Developmental exposure to bisphenol A (BPA), an endocrine-disrupting contaminant, impairs cognitive function in both animals and humans. However, whether BPA affects the development of primary sensory systems, which are the first to mature in the cortex, remains largely unclear. Using the rat as a model, we aimed to record the physiological and structural changes in the primary auditory cortex (A1) following lactational BPA exposure and their possible effects on behavioral outcomes. We found that BPA-exposed rats showed significant behavioral impairments when performing a sound temporal rate discrimination test. A significant alteration in spectral and temporal processing was also recorded in their A1, manifested as degraded frequency selectivity and diminished stimulus rate-following by neurons. These post-exposure effects were accompanied by changes in the density and maturity of dendritic spines in A1. Our findings demonstrated developmental impacts of BPA on auditory cortical processing and auditory-related discrimination, particularly in the temporal domain. Thus, the health implications for humans associated with early exposure to endocrine disruptors such as BPA merit more careful examination.
Humans ; Rats ; Animals ; Benzhydryl Compounds/toxicity* ; Phenols/toxicity* ; Auditory Perception/physiology* ; Neurons/physiology*

BACKGROUND: Traditional toxicological studies focus on individual compounds. However, this single-compound approach neglects the fact that the mixture exposed to human may act additively or synergistically to induce greater toxicity than the single compounds exposure due to their similarities in the mode of action and targets. Mixture effects can occur even when all mixture components are present at levels that individually do not produce observable effects. So the individual chemical effect thresholds do not necessarily protect against combination effects, an understanding of the rules governing the interactive effects in mixtures is needed. The aim of the study was to test and analyze the individual and combined estrogenic effects of a mixture of three endocrine disrupting chemicals (EDCs), bisphenol A (BPA), nonylphenol (NP) and diethylstilbestrol (DES) in immature rats with mathematical models. METHOD: In the present study, the data of individual estrogenic effects of BPA, NP and DES were obtained in uterotrophic bioassay respectively, the reference points for BPA, NP and DES were derived from the dose-response ralationship by using the traditional no observed adverse effect (NOAEL) or lowest observed adverse effect level (LOAEL) methods, and the benchmark dose (BMD) method. Then LOAEL values and the benchmark dose lower confidence limit (BMDL) of single EDCs as the dose design basis for the study of the combined action pattern. Mixed prediction models, the 3 × 2 factorial design model and the concentration addition (CA) model, were employed to analyze the combined estrogenic effect of the three EDCs. RESULTS: From the dose-response relationship of estrogenic effects of BPA, NP and DES in the model of the prepuberty rats, the BMDL(NOAEL) of the estrogenic effects of BPA, NP and DES were 90(120) mg/kg body weight, 6 mg/kg body weight and 0.10(0.25) μg/kg body weight, and the LOAEL of the the estrogenic effects of three EDCs were 240 mg/kg body weight, 15 mg/kg body weight and 0.50 μg/kg body weight, respectively. At BMDL doses based on the CA concept and the factorial analysis, the mode of combined effects of the three EDCs were dose addition. Mixtures in LOAEL doses, NP and DES combined effects on rat uterine/body weight ratio indicates antagonistic based on the CA concept but additive based on the factorial analysis. Combined effects of other mixtures are all additive by using the two models. CONCLUSION Our results showed that CA model provide more accurate results than the factorial analysis, the mode of combined effects of the three EDCs were dose addition, except mixtures in LOAEL doses, NP and DES combined effects indicates antagonistic effects based on the CA model but additive based on the factorial analysis. In particular, BPA and NP produced combination effects that are larger than the effect of each mixture component applied separately at BMDL doses, which show that additivity is important in the assessment of chemicals with estrogenic effects. The use of BMDL as point of departure in risk assessment may lead to underestimation of risk, and a more balanced approach should be considered in risk assessment.
Animals ; Benzhydryl Compounds ; toxicity ; Diethylstilbestrol ; toxicity ; Dose-Response Relationship, Drug ; Drug Interactions ; Endocrine Disruptors ; toxicity ; Estrogens ; toxicity ; Models, Theoretical ; Phenols ; toxicity ; Rats ; Rats, Sprague-Dawley ; Risk Assessment

The reproductive toxicity of environmental endocrine disruptors has attracted substantial attention from researchers in recent years. Bisphenol A (BPA) is among the most prominent environmental estrogens worldwide, demonstrated to be related with the impairment of male reproductive function as well as other health problems, such as diabetes, obesity, cardiovascular diseases, and cancer. BPA acts primarily by mimicking antiandrogenic and estrogenic effects, disturbing the hypothalamic-pituitary-testicular axis and modulating gene expressions and enzyme activities in the hormone biosynthesis affecting steroids or its receptors. BPA is also involved in DNA methylation and the effects of epigenetics, resulting in dyszoospermia, oligoasthenoteratospermia/azoospermia and/or infertility in males. This review addresses the effects of BPA on male reproductive function, focusing on the mechanisms of its toxicity on spermatogenesis, semen quality, and the reproductive system.
Benzhydryl Compounds ; toxicity ; Endocrine Disruptors ; toxicity ; Endocrine System ; drug effects ; Environmental Pollutants ; toxicity ; Estrogens ; toxicity ; Humans ; Infertility, Male ; chemically induced ; Male ; Phenols ; toxicity ; Semen Analysis ; Spermatogenesis ; drug effects

To study the toxicokinetics of bakuchiol, hepatic and renal toxicity in rats after single oral administration of Psoraleae Fructus and combined with Glycyrrhizae Radix et Rhizoma, in order to provide scientific evidences for clinical safe medication use. A total of 35 SD rats were randomly divided into seven groups: vehicle (distilled water) control group, Glycyrrhizae Radix et Rhizoma group, positive control (aristolochic acid A) group, Psoraleae Fructus (40 g x kg(-1)) group( both male and female rats), Psoraleae Fructus and Glycyrrhizae Radix et Rhizoma (40 +20) g x kg(-1) group (both male and female rats). HPLC-UV method was used to determine the concentration of bakuchiol in rat plasma at different time points after single oral administration. Plasma alanine transaminase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), plasma creatinine (Cr), N-acetyl-β-D-glucosaminidase (NAG) and kidney injury molecule 1 (Kim-1) were measured after administration for 24 h. The main toxicokinetics parameters of bakuchiol in rats exert significantly gender difference. When Psoraleae Fructus combination with Glycyrrhizae Radix et Rhizoma, the total area under the plasma concentration-time curve( AUC), C(max), and plasma clearance (CL) of bakuchiol were increased, respectively; CL, half-life (t½) were decreased, and T(max) were prolonged. The biochemical indicators (including ALT, AST, BUN, Cr and KIM-1 level) in different dose of Psoraleae Fructus groups, were found no statistically significant difference when compared with vehicle control group. The level of NAG in both Psoraleae Fructus and compatibility with Glycyrrhizae Radix et Rhizoma groups were significant increased (P < 0.05). There are obvious effects on toxicokinetics of bakuchiol in rats when Psoraleae Fructus combined with Glycyrrhizae Radix et Rhizoma. Renal toxicity induced by Psoraleae Fructus at high dose was observed after single oral administration and no liver damage in rats was found.
Administration, Oral ; Animals ; Female ; Glycyrrhiza ; toxicity ; Kidney ; drug effects ; Liver ; drug effects ; Male ; Phenols ; pharmacokinetics ; toxicity ; Psoralea ; toxicity ; Rats ; Rats, Sprague-Dawley ; Rhizome ; toxicity ; Toxicokinetics

Bisphenol A (BPA) is a commonly used phenolic environmental estrogen. Long-term exposure of female mammalians to BPA can lead to endocrine disorders, followed by the morphological and functional changes in ovary, uterus, vagina, and oviducts. The interactions of BPA with various target molecules or tissues will cause different effects. To further elucidate the effects of BPA on female reproductive system, we review the changes in the structure and functions of female reproduction system after BPA exposure and their possible mechanisms.
Benzhydryl Compounds ; toxicity ; Endocrine Disruptors ; toxicity ; Estrogens, Non-Steroidal ; toxicity ; Female ; Humans ; Ovary ; drug effects ; Phenols ; toxicity ; Uterus ; drug effects ; Vagina ; drug effects

OBJECTIVETo explore the effect of environmental estrogens on the proliferation of breast cancer cell line MCF-7.

METHODSThe tested compounds were n-4-nonyphenol, Bisphenol A and dibutylphthalate. Human estradiol-dependent MCF-7 breast cancer cells were grown in DMEM medium containing 10% bovine serum. Five days before the addition of the test compounds, the cells were washed by phosphate-buffered saline, and the medium was substituted with a phenol red-free DMEM medium containing 5% dextral charcoal-stripped FBS. The respective test compound was added in fresh medium and the control cell received only the vehicle (ethanol). The proliferation of MCF-7 was analyzed by the MTT assay, (3)H-TdR incorporation assay and flow cytometry.

RESULTSCompared with the ethanol control, the proliferation and DNA synthesis of the test cells treated with n-4-nonyphenol (8 x 10(-7) mol/L, 96 h), Bisphenol A (8 x 10(-7) mol/L, 96 h) or dibutylphthalate (32 x 10(-6) mol/L, 96 h) treatment was markedly enhanced in a time-dependent and dose-dependent manner.

CONCLUSIONn-4-Nonyphenol, Bisphenol A and dibutylphthalate enhanced the proliferation of human breast cancer cell in vitro, which may demonstrate an estrogenic activity.

Benzhydryl Compounds ; Breast Neoplasms ; pathology ; Cell Division ; drug effects ; Cell Line, Tumor ; Dibutyl Phthalate ; toxicity ; Environmental Pollutants ; toxicity ; Estrogens, Non-Steroidal ; toxicity ; Female ; Humans ; Phenols ; toxicity

The research on endocrine disrupters has become one of the key directions in the field of environmental medical science. Nonylphenol ethoxylates (NPEs) are widely used in industry and family washing as one of the non-ionic surfactants. NPEs can be degraded biologically to nonylphenol (NP), whose estrogenic effects or toxicity may do harm to the reproductive systems of male fish, amphibians and mammals. Thus it is an urgent affair to develop perfect assays, evaluate the harm of these chemicals to human beings, find the exact mechanism of action and restrict the use of NPEs.
Animals ; Dose-Response Relationship, Drug ; Fishes ; Genitalia, Male ; drug effects ; Male ; Phenols ; toxicity ; Rats ; Water Pollutants, Chemical ; toxicity ; Xenopus

OBJECTIVETo study the correlation of toxicity with biodegradability (BODT) in order to promote QSBR development and understand the degradation mechanism.

METHODSToxicity of substituted phenols to river bacteria was determined by the turbidities that were measured using a spectrophotometer (UV-190) at 530 nm against a blank control. The biodegradability of substituted phenols was expressed as BODT and the DO concentrations were determined by the iodometric titration method.

RESULTSThe BODT and toxicity(log 1/IC50) of 12 substituted phenols to bacteria from the Songhua River were determined respectively. The correlation of biodegradability with toxicity was developed: BODT=8.21 (+/-2.22) pKa -32.44 (+/-8.28) log 1/IC50 +89.04 (+/-38.20), n=12, R2=0.791, R2(adj)=0.745, SE=9.134, F=17.066, P=0.001.

CONCLUSIONThe BODT of substituted phenols was influenced by their toxicity and the ionization constant pKa. The stronger the toxicity, the less readily the compound was degraded by river bacteria.

Bacteria ; metabolism ; Biodegradation, Environmental ; Data Interpretation, Statistical ; Models, Biological ; Phenols ; chemistry ; metabolism ; toxicity ; Rivers ; microbiology ; Water Pollutants, Chemical ; metabolism ; toxicity

OBJECTIVETo investigate the relationship of time-concentration of bisphenol A (BPA) in male Sprague-Dawley (SD) rats after single oral BPA administration.

METHODSA total of 66 specific pathogen free (SPF) SD male rats were divided into 10 experimental groups and control group (n = 6). The experimental group rats were treated with BPA of 300 mg/kg by oral gavage and blood samples were taken from one group at 0.5, 1, 2, 4, 6, 12, 24, 36, 60, 84 h time point after oral administration, respectively. The serum BPA concentration was determined by fluorescence-high performance liquid chromatography (FL-HPLC) analysis.

RESULTSAfter oral administration of 300 mg/kg, the total serum BPA concentration of 17.13 microg/ml was the highest in rats at 1 h, then decreased, but it increased to 15.18 microg/ml again at 24 h, then gradually decreased to 0.51 microg/ml at 84 h. The level of serum free BPA was lower than that of total serum BPA after oral administration, the serum free BPA was 0.57 microg/ml at 0.5 h after oral administration. The serum free BPA level decreased to 0.06 microg/ml at 1 h, 0.03 microg/ml at 4 h, 0.01 microg/ml at 36 h after oral administration. The free BPA was only 4.15% (0.57/13.73) in total BPA in serum at 0.5 h after oral administration of 300 mg/kg BPA.

CONCLUSIONThese results suggested that conjugated BPA was the main metabolite of BPA in rat serum after single oral administration. Enterohepatic circulation of BPA glucuronide in rats may results in two peak levels of total BPA in serum.

Animals ; Benzhydryl Compounds ; Male ; Phenols ; blood ; pharmacokinetics ; toxicity ; Rats ; Rats, Sprague-Dawley ; Serum ; metabolism ; Time Factors

OBJECTIVE: Bisphenol A (BPA) is a monomer primarily used in the production of polycarbonate plastic and epoxy resins. Bisphenol F (BPF) is apparently the main BPA replacement that is used increasingly. BPF has been detected in canned food, thermal paper receipts, and soft drinks. In the present experiment, we did both in vitro and in vivo studies to evaluate the effect of low and high-dose BPF exposures on testosterone concentration, oxidative stress, and antioxidants activity in reproductive tissues of male rats. METHODS: Adult (80-90 days old) male Sprague Dawley rats (n = 36) obtained from the rodent colony of Animal Sciences Department of Quaid-i-Azam University. The direct effects of BPF on the antioxidant enzymes and testosterone secretion were measured in vitro and in vivo studies. In an in vivo experiment, adult male Sprague Dawley rats (n = 42) were exposed to different concentrations of bisphenol F (1, 5, 25, and 50 mg/kg/d) for 28 days. Various biochemical parameters were analyzed including the level of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), reactive oxygen species (ROS), and lipid peroxidation (LPO). Moreover, sperm motility, daily sperm production (DSP), comet assay, and histological analysis were performed. RESULTS: In vitro study showed that BPF exposure significantly (p < 0.05) induced oxidative stress biomarkers, i.e., ROS and LPO, while it did not change antioxidant enzyme and testicular testosterone concentration. Whereas, an in vivo study revealed that BPF induced dose-dependent effect and high-dose (100 mg/kg) exposure of BPF significantly reduced tissue protein (p < 0.05) content, CAT (p < 0.001), SOD (p < 0.05), and POD (p < 0.05) levels while significantly (p < 0.05) augmented ROS and lipid peroxidation. Furthermore, BPF reduces testosterone, LH, and FSH secretion in a dose-dependent manner. Significant (p < 0.001) reduction in plasma and intra-testicular testosterone, LH, and FSH was noticed at 100 mg/kg BFP dose. High-dose exposure reduces spermatogenesis. CONCLUSION BPF showed an antagonistic effect on male reproductive hormones and induce alterations in testicular morphology. Increased oxidative stress and decreased testicular antioxidant status might be the underlying mechanism of BFP-induced testicular toxicity.
Animals ; Antioxidants ; metabolism ; Benzhydryl Compounds ; toxicity ; Dose-Response Relationship, Drug ; Environmental Pollutants ; toxicity ; Male ; Oxidative Stress ; drug effects ; Phenols ; toxicity ; Rats ; Rats, Sprague-Dawley ; Testosterone ; metabolism