Repeated 28-day oral toxicity study of vinclozolin in rats based on the draft protocol for the "Enhanced OECD Test Guideline No. 407" to detect endocrine effects

Acute and Sub-chronic Toxicity Study of Recombinant Bovine Interferon Alpha in Rodents

INTRODUCTION

Recombinant bovine interferon alpha (rBoIFN-α) has been demonstrated to have antiviral activity. However, no conduct of acute or chronic toxicity tests has been reported.

MATERIAL AND METHODS

Specific pathogen-free Sprague Dawley rats were administered doses at different concentrations through intraperitoneal or intravenous injection. After the administration (single for an acute toxicity test over 14 days or daily for a sub-chronic toxicity test over 30 days), the rats' behaviour and other indicators and the degree of toxic reaction were continuously monitored. Blood was collected for haematological and serum biochemical examinations. At the end of the experiments, the rats were sacrificed for necropsy and histopathological tissue analysis.

RESULTS

The external performance, behaviour characteristics, and changes in body temperature and body weight of the rats in each subgroup were comparable to the normal control subgroup. Except for a few cases, there were no lesions in the viscera's pathological structures, and the blood parameters and biochemical indicators were not noticeably different from those of the control subgroup.

CONCLUSION

This study suggests that rBoIFN-α seems to be safe for rats, and its use may foster the development of the cattle industry in China by protecting livestock health.

Effect of Lepidium meyenii (maca) on testicular function of mice with chemically and physically induced subfertility

The aim of this study was to evaluate the effect of Lepidium meyenii (maca) in chemically and physically subfertile mice. After 35 days, the following groups of mice were evaluated: control, sham, chemical subfertility, chemical subfertility-maca-supplemented, physical subfertility, physical subfertility-maca-supplemented and maca-supplemented only. Motility (32.36% ± 5.34%) and sperm count (44.4 ± 5.37 × 10(6) /ml) in the chemically and physically subfertile mice (11.81% ± 4.06%, 17.34 ± 13.07 × 10(6) /ml) decreased compared to the control (75.53% ± 2.97% and 57.4 ± 19.6 10(6) /ml) and sham (53.5% ± 7.86% and 58.4 ± 14.10 10(6) /ml). Maca was able to reverse the deleterious effect of motility (76.36 ± 1.97) as well as sperm count (53.5 ± 9.18 × 10(6) /ml) on chemical subfertility. In contrast, maca did not reverse the effects of induced physical subfertility nor motility (18.78% ± 14.41%) or sperm count (20.17 ± 11.20 × 10(6) /ml). The percentage of sperm DNA fragmentation in the physically subfertile mice increased (11.1% ± 19.29%) compared to the control (0.84% ± 0.85%). However, in the physically subfertile group, maca decreased sperm DNA fragmentation (2.29% ± 2.30%) closer to the sham (1.04% ± 0.62%) and the control (0.84% ± 0.85%). The group supplemented only with maca showed 0.54% ± 0.50% of spermatozoa with DNA fragmentation. Yet, the differences observed were statistically not significant. In conclusion, it appears that maca activates the cytochrome P450 system after chemically induced subfertility. However, it does not reverse the low mitochondrial membrane potential in spermatozoa compromised in the physical subfertility group.

Determination of endocrine disruptors and endogenic androgens and estrogens in rat serum by high-performance liquid chromatography-tandem mass spectrometry

To simultaneously measure some targeted endocrine disruptors and several forms of sex hormones in rat serum, an accurate analytical procedure was developed. First, a comparison between a polymeric-based solid-phase extraction (SPE) and a micro-extraction by packed sorbent was performed to choose the optimal method to extract and concentrate the analytes: bisphenol A, atrazine, vinclozolin metabolite, testosterone, androstenedione, estrone, estradiol, estrone-sulfate and glucuronide and estradiol-sulfate and glucuronide. The analyses were then performed by high-performance liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) with electrospray ionisation in positive and negative modes. The protocol based on SPE was validated using the ICH/2005 guidelines. The validation demonstrated good performance in terms of linearity (R(2)>0.99), recovery (71-90%) and repeatability (relative standard deviation: 1-18%). The method was sensitive with LOQ comprised between 0.1 and 0.4 ng/ml for androgens and between 0.098 and 10.2 ng/ml for estrogens. The results obtained on the serum of rats exposed to the targeted endocrine disruptors showed the suitability of this analytical strategy.

Chronic dietary exposure to a low-dose mixture of genistein and vinclozolin modifies the reproductive axis, testis transcriptome, and fertility

BACKGROUND

The reproductive consequences and mechanisms of action of chronic exposure to low-dose endocrine disruptors are poorly understood.

OBJECTIVE

We assessed the effects of a continuous, low-dose exposure to a phytoestrogen (genistein) and/or an antiandrogenic food contaminant (vinclozolin) on the male reproductive tract and fertility.

METHODS

Male rats were exposed by gavage to genistein and vinclozolin from conception to adulthood, alone or in combination, at low doses (1 mg/kg/day) or higher doses (10 and 30 mg/kg/day). We studied a number of standard reproductive toxicology end points and also assessed testicular mRNA expression profiles using long-oligonucleotide microarrays.

RESULTS

The low-dose mixture and high-dose vinclozolin produced the most significant alterations in adults: decreased sperm counts, reduced sperm motion parameters, decreased litter sizes, and increased post implantation loss. Testicular mRNA expression profiles for these exposure conditions were strongly correlated. Functional clustering indicated that many of the genes induced belong to the "neuroactive ligand-receptor interactions" family encompassing several hormonally related actors (e.g., follicle-stimulating hormone and its receptor). All exposure conditions decreased the levels of mRNAs involved in ribosome function, indicating probable decreased protein production.

CONCLUSIONS

Our study shows that chronic exposure to a mixture of a dose of a phytoestrogen equivalent to that in the human diet and a low dose-albeit not environmental-of a common anti-androgenic food contaminant may seriously affect the male reproductive tract and fertility.

Effects of a 5-day treatment with vinclozolin on the hypothalamo-pituitary-gonadal axis in male rats

Vinclozolin (VZ), a potent antiandrogenic fungicide, is known to interfere with male reproductive function. Little data are currently available regarding possible impacts of VZ on brain function, particularly neuroendocrine activity and regulation of the hypothalamo-pituitary-gonadal (HPG) axis. Therefore, we examined the effects of VZ on gene expression in the brain (MBH/ME, MPOA/AH, striatum, hippocampus), pituitary, prostate, seminal vesicles, and epididymis of 4-month-old male rats treated daily by gavage for 5 days with VZ (150 mg/kg body weight/day). Alterations in levels of serum hormones and gene expression were determined by RIA and qRT-PCR, respectively. Our results revealed that (i) VZ decreases epididymis weights, increases serum levels of LH and T, and decreases serum TSH and total T(4) levels; (ii) VZ affects the hypothalamic expression of both estrogen receptor (ERs) subtypes, ERalpha and ERbeta; (iii) in the extrahypothalamic brain areas, VZ alters expression of ERs and androgen receptor (AR); (iv) in the pituitary, VZ up-regulates expression of the GnRH receptor, LHbeta, alpha-subunit, and TERP-1/-2; (v) in the ventral prostate, VZ increases and decreases levels of AR and ERbeta mRNA, respectively; (vi) in the seminal vesicles, VZ increases levels of AR and ERalpha mRNA expressions; (vii) in the epididymis, VZ up-regulates AR and ERbeta mRNA expression. These results indicate that in vivo VZ is not a 'pure' antiandrogen, since it exerts mixed AR antagonistic/ERs agonistic actions observed at the levels of mRNA expression of selected androgen- and estrogen-regulated genes in the CNS, pituitary, and male accessory sex organs.

Subacute oral toxicity study of bisphenol F based on the draft protocol for the “Enhanced OECD Test Guideline no. 407”

Since bisphenol F (4,4'-dihydroxydiphenylmethane) has been reported to exhibit estrogen agonistic properties in the uterotrophic assay, we performed a 28-day repeated-dose toxicity study (enhanced OECD test guideline No. 407) on bisphenol F based on the OECD draft protocols to determine whether it has endocrine-mediated properties. Bisphenol F was orally administered at doses 0, 20, 100 and 500 mg/kg per day for at least 28 days, but no clear endocrine-mediated changes were detected, and it was concluded to have no endocrine-mediated effects in young adult rats. On the other hand, the main effect of bisphenol F was concluded to be liver toxicity based on clinical biochemical parameters and liver weight, but without histopathological changes. The no-observed-effect level for bisphenol F is concluded to be under 20 mg/kg per day since decreased body weight accompanied by decreased serum total cholesterol, glucose, and albumin values were observed in the female rats given 20 mg/kg per day or higher doses of bisphenol F.

Uterotrophic assay, Hershberger assay, and subacute oral toxicity study of 4,4´-[1-[4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl]ethylidene]bis[phenol] based on the OECD draft protocols

We performed an uterotrophic assay, the Hershberger assay, and a 28-day repeated-dose toxicity study (enhanced OECD test guideline No. 407) of 4,4 -[1-[4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl]ethylidene]bis[phenol] based on the OECD draft protocols. In the uterotrophic assay, female SD rats were subcutaneously injected with the chemical at doses of 0, 100, 300, and 1,000 mg/kg on each of 3 days from postnatal day 20 to day 22, and the uterine weight of rats given the 1,000 mg/kg dose of the test chemical plus ethinyl estradiol decreased. In the Hershberger assay, the test chemical was orally administered at doses of 0, 100, 300, and 1,000 mg/kg day to castrated male SD rats for ten consecutive days beginning on postnatal day 56, and no changes were observed. On the other hand, when the test chemical was orally administered at doses 0, 100, 300, and 1,000 mg/kg day for at least 28 days, a decrease in LH values in rats of both sexes and a decrease in FSH and estradiol values in female rats were detected in the 1,000 mg/kg group, and abnormal estrous cycles, uterine glandular atrophy, persistence of ovarian corpora lutea, vaginal epithelial mucification, and mammary glandular hyperplasia were also observed in one female rat in the 1,000 mg/kg group. Therefore, the uterotrophic assay used in this study showed that the chemical has the estrogen-antagonist properties, and some potentially endocrine-mediated effects were detected in growing rats based on the results of the enhanced OECD test guideline No. 407. However, the changes were observed in rats given a high dose of the chemical, 1,000 mg/kg day.

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

Female reproductive function depends upon the exquisite control of ovarian steroidogenesis that enables folliculogenesis, ovulation, and pregnancy. These mechanisms are set during fetal and/or neonatal development and undergo phases of differentiation throughout pre- and post-pubescent life. Ovarian development and function are collectively regulated by a host of endogenous growth factors, cytokines, gonadotropins, and steroid hormones as well as exogenous factors such as nutrients and environmental agents. Endocrine disruptors represent one class of environmental agent that can impact female fertility by altering ovarian development and function, purportedly through estrogenic, anti-estrogenic, and/or anti-androgenic effects. This review discusses ovarian development and function and how these processes are affected by some of the known estrogenic and anti-androgenic endocrine disruptors. Recent information suggests not only that exposure to endocrine disruptors during the developmental period causes reproductive abnormalities in adult life but also that these abnormalities are transgenerational. This latter finding adds another level of importance for identifying and understanding the mechanisms of action of these agents.

Repeated 28-day oral toxicity study of ketoconazole in rats based on the draft protocol for the “Enhanced OECD Test Guideline No. 407” to detect endocrine effects

We performed a 28-day repeated-dose toxicity study of ketoconazole, a widely used an antimycotic drug, based on the draft protocol of the "Enhanced OECD Test Guideline 407" (Enhanced TG407) to investigate whether ketoconazole has endocrine-mediated properties according to this assay. Seven-week-old SD rats were administered with ketoconazole daily by oral gavage at doses of 0, 6.25, 25 or 100 mg kg(-1) day(-1) for at least 28 days. The ketoconazole-treated male rats showed reduction of epididymis and accessory sex organ weights, spermatid retention in the seminiferous tubules, decrease of testosterone and increases of estradiol, luteinizing hormone (LH) and follicular stimulating hormone (FSH). A prolongation of the estrous cycle and increases of estradiol, LH and FSH were observed in the treated female rats. Thyroxin and triiodothyronine were decreased and thyroid-stimulating hormone was increased in both sexes; however, there were no compound-related microscopic lesions in the thyroid gland or changes in the thyroid weight. The endocrine-related effects of ketoconazole could be detected by the parameters examined in the present study based on the Organization for Economic Cooperation and Development (OECD) protocol, suggesting that the Enhanced TG407 protocol should be a suitable screening test for detection of endocrine-mediated effects of chemicals.