Oxidative stress in the kidney of reproductive male rats during aging Paulo V.G. Alabarse a , Tiago B. Salomon a, b , Tássia M. Medeiros a, b , Fernanda S. Hackenhaar a , Artur K. Schüller b , Guilherme Ehrenbrink b , Mara S. Benfato a, ⁎ a Programa de Pós-Graduação em Biologia Celular e Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil b Laboratório de Estresse Oxidativo, Departamento de Biofísica, IB, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil abstract article info Article history: Received 3 December 2010 Received in revised form 6 April 2011 Accepted 12 May 2011 Available online 17 May 2011 Section Editor: Christiaan Leeuwenburgh Keywords: Reproduction Antioxidant enzymes Antioxidant compounds Hormones Oxidative damage Reproduction alters the male physiology. We performed a comprehensive examination of oxidative stress in the kidneys of male rats with (experienced) or without (naïve) reproductive activity during aging. Oxidative stress was assessed by measuring the activity of catalase, glutathione peroxidase, glutathione S-transferase, and superoxide dismutase, and by measuring protein carbonylation, lipid peroxidation, nitrite and nitrate levels, vitamin C levels, and glutathione (total, reduced, and oxidized forms) levels, and metabolism was accessed by aconitase activity in kidney tissue, as well as testosterone and estradiol levels in serum. Reproductively active animals exhibited increased testosterone levels and altered metabolism. Aging affects tissues and organs and contributes to their functional decline. Elderly naïve rats showed high nitrite and nitrate levels. The experienced rats had less damage in elderly ages, probably because they had higher antioxidant amount and antioxidant enzyme activities at earlier ages, which would have avoided oxidative damage seen in naïve group, and because of the metabolism decline. Glutathione increase in naïve elder rats probably was induced for direct protection against oxidative damage and indirect protection by higher glutathione peroxidase and glutathione S-transferase activities. Linear regression shows that lipid peroxidation levels explained vitamin C levels (B standardized value of 0.42), indicating that vitamin C was properly produced or recruited into kidneys to combat lipid peroxidation. Catalase activity reflected the protein carbonylation and lipid peroxidation levels (B standardized values of 0.28 and 0.48). These results add comprehensive data regarding changes in oxidative stress during aging, and suggest an explanation for the costs of reproduction. © 2011 Elsevier Inc. All rights reserved. 1. Introduction Reproduction causes changes in male vertebrates, including morphological, behavioral, and physiological alterations (Miles et al., 2007). Reproductive success incurs some metabolic costs, and pre- vious studies have suggested that reproduction causes oxidative stress (Alonso-Alvarez et al., 2004, 2007; Arenas-Rios et al., 2007; Harshman and Zera, 2007; Wang et al., 2001; Wiersma et al., 2004). Oxidative stress is related to aging (Harman, 1956) and is an important issue because aging is accompanied by an increased incidence of renal disease and associated morbidity, which pose a pressing problem in terms of public health and costs (Dowling and Simmons, 2009). Most studies concerning reproductive activity and oxidative stress have been restricted to invertebrates such as Drosophila melanogaster (Harshman and Zera, 2007; Wang et al., 2001) or Caenorhabditis elegans (Harshman and Zera, 2007), and few studies have addressed vertebrates (Alonso-Alvarez et al., 2004; Arenas-Rios et al., 2007; Costantini, 2008; Wiersma et al., 2004; Dowling and Simmons, 2009). Studies on vertebrates have typically been limited either to females (lactation, number of litters, size of litter) (Speakman, 2008), or have related to male behavior (Hull and Dominguez, 2007). We recently reported an analysis of brains of reproductive male rats during aging, which is, to our knowledge, the only study focusing on aging and oxidative stress in breeding male mammals (Alabarse et al., 2011). In this study, using controlled conditions for temperature, food access, and light/dark cycle, we identified changes in rat brain associated with oxidative stress accompanying reproductive experience. Reactive oxygen species (ROS), which can be produced by mito- chondria and peroxisomes, can cause oxidative damage including protein modification and lipid peroxidation (Abegg et al., 2010; Gobe and Crane, 2010; Gredilla and Barja, 2005; Guevara et al., 2009; Herlein et al., 2009; Razmara et al., 2007). Inhibition of ROS production may protect cells from dysfunction and may prevent cell death. This has been important in kidney research where studies on antioxidants are focused on developing therapeutic strategies to prevent renal cell oxidative damage (Gobe and Crane, 2010; Jankauskas et al., 2010). Among these are studies of metal-induced renal alterations related to oxidative stress produced by exposure to cadmium, lead, selenium, iron, and zinc (Gobe and Crane, 2010; Experimental Gerontology 46 (2011) 773–780 ⁎ Corresponding author at: Departamento de Biofísica, IB, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500 prédio 43431, Porto Alegre, RS, 91501-970 Brazil. Tel.: +55 51 33087603; fax: +55 51 33087003. E-mail address: mara.benfato@ufrgs.br (M.S. Benfato). 0531-5565/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.exger.2011.05.006 Contents lists available at ScienceDirect Experimental Gerontology journal homepage: www.elsevier.com/locate/expgero