Toluene inhalation induced 8-hydroxy-2′-deoxyguanosine formation as the peroxidative degeneration in rat organs
Introduction
Toluene is the most commonly abused reagent in the young generation. The toluene, which is the chief ingredient of the organic solvent such as paint thinner, is a well known neurotoxic material, and it is suggested to influence behavior [1]. Recently, many influences of toluene on neurons were reported [2], [3], [4], [5]. We previously examined a disorder of the central nervous system by toluene inhalation using molecular biological and immunohistochemical techniques [6], [7], [8]. However, there have been few studies about the oxidative DNA damage the toluene inhalation in various organs including neurons [9], [10], [11], [12], [13], [14]. In the present study, we elucidated the peroxidative damage in various organs due to toluene inhalation, examining immunoreactivity of 8-hydroxy-2′-deoxyguanosine (8-OH-dG), formation of oxidative DNA damage, 4-hydroxy-nonenal (4-HNE), formation of lipid peroxidation, and superoxide dismutase (SOD), enzymes of the activated oxygen elimination, and quantitatively analyzing amount of 8-OH-dG and lipid peroxide (LPO).
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Animal treatment
Male Wistar rats weighing 180–200 g were obtained from Japan SLC (Shizuoka, Japan) and were bred on a 12 h light–12 h dark schedule with food and water available ad libitum. Rats were exposed to toluene (1500 ppm for 4 h per day) for 7 days. Control rats in separate chambers were exposed to air concurrently with the toluene groups.
Immunohistochemical staining
For immunohistochemical analysis, animals were perfused through the ascending aorta with 0.01 M phosphate-buffered saline (PBS, pH 7.2) followed by 4%
Immunohistochemical staining of 8-OH-dG
Results of immunohistochemical findings of 8-OH-dG are summarized in Table 1. In the brain, immunoreactivity of 8-OH-dG was observed only in the granule cells of the cerebellum of toluene treated rats. However, purkinje cells in the cerebellum, and pyramidal cells and granule cells in the hippocampus were not stained in controls or treated rats. In the lung, immunoreactivity was enhanced in nuclei of blood vessels, bronchiole endothelium cells and interstitial cells by toluene exposure. Hepatic
Discussion
With regard to the mechanism of cell and tissue injury by organic solvents, immediate peroxidative injury to the lipid, especially the cell membrane was reported [15], [16]. In reactive oxygen species that cause peroxidative damage, there are superoxide, hydrogen peroxide, hydroxy radical, and singlet oxygen. The generated superoxide is immediately reduced to hydrogen peroxide by SOD. Superoxide or hydrogen peroxide accumulates in the organism when the enzyme balance of these active oxygen
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