix. Our especial interest to XA is related with 2 facts: 1. XA in the contrary to all other D80X is easy formed in human organism as result of disturbances