GnRH and GtH cells of juvenile fish are affected bu endosulfan, a widely used organochlorine pesticide.

PIAZZA, Y. G.; PANDOLFI, M; GENOVESE, G; DA CUÑA, R.; LO NOSTRO, F. L.

Buenos Aires

Congreso; 7th International symposium of fish endocrinology.; 2012

The organochlorine insecticide endosulfan (ES) can act on the hypothalamus-pituitary-gonad axis and affect reproduction in vertebrates. ES is banned in several countries due to its high toxicity to non-target animals but is still widely used in Argentina. We analyzed the effect of ES in sexually undifferentiated and differentiated juveniles of the freshwater cichlid fish Cichlasoma dimerus. Larvae were exposed to environmentally relevant concentrations of ES (0.03 & 0.1 µg/L) for 30 and 90 days. Head and trunk were processed for IHQ and histology. Cell morphometry and optical density of GnRH I, II & III, FSH & LH cells were measured. Sex ratio and feeding behaviour was not affected. Gonads showed no morphological or histological changes. At 30 days, GnRH I neurons showed decreased and FSH cells increased activity. At 90 days, GnRH I & FSH cells were hypertrophied; GnRH II & III cells exhibited decreased synthesis. These results suggest that at 30 days, when the connection between GnRH I and GtHs cells is not yet established, only the most susceptible cell types respond independently to ES. After 90 days, the connection is established and the effects of ES on GnRHs cause FSH cell hypertrophy. Due to the lack of effect on gonads, other mechanisms would counteract the increase of FSH.