Assessment of antifertility activities of abamectin pesticide in male rats.

The effects of abamectin pesticide on fertility of adult male Sprague-Dawley rats were investigated. Adult male rats were exposed to tap water containing 0, 571, 857, or 1714 ppm abamectin for 6 weeks. Based on fluid consumption, animals received 0, 1.19, 1.87, and 2.13 mg/animal/day abamectin, respectively. Fertility was significantly reduced in male rats ingesting abamectin at all three doses in that the number of females impregnated by them was significantly reduced. The number of viable fetuses was significantly reduced in females mated with males that ingested abamectin at 1.87 or 2.13 mg/animal/day. Significant increases in the total number of resorptions and the number of females with resorptions were observed in females mated with the exposed males at all three concentrations. The body weight gain and water consumption were significantly lower in males that ingested 2.13 mg/animal/day abamectin. Likewise, ingestion of abamectin at all three concentrations caused a significant increase in the weight of testes. Epididymal and testicular sperm counts and daily sperm production were significantly decreased in exposed males. The serum level of testosterone was significantly reduced, whereas the serum level of follicle-stimulating hormone was significantly increased in males that ingested abamectin at a concentration of 2.13 mg/animal/day. Histological evaluation of the testes revealed several abnormalities including infiltration with congested blood vessels with marked hemorrhage and a significant accumulation of connective tissue surrounding the seminiferous tubules. These results strongly suggest the adverse effects of abamectin pesticide on male rat fertility.