Impact of polychlorinated biphenyl Aroclor 1254 on testicular antioxidant system in adult rats

d-ribose- l-cysteine abrogates testicular maladaptive responses induced by polychlorinated bisphenol intoxication in rats via activation of the mTOR signaling pathway mediating inhibition of apoptosis, inflammation, and oxidonitrergic flux

Male reproductive maladaptive responses are becoming a global health concern and also a social issue. Polychlorinated biphenyls (PCBs) are a member of halogenated aromatic environmental pollutants with diverse environmental matrices. This study was conducted to explore the mechanisms of PCBs-induced testicular maladaptive responses and the potential reversal effects of d-ribose- l-cysteine (DRLC) on testicular injury induced by administration of PCBs (2 mg/kg) for 30 days. DRLC (50 mg/kg) was administered orally for 15 days starting from Days 16 to 30 after the initial 15 days of treatment with PCB. All assays were carried out using established protocols. Administration of DRLC at 50 mg/kg after treatment with PCBs enhances body and testicular weights, gonadotropins (luteinizing hormone and follicle-stimulating hormone), testosterone and poor sperm quality. DRLC also reduced testicular injury score, improved spermatogenesis scoring, reduced oxidative stress biomarkers (malondialdehyde), as well as restored the reduced activities of antioxidant enzymes (glutathione peroxidase, superoxide dismutase, and catalase) and decreases pro-inflammatory response (tumor necrosis factor-alpha and NO). More so, DRLC treatment abrogates testicular DNA fragmentation and downregulated p53 and caspase 3 activities and upregulated the concentration of autophagy-related protein (mammalian target of rapamycin [mTOR] and Atg7). DRLC abates testicular deficit induced by PCBs intoxicated rats via activation of the mTOR signaling pathway mediating inhibition of apoptosis, Inflammation and oxidative flux.

Geographic and Ethnic Variations in Serum Concentrations of Legacy Persistent Organic Pollutants among Men in the Nenets Autonomous Okrug, Arctic Russia

The overwhelming majority of Arctic biomonitoring studies in humans include either pregnant or non-pregnant women of reproductive age while little attention is paid to toxic compounds concentrations in men. This study contributes with information of the present amounts of persistent organic pollutants (POPs) in men living in Arctic Russia. We studied the serum concentrations of 11 polychlorinated biphenyl (PCB) congeners and 17 organochlorine pesticides (OCPs) and some of their metabolites in samples collected from 92 adult men (mean age 43 years) from seven different settlements in Nenets Autonomous Okrug (NAO). The median concentrations of individual PCB congeners increased in the order PCB 183, PCB 180, PCB 118, PCB 138, PCB 153. The concentrations of o, p′-DDD, p, p′-DDD, aldrin, mirex and 1,2,3,5-TCB were in most cases below the quantification limit. The observed concentrations of PCBs and chlorinated pesticides were in the same range as those found in similar groups of women of these territories, but lower than of men in other Arctic countries. However, significant geographic differences between the settlements were observed with exceptionally high concentrations of PCBs in the Islands group. The highest serum ∑PCBs and β-HCH levels were observed in adult males aged 60–78 years. We found significant variations in serum concentrations of POPs across settlements and ethnic groups with exceptionally high concentrations of PCBs among the residents of the Arctic islands. At the same time, our findings suggest a considerable decrease in serum concentration of POPs over the last decade.

Impact of quercetin on tight junctional proteins and BDNF signaling molecules in hippocampus of PCBs-exposed rats

Polychlorinated biphenyls (PCBs) consist of a range of toxic substances which are directly proportional to carcinogenesis and tumor-promoting factors as well as having neurotoxic properties. Reactive oxygen species, which are produced from PCBs, alter blood–brain barrier (BBB) integrity, which is paralleled by cytoskeletal rearrangements and redistribution and disappearance of tight junction proteins (TJPs) like claudin-5 and occludin. Brain-derived neurotrophic factor (BDNF), plays an important role in the maintenance, survival of neurons and synaptic plasticity. It is predominant in the hippocampal areas vital to learning, memory and higher thinking. Quercetin, a flavonoid, had drawn attention to its neurodefensive property. The study is to assess the role of quercetin on serum PCB, estradiol and testosterone levels and mRNA expressions of estrogen receptor α and β, TJPs and BDNF signaling molecules on the hippocampus of PCBs-exposed rats. Rats were divided into 4 groups of 6 each. Group I rats were intraperitoneally (i.p.) administered corn oil (vehicle). Group II received quercetin 50 mg/kg/bwt (gavage). Group III received PCBs (Aroclor 1254) at 2 mg/kg bwt (i.p). Group IV received quercetin 50 mg/kg bwt (gavage) simultaneously with PCBs 2 mg/kg bwt (i.p.). The treatment was given daily for 30 days. The rats were euthanized 24 h after the experimental period. Blood was collected for quantification of serum PCBs estradiol and testosterone. The hippocampus was dissected and processed for PCR and Western blot; serum PCB was observed in PCB treated animals, simultaneously quercetin treated animals showed PCB metabolites. Serum testosterone and estradiol were decreased after PCB exposure. Quercetin supplementation brought back normal levels. mRNA expressions of estrogen α and β were decreased in the hippocampus of PCB treated rats. TJPS and BDNF signalling molecules were decreased in hippocampus of PCB treated rats. Quercetin supplementation retrieved all the parameters. Quercetin alone treated animals showed no alteration. Thus in PCB caused neurotoxicity, quercetin protects and prevents neuronal damage in the hippocampus.

Intracellular toxicity exerted by PCBs and role of VBNC bacterial strains in biodegradation

Polychlorinated biphenyls (PCBs) are xenobiotic compounds that persists in the environment for long-term, though its productivity is banned. Abatement of the pollutants have become laborious due to it's recalcitrant nature in the environment leading to toxic effects in humans and other living beings. Biphenyl degrading bacteria co-metabolically degrade low chlorinated PCBs using the active metabolic pathway. bph operon possess different genetic arrangements in gram positive and gram negative bacteria. The binding ability of the genes and the active sites were determined by PCB docking studies. The active site of bphA gene with conserved amino acid residues determines the substrate specificity and biodegradability. Accumulation of toxic intermediates alters cellular behaviour, biomass production and downturn the metabolic activity. Several bacteria in the environment attain unculturable state which is viable and metabolically active but not cultivable (VBNC). Resuscitation-promoting factor (Rpf) and Rpf homologous protein retrieve the culturability of the so far uncultured bacteria. Recovery of this adaptive mechanism against various physical and chemical stressors make a headway in understanding the functionality of both environmental and medically important unculturable bacteria. Thus, this paper review about the general aspects of PCBs, cellular toxicity exerted by PCBs, role of unculturable bacterial strains in biodegradation, genes involved and degradation pathways. It is suggested to extrapolate the research findings on extracellular organic matters produced in culture supernatant of VBNC thus transforming VBNC to culturable state.

Lycopene reduces in utero bisphenol A exposure-induced mortality, benefits hormones, and development of reproductive organs in offspring mice

This study was conducted to investigate the protective effect of lycopene on reproductive toxicity induced by in utero exposure to bisphenol A (BPA) in offspring mice. Pregnant mice in the BPA model group were given orally 500 mg/kg/day BPA from pregnant day (PD)8 to PD14. Mice of lycopene group were gavaged with 20 mg/kg/day lycopene from PD1 to PD7 and then given 500 mg/kg/day BPA from PD8 to PD14. Results showed that lycopene reduced the elevated mortality in offspring mice of the mother exposed to BPA. BPA lowered the levels of testosterone, luteinizing hormone, and follicle-stimulating hormone while lycopene treatment increased the levels significantly. BPA elevated estradiol while lycopene lowered estradiol in the offspring. BPA caused testicular damage as shown by less Leydig cells and ovarian injury as shown by less corpus granules in adult offspring, while lycopene decreased the damages. Maternal exposure to BPA increased Bax and decreased Bcl-2 in testicular and ovary tissues in the offspring mice. Lycopene decreased Bax in testis and ovary and increased Bcl-2 in ovary tissues in the offspring mice. These findings suggest lycopene has protective effects on in utero BPA exposure-induced reproductive toxicity in offspring mice.

Lipoic acid and Calligonum comosumon attenuate aroclor 1260-induced testicular toxicity in adult rats

Aroclor 1260 is one of the more representative polychlorinated biphenyls found in biota. This study was designed to delineate the testicular toxicity of Aroclor 1260 and to elucidate the potential protective role of Calligonum comosum (C. comosum) and lipoic acid in adult rats. Aroclor 1260 was dissolved in corn oil and given to rats by gavage at doses 0, 20, 40, or 60 mg/kg/day for 15 consecutive days (Groups I, II, III, and IV, respectively). Groups V and VI were pretreated with C. comosum (200 mg/kg/day) and lipoic acid (35 mg/kg/day) respectively 24 h before Aroclor 1260 (40 mg/kg/day) treatment for 15 consecutive days. Aroclor 1260 (20, 40 or 60 mg/kg/day) treatment significantly decreased testes weight, sperm count and motility and daily sperm production. Serum testosterone was significantly decreased in response to treatment with 40 and 60 mg/kg/day of Aroclor 1260. LDH-X activity was significantly decreased at the three dose levels. Hydrogen peroxide (H₂ O₂ ) production (in a dose-related manner) and lipid peroxidation were significantly increased in response to Aroclor 1260 (20, 40, or 60 mg/kg/day) treatment. Aroclor 1260 at the three dose levels decreased the activities of the antioxidant enzymes SOD, CAT, GPx, and GR and the non-enzymatic antioxidant GSH level. CAT, GPx and GSH showed a dose-response effect. These abnormalities were effectively attenuated by pretreatment with C. comosum (200 mg/kg/day) or lipoic acid (35 mg/kg/day). Histopathological examination showed a dose-related increase in morphological abnormalities of the testis in response to Aroclor 1260 treatment. In conclusion, Aroclor 1260 induced testicular toxicity at least, in part, by induction of oxidative stress. By reversal of biochemical and morphological changes towards normalcy, the cytoprotective role of C. comosum and lipoic acid is illuminated. In comparison, lipoic acid was more protective than C. comosum extract against testicular toxicity induced by Aroclor 1260. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1147-1157, 2017.

A relevant exposure to a food matrix contaminated environmentally by polychlorinated biphenyls induces liver and brain disruption in rats

Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants present in dietary fats. Most studies evaluating PCB effects have been conducted with a single compound or a mixture of PCBs given as a single acute dose. The purpose of this study was to evaluate in vivo PCB toxicity in a realistic model of exposure: a low daily dose of PCBs (twice the tolerable daily intake (TDI)), chronically administered (8 weeks) to rats in contaminated goat milk. Liver and brain PCB toxicities were investigated by evaluating oxidative stress status and mitochondrial function. PCB toxicity in the liver was also estimated by transaminase enzymatic activity. This study shows that even at low doses, chronic PCB exposure resulted in a statistically significant reduction of mitochondrial function in liver and brain. In the liver, oxygen consumption in the condition of adenosine triphosphate (ATP) production (state 3) decreased by 22-29% (p < 0.01), according to the respiratory substrates. In the brain, respiratory chain complexes II and III were reduced by 24% and 39%, respectively (p < 0.005). The exposed rats presented higher lipid peroxidation status (+20%, p < 0.05) and transaminase activity (+30%, p < 0.05) in the blood. Thus, our study showed that exposure of rats to a daily realistic dose of PCBs (twice the TDI in a food complex mixture of environmental origin) resulted in multiple disruptions in the liver and brain.

Tributyltin-mediated hepatic, renal and testicular tissue damage in male Syrian hamster (Mesocricetus auratus): a study on impact of oxidative stress

Organotin compounds are a versatile group of organometallic chemicals that are used in a variety of industrial and agricultural applications. Tributyltin (TBT), a common organotin, brings about severe spermatotoxic and organotoxic effects. However, information about the adverse effects of TBT on liver, kidney and testis is scanty. Hence, the present study was undertaken to elucidate the TBT-mediated oxidative stress-induced impairments in these organs. Administration of TBT through oral route at increasing doses of 50, 100 and 150 ppm for 65 days to male Syrian hamsters resulted in drastically decreased activities of antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase and decreased mean levels of non-enzymatic antioxidants (reduced glutathione, vitamin C, and vitamin E) followed by a dramatic increase in the levels of lipid peroxidation in the liver, kidney and testis as compared to the control animals. Significantly high levels of serum urea, creatinine, uric acid and bilirubin were observed in TBT-treated hamsters. Also, TBT treatment induced drastic histopathological changes in the liver, kidney and testis combined with remarkable changes in serum levels of tissue injury marker enzymes Aspartate transaminases, Alkaline phosphatase and Alanine transaminase. These data affirm that exposure to TBT can lead to oxidative stress-induced damage to liver, kidney and testis.

Quercetin ameliorates polychlorinated biphenyls-induced testicular DNA damage in rats

Polychlorinated biphenyls (PCBs) are a group of environmental contaminants widely reported to cause gonadal toxicity in both humans and animals. This study investigated the amelioratory role of quercetin in PCBs-induced DNA damage in male Wistar rats. Polychlorinated biphenyls were administered intraperitoneally at a dose of 2 mg kg(-1) alone or in combination with quercetin (orally) at 50 mg kg(-1) for 25 days. Quercetin modulation of PCBs-induced gonadal toxicity was evaluated using selected oxidative stress indices, comet assay, measurement of DNA concentration and histology of the testes. Administration of PCBs alone caused a significant (P < 0.05) depletion in the total thiol level in testes of treated rats. Conversely, the levels of reactive oxygen species (ROS) and thiobarbituric acid reactive substances (TBARS) production were markedly elevated in testes of PCBs-treated rats compared with control. Further, PCBs exposure produced statistically significant increases in DNA tail migration, degraded double-stranded DNA (dsDNA) concentration and histological alterations of testes of the treated rats compared to control. Quercetin cotreatment significantly improved the testicular antioxidant status, decreased DNA fragmentation and restored the testicular histology, thus demonstrating the protective effect of quercetin in PCBs-treated rats.

Phenotypic malignant changes and untargeted lipidomic analysis of long-term exposed prostate cancer cells to endocrine disruptors

Endocrine disruptors (EDs) are a class of environmental toxic molecules able to interfere with the normal hormone metabolism. Numerous studies involve EDs exposure to initiation and development of cancers, including prostate cancer. In this work, three different EDs (aldrin, aroclor 1254 and chlorpyrifos (CPF)) were investigated as potential inducers of a malignant phenotype in DU145 prostate cancer cells after a chronic exposure. Epithelial to mesenchymal transition (EMT) induction, proliferation, migration, colony formation and release of metalloproteinase 2 (MMP-2) were analyzed in 50-day exposed cells to the selected EDs. As a result, aldrin and CPF exposure led to an EMT induction (loss of 16% and 14% of E-cadherin levels, respectively, compared to the unexposed cells). Aroclor and CPF presented an increased migration (134% and 126%, respectively), colony formation (204% and 144%, respectively) and MMP-2 release (137% in both cases) compared to the unexposed cells. An untargeted lipidomic analysis was performed to decipher the lipids involved in the observed transformations. As general results, aldrin exposure showed a global decrease in phospholipids and sphingolipids, and aroclor and CPF showed an increase of certain phospholipids, glycosphingolipids as well as a remarkable increase of some cardiolipin species. Furthermore, the three exposures resulted in an increase of some triglyceride species. In conclusion, some significant changes in lipids were identified and thus we postulate that some lipid compounds and lipid metabolic pathways could be involved in the acquisition of the malignant phenotype in exposed prostate cancer cells to the selected EDs.

Effects of Atrazine on Reproductive Health of Nondiabetic and Diabetic Male Rats

The aim of the present study was to investigate the effects of low dose of atrazine on reproductive system of male Wistar rats. 16 rats were divided into four groups of four animals each. Group I (nondiabetic) and group III (diabetic) animals served as controls that received safflower oil (300 μL/kg bw/day), respectively. Group II (nondiabetic) and group IV (diabetic) animals received atrazine (300 μg/kg bw/day). Nonsignificant decrease in the activities of antioxidant and steroidogenic enzymes and sperm parameters suggests that atrazine did not produce any effect on reproductive system of rats. Histological findings also revealed that atrazine at a dose of 300 μg/kg bw did not produce any testicular toxic effects in nondiabetic and diabetic atrazine treated rats. Low dose of atrazine did not show reproductive toxicity in rats. To know the effects of atrazine in diabetic rats further studies have to be carried out with increased concentration of atrazine.

Lycopene supplementation prevents reactive oxygen species mediated apoptosis in Sertoli cells of adult albino rats exposed to polychlorinated biphenyls

Sertoli cell proliferation is attenuated before attaining puberty and the number is fixed in adult testes. Sertoli cells determine both testis size and daily sperm production by providing physical and metabolic support to spermatogenic cells. Polychlorinated biphenyls (PCBs) exposure disrupts functions of Sertoli cells causing infertility with decreased sperm count. On the other hand, lycopene is improving sperm count and motility by reducing oxidative stress in humans and animals. Hence we hypothesized that PCBs-induced infertility might be due to Sertoli cell apoptosis mediated by oxidative stress and lycopene might prevent PCBs-induced apoptosis by acting against oxidative stress. To test this hypothesis, animals were treated with vehicle control, lycopene, PCBs and PCBs + lycopene for 30 days. After the experimental period, the testes and cauda epididymidis were removed for isolation of Sertoli cells and sperm, respectively. We observed increased levels of oxidative stress markers (H2O2 and LPO) levels, increased expression of apoptotic molecules (caspase-8, Bad, Bid, Bax, cytochrome C and caspase-3), decreased anti-apoptotic (Bcl2) molecule and elevated apoptotic marker activity (caspase-3) in Sertoli cells of PCBs-exposed animals. These results were associated with decreased sperm count and motility in PCBs exposed animals. On the other hand, lycopene prevented the elevation of Sertoli cellular apoptotic parameters and prevented the reduction of sperm parameters (count and motility). The data confirmed that lycopene as an antioxidant scavenged reactive oxygen substances, prevented apoptosis, maintained normal function in Sertoli cells and helped to provide physical and metabolic support for sperm production, thereby treating infertility in men.

Aroclor 1254 induced oxidative stress and mitochondria mediated apoptosis in adult rat sperm in vitro

Aroclor 1254, a commercial mixture of highly toxic environmental pollutant, is known to cause testicular toxicity. The present study was undertaken to delineate and elucidate the nature and the mechanism of action of Aroclor 1254 on rat sperm in vitro. Sperm of adult rat were incubated with 10(-9)M, 10(-8)M or 10(-7)M of Aroclor 1254 for 3h. Sperm motility was significantly decreased. Moreover, sperm viability, acrosome reaction and mitochondrial membrane potential (Δψm) were significantly decreased in a dose-related pattern. DNA integrity was significantly decreased at 10(-8)M and 10(-7)M of Aroclor 1254, while it did not show any significant change at 10(-9)M. Aroclor 1254 induced downstream events included cytochrome c release and caspase-3 activation, in a dose-related manner. ATP content was decreased while protein carbonyl content was significantly increased in a dose-related manner. The oxidative stress status was also assessed. Hydrogen peroxide (H2O2) production and lipid peroxidation (LPO) were significantly increased in a dose-related pattern. The antioxidant enzymes SOD, CAT and GPx were significantly decreased, while at a concentration of 10(-9)M of Aroclor 1254, GR activity did not show any significant change. The non-enzymatic antioxidant (GSH) was significantly decreased in a dose-dependent manner. In conclusion; our data clearly show that Aroclor 1254 induces toxicity, oxidative stress and culminating in mitochondria mediated apoptosis in rat sperm.

Impact of lycopene on epididymal androgen and estrogen receptors' expression in polychlorinated biphenyls-exposed rat

The aim of the study was to evaluate the androgen (AR) and estrogen receptors' (ER) expression in epididymis of polychlorinated biphenyls (PCBs)-exposed rats. The rats were assigned to groups. Group I controls were treated with corn oil 80 µL/d intraperitoneally (ip), group II were treated with 2 mg/kg/d of A1254 ip; and group III were treated with 2 mg/kg/d of A1254 ip along with simultaneous oral supplementation of 4 mg/kg/d lycopene . The treatment was given daily for 30 days. After 24 hours of treatment, the rats were killed, and the epididymal regions (caput, corpus, and cauda) were dissected out, weighed, and prepared to estimate the levels of sialic acid, glyceryl phosphoryl choline (GPC), hydrogen peroxide (H2O2), and lipid peroxidation (LPO). The messenger RNA (mRNA) expressions of AR, ERα, and ERβ were analyzed by reverse transcriptase-polymerase chain reaction, and ERα and ERβ protein expressions were analyzed by immunoblotting. The toxicity of PCBs was also confirmed by histology. There was a marked decrease in epididymal weight, sialic acid, and GPC levels, while oxidative stress markers H2O2 and LPO were increased in PCBs-treated rats. The mRNA and protein expression of AR, ERα, and ERβ were decreased in PCBs-treated groups, and the histology confirms the cytoplasmic damage in the regions of caput, corpus, and cauda in PCBs-treated rats. Simultaneous supplementation of lycopene to PCBs-exposed rats resulted in significant decrease in the oxidative stress markers as that of control, while the AR, ERα, and ERβ gene expressions were near to control. The results suggest that lycopene has ameliorative effect against PCBs-induced toxicity in epididymis.

Disruption of reproductive aging in female and male rats by gestational exposure to estrogenic endocrine disruptors

Polychlorinated biphenyls (PCBs) are industrial contaminants and known endocrine-disrupting chemicals. Previous work has shown that gestational exposure to PCBs cause changes in reproductive neuroendocrine processes. Here we extended work farther down the life spectrum and tested the hypothesis that early life exposure to Aroclor 1221 (A1221), a mixture of primarily estrogenic PCBs, results in sexually dimorphic aging-associated alterations to reproductive parameters in rats, and gene expression changes in hypothalamic nuclei that regulate reproductive function. Pregnant Sprague Dawley rats were injected on gestational days 16 and 18 with vehicle (dimethylsulfoxide), A1221 (1 mg/kg), or estradiol benzoate (50 μg/kg). Developmental parameters, estrous cyclicity (females), and timing of reproductive senescence were monitored in the offspring through 9 months of age. Expression of 48 genes was measured in 3 hypothalamic nuclei: the anteroventral periventricular nucleus (AVPV), arcuate nucleus (ARC), and median eminence (females only) by real-time RT-PCR. Serum LH, testosterone, and estradiol were assayed in the same animals. In males, A1221 had no effects; however, prenatal estradiol benzoate increased serum estradiol, gene expression in the AVPV (1 gene), and ARC (2 genes) compared with controls. In females, estrous cycles were longer in the A1221-exposed females throughout the life cycle. Gene expression was not affected in the AVPV, but significant changes were caused by A1221 in the ARC and median eminence as a function of cycling status. Bionetwork analysis demonstrated fundamental differences in physiology and gene expression between cycling and acyclic females independent of treatment. Thus, gestational exposure to biologically relevant levels of estrogenic endocrine-disrupting chemicals has sexually dimorphic effects, with an altered transition to reproductive aging in female rats but relatively little effect in males.

Dynamic postnatal developmental and sex-specific neuroendocrine effects of prenatal polychlorinated biphenyls in rats

Gestational exposures to estrogenic compounds, both endogenous hormones and exogenous endocrine-disrupting chemicals (EDCs), have long-term effects on reproductive physiology and behavior. We tested the hypothesis that prenatal treatment of rats with low doses of Aroclor 1221 (A1221), a weakly estrogenic polychlorinated biphenyl mix previously used in industry, or estradiol benzoate (EB), alters development of the hypothalamus in a sexually dimorphic manner and subsequently perturbs reproductive function. Pregnant Sprague-Dawley rats were injected on embryonic days 16 and 18 with vehicle (dimethylsulfoxide), A1221 (1 mg/kg), or EB (50 μg/kg). Developmental milestones were monitored, and on postnatal days 15, 30, 45, and 90, 1 male and 1 female per litter were euthanized. Because of their key roles in the mediation of steroid actions on reproductive function, the anteroventral periventricular nucleus (AVPV) and the arcuate nucleus (ARC) were punched for a low-density quantitative PCR array of 48 neuroendocrine genes and analysis of DNA methylation of a subset of genes. Gestational exposure to A1221 or EB delayed the timing of puberty in males and disrupted estrous cyclicity in females. In the AVPV, 28 genes were affected by treatment in a developmental stage-specific manner, mostly in females, which exhibited a masculinized expression profile. This included 2 clock genes, Per2 and Arntl, implicating circadian circuits as being vulnerable to endocrine disruption. DNA methylation analysis of 2 genes, Per2 and Ar, showed no effect of EDCs and suggested alternative mechanisms for the altered mRNA levels. In the ARC, 12 genes were affected by treatment, mostly in males, again with dynamic developmental changes. Bionetwork analysis of relationships among genes, hormones, and physiological markers showed sexually dimorphic effects of estrogenic EDC exposures, with the female AVPV and the male ARC being most vulnerable, and provided novel relationships among hypothalamic genes and postnatal reproductive maturation.

Polychlorinated biphenyls impair blood–brain barrier integrity via disruption of tight junction proteins in cerebrum, cerebellum and hippocampus of female Wistar rats

Polychlorinated biphenyls (PCBs) comprise a ubiquitous class of toxic substances associated with carcinogenic and tumor-promoting effects as well as neurotoxic properties. Reactive oxygen species, which is produced from PCBs, alters blood–brain barrier (BBB) integrity, which is paralleled by cytoskeletal rearrangements and redistribution and disappearance of tight junction proteins (TJPs) like claudin-5 and occludin. Quercetin, a potent antioxidant present in onion and other vegetables, appears to protect brain cells against oxidative stress, a tissue-damaging process associated with Alzheimer’s and other neurodegenerative disorders. The aim of this study is to analyze the role of quercetin on oxidative stress markers and transcription of transmembrane and cytoplasmic accessory TJPs on cerebrum, cerebellum and hippocampus of female rats exposed to PCBs. Rats were divided into the following four groups. Group I: received only vehicle (corn oil) intraperitoneally (i.p.); group II: received Aroclor 1254 at a dose of 2 mg/kg body weight (bwt)/day (i.p); group III: received Aroclor 1254 (i.p.) and simultaneously quercetin 50 mg/kg bwt/day through gavage and group IV: received quercetin alone gavage. From the experiment, the levels of hydrogen peroxide, lipid peroxidation and thiobarbituric acid reactive substances were observed to increase significantly in cerebrum, cerebellum and hippocampus as 50%, 25% and 20%, respectively, after exposure to PCB, and the messenger RNA expression of TJP in rats exposed to PCBs is decreased and is retrieved to the normal level simultaneously in quercetin-treated rats. Hence, quercetin can be used as a preventive medicine to PCBs exposure and prevents neurodegenerative disorders.

Exogenous arachidonate restores the dimethoate-induced inhibition of steroidogenesis in rat interstitial cells

The present work studies the potential restorative effect of polyunsaturated fatty acids (PUFA, 5 μM/24 h) on the dimethoate (DMT)-induced inhibition of testosterone biosynthesis in Leydig cells isolated from rat testes. Various fatty acids (FA) from the n-6 (18:2, 20:3, 20:4, 22:4 and 22:5) and n-3 (18.3, 20:5, 22:5, 22:6) series were assayed in Leydig cells, alone (as delipidated BSA complexes) and in combination with DMT (1 ppm). The n-6 FA stimulated lipid peroxidation (LPO) and inhibited the activities of steroidogenic enzymes (3β- and 17β-hydroxysteroid dehydrogenases). The n-3 FA exerted an anti-oxidant effect, decreasing the production of thiobarbituric-acid reactive substances (TBARS) and inhibiting phospholipase A(2) activity. The biosynthesis of testosterone in DMT-treated cultures was completely normalized by ARA (20:4n-6) and partially restored by the addition of 20:3n-6, increasing ARA content inside the mitochondria. The other FA assayed failed to restore androgenesis. COX-2 protein and prostaglandin F2α and E2 production were stimulated by 20:3n-6, ARA, 18:3n-3 and 20:5 n-3. COX-2 protein decreased upon addition of 22:5n-3 and 22:6n-3. StAR protein was increased by ARA and partially increased by 20:3n-6, likely due to its metabolic conversion into ARA. Both FA increased the mitochondrial cholesterol pool available for testosterone biosynthesis. The rate of androgenesis is likely the result of various regulatory factors acting concomitantly on the physiology of Leydig cells.

Polychlorinated biphenyls-induced oxidative stress on rat hippocampus: a neuroprotective role of quercetin

Present study is aimed to evaluate the ameliorative role of quercetin on PCBs-induced oxidative stress in hippocampus of Wistar rats. Group I rats received vehicle (corn oil) intraperitoneally (i.p); Group II received quercetin 50 mg/kg bwt/day (gavage); Group III received PCB 2 mg/kg bwt/day (i.p); Group IV received PCB (i.p) and simultaneously quercetin through gavage. After 30 days, rats were euthanized and hippocampus was dissected from each rat brain. Oxidative stress was assessed by determining the levels of H₂O₂, LPO, Pcc, and alteration in the functional markers such as CK, AchE, and ATPases activities in the hippocampus of control and experimental animals. A significant increase in the levels of stress markers and decrease in level of functional markers were observed in PCBs-treated rats. Moreover DNA fragmentation and histological studies were ascertained to confirm PCBs toxicity. In conclusion, quercetin shows a protective role against PCBs-induced oxidative damage in rat hippocampus.

Combined effects of repeated administration of 2,3,7,8-tetrachlorodibenzo-p-dioxin and polychlorinated biphenyls on kidneys of male rats

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and polychlorinated biphenyls (PCBs) are persistent environmental contaminants that exist as complex mixtures in the environment, but the possible interactions of TCDD and PCBs have not been systematically investigated. The main objective of this study was to investigate the combined nephrotoxic effects of TCDD and PCBs on rats and to reveal the potential interactions between TCDD and PCBs. Male Sprague-Dawley rats were intragastrically administered TCDD (10 microg/kg), PCBs (Aroclor 1254, 10 mg/kg), or the combination (10 microg/kg TCDD + 10 mg/kg Aroclor 1254). After 12 consecutive days of exposure, all treatments induced nephrotoxicity, as evidenced by significant increases in the levels of serum creatinine and blood urea nitrogen, changes of kidney histopathology, and significant renal oxidative stress. Most of these effects were more remarkable in the combined-exposure group. Furthermore, all treatments induced renal cytochrome P450 1A1 (CYP1A1) protein expression, and the induction was more conspicuous in the combined-exposure group. These findings suggested that the nephrotoxicity induced by TCDD and PCBs in the present study might be attributable to the high expression of CYP1A1. In addition, the result of the two-way analysis of variance revealed that the combined effects of TCDD and PCBs were complicated, being additive, synergistic, or antagonistic depending on the selection of toxicity end points under the present experimental condition. This study demonstrates that combined exposure to TCDD and PCBs induced significant nephrotoxicity in rats, and there were complicated interactions between the two pollutants on the nephrotoxicity.

Involvement of lipids in dimethoate-induced inhibition of testosterone biosynthesis in rat interstitial cells

The mechanism involved in the inhibition of testosterone (Te) biosynthesis after a sub-chronic exposure to low doses of dimethoate (D) was studied in rat interstitial cells (IC). Expression of COX-2 in IC isolated from D-treated rats increased by 44% over C data, while transcription of StAR decreased by approx. 50% and the expression of this protein was diminished by approximately 40%. PGE(2) and PGF(2alpha) were increased by 61 and 78%, respectively. Te concentration decreased by 49% in IC homogenates. Concomitantly, plasma concentration of LH and FSH both increased. Araquidonate (ARA) and C(22) fatty acyl chains in phospholipids from IC mitochondrial fraction decreased by approx. 30% after D treatment. Protein carbonyls, lipoperoxides and nitrite content increased while alpha-tocopherol and the antioxidant capacity of the soluble cellular fraction decreased significantly. Stimulation with h-CG 10 nM overnight failed to overcome the inhibition caused by D on both Te biosynthesis and 3beta- and 17beta-hydroxysteroid dehydrogenases. Decreased Te biosynthesis may be attributed to (1) inhibition of StAR protein activity due to the stimulation of COX-2 and the overproduction of PGF(2alpha), (2) decreased stimulatory effect of ARA on StAR with a subsequent reduction in the availability of CHO for the androgenic pathway, and/or (3) indirect inhibition of steroidogenic enzymes by a lower transcriptional rate caused by elevated PGF(2alpha). Rofecoxib administration prevents the deleterious effect(s) exerted by D.

Attenuating effect of daidzein on polychlorinated biphenyls-induced oxidative toxicity in mouse testicular cells

The attenuating effect of daidzein (DAI) on oxidative toxicity induced by Aroclor 1254 (A1254) was investigated in mouse testicular cells. Cells were exposed to A1254 alone or with DAI. The oxidative damage was estimated by measuring malondialdehyde (MDA) formation, superoxide dismutase (SOD) activity and glutathione (GSH) content. Results show that A1254 induced a decrease of germ cell number, an elevation in thiobarbituric acid reactive substances (TBARS) but a decrease in SOD activity and GSH content. However, simultaneous supplementation with DAI decreased TBARS level and increased SOD activity and GSH content. Consequently, dietary DAI may restore the intracellular antioxidant system to attenuate the oxidative toxicity of A1254 in testicular cells.

Oxidative stress modulates membrane bound ATPases in brain regions of PCB (Aroclor 1254) exposed rats: Protective role of α-tocopherol

Polychlorinated biphenyls (PCBs) are a class of widely dispersed and environmentally persistent organic compounds. PCBs exhibit a wide range of toxicological effects including neurotoxicity. Vitamin E (alpha-tocopherol) is an important lipid soluble antioxidant placed in a special region of membranes. Large amounts of energy are required to maintain the signaling activities of the cells in the central nervous system (CNS). Membrane proteins that control ion gradients across organellar and plasma membranes appear to be particularly susceptible to oxidation-induced changes. The aim of this study was to determine the protective role of vitamin E on Aroclor 1254 induced modulation in membrane bound ATPases in brain regions of rats. One group of rats received corn oil as vehicle for 30days as control. The other group of rats were administered Aroclor 1254 at a dose of 2mgkg(-1) bwday(-1) intraperitoneally for 30days. One group of rats received vitamin E (50mgkg(-1) bwday(-1)) orally simultaneously with Aroclor 1254 for 30days. After 30days, the animals were euthanized and the brain was dissected to hypothalamus and hippocampus to determine the following parameters. Hydrogen peroxide (H2O2), Lipid peroxidation (LPO) and the activities of Na+K+-ATPase, Ca2+-ATPase and Mg2+-ATPase were determined. Reduced glutathione (GSH) level was also determined. Activities of all the enzymes were decreased while an increase in H2O2 and LPO were observed in selected brain regions of PCB treated animals. Simultaneous vitamin E treatment in PCB exposed animals restored all the parameters significantly. These results suggest that oxidative stress is involved in the inhibitory effect of PCB (Aroclor 1254) on membrane bound ATPases in selected brain regions. alpha-tocopherol acts against PCB induced neurotoxicity by decreasing oxidative stress.

Effects of vitamins C and E on steroidogenic enzymes mRNA expression in polychlorinated biphenyl (Aroclor 1254) exposed adult rat Leydig cells

Polychlorinated biphenyls (PCBs) are ubiquitous and persistent environmental contaminants that disturb normal endocrine functions including gonadal functions in humans and mammals. The present study was conducted to elucidate the protective role of vitamins C and E against Aroclor 1254-induced changes in Leydig cell steroidogenic acute regulatory (StAR) protein and steroidogenic enzymes mRNA expression. Adult male rats were dosed for 30 days with daily intraperitoneal (i.p.) injection of 2 mg/kg Aroclor 1254 or vehicle (corn oil). One group of rats was treated with vitamin C (100 mg/kg bw day) while the other group was treated with vitamin E (50 mg/kg bw day) orally, simultaneously with Aroclor 1254 for 30 days. One day after the last treatment, animals were euthanized and blood was collected for the assay of serum hormones such as luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone and estradiol. The serum androgen binding protein was also estimated. Testes were quickly removed and Leydig cells were isolated in aseptic condition. Purity of Leydig cells was determined by 3beta-hydroxysteroid dehydrogenase (3beta-HSD) staining methods. Purified Leydig cells were used for quantification of androgen and estrogen receptors. In addition, total RNA was isolated from control and treated Leydig cells to monitor the steady-state mRNA levels by RT-PCR for StAR protein, cytochrome P(450)scc, 3beta-HSD and 17beta-HSD. Aroclor 1254 treatment significantly reduced the serum LH, FSH, testosterone, estradiol and androgen binding protein. In addition to this, Leydig cell androgen and estrogen receptors were markedly decreased. RT-PCR analysis of StAR mRNA level did not alter Aroclor 1254 treatment while steroidogenic enzymes such as cytochrome P(450)scc, 3beta-HSD and 17beta-HSD mRNAs were drastically decreased in Aroclor 1254 treatment. However, the simultaneous administration of vitamins C or E in Aroclor 1254-exposed rats resulted a significant restoration of all the above-mentioned parameters to the control level. These observations suggest that vitamins C and E have ameliorative role against PCBs-induced testicular Leydig cells dysfunction.

PCB (Aroclor 1254) enhances oxidative damage in rat brain regions: protective role of ascorbic acid

PCBs are one of the environmental toxicants and neurotoxic compounds which induce the production of free radicals leading to oxidative stress. Oxidative stress is a contributing factor to alteration caused in neurodegenerative processes. The ability of Vitamin C to retard oxidative processes has been recognized for many years. Therefore, the present experiment was carried out to determine the antioxidant role of ascorbate on Aroclor 1254 induced oxidative stress in brain regions of albino rats. One group of rats received corn oil as vehicle for 30 days as control. The other group of rats were administered Aroclor 1254 at a dose of 2 mg/kg bw/day intraperitoneally for 30 days. One group of rats received Vitamin C (100 mg/kg bw/day) orally simultaneously with Aroclor 1254 for 30 days. The brain was dissected to cerebral cortex (Cc), cerebellum (C) and hippocampus (H). Enzymatic and non-enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST), reduced glutathione (GSH) and Vitamin C were estimated. Hydrogen peroxide (H(2)O(2)), lipid peroxidation (LPO) and acetylcholine esterase activity (AchE) were determined. Activities of SOD, CAT, GPx, GST, AchE and the concentration of GSH, Vitamin C were decreased while an increase in H(2)O(2) and LPO were observed in brain regions of PCB treated animals. Vitamin C administration retrieved all the parameters except GST, significantly. These results suggest that PCB induces oxidative stress in rat brain by decreasing the activities of antioxidant enzymes, which can be protected by Vitamin C treatment.

Assessment of the pro-oxidant activity of uranium in kidney and testis of rats

The pro-oxidant activity of uranium (U) was assessed in kidney and testes of male rats, tissues in which toxic effects of this metal are well established. Eight groups of Sprague-Dawley rats received uranyl acetate dihydrate (UAD) in the drinking water at 0, 10, 20, and 40 mg/kgday for 3 months. Rats in four groups were concurrently subjected to restraint during 2 h/day throughout the study. Histopathological examination of the kidneys revealed an angiomatose transformation in U-treated animals. In kidney, thiobarbituric acid-reactive substances (TBARS) levels and oxidized glutathione (GSSG) activity were correlated with U exposure. The superoxide dismutase (SOD) activity was significantly enhanced in both kidney and testis. Oral UAD administration induced a decrease of glutathione reductase (GR) and reduced glutathione (GSH) in the male reproductive tract. The results of this study suggest that graded doses of U elicit depletion of the antioxidant defence system of the rat and induce oxidative stress in testes and kidneys. Although at the current U doses, restraint stress scarcely showed additional adverse effects, its potential influence should not be underrated.

Role of alpha-tocopherol on antioxidant status in liver, lung and kidney of PCB exposed male albino rats

Polychlorinated biphenyls (PCB) are widespread, lipophilic environmental pollutants which have been identified as contaminants in almost every component of the global ecosystem including fish, wildlife, and human adipose tissue, breast milk, and serum. Several studies have shown that PCBs can cause oxidative damage to biomolecules, in the form of lipid peroxidation, modulation of antioxidant enzymes, and oxidative stress. In the present study, we have sought to investigate the effects of alpha-tocopherol (vitamin E) on antioxidant status of PCB-induced toxicity in male Wistar rats. The protective effect of alpha-tocopherol (50mg/kg body weight/day) was tested in PCB-induced toxicity in rat liver, lung, and kidney. We report here that the oral supplementation of alpha-tocopherol was found to maintain the cellular redox status by maintaining the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase accompanied with glutathione and vitamin E levels and down regulation in the levels of lipid peroxides, hydroxyl radical and hydrogen peroxides generation in PCB treated rats. Therefore, our present study demonstrates the PCB-induced deficits in antioxidant enzyme activities and increase in reactive oxygen species and lipid peroxidation levels in liver, kidney, and lung which can be overcome through simultaneous supplementation with alpha-tocopherol.

Studies on the protective role of vitamin C and E against polychlorinated biphenyl (Aroclor 1254)--induced oxidative damage in Leydig cells

Free radical production and lipid peroxidation are potentially important mediators in testicular physiology and toxicology. Polychlorinated biphenyls (PCBs) are global environmental contaminants that cause disruption of the endocrine system in human and animals. The present study was conducted to elucidate the protective role of vitamin C and E against Aroclor 1254-induced changes in Leydig cell steroidogenesis and antioxidant system. Adult male rats were dosed for 30 days with daily intraperitoneal (ip) injection of 2 mg/kg Aroclor or vehicle (corn oil). One group of rats was treated with vitamin C (100 mg/kg bw/day) while the other group was treated with vitamin E (50 mg/kg bw/day) orally, simultaneously with Aroclor 1254 for 30 days. One day after the last treatment, animals were euthanized and blood was collected for the assay of serum hormones such as luteinizing hormone (LH), thyroid stimulating hormone (TSH), prolactin (PRL), triiodothyronine (T(3)), thyroxine (T(4)), testosterone and estradiol. Testes were quickly removed and Leydig cells were isolated in aseptic condition. Purity of Leydig cells was determined by 3beta-hydroxysteroid dehydrogenase (3beta-HSD) staining method. Purified Leydig cells were used for quantification of cell surface LH receptors and steroidogenic enzymes such as cytochrome P(450) side chain cleavage enzyme (P(450)scc), 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and 17beta-hydroxysteroid dehydrogenase (17beta- HSD). Leydig cellular enzymatic antioxidants superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), gamma-glutamyl transpeptidase (gamma-GT), glutathione-S-transferase (GST) and non-enzymatic antioxidants such as vitamin C and E were assayed. Lipid peroxidation (LPO) and reactive oxygen species (ROS) were also estimated in Leydig cells. Aroclor 1254 treatment significantly reduced the serum LH, TSH, PRL, T(3), T(4), testosterone and estradiol. In addition to this, Leydig cell surface LH receptors, activities of the steroidogenic enzymes such as cytochrome P(450)scc, 3beta-HSD, 17beta-HSD, antioxidant enzymes SOD, CAT, GPX, GR, gamma-GT, GST and non-enzymatic antioxidants such as vitamin C and E were significantly diminished whereas, LPO and ROS were markedly elevated. However, the simultaneous administration of vitamin C and E in Aroclor 1254 exposed rats resulted a significant restoration of all the above-mentioned parameters to the control level. These observations suggest that vitamin C and E have ameliorative role against adverse effects of PCB on Leydig cell steroidogenesis.

Antioxidant effect of ascorbic acid on PCB (Aroclor 1254) induced oxidative stress in hypothalamus of albino rats

BACKGROUND

PCBs are one of the environmental toxicants and neurotoxic compounds which induce the production of free radicals leading to oxidative stress. Vitamin C is well known as an outstanding antioxidant. We determined the protective role of ascorbate on hypothalamic antioxidant system of Aroclor 1254 exposed rats.

METHODS

The rats were injected Aroclor 1254 at a dose of 2 mg/kg bw/day intraperitoneally for 30 days. One group of rats received vitamin C (100 mg/kg bw/day) orally simultaneously with Aroclor 1254 for 30 days. Twenty-four hours after last treatment, the animals were killed and hypothalamic region was separated from brain tissue. Enzymatic and non-enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and vitamin C were estimated. Hydrogen peroxide (H(2)O(2)), lipid peroxidation (LPO) and acetylcholine esterase (AchE) activity were determined. Serum gonadotropins such as luteinizing hormone (LH) and follicle stimulating hormone (FSH) were also assayed.

RESULTS

Activities of SOD, CAT, GPx, GR, AchE and the concentration of vitamin C were decreased while an increase in H(2)O(2) and LPO were observed in hypothalamus of PCB treated animals. LH and FSH concentrations were also decreased in serum of PCB exposed animals. Vitamin C administration retrieved all the parameters significantly except serum hormonal profiles.

CONCLUSION

PCB induces oxidative stress in hypothalamus by decreasing the activities of antioxidant enzymes, which can be protected by vitamin C treatment.

Effects of methyl parathion (o,o-dimethyl o-4-nitrophenyl phosphorothioate) on rat sperm morphology and sperm count, but not fertility, are associated with decreased ascorbic acid level in the testis

Methyl parathion (MP; o,o-dimethyl o-4-nitrophenyl phosphorothioate) is an organophosphorous pesticide used world wide to spray agricultural crops. The present study was aimed to investigate the genotoxic and cytotoxic effects on male germ cells and their possible relation with testicular ascorbic acid levels. Adult male Wistar rats (n=5/group) received MP at 0, 0.5, or 1 mg/kg (experiments 1 and 2) for 12 days and 0, 0.75 or 1.5 mg/kg (experiment 3) for 25 days (i.p.) everyday at intervals of 24 h. The epididymal sperm count, sperm abnormalities and testicular ascorbic acid levels (by 2,4-dinitrophenyl hydrazine method) were estimated on days 130, 77 and 17 following the last exposure in experiments 1, 2, and 3, respectively. Virgin untreated female rats were mated with treated males from experiments 2 and 3 for a week effective from day 35 to 41 after the first treatment, and fertility indices were measured after the birth of pups. Sperm count was decreased in experiments 2 and 3 (P<0.01), and in all three experiments, the abnormal sperms increased (P<0.001). Concomitantly, the ascorbic acid levels decreased in the testis (P<0.05-0.001; one-way ANOVA and Bonferroni's post hoc test). The body weights of offspring of treated males did not show significant changes from those of the controls, although there were some decreases observed. MP reduced the lactation index in experiment 2 (P<0.001; Chi-square test). The number of pups/parent along with fertility indices showed some numerical decrease but without any statistical significance. The present findings suggest that MP is a weak genotoxic and cytotoxic agent in the rat exposed to human exposure dose-levels, and that these effects, except the fertility are well correlated with decreased ascorbic acid level in the testis. Furthermore, MP-induced changes in the germ cells do not have any significant effects on F1 generation.

Effect of Aroclor 1254 on Sertoli cellular antioxidant system, androgen binding protein and lactate in adult rat in vitro

Polychlorinated biphenyls (PCBs) are persistent and bioaccumulative environmental toxicants. Previous studies suggested that PCBs (Aroclor 1254) induce toxic effects including reproductive toxicity. The present study was designed to investigate the impact of Aroclor 1254 on Sertoli cellular function and antioxidant system of adult rat in vitro. Sertoli cells were isolated from adult rat testes and treated with various concentrations (10(-10) to 10(-7) M) of Aroclor 1254 for 6, 12 and 24 h. After the treatment period, cell viability was assessed and the Sertoli cellular antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), gamma-glutamyl transpeptidase (gamma-GT) and glutathione reductase (GR) and lipid peroxidation (LPO) were assayed. In addition, androgen binding protein (ABP) and lactate secretions were also quantified in Sertoli cell culture medium. Sertoli cellular viability and activity of antioxidant enzymes were significantly reduced in Aroclor 1254 (10(-10) to 10(-7) M) treatment for 6, 12 and 24 h whereas, the Sertoli cellular lipid peroxidation was significantly increased in a dose and duration dependent manner. In addition, ABP secretion diminished and lactate secretion was significantly elevated in the same manner. To conclude, the present study suggested that Aroclor 1254 disrupts Sertoli cellular metabolic functions such as ABP, lactate secretions and activity of antioxidant enzymes.