Bulletin of Experimental Biology and Medicine, Vol. 159, No. 1, May, 2015. PHARMACOLOGY AND TOXICOLOGY. Antioxidant Defense System after Single and ...
DOI 10.1007/s10517-015-2884-y
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Bulletin of Experimental Biology and Medicine, Vol. 159, No. 1, May, 2015
PHARMACOLOGY AND TOXICOLOGY Antioxidant Defense System after Single and Chronic Administration of Obestatin and Its Fragment (1-4) to Normal and Overweight Male Rats E. E. Khirazova, A.A.Bayzhumanov*, E. S. Motorykina, A. A. Devyatov, M. V. Maslova, A. V. Graf, N. A. Sokolova, M. G. Golubeva, and A. A. Kamenskii Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 159, No. 1, pp. 46-48, January, 2015 Original article submitted February 27, 2014 We studied the effects of anorectic peptide obestatin and its fragment (1-4) on the antioxidant defense system in animals with normal and experimentally induced increased body weight. In rats with normal body weight, no changes in activity of the antioxidant defense system 1 week after single administration of the substances. After chronic administration of obestatin and fragment (1-4) for 1 week, total antioxidant capacity of the plasma decreased; obestatin also lowered the content of TBA-reactive products. In the overweight rats, SOD-like activity in the plasma increased 1 week after chronic administration of obestatin. Hence, obestatin and its fragment (1-4) induced changes in the antioxidant defense system only after chronic administration. Key Words: obestatin; antioxidant defense system; overweight The interest to the mechanisms of appetite regulation is dictated by high prevalence of appetite disorders finally leading to obesity. The intricate system of appetite regulation includes a large set of regulatory factors, among which attention is paid to obestatin (OS). OS was first isolated from rat stomach. It consists of 23 amino acid residues and represents a product of posttranslational processing of preproghrelin [13]. OS was also found in the duodenum, jejunum, pancreas, spleen, mammary gland, breast milk, blood plasma, Leydig cells, and salivary glands [3,4,6,7,10]. Analysis of plasma levels of OS under various physiological conditions showed that it is significantly lower in obese people and significantly higher in patients with Department of Human and Animal Physiology, *Department of Biophysics, Biological Faculty, M. V. Lomonosov State Moscow University, Moscow, Russia. Address for correspondence: ekhirazova@ gmail.com. E. E. Khirazova
anorexia in comparison with healthy persons [8,12]. The level of OS is associated with obesity not only in adults but also in children [14]. The study of the effects of OS fragments is of particular interest; however, published reports are limited. We have previously demonstrated marked anorectic effect of both OS and it fragment (1-4) (OS1-4) after single intranasal administration in a dose of 300 nmol/kg [2]. Since rapid changes in body weight, i.e. caused by metabolic changes in the adipose tissue, can lead to oxidative stress, the purpose of this study was to investigate functional state of the antioxidant defense (AOD) system after single and chronic administration of OS and OS1-4 in normal and overweight rats. To this end, the levels of some AOD system enzymes, non-enzymatic antioxidants, and markers of oxidative stress were measured 1 week after discontinuation of the substances, when persistent and lasting effects
0007-4888/15/1591038 © 2015 Springer Science+Business Media New York
E. E. Khirazova, A.A.Bayzhumanov, et al.
of the peptides on body weight and food intake were recorded [2].
MATERIALS AND METHODS The work was carried out on 72 Wistar male rats weighing 250-300 g. All experiments were performed in accordance with the ethical principles and regulations of the European Science Foundation and Declaration of Helsinki of the humane treatment of animals. We used rat OS (FNAPFDVGIKLSGAQYQQHGRAL-NH2) and OS1–4 (FNAP-NH2) synthesized at the Laboratory for Synthesis of Peptides, Russian Research Cardiology Research-and-Production Complex, Ministry of Health of the Russian Federation. The preparations were diluted with 0.85% NaCl. In series I, the compounds were administered intranasally in a dose of 300 nmol/kg once or chronically (daily for 5 days) to rats with normal weight. Control animals received the same volume of saline. In series II, we studied the effects of OS and OS1–4 on AOD system in rats with experimentally induced obesity. The rats were fed a specialized high-fat diet (metabolizable energy 3900 kcal per 100 g) for 2 months. After 2 months, body weight of experimental animals exceed the weight of animals maintained on the standard balanced feed (metabolizable energy, 310 kcal per 100 g) by10%. OS and OS1–4 were administered to animals with increased body weight intranasally at 300 nmol/kg daily for 5 days. Control animals with increased body weight received an equivalent volume of saline. Blood samples were taken after decapitation 1 week after administration of the substances and treated with heparin (10 U/ml). Total antioxidant capacity of blood plasma [5], blood level of non-protein thiols,
39 SOD activity in hemolysate and blood plasma, catalase activity in the blood, and the level of TBA-reactive compounds [1] were measured.
RESULTS We revealed no changes in activity of the examined enzymes of AOD system, content of low molecular weight antioxidants, and oxidative stress markers 1 week after single intranasal administration of OS and OS1–4. After chronic administration of the examined substances, SOD and catalase activities were not changed, but the total antioxidant capacity of plasma and the level of TBA-active products decreased (Fig. 1, a). These changes can be explained by the capacity of OS to inhibit LPO and reduce the content of LPO endproducts, which manifested in the decrease in TBAreactive product content. LPO can enhance generation of free radicals. Thus, products of arachidonic acid oxidation by cyclooxygenase-1 stimulate generation of ROS [9]. Therefore, inhibition of LPO can lead to the decrease in the content of not only end-products, but also ROS. Inhibition of ROS generation could lead to a decrease in the production of low-molecular-weight antioxidants via the feedback mechanisms and hence to a decrease in the total plasma antioxidant capacity. This theory agrees with the anti-inflammatory properties of OS, in particular, reduction of LPO activity, inhibition of secretion of pro-inflammatory cytokines, and activation of the release of anti-inflammatory cytokines [11]. Activity of AOD system did not change in overweight rats compared to animals with normal weight. Evaluation of the functional state of the AOD system 1 week after administration of the examined substanc-
Fig. 1. Effect of chronic intranasal administration of OS and OS1-4 on parameters of AOD system in male rats with normal (a) and increased (b) body weight. 1) Plasma SOD activity; 2) SOD activity in blood hemolysate; 3) catalase activity in blood hemolysate; 4) blood level of non-protein thiols; 5) antioxidant capacity of blood plasma; 6) plasma level of TBA-active products. Dark bars, controls (n=8); hatched bars, OS (n=8); light bars, OS1-4 (n=8). *p
