Imed Messaoudi

Influence of combined treatment with zinc and selenium on cadmium induced testicular pathophysiology in rat

The present study was conducted to evaluate the potential benefit of combined treatment with zinc (Zn) and selenium (Se) in reversing cadmium (Cd)-induced testicular pathophysiology compared to Se or Zn treatment alone in rats. For this purpose, male rats received either tap water, Cd, Cd+Zn, Cd+Se or Cd+Zn+Se in their drinking water, for 35 days. Cd exposure caused a significant decrease in plasma and testicular concentrations of Se and Zn which was accompanied by decreased plasma testosterone level, sperm count and motility, enzymatic activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) as well as by increased lipid peroxidation (as malondialdehyde, MDA). With Se or Zn administration, during exposure to Cd, only partial corrective effects on depletion of testicular and plasma Se and Zn levels, sperm characteristics and oxidative stress have been observed. The combined treatment of Cd-exposed animals with Se and Zn assured a more significant decrease in plasma and testicular Cd concentrations and a more efficient protection against the observed testicular damage as evidenced by the total prevention of both Se and Zn deprivation and by the entire restoration of the sperm motility and the testicular antioxidant status.

Reversal of cadmium-induced oxidative stress in rat erythrocytes by selenium, zinc or their combination

The aim of this study was to evaluate the potential benefit of combined treatment with zinc (Zn) and selenium (Se) in reversing cadmium (Cd)-induced oxidative stress in erythrocytes, compared to Se or Zn treatment alone in rats exposed to Cd. For this purpose, 30 adult male Wistar albino rats were equally divided into control and four treated groups received either 200ppm Cd (as CdCl(2)), 200ppm Cd+500ppm Zn (as ZnCl(2)), 200ppm Cd+0.1ppm Se (as Na(2)SeO(3)), or 200ppm Cd+500ppm Zn+0.1ppm Se in their drinking water for 35 days. Marked alterations of antioxidative system were found in Cd-treated rats. Activities of catalase (CAT) and glutathione peroxidise (GSH-Px) as well as the total glutathione (GSH) contents in erythrocytes were significantly decreased, whereas the activity of total superoxide dismutase (SOD) was significantly increased. The treatment of Cd-exposed rats with Se alone had no significant effect on the Cd-induced increase in the SOD activity but increased significantly the CAT and GSH-Px activities and partially reversed Cd-induced depletion of GSH levels in erythrocytes. The treatment of Cd-exposed animals with Zn alone partially reversed Cd-induced increase in SOD activity and Cd-induced decrease in GSH-Px activity. The combined treatment of Cd-exposed animals with Se and Zn was more effective than that with either of them alone in reversing Cd-induced decrease in CAT and GSH-Px activities and Cd-induced increase in SOD activity. This treatment also partially restored Cd-induced depletion of GSH. These results could be important for the further development of better treatments for people and/or animals exposed to Cd.

Cadmium bioaccumulation in three benthic fish species, Salaria basilisca, Zosterisessor ophiocephalus and Solea vulgaris collected from the Gulf of Gabes in Tunisia

To select a marine teleost fish which can be used as a bioindicator of cadmium (Cd) pollution in the Gulf of Gabes in Tunisia, Cd concentrations in liver and gill were compared in three benthic fish species including Salaria basilisca, Zosterisessor ophiocephalus and Solea vulgaris. Fish samples were collected from three selected sites in the Gulf of Gabes, with different degrees of Cd contamination: the industrialized coast of Sfax (S1), the coast of Douar Chatt (S2) and the coast of Luza (S3). The results shows that Cd concentrations in both sediment and water collected from S1 were significantly higher (p < 0.0001) than those from S2 and S3. For each species, Cd concentrations, in both liver and gill, showed the decreasing order: S1 > S2 > S3. The highest concentration of Cd was detected in the liver of S. basilisca, and only S. basilisca showed bioaccumulation factors (BAF) greater than 1 in all studied sites. In S1 and S2, BAF values respect the following order: S. basilisca > Z. ophiocephalus > S. vulgaris. These results of significant bioaccumulation of Cd, in terms of hepatic concentrations and bioaccumulation factors, indicated that S. basilisca can be used as bioindicator to evaluate the evolution of Cd pollution in the Gulf of Gabes.

Study on the sensitivity to cadmium of marine fish Salaria basilisca (Pisces: Blennidae)

The present study tested the sensitivity of Salaria basilisca to water-cadmium (Cd) contamination. For this purpose, liver somatic index (LSI), Cd concentrations and the activities of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were measured in the liver of S. basilisca exposed to Cd-contaminated water (2 mg Cd/L as CdCl2) for 14 and 28 d. The results showed that the LSI decreased significantly after 14 and 28 d of Cd-exposure. Cd bioaccumulation in the liver resulted in an increasing uptake up to 42 microg/g dry weight after 28 d of exposure. Activities of CAT and SOD were significantly increased with increasing exposure time. A significant increase in GSH-Px activity, under Cd influence, was observed during 14-day exposure period (p < 0.0001). However, a significant decrease (p < 0.05) in this activity with respect to control fish was registered after 28 d of Cd-exposure. These results showed that Cd accumulation in the liver of S. basilisca could induce oxidative stress as demonstrated by changes in the antioxidant enzyme activities. Results also emphasized that S. basilisca may considered as a sensitive species to Cd exposure.

Evaluation of involvement of testicular metallothionein gene expression in the protective effect of zinc against cadmium-induced testicular pathophysiology in rat

To investigate the effects of exposure to Cd and Zn on testicular MT-1 and MT-2 gene expression and evaluate their involvement in Zn protection against Cd-induced testicular pathophysiology, male rats received either tap water, Cd or Cd+Zn in their drinking water for 35 days. Cd induced histopathological changes in testicular tissues were accompanied by decreased plasma testosterone level, plasma and testicular Zn concentrations, oxidative stress, and by increased MT-1 and MT-2 gene expression. Co-treatment with Cd and Zn reversed the Cd-induced decrease testosterone level and SOD activity, decreased testicular Cd accumulation and partially restored Cd-induced histological changes, lipid peroxidation, and Zn depletion. The increase of testicular MT-1 and MT-2 gene expression under Cd influence was significantly reduced in Cd+Zn group. These data suggest that Zn enhances the protection against Cd-induced testicular pathophysiology through non-MT gene expression mechanisms but essentially by preventing Cd accumulation, Zn deprivation and by ameliorating the testicular antioxidant status.

Involvement of selenoprotein P and GPx4 gene expression in cadmium-induced testicular pathophysiology in rat.

To investigate the effect of co-exposure to cadmium (Cd) and selenium (Se) on selenoprotein P (SelP) and phospholipid hydroperoxide glutathione peroxidase (GPx4) gene expression in testis and to evaluate their possible involvement in Cd-induced testicular pathophysiology, male rats received either tap water, Cd or Cd+Se in their drinking water for 5 weeks. Cd exposure caused a down-regulation of SelP and GPx4 gene expression and a significant decrease in plasma and testicular concentrations of Se. These changes were accompanied by decreased plasma testosterone level, sperm count and motility, GSH content, protein-bound sulfhydryl concentration (PSH), enzymatic activities of catalase (CAT) and glutathione peroxidase (GSH-Px) as well as by increased glutathione-S-transferase (GST) activity, lipid peroxidation (as malondialdehyde, MDA) and proteins carbonyls (PC). The decrease of testicular SelP and GPx4 gene expression under Cd influence was significantly restored in Cd+Se group. Co-treatment with Cd and Se also totally reversed the Cd-induced depletion of Se, decrease in plasma testosterone level and partially restored Cd-induced oxidative stress and decrease in sperm count and motility. Taken together, these data suggest that down-regulation of SelP and GPx4 gene expression induces plasma and testicular Se depletion leading, at least in part, to Cd-induced testicular pathophysiology.

Comparative study of the sensitivity to cadmium of two populations of Gambusia affinis from two different sites.

This study aims to demonstrate the influence of animals’ origin on their sensitivity toward heavy metals. For this purpose, we compared LC50 of cadmium in two populations of Gambusia affinis captured in two geographically isolated environments in the east of Tunisia; Oued El Gsil in the city of Monastir (S2) and Oued Chenini in the region of Gabes (S1). Although physicochemical parameters of the water (pH, dissolved oxygen and salinity) are similar in the two studied sites, cadmium concentrations in water, sediments and fish tissues from S1 are significantly higher (P < 0.01) than those from S2, 48-h and 96-h LC50 of the (S1) population are significantly higher than those from S2. In the same way, the offspring of the polluted site (S1) population exhibit 48-h and 96-h LC50 values much higher than those of the reference site (S2) population. These results show that the population of the Gabes region is more resistant to cadmium than that of the Monastir region and that this resistance could have a genetic basis. These results indicate the influence of the origin of animals that has to be taken into account not only in laboratory toxicity tests, but also in field ecotoxicological studies.

Involvement of cd bioaccumulation in spinal deformities occurrence in natural populations of Mediterranean killifish.

The aim of this study was to investigate the possible influence of environmental exposure to cadmium (Cd) on the spinal deformities occurrence in the Mediterranean killifish, Aphanius fasciatus (Pisces: Cyprinodontidae). For this purpose, some indicators of skeletal bone mineralization, Cd, and calcium (Ca) concentrations in spinal column as well as bioaccumulation of Cd from the water and the sediment have been compared in normal and deformed fish collected from polluted (S1) and nonpolluted (S2) areas in the Gulf of Gabès in Tunisia. When compared to the normal fish, the deformed fish showed signs of spinal column demineralization such as significant decrease in the ash weight/dry weight ratio, percentage of nonorganic components content, and Ca concentration. Cd concentrations in spinal column and liver were significantly higher in deformed fish than in normal fish. A highly significant negative correlation (r = −0.915, p < 0.01) between Cd and Ca concentrations was noted in spinal column of deformed fish. Bioaccumulation factors of Cd in the liver from the water and the sediment in deformed fish were also significantly higher (p < 0.0001) than in normal fish from S1 and S2. These findings suggest that the ability to accumulate large amount of Cd may represent a potential risk to induce spinal deformities in natural populations of Mediterranean killifish.

Cadmium-induced ovarian pathophysiology is mediated by change in gene expression pattern of zinc transporters in zebrafish (Danio rerio)

This study explored the potential for expression pattern of genes encoding zinc (Zn) transporters to be involved in the cadmium (Cd)-induced reproductive toxicity in female of zebrafish. For this purpose, oocytes maturity and ovarian histology as well as Cd, Zn and metallothioneins (MTs) accumulation and expression of genes encoding Zrt-,Irt-related protein 10 (ZIP10), Zn transporter 1 (ZnT1) and zebrafish metallothionein (zMT) were examined in ovaries of adult zebrafish exposed to 0.4 mg/L Cd in water and supplemented with Zn (5 mgkg(-1)) in their diet for 21 days. Cd-exposure decreased the expression of ZnT1 and caused up-regulation of ZIP10 and zMT gene expression. These changes were accompanied by increased Cd and MTs accumulation, decreased Zn contents as well as by histopathological damages in ovarian tissues. The co-exposure of fish to Cd and Zn abolished ZnT1 down-regulation and rendered a persistently increased ZIP10 mRNA level. This treatment also decreased Cd and MTs accumulation, reversed Cd-induced Zn depletion and partially restored Cd-induced histological changes in ovarian tissues. These results imply that the downregulation of ZnT1 as well as the overexpression of ZIP10, in responses to the ovarian Zn depletion induced by Cd, play a major role in Cd accumulation and consequently in its toxicity. The protective effect of dietary Zn supplementation against Cd-induced toxicity is mediated, at least in part, by the increase of Zn availability and subsequently the induction of ZnT1 gene expression.

Evaluation of environmental impact on natural populations of the Mediterranean killifish Aphanius fasciatus by quantitative RNA biomarkers.

The Mediterranean killifish, Aphanius fasciatus (Valenciennes, 1821) represents an excellent sentinel species for analysis of environmental impact in coastal areas. Quantitative changes on liver mRNA levels of five stress-related genes--metallothionein (metal exposure), vitellogenin, (estrogenic effects), cytochrome P4501A (CYP1A, dioxin-like compounds), superoxide dismutase (oxidative stress) and HSP70 (general stress)--were tested as markers of exposure to pollutants both in natural populations and in experimental treatments with model effectors. Analysis of fish from a metal-contaminated site in the Tunisian coast (Sfax) indicated that fish presenting spinal deformities (eight times more frequent at this site than in reference sites) showed increased levels of hepatic CYP1A mRNA levels compared to non-deformed fish from the same site or from the reference Louza site, suggesting a combined impact by metals and organic pollutants. Due to the strategy used in their design, these quantitative RNA markers will likely be useful to analyze environmental impacts on other related fish species.