外文翻譯--口服二苯基二硒對鎘致大鼠肝損傷的保護(hù)作用（英文）

1、Chemico-Biological Interactions 171 (2008) 15–25Available online at www.sciencedirect.comOral administration of diphenyl diselenide protects against cadmium-induced liver damage in ratsLysandro Pinto Borges, Ricardo Bran

2、d? ao, Benhur Godoi, Cristina W. Nogueira, Gilson Zeni ?Departamento de Qu´ ?mica, Centro de Ci? encias Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria CEP 97105-900, RS, BrazilReceived 12 June 2

3、007; received in revised form 6 September 2007; accepted 7 September 2007 Available online 19 September 2007AbstractCadmium is an environmental toxic metal implicated in human diseases. In the present study, the effect o

4、f diphenyl diselenide, (PhSe)2, on sub-chronic exposure with cadmium chloride (CdCl2) was investigated in rats. Male adult Swiss albino rats received CdCl2 (10 ?mol/kg, orally) and (PhSe)2 (5 ?mol/kg, orally) for a perio

5、d of 30 days. A number of parameters were examined as indicators of toxicity, including hepatic and renal damage, glucose and glycogen levels and markers of oxidative stress. Cadmium content, liver histology, ?-aminolevu

6、linate dehydratase (?-ALA-D) activity, metallothionein (MT) levels were also evaluated. Cad- mium content determined in the tissue of rats exposed to CdCl2 provides evidence that the liver is the major cadmium target whe

7、re (PhSe)2 acts. The concentration of cadmium in liver was about three fold higher than that in kidney, and (PhSe)2 reduced about six fold the levels of this metal in liver of rats exposed. Rats exposed to CdCl2 showed h

8、istological alterations abolished by (PhSe)2 administration. (PhSe)2 administration ameliorated plasma malondialdehyde (MDA) levels, aspartate aminotransferase (AST), ala- nine aminotransferase (ALT), alkaline phosphatas

9、e (ALP), lactate dehydrogenase (LDH) and gamma-glutamyl transferase (GGT) activities increased by CdCl2 exposure. Urea and bilirubin levels increased by CdCl2 exposure were also reduced by (PhSe)2. In conclusion, this st

10、udy demonstrated that co-treatment with (PhSe)2 ameliorated hepatotoxicity and cellular damage in rat liver after sub-chronic exposure with CdCl2. The proposed mechanisms by which (PhSe)2 acts in this experimental protoc

11、ol are its antioxidant properties and its capacity to form a complex with cadmium. © 2007 Elsevier Ireland Ltd. All rights reserved.Keywords: Cadmium; Selenium; Diphenyl diselenide; Liver damage; Oxidative stress1.

12、IntroductionCadmium is one of the most important toxic chem- icals due to its increasing level in the environment as a result of tobacco smoking, industrial and agricultural practices [1,2]. It has a very long biological

13、 half-life? Corresponding author. Tel.: +55 55 3220 8140; fax: +55 55 3220 8978. E-mail address: gzeni@quimica.ufsm.br (G. Zeni).(10–30 years) in humans and its toxicity is dependent on the route, dose and duration of ex

14、posure [2–4]. Acute cadmium intoxication induced primarily hepatic and tes- ticular damage whereas, chronic exposure resulted in renal injury and osteotoxicity [4–6]. Parenteral adminis- tration of cadmium in rats caused

15、 a severe hepatic injury in the form of hepatocellular necrosis [7]. The molecular mechanism that may be responsible for the toxicity of cadmium involves oxidative stress by disturbing the antioxidant defense systems and

16、 by pro- ducingreactiveoxygenspecies[8–10].Inviewofthefact0009-2797/$ – see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.cbi.2007.09.005L.P. Borges et al. / Chemico-Biological Interac

17、tions 171 (2008) 15–25 17liver was digested in 2 mL of 30% KOH solution. Fol- lowed 10 min in boiling water bath, 2 mL of ethanol was added to the tubes to precipitate glycogen. After precipi- tation, glycogen was resusp

18、ended in 0.2 mL 5N HCl and 0.8 mL distilled water. The glycogen content was mea- sured with iodine reagent at 460 nm and expressed as gram of glycogen/100 g of liver.2.8. Malondialdehyde (MDA) levelsAn aliquot (200 ?L) o

19、f plasma individual samples was used to carry out MDA assay. This procedure was used for samples from all groups. The method used for analysis was automated ELISA-IMMUNO-ASSAY.2.9. δ-Aminolevulinate dehydratase (δ-ALA-D)

20、 activityHepatic ?-ALA-D activity was assayed by the method of Sassa [34] by measuring the rate of product (por- phobilinogen) formation except that 1 M potassium phosphate buffer, pH 6.8 and 12 mM of aminolevulinic acid

21、 (ALA) were used. Incubations were carried out for 30 min at 39 ?C. The reaction product was deter- mined using modified Ehrlich’s reagent at 555 nm, with a molar absorption coefficient of 6.1 × 104 M?1 for the Ehrl

22、ich–porphobilinogen salt.2.10. Catalase activityHepatic catalase activity was determined by the decomposition of H2O2 according to Aebi [35].2.11. Superoxide dismutase activitySuperoxide dismutase (SOD) activity in liver

23、 homogenate was assayed spectrophotometrically as described by Misra and Fridovich [36]. This method is based on the capacity of SOD in inhibiting autoxidation of adrenaline to adrenochrome. The color reaction was measur

24、ed at 480 nm. One unit of enzyme was defined as the amount of enzyme required to inhibit the rate of epinephrine autoxidation by 50% at 26 ?C.2.12. Glutathione S-transferase activityHepatic glutathione S-transferase (GST

25、) activity was assayed through the conjugation of glutathione with 1-chloro-2,4-dinitrobenzene (CDNB) at 340 nm as described by Habig et al. [37].2.13. Ascorbic acid levelsHepatic ascorbic acid determination was performe

26、d as described by Jacques-Silva et al. [38]. Protein (liver) was precipitated in 10 volumes of a cold 4% trichloroacetic acid solution. An aliquot of homoge- nized sample (300 mL), in a final volume of 1 mL of the soluti

27、on, was incubated at 38 ?C for 3 h, then 1 mL H2SO4 65%(v/v)wasaddedtothemedium.Thereaction product was determined using color reagent contain- ing 4.5 mg/mL dinitrophenyl hydrazine and CuSO4 (0.075 mg/mL).2.14. Nonprote

28、in thiols (NPSH) contentHepatic NPSH levels were determined by the method of Ellman [39]. A sample of supernatant (500 ?L) was mixed (1:1) with 10% trichloroacetic acid (500 ?L). After centrifugation, the protein pellet

29、was discarded and free –SH groups were determined in a clear super- natant. An aliquot (100 ?L) of supernatant was added in a 1 M potassium phosphate buffer (850 ?L), pH 7.4, and 10 mM 5,5?-dithio-bis(2-nitrobenzoic acid

30、) (DTNB) (50 ?L). The color reaction was measured at 412 nm.2.15. Metallothionein (MT) contentMetallothionein content determination of liver was assayed according to the method of Viarengo et al. [40] as modified by Petr

31、ovic et al. [41]. Aliquots of 1 mL of supernatant were added with 1.05 mL of cold (?20 ?C) absolute ethanol and 80 ?L of chloroform; the samples were then centrifuged at 6000 × g for 10 min. The collected supernatan

32、t was combined with three volumes of cold ethanol (?20 ?C), maintained at ?20 ?C for 1 h and centrifuged at 6000 × g for 10 min. The metallothionein-containing pellets were then rinsed with 87% ethanol and 1% chloro

33、form and centrifuged at 6000 × g for 10 min. The metallothionein content in the pellet was evaluated using the colorimetric method with Ellman’s reagent. The pellet was resuspended in 150 ?L 0.25 M NaCl and subseque

34、ntly 150 ?L 1N HCl-containing EDTA 4 mM were added to the sample. A volume of 4.2 mL 2 M NaCl-containing 0.43 mM DTNB buffered with 0.2 M Na–phosphate, pH 8.0 [39] was then added to the sample at room temperature. The sa

35、mple was finally centrifuged at 3000 × g for 5 min and the supernatant absorbance was evaluated at 412 nm.2.16. Protein determinationProtein was measured by the method of Lowry et al.[42] using bovine serum albumin