Assesment of the endocrine disruptive potential of endosulfan in Cichlasoma dimerus (Perciformes, Cichlidae).

DA CUÑA, R.; PANDOLFI, M.; ANSALDO, M.; PIOL, N.; VERRENGIA GUERRERO, N.; MAGGESE, M. C.; LO NOSTRO, F.

New Orleans, Louisiana, USA

Congreso; SETAC North America 30th Annual Meeting; 2009

SETAC North America

Runoff of pesticides used in agriculture can reach water bodies and act as an endocrine disruptor in fish by interfering with the normal functions of the hormones that regulate reproduction. The organochlorine insecticide endosulfan (ES) is still used in several countries despite showing high toxicity to non-target animals. We assessed the effect of ES as an endocrine disruptor in the South American freshwater cichlid fish Cichlasoma dimerus. Four experimental protocols were used: in vitro gonad and pituitary cultures, and 3 exposure regimes to waterborne ES. Testes and ovaries of adult fish were cultured for 3 hrs with ES and/or luteinizing hormone (LH). Testosterone (T) and Estradiol (E2) levels were measured in media using radioimmunoassay and electrochemoluminiscence assay, respectively. Pituitaries were cultured with or without ES for 3 days. LH and follicle-stimulating hormone (FSH) were detected in media by Western blot. Adult fish were exposed to environmentaly relevant concentrations of ES for 96 hrs (acute exposure, AE), two weeks (short subchronic exposure, SSC) or two months (long subchronic exposure, LSC). Pituitaries were homogenized in order to detect LH and FSH. Gonads were processed for histology. A portion of testes was homogenized to measure the activity of the enzyme gamma-glutamil transpeptidase (gGT), Sertoli cell function marker. The activity of the enzyme acetyl cholinesterase (AChE) was also evaluated in brain. In cultured gonads ES alone had no effect on E2 and T levels; LH caused a marked increase in levels of both hormones, which was diminished by the joint addition of ES. Pituitaries cultured with ES, as well as pituitaries of fish exposed to high concentrations of ES in SSC and LSC exhibited a small decrease in ir-FSH content. No effect was seen in AE or in LH ir-levels between treatments or exposure regimes. Testes of all exposed animals showed an abnormal spermatogenesis with an uncharacteristic amount of sperm. At the highest concentrations assayed (AE) the lobular structure was disrupted and immature germ cells were observed in the lumen. The activity of gGT was increased in AE, whereas it decreased upon subchronic exposures, indicating that the changes found in testes could be due to an altered Sertolli cell function early during the exposure. Despite its known neurotoxic effect, ES did not affect AChE activity, suggesting its action follows other neuronal pathways.