Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı 2

The Role of Tempol ın the Lıver of Rats Treated wıth Lıpopolysaccharıde
Endotoxemia has been described as causing severe damage of a widespread bacterial infection derived from blood by spreading from a tissue to other tissue. Endotoxemia has changed to the sepsis causing multiple organ deficiency, systemic inflammation and hypotension despite fluid resuscitation and drugtreatment. Sepsis has been also characterized by hypotension, vascular hyporeactivity to vasoconstrictor agents, myocardial dysfunction, and distribution of organ blood flow.
Lipopolysaccharide (LPS) using to create experimental sepsis models is an endotoxin found in the cellular wall structure of Gram (-) bacteria. The increased level of LPS in the vascular system has a key role in releasing of cytokines and occurrence of systemic inflammatory response. The formation of free radicals can also trigger in the case of the inflammatory response resulting fromthe endotoxins such as LPS. Additionally, they have been formed in various cellular events occurring under certain physiological conditions. They have different chemical structures such as hydroxyl, superoxide, NO and lipid peroxide.

These free radicalsare eliminated by a complex antioxidant systemin normal physiological conditions. The balance of oxidant/antioxidant system is broken down, depending on the increasing of free radical formation rate or the decreasing of antioxidant defense system activity. This causes oxidative stress. Natural and cellular antioxidants consist of enzymes and some molecules in the organisms. For instance, the enzymes such as SOD, catalase, glutathione peroxidase, hydroperoxidase, cytochrome C oxidase playing role in various reactions bear an antioxidant feature. Superoxide dismutase is an antioxidant enzyme which catalysis changing from the superoxide free radical to H2O and molecular oxygen (O2). TEMPOL is a scavenger eliminating the formations and the effects of many free radicals such as superoxide anions, hydroxyl radicals and peroxynitrite. Moreover, tempol has been widely studied to investigate effects of increased ROT level with hypertension and endothelial dysfunction in the experimental animal models. In our study, tempol was chosen because of its SOD mimetic, its low molecular weight, its stabile piperidine nitroxide group and easy passing through biological membranes.

In this study, it is composed of four groups to investigate effects of tempol on liver damage induced by the injection of LPS intraperitoneally (ip) (male Wistar albino rats weighed 200-300 gr). Group I was the animals FTS-injected, group II; LPS-injected (E.coli, 15 mg/kg, ip, Serotype 026:B6), group III; tempol-injected (100 mg/kg, ip) after 3 hours of LPS injection, group IV; tempol-injected after 3 hours of FTS injection. Blood samples were collected from the heart for biochemical analysis and liver tissue samples were taken for immunohistochemical and biochemical analysis after finalization of the experiments.
Light microscopic observations showed that the administration of LPS caused some pathological changes in the liver tissue. The cell borders of hepatocytes were not evident and there was notradial structure around the central veins. Kupffer cells were evident and large. The leukocytes were observed in the enlarged and irregular sinusoids. Many leucocytes were detected in lumen of central veins and endothelial line of the veinlost its continuity. In the same time, the levelsof aspartate aminotransferase (AST) and alanine aminotransferase (ALT) increased in the plasma and liver tissue in LPS group. The tissue level of C-reactive protein (CRP) also increased butthe levels of SOD decreased in the same group. It was detected strong immunoreactivity of inducible nitric oxide synthase (iNOS) while immunoreactivity of the endothelial nitric oxide synthase (eNOS) was weak in the liver tissue sections of LPS injected animals. Additionally, myeloperoxidase (MPO)-stained leukocytes accumulated in sinusoidal lumen and attached to endothelial layer of the vessels and they widely spread out to portal areas in the liver tissue. In tempol administrated group after LPS injection, the liver morphology exhibited the similar morphology both in partly LPS group and partly control group. It was detected to decrease plasma and tissue levels of AST and ALT. However, plasma levels of AST and ALT were lower than those of tissue levels in this group. The decreased SOD levels weredetected to increase when tempol was injectedtothe endotoxemic animals. In addition to this, the tissue levels of SOD were high when compared to theircontrol levels. Tempol administration did not prevent the increase of CRP levels in the liver tissue of LPS group. Immunoreactivitiy of eNOSin tempol injected group after 3 hours of LPS injection were stronger and the iNOS immunoreactivity were weaker than those of LPS injected animals. The distribution and the location of MPO-stained leukocytes were similar with LPS group. However, tempol administration did not change the distributions of MPO-stained leukocytes in liver tissues of LPS injected animals. The histology of liver tissue was similar to control groupin tempol given control animals. Moreover, eNOS immunoreactions, plasma levels of AST and SOD, plasma levels of CRP were similar to control groups. However, iNOS immunoreactions, plasma and tissue levels of ALT and tissue levels of SOD were higher than control groupin tempol given animals.

In conclusion, no changes in the tissue level of increased CRP and the similarity with LPS group in the distribution of MPO-stained leukocytes after tempol injection in the animals given LPS revealed that tempol did not show any kind of regulatory effect on sepsis pathogenesis in the time and dose applied. Besides, decreased levels of AST and ALT, which are markers for liver damage, and especially their decreased plasma levels, and no changings in the liver morphology of the animals given tempol made us think that when application time and dose of tempol were adjusted, itcan be a good antioxidant for treatment of oxidative stress.