The Effect of Chronic Exposure with Imidacloprid Insecticide on Fertility in Mature Male Rats

Background: This study was conducted to evaluate the effect of chronic exposure to imidacloprid (IM) insecticide on male testicular tissue, sperm morphology and testosterone levels in the serum of mature male rats. Materials and Methods: Animals were divided into and control-sham groups. The test group was subdivided into two groups of rats which were administered doses of 225 and 112 mg/kg IM per group. Each test group received the designated oral dose of IM once daily, for 60 days while the control-sham group received corn oil (0.2 ml/day) for the same time period. Results: Clinical observations demonstrated decreased movement, staggering gait, occasional trembling, diarrhea and spasms in the test groups. No clinical signs were seen in control-sham rats. Light microscopic analyses revealed increased thickness of tunica albuginea, obvious edema in the sub-capsular and interstitial connective tissue, atrophied seminiferous tubules, arrested spermatogenesis, negative tubular differentiation and repopulation indexes, decreased Leydig cells/ mm2 of interstitial tissue, hypertrophy and cytoplasmic granulation of the Leydig cells, vasodilation and thrombosis, elevated death, as well as immature and decreased immotile sperm velocity. Hormonal investigations showed significant (p < 0.05) decrease in serum testosterone levels. No hormonal changes were seen in the testosterone levels of the control-sham group. Conclusion: The current data provide inclusive histological feature of chronic IM exposure in two doses with an emphasis on reproductive disorders including a histological adverse effect on testicular tissue, spermatogenesis, sperm viability, velocity and abnormality which potentially can cause infertility.