Process Biochemistry 40 (2005) 903–908 Age-related changes in antioxidant status and oxidative damage to lipids and dna in mitochondria of rat liver V. Valls a , C. Peiro b , P. Muñiz c,∗ , G.T. Saez b a Dpto. Pediatr´ıa, Ginecolog´ıa y Obstrecticia, Facultad de Medicina, Universidad de Valencia, Valencia, Spain b Dpto. Bioqu´ımica y Biolog´ıa Molecular, Facultad de Medicina, Universidad de Valencia, Valencia, Spain c Area de Bioqu´ımica y Biolog´ıa Molecular, Facultad de Ciencias, Universidad de Burgos, Plaza de Misael Banuelos s/n 09001 Burgos, Spain Received 28 October 2003; received in revised form 29 January 2004; accepted 20 February 2004 Abstract To investigate the correlation between oxidative stress and mitochondrial damage with aging, antioxidant system, levels of oxidative DNA damage and as an index of the loss of plasma membrane integrity lipid peroxidation and membrane potential were studied. Results showed that the activities of antioxidant enzymes superoxide dismutase (SOD) and catalase significantly decreased during aging, however glutathione peroxidase (GSH-PX) increased in the aged mitochondria and glutathione (GSH) did not change during aging. No statistical difference was observed in the lipid peroxidation of mitochondria between young and old animals. The level of oxidative DNA damage (measured as 8oxo-dG) tended to increase during aging. © 2004 Elsevier Ltd. All rights reserved. Keywords: Antioxidant enzymes; GSH; Lipid peroxidation; DNA damage; Membrane potential 1. Introduction Mitochondria are the major intracellular source and target sites of reactive oxygen species (ROS) that are continually generated as by-products of aerobic metabolism in animals [1–3]. It has been demonstrated that mitochondrial respira- tory function declines with age [4,5]. Mitochondria is the metabolic centre of the cell, and the mitochondrial electron transport chain is a major site for intracellular free radical formation [6,7]. From these, high degrees of oxidative dam- age to mitochondrial components take place. This oxidative damage is promoted by the attack of free radicals on mem- brane polyunsaturated fatty acids, proteins and DNA [8,9]. Because ROS generation is a continuous and physiolog- ical occurrence, mitochondria possess an efficient antiox- idant system that protects them from oxidative damage. These defences can be provided by specific enzymes, such as superoxide dismutase (SOD), glutathione preroxidase ∗ Corresponding author. Tel.: +34-6-94725-8800x8210; fax: +34-6-94725-8731. E-mail address: pmuniz@ubu.es (P. Muñiz). and catalase and also by non-enzymic compounds such us vitamin E and glutathione (GSH) [1]. Endogenous damage to mitochondrial DNA (mtDNA) by free radicals is believed to be a major contributory fac- tor to aging. Recently a large number of the studies have associated mitochondrial dysfunction caused by ROS with programmed cell death (apoptosis) [10,11]. Mitochondria provide energy for basic metabolic processes, and their de- cay with age impairs cellular metabolism and leads to cel- lular death [9]. Oxidative mitochondrial DNA lesions may be responsible for the age-associated increase in mtDNA mutations. Increased oxidants may also contribute to alter- ations in mitochondrial membrane fluidity and phospholipid composition that occur during aging [12]. The present study investigated the correlation between ox- idative stress and aging. For this the activity of antioxidant enzymes and non-enzymic antioxidants (GSH and Vitamin E) were studied. A oxidative damage measured as lipid per- oxides (MDA) of mitochondria, the membrane potential and damage to mtDNA were also analysed. The association of free radicals, scavenging enzyme activities, DNA damage and functional deterioration of liver mitochondria during the aging process is discussed. 0032-9592/$ – see front matter © 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.procbio.2004.02.025