Efeitos do Thiodan® em fígado e em ovários em maturação avançada de lambaris Astyanax bimaculatus

• Autor(a) principal: Marcon, Lucas
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1470
• topic: Pesticidas; Peixe; Reprodução; Pesticides; Fish; Playback; CNPQ::CIENCIAS AGRARIAS::RECURSOS PESQUEIROS E ENGENHARIA DE PESCA::RECURSOS PESQUEIROS DE AGUAS INTERIORES

The pesticide Thiodan® (350g.L-1 of endosulfan) is an organochlorine insecticide used in various monocultures that may reach aquatic ecosystems and affect reproduction and the health of fish populations. The liver is a major organ for the biotransformation of many xenobiotics, and it can be damaged if the fish are exposed to a high level of chemical substances. The fish ovaries have oocytes at different stages of development that are surrounded by zona radiata, follicular basal membrane and teca cells to form the follicular complex. Stressor products may cause an increase or decrease in the diameter of the secondary follicles, vitellogenic depletion, a change the number of follicles at different stages of development and an increase the incidence of atresia. The present study aimed to evaluate the effects of Thiodan® on the liver and ovaries of Astyanax bimaculatus through morphological, morphometric and immunohistochemistry analysis. The groups of fish were exposed to the toxic substances divided in four experiments: without adaptation and no feeding, feeding without adaptation, with adaptation and no feeding, with adaptation and feeding. All experiments used three different concentrations of Thiodan® lower than the LC50 of 13.67 &#956;g.L-1 previously determined in the laboratory in accordance with the Brazilian Standard Regulation - NBR 15088 (ABNT, 2007). The concentrations used in each experiment were 1.15, 2.3 and 5.6 &#956;g.L-1, and a control group with three repetitions using ten fish in each aquarium. After 96h, six fish from each group were captured and anesthetized with benzocaine (1:10000) according to the norms of the Ethics Committee of the Veterinary Department/UFV (protocol 24/2009). Livers and ovaries were collected and processed by histological techniques. The slides were examined under the light microscope Olympus CX31. Were obtained digital images of 10 random fields per animal at 20X and 40X objective for evaluation. The characteristics of the water used in acute tests were maintained in a stable system in accordance to the recommendations of NBR 15088 (ABNT, 2007). In the experiment 1 (without adaptation/no feeding) at the concentration of 5.6 mg.L-1 of Thiodan® (0.10 ± 0.0), the intensity of the PAS reaction was lower in the cytoplasm of hepatocytes when compared to the control group (1.33 ± 0.51). In the same experiment, differences in glycogen depletion were (P<0.05) when compared to the concentrations 1.15 g.L-1 (2.66 ± 0.81) and 2.3 g.L-1 (3.00 ± 0.0). In addition, changes in the diameter of nuclei and cytoplasm of hepatocytes in all experiments were observed, and an increase in the number of hepatocyte nuclei in groups exposed to Thiodan® was associated with a reduction in the amount of cytoplasm. However, the IHA was maintained between 4.33 to 8.33 (control group); 18.50 to 28.83 (1.15 mg.L-1 group); 20.33 to 28.33 (2.3 g.L-1 group) and 23.66 to 27.66 (5.6 g.L-1 group). These results suggest that Thiodan® may be influencing liver functions to increase glycogen mobilization according to higher concentrations of exposition. The changes observed in the livers of A. bimaculatus were not severe, classified as stage I and II that indicate repairable damage to liver tissue in all experiments. It was observed in the ovaries that the action of Thiodan® in sublethal levels did not affect (P<0.05) the morphology of the different stages of follicle development. However, the experiments demonstrated an adaptation response in the number of primary and secondary follicles compared to fish without adaptation. In addition, there was a growing incidence of atretic follicles and increased diameter of the secondary follicles in the groups exposed to Thiodan® in all experiments. These results suggest an adaptive response to offset reproductive loss where in unfavorable conditions. The immunohistochemical analysis showed increasing and uniform labeling throughout the follicular development for integrin &#946;1 and collagen type IV. However, caspase 3 was observed only in the secondary ovarian follicular complex, even when fish were exposed to different concentrations of Thiodan®, which characterizes the integrity of follicular cells and the apoptotic pathway-dependent caspase-3, which may be activated for future follicular regression.