PARENT SESSION
TOXICOLOGY

Monday, August 2, 2004
10:30 AM–12:30 PM
Buchanan Courtyard

(85) EFFECT OF MALATHION ON EARLY EMBRYO DEVELOPMENT OF IN VITRO-FERTILIZED PORCINE OOCYTES.

Ducolomb, Yvonne¹, González, Guadalupe¹, Fierro, Reyna, González-Márquez, Humberto¹, Casas, Eduardo¹, Betancourt, Miguel¹, ¹ Universidad Autonoma Metropolitana-Iztapalapa, México, DF, México

ABSTRACT- Insecticides are necessarily world wide used; however most of them do not have an adequate toxicological evaluation, especially concerning their reproductive effects. Most of the studies have been performed in rodents in vivo, showing a decrease in fertility. The aim of this study was to determine the effect of malathion in early embryo development of in vitro fertilized porcine oocytes. Ovaries were collected from slaughtered prepubertal gilts. Cumulus-oocyte complexes were matured in protein free TCM-199 at 39° C in 5%CO₂ in air with 100% relative humidity for 44 h. For IVF, fresh semen was diluted, centrifuged and sperm were transferred to TBM modified containing the oocytes, to give a final sperm concentration of 5 x 10⁵ cells/ml. Oocytes and sperm were coincubated for 7 h, then transferred to embryo culture medium NCSU-23 containing a final concentration of 0 (control), 50, 100, and 500 M malathion. Four assays were performed with a total of 458 oocytes (average of 114 oocytes per concentration). Data were analyzed using Mann-Whitney test. Percentage of embryo that cleaved, reach morula and embryo viability were assessed. Embryo development was evaluated 137 h after the beginning of incubation with malathion. The control was considered as 100%. The rate of cleavage decreased to 89, 68 and 31% in 50, 100 and 500 M malathion respectively. Morula development was 67, 49 and 9% respectively. A significant difference was observed in cleavage and morula development in the 500 M vs. the control group (p< 0.05). After 185 h, embryo viability was assessed with MTT stain, showing 65, 66 and 5% respectively. All concentrations were significantly different from the control group (p<0.05). It can be concluded that malathion is detrimental for embryo cleavage, development and viability in vitro. This project was partially supported by CONACyT, Mexico (37923-B).

KEY WORDS: Embryo Development, IVF, Malathion, Porcine