Evaluation of a Two-Generation Reproduction Toxicity Study Adding Endopoints to Detect Endocrine Disrupting Activity Using Vinclozolin

Abstract

-A two-generation reproduction toxicity study in rats adding extra endpoints to detect endocrine disrupting activity was conducted using vinclozolin by dietary administration at 0, 40, 200, and 1000 ppm, for investigation of its utility. The extra endpoints included anogenital distance (AGD), nipple development, sexual maturation (vaginal opening and preputial separation), estrous cycle, spermatogenesis, sex organ weights, and blood hormone concentrations (thyroid and sex hormones). Hepatic drugmetabolizing enzyme activities were also measured. The results revealed changes due to vinclozolin in the AGD, nipple development, sexual maturation, sex organ weights, and blood sex hormone concentrations in males of both parental animals and offspring, even at the lowest dose of 40 ppm, confirmed by results for the classical endpoints of histopathological examination at 200 ppm and mating at 1000 ppm. The effects on parental males included increased pituitary and testis weights, and decreased epididymis weights at 1000 ppm in both generations, and decreased prostate and epididymis weights at 200 and 1000 ppm and seminal vesicle weights at 1000 ppm in F1 males. Histopathological examination revealed hypertrophy of the basophilic cells in the pituitary at these two doses, and diffuse hyperplasia of the testicular interstitial cells and atrophy of the seminal vesicle mucosa at 1000 ppm in F0 and F1 males. In addition, F1 males demonstrated decrease in prostate fluid at 200 and 1000 ppm. Blood hormone analysis revealed increases in LH, FSH, testosterone, and DHT in F0 and F1 males at 1000 ppm. General toxicological effects included suppressed body weight gain in F0 and F1 females and in F1 males, and reduced food consumption in F0 and F1 females at 1000 ppm. Histopathological examination revealed centrilobular hepatocellular hypertrophy in males at 200 and 1000 ppm and in females at 1000 ppm, increased lipid droplets in the adrenal zona fasciculata and zona glomerulosa in males at 200 and 1000 ppm and in females at 40 ppm and above, and hyperplasia of ovarian interstitial cells and vacuolation of lutein cells in females at 1000 ppm in both generations. Almost all the tissue changes were accompanied by changes in weights. Decreases in T3 and/or T4 were observed in both sexes and generations at 1000 ppm and in F0 females at 200 ppm. However, these were presumed to be secondary to induction of hepatic drugmetabolizing enzymes, activities being increased for a range of enzymes in both sexes and generations at 1000 ppm. Rise in BROD activity was the most prominent, suggesting that vinclozolin mainly induces CYP2B. As for effects on reproductive function, a marked decrease in the fertility index caused by male infertility was observed in F1 animals at 1000 ppm. However, no effects on spermatogenesis were seen in either F0 or F1 males. Since cleft prepuce and penile hypoplasia were observed in infertile males, it is probable that the cause of infertility in F1 males was related to morphological abnormalities in the extern...

Developmental exposure to environmental endocrine disruptors: Consequences within the ovary and on female reproductive function☆

“…In adult female rats, vinclozolin induced alterations in the serum profiles of LH and the E 2 :testosterone ratio, which could collectively account for the prolongation of estrous cycle duration that was measured in these animals [133]. In a two-generation reproductive toxicity study, 40-1000 ppm dietary vinclozolin resulted in hyperplasia of ovarian interstitial cells and vacuolation of lutein cells in females of both generations [134].…”

“…In adult female rats, vinclozolin induced alterations in the serum profiles of LH and the E 2 :testosterone ratio, which could collectively account for the prolongation of estrous cycle duration that was measured in these animals [133]. In a two-generation reproductive toxicity study, 40-1000 ppm dietary vinclozolin resulted in hyperplasia of ovarian interstitial cells and vacuolation of lutein cells in females of both generations [134].In studies using pregnant rats that were given oral vinclozolin (3.0-10μg/ml), it has been shown that this compound antagonizes the androgenic effects of testosterone propionate in male and female embryos [135]. Further analysis of the in utero effects of vinclozolin revealed that male embryos underwent feminization and female embryos became masculinized when dams were given vinclozolin.…”

On the impact of second generation mating and offspring in multi-generation reproductive toxicity studies on classification and labelling of substances in Europe

“…In two earlier two-generation studies, reduced fertility in the P0 and P1 generations was observed through reduced live birth indices (Hellwig, 1992;. Moreover, Matsuura et al (2005) found histopathological effects on adrenals, pituitary, testis, seminal vesicles, and ovaries in P0 and P1. In addition, T4 was dose-dependently decreased, anogenital distance was reduced, and preputial separation was delayed in F1 males.…”

“…Accepted for publication in "Regulatory Toxicology and Pharmacology dd.18-8-2011 Matsuura et al (2005) reported a reduced fertility in the P1 but not in the P0 males. In two earlier two-generation studies, reduced fertility in the P0 and P1 generations was observed through reduced live birth indices (Hellwig, 1992;.…”

Reproductive Toxicology of Environmental Toxicants: Emerging Issues and Concerns

“…persistent changes occurred in the gene expression [242]. In the case of VCZ two-generation studies reveal that when given in the diet to pregnant rats changes occur in the ano-genital distance, sex organ weights, sexual maturation and blood hormones in both F1 and F2 male offspring [244,245]. The effects of VCZ are permanent and are most pronounced when administered transiently during the period of gonadal sex differentiation [246,247].…”