PH24 Environmental Assessment, Environmental Toxicology
Exhibit Hall
8:00 AM - Thursday
(PH265) Reprodutive and toxics effects of fipronil in Wistar rats.
Ohi, M.1, Martino Andrade, A.J.2, Nascimento, A.J.1, Silva de Assis, H.C1, Dalsenter, P.R.1, 1 Universidade Federal do Parana, Curitiba, Parana, Brasil2 Free University of Berlin, Berlin, Brandenburg, Germany
ABSTRACT- Fipronil (FrontlineR TopSpotTM) is a pesticide derived from fenilpirazol, which acts as a competitive inhibitor of GABA. It is widely used in veterinary medicine as well as a food-use pesticide in Brazil. However, the information regarding its effects on animal reproduction is scarce. A single dose of fipronil was topically applied to rats. Different concentrations (70, 140, 200, 280, 400 or 500 mg/kg) were used depending on the assay. The median dose lethal (DL50); barbituric sleep; estrous cycle normality; reproductive indexes; pregnancy and litter data; body weight gain; plasma progesterone and estradiol levels were investigated. The DL50 was 865 mg/kg. The fipronil increased sleep latencies (7.2 ± 0.9 min) in the rats treated with 70 mg/kg when compared to control animals (4.7 ± 0.1 min). These results, associated with external signs of CNS stimulation observed in the DL50 study, are consistent with the effects described for drugs that act as GABAA inhibitors. Regarding reproductive effects, fipronil significantly increased the length of the estrous cycle after a single topic exposure of 70 mg/kg (9.7 ± 1.18 days) or 280 mg/kg (14.5 ± 1.45 days) when compared to control (4.8 ± 0.17 days). Fipronil also reduced the pregnancy index (67%) in the highest dose group (280 mg/kg). However, pregnancy length, litter size, live birth index and 7-day survival index were not affected at all. Plasma progesterone and estradiol levels, obtained in different periods after treatment with fipronil (70 mg/kg), were significantly different 96 hours after treatment, when compared to controls. These changes in hormone concentrations may be responsible for the alterations seen in estrous cycle and pregnancy index. In summary, the results indicate that fipronil may alter the reproductive function in rats. However, to extrapolate the data to other species such as cats and dogs, further experiments should be performed.
Key words: gaba, fipronil, reprodutive indexes