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Introduction Thyroid hormones (TH) are required for the normal function of most tissues of the body, playing essential roles in growth, development, differentiation, and metabolism, with major effects on O 2 consumption and metabolic rate (Videla, 2000). Hyperthyroidism is associated with an increased metabolic rate due to increments in the rate of oxygen consumption in target tissues. Acceleration of aerobic metabolism by thyroid hormones enhances the generation of oxidative stress (Aydin, 2006) Oxidative stress is regarded as a pathogenic factor in hyperthyroidism. Clinical and experimental studies reported increased levels of free oxygen radicals and a decreased antioxidant status in thyrotoxicosis (Karbownik, and Lewinski, 2003). Free oxygen radicals are general mediators of signal transduction pathways, which are able to induce cytokine production from various cell types (Siddiqi et al .,1999). Studies attesting to the role of antioxidants, of which potentially inhibit the activation of oxidant-mediated transcription factors, reported that these antioxidants also prevent the transcriptional activation of inflammatory cytokines (PaoloDeVito et al., 2011). Oxidative stress accompanying hyperthyroidism is caused by increased synthesis of reactive oxygen species (ROS) and changes in the antioxidant defense system (Lampka et al., 2006). ROS have a high reactivity potential, therefore they are toxic and can lead to oxidative damage in cellular macromolecules such as proteins, lipids and DNA (Araujo et al .,2006) .In fact, the cell contains a variety of substances capable of scavenging the free radicals, protecting them from harmful effects. Among the enzymatic antioxidants, are glutathione reductase (GR), glutathione peroxidase (GPx), catalase (CAT),superoxide dismutase (SOD), while the non-enzymatic antioxidants are glutathione(GSH), vitamin E, vitamin C, 1 β-carotene, and flavonoids (Messarah et al., 2007). When ROS generation exceeds the antioxidant capacity of cells, oxidative stress develops (Sies, 1997). This phenomenon has been related to many pathological conditions (Freeman and Crapo, 1982; Halliwell and Gutteridge, 1990) and it has also been suggested that some complications of hyperthyroidism are due to thyroid hormone-induced oxidative stress in target tissues (Asayama, and Kato, 1990). Life means a continuous struggle for energy, which is required to fight against entropy. The most effective way to obtain energy is oxidation. Oxidative processes predominantly occur in mitochondria (Mircescu, 2008). On the other hand, mitochondria are one of the favorite targets of thyroid hormones. During thyroid hormone synthesis, there is a constant production of hydrogen peroxide, which is absolutely indispensable for iodine oxidation in the presence of thyroid peroxidase. In recent years, the possible correlation between impaired thyroid gland function and reactive oxygen species has been increasingly taken into consideration (Vitale et al., 2000). Thyroid hormones are the most important factors involved in the regulation of the basal metabolic state, as well as in the oxidative metabolism (Asayama, and Kato, 1990). Thyroid hormones can cause many changes in the number and activity of mitochondrial respiratory chain enzymes, which may result in the increased generation of ROS (Mano et al., 1995; Guerrero et al .,1999). Experimental studies and epidemiological data suggest that hyperthyroidism is associated with a general increase in tissue oxidative stress. Great controversy exists as to whether hyperthyroidism is associated with an increase or a decrease in the activities of antioxidant enzymes (Seven et al ., 1996 ; Komosinska-Vassev et al., 2000). Vitamin E is a potent lipid soluble antioxidant in biological systems with the ability to directly quench free radicals and function as membrane stabilizer 2 (Subudhi et al., 2008). Antioxidants treatments might be helpful in reducing the oxidative damage due to hyperthyroidism. The antioxidant protection of natural plants is a promising therapeutic remedy for free radical pathologies (Halverson et al .,2002 ). Among myriad natural plants, red cabbage (RC) (Brassica oleracea var capitata) and other Brassica vegetables, vegetables endemic to the Mediterranean region, have been found to have antioxidant, antihyperglycemic( Roman-Ramos et al .,1995 ; Grover et al .,2003 ; Yokozawa et al .,2003 ), anticancer (Fahey et al .,1997; . Komatsu et al .,2002 ; Fowke et al .,2003),and hypocholesterolemic (Komatsu et al .,1998) properties. RC extract has also preventive oxidative stress induced in livers and brains of animals exposed to paraquate (Igarashi et al., 2000 ) N-methyl-D-aspartate (Lee et al., 2002). The principle constituents of RC are isothiocyanates (glucosinolate), vitamins A, B, C and anthocyanins. (Repetto and Leusy,2002 ; Jagdish et al., 2006 ). Anthocyanins, a group of phenolic natural pigments present in RC, were found to have the strongest antioxidizing power of 150 flavonoids (Barbara et al., 2008). Looking into overall literature, the objective of the present investigation is to evaluate the possible relationship between the dynamics of oxidative stress and thyroid hormones levels under inflammatory cytokine induction as well as to verify if thyroxine has a role in the induction of oxidative stress. Aim of this study to investigate effect of the RCE on the thyroid hormone, cytokine level, lipid profile level, liver enzyme level, enzymatic antioxidant level and histological change in thyroid gland. 3