EXPERIMENTAL ANDTOXICOLOGIC PATHOLOGY Experimental and Toxicologic Pathology 56 (2005) 377–383 Antioxidant and detoxifying enzymes in the liver of rats after subchronic inhalation of the mixture of cyclic hydrocarbons Katarı´na Holovska´ Jr. a,Ã , Anna Sobekova´ a , Katarı´na Holovska´ a , Viera Lena´rtova´ a , Peter Javorsky` b , Jaroslav Lega´th a , L’ubomı´r Lega´th c , Milan Maretta a a University of Veterinary Medicine, Komenske´ho 73, 041 81 Kosˇice, Slovakia b Institut of Animal Physiology SAS, S ˇ olte´sovej 4, 040 01 Kosˇice, Slovakia c University of Pavol Jozef S ˇ afarik, Trieda SNP1, 040 01 Kosˇice, Slovakia Received 9 August 2004; accepted 12 January 2005 Abstract The activity of antioxidant and detoxifying enzymes, superoxide dismutase (SOD), glutathione peroxidase (GSHPx), glutathione-S-transferase (GST), the SOD isoenzyme patterns and the contents of thiobarbituric acid reactive substances (TBARS), were determined in the livers of male and female rats after subchronic inhalation of mixtures of benzene, cyclohexanone and cyclohexane. Except for decreased GSHPx (with substrate cumene hydroperoxide) and GST activities in female rats, no differences in the activities of antioxidant and detoxifying enzymes and TBARS content occurred. Between the activities of GSHPx and GST was observed an indirect relationship. The activities of GSHPx-cum and GST were influenced by sex. r 2005 Elsevier GmbH. All rights reserved. Keywords: Cyclic hydrocarbons; Rats; Liver; Antioxidant enzymes; Isoenzyme pattern SOD Introduction Benzene, cyclohexanone and cyclohexane are the important substances widely used in an industry. Benzene is fairly soluble in water and is removed from the atmosphere in rain. The primary routes of exposure are inhalation of contaminants, especially in the areas with high traffic, and consumption of contaminated drinking water. Benzene is converted into a variety of metabolites, but the major one is phenol. Benzene can be enzymatically bioactivated to reactive intermediates that can lead to increased formation of reactive oxygen species (ROS) (Winn, 2003). Some studies have demonstrated that a lot of chemical compounds such as pesticides, herbicides, metals, many organic compounds can generate extre- mely ROS (Winzer et al., 2002). ROS damage cellular macromolecules causing lipid peroxidation and nucleic acid and protein alterations. Their formation is con- sidered as a pathobiochemical mechanism involved in the initiation or progression phase of various diseases such as atherosclerosis, ischemic heart diseases, diabetes, initiation of carcinogenesis or liver diseases (Halliwell and Gutteridge, 1999; Hoffman et al., 1989; Southorn and Powis, 1988; Yagi, 1994). Therefore, the concentra- tions of ROS have to be controlled by several defense mechanisms, which involve also a number of antiox- idant and detoxifying enzymes. Antioxidant enzymes play a crucial role in maintaining cells homeostasis. ARTICLE IN PRESS www.elsevier.de/etp 0940-2993/$ - see front matter r 2005 Elsevier GmbH. All rights reserved. doi:10.1016/j.etp.2005.01.002 Ã Corresponding author. Fax: +421 55 6334768. E-mail address: holovska@hotmail.com (K. Holovska´ Jr.).