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PCBs Tox Hazard ID

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The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Effect of 2,3',4,4',5-pentachlorobiphenyl exposure on endometrial receptivity and the methylation of HOXA10

Authors: Qu, XL; Ming-Zhang; Yuan-Fang; Wang, H; Zhang, YZ (2018) Reproductive Sciences 25:256-268. HERO ID: 3982693

[Less] Polychlorinated biphenyls (PCBs) are one of the most common endocrine-disrupting chemicals and have . . . [More] Polychlorinated biphenyls (PCBs) are one of the most common endocrine-disrupting chemicals and have obvious toxicity on human reproductive development. The aim of our study was to investigate the toxicity of chronic 2,3',4,4',5-pentachlorobiphenyl (PCB 118) exposure on embryo implantation and endometrial receptivity, with the possible mechanism of DNA methylation involved. Virgin CD-1 female mice (3 weeks old) were housed and orally treated with PCB 118 (0, 1, 10, 100 μg/kg) for a month. After mating with fertile males, the pregnant mice were killed on gestation day 4.5. Compared with the control group, implantation failures were observed in 1 μg/kg PCB 118- and 100 μg/kg PCB 118-treated groups. Abnormal endometrial morphology with open uterine lumens and densely compact stromal cells and poorly developed pinopodes were substantially in response to PCB 118 doses above, as well as the significant downregulation of implantation-associated genes (estrogen receptor 1, homeobox A10 [HOXA10], integrin subunit beta 3) and hypermethylation in the promoter region of HOXA10 further. It was confirmed that chronic exposure to PCB 118 produced an increased number of implantation failures in association with a defective uterine morphology during the implantation period. Alterations in methylation of HOXA10 could explain, at least in part, the mechanism of effects of PCB 118 exposure on the implantation process.

Journal Article
Journal Article

Polychlorinated biphenyls-153 induces metabolic dysfunction through activation of ROS/NF-κB signaling via downregulation of HNF1b

Authors: Wu, H; Yu, W; Meng, F; Mi, J; Peng, J; Liu, J; Zhang, X; Hai, C; Wang, X (2017) Redox Biology 12:300-310. HERO ID: 3872275

[Less] Polychlorinated biphenyls (PCB) is a major type of persistent organic pollutants (POPs) that act as . . . [More] Polychlorinated biphenyls (PCB) is a major type of persistent organic pollutants (POPs) that act as endocrine-disrupting chemicals. In the current study, we examined the mechanism underlying the effect of PCB-153 on glucose and lipid metabolism in vivo and in vitro. We found that PCB-153 induced per se and worsened high fat diet (HFD)-resulted increase of blood glucose level and glucose and insulin intolerance. In addition, PCB-153 induced per se and worsened HFD-resulted increase of triglyceride content and adipose mass. Moreover, PCB-153 concentration-dependently inhibited insulin-dependent glucose uptake and lipid accumulation in cultured hepatocytes and adipocytes. PCB-153 induced the expression and nuclear translocation of p65 NF-κB and the expression of its downstream inflammatory markers, and worsened HFD-resulted increase of those inflammatory markers. Inhibition of NF-κB significantly suppressed PCB-153-induced inflammation, lipid accumulation and decrease of glucose uptake. PCB-153 induced oxidative stress and decreased hepatocyte nuclear factor 1b (HNF1b) and glutathione peroxidase 1 (GPx1) expression in vivo and in vitro. Overexpression of HNF1b increased GPx1 expression, decreased ROS level, decreased Srebp1, ACC and FAS expression, and inhibited PCB-153-resulted oxidative stress, NF-κB-mediated inflammation, and final glucose/lipid metabolic disorder. Our results suggest that dysregulation of HNF1b/ROS/NF-κB plays an important role in PCB-153-induced glucose/lipid metabolic disorder.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Congener-Specific Disposition of Chiral Polychlorinated Biphenyls in Lactating Mice and Their Offspring: Implications for PCB Developmental Neurotoxicity

Authors: Kania-Korwel, I; Lukasiewicz, T; Barnhart, CD; Stamou, M; Chung, H; Kelly, KM; Bandiera, S; Lein, PJ; Lehmler, HJ (2017) Toxicological Sciences 158:101-115. HERO ID: 3982697

[Less] Chiral polychlorinated biphenyl (PCB) congeners have been implicated by laboratory and epidemiological . . . [More] Chiral polychlorinated biphenyl (PCB) congeners have been implicated by laboratory and epidemiological studies in PCB developmental neurotoxicity. These congeners are metabolized by cytochrome P450 (P450) enzymes to potentially neurotoxic hydroxylated metabolites (OH-PCBs). The present study explores the enantioselective disposition and toxicity of two environmentally relevant, neurotoxic PCB congeners and their OH-PCB metabolites in lactating mice and their offspring following dietary exposure of the dam. Female C57BL/6N mice (8 weeks old) were fed daily, beginning two weeks prior to conception and continuing throughout gestation and lactation, with 3.1 µmol/kg bw/d of racemic 2,2',3,5',6-pentachlorobiphenyl (PCB 95) or 2,2',3,3',6,6'-hexachlorobiphenyl (PCB 136) in peanut butter; controls received vehicle (peanut oil) in peanut butter. PCB 95 levels were higher than PCB 136 levels in both dams and pups, consistent with the more rapid metabolism of PCB 136 compared to PCB 95. In pups and dams, both congeners were enriched for the enantiomer eluting second on enantioselective gas chromatography columns. OH-PCB profiles in lactating mice and their offspring were complex and varied according to congener, tissue and age. Developmental exposure to PCB 95 vs. PCB 136 differentially affected the expression of P450 enzymes as well as neural plasticity (arc and ppp1r9b) and thyroid hormone-responsive genes (nrgn and mbp). The results suggest that the enantioselective metabolism of PCBs to OH-PCBs may influence neurotoxic outcomes following developmental exposures, a hypothesis that warrants further investigation.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Dioxin-like rather than non-dioxin-like PCBs promote the development of endometriosis through stimulation of endocrine-inflammation interactions

Authors: Huang, Q; Chen, Y; Chen, Q; Zhang, H; Lin, Y; Zhu, M; Dong, S (2017) Archives of Toxicology 91:1915-1924. HERO ID: 3982661

[Less] Polychlorinated biphenyls (PCBs) contain 209 congeners with various structure-activities. Exposure to . . . [More] Polychlorinated biphenyls (PCBs) contain 209 congeners with various structure-activities. Exposure to PCBs was related to disorders of female reproduction. Endometriosis (EM) is an estrogen- and inflammation-dependent disease with high prevalence and severe health outcomes. Epidemiological studies have shown the effects of PCBs exposure on EM in regard to various structures of PCBs. However, little evidence is available from the toxicology considering the structure of PCBs. In the study, environmentally relevant concentrations of PCBs were used to treat primary cultured endometrial cells and an EM mouse model. Dioxin-like CB126, but not non-dioxin-like CB153, significantly enhanced 17β-estradiol (E2) biosynthesis in a dose-dependent manner. Among the genes related to estrogen metabolism, the level of 17β-hydroxysteroid dehydrogenase 7 (HSD17B7) showed significant increase following CB126 exposure. We further found that CB126 exposure decreased the methylation of the HSD17B7 promoter. Elevated expression of HSD17B7 was observed in the eutopic endometrium of EM patients. CB126 rather than CB153 triggered the inflammatory response by directly stimulating the secretion of inflammatory factors and indirectly reducing the level of lipoxin A4 (LXA4). Furthermore, the inflammation enhanced the expression of HSD17B7. Antagonism of the aryl hydrocarbon receptor (AhR) diminished the effects induced by CB126. In vivo, the PCB-treated EM mouse model confirmed that CB126 rather than CB153 increased the levels of both E2 and inflammatory factors in peritoneal fluid and promoted the development of endometriotic lesions. In all, CB126, but not CB153, triggered EM development by stimulating estrogen biosynthesis, inflammation and their interactions and that these effects were mediated by the AhR receptor.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Lactational exposure effect of polychlorinated biphenyl on rat sertoli cell markers and functional regulators in prepuberal and puberal F1 offspring

Authors: Priya, ES; Kumar, TS; Balaji, S; Bavithra, S; Singh, PR; Sakthivel, D; Sankar, BR; Arunakaran, J (2017) Journal of Endocrinological Investigation 40:91-100. HERO ID: 3982675

[Less] PURPOSE: Polychlorinated biphenyls (PCBs) are persistent and bioaccumulative environmental . . . [More] PURPOSE: Polychlorinated biphenyls (PCBs) are persistent and bioaccumulative environmental toxicants acting as endocrine disruptors. Many researches evidenced that PCBs affect the male reproductive system in adult rats and it can transfer from mother to offspring through milk. We investigated whether the lactational exposure to PCBs affects the Sertoli cell function in F1 offspring.

METHODS: Dams were orally treated with different doses of PCB-Aroclor 1254 (1, 2 and 5 mg/kg bw/day, respectively) from postpartum day 1-20. Male offspring rats were killed on PND 21 and PND 60. Testes were used both for histological study and to isolate Sertoli cell. Serum and testicular interstitial fluid (TIF) levels of testosterone, ABP and estradiol were analyzed by ELISA method. The mRNA and protein expressions of follicle-stimulating hormone (FSHR), androgen-binding protein (ABP), Inhibinβ, androgen receptor (AR) and estrogen receptor (ERβ) were studied using real-time PCR and immunoblotting, respectively.

RESULTS: The testicular architecture was altered in PCB-treated groups of both prepuberal and puberal rats. Testosterone, estradiol and androgen-binding protein levels were altered in both serum and TIF in PCB treated groups. The gene expression level of FSHR, ABP, ERβ and AR was decreased in a dose-dependent manner, whereas Inhibinβ gene expression level was increased in PCB-treated groups.

CONCLUSION: Lactational exposure to PCB affects both the histoarchitecture of testis, Sertoli cell maker and functional regulators in both prepuberal and puberal F1 male progeny.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Liver metabolic disruption induced after a single exposure to PCB126 in rats

Authors: Chapados, NA; Boucher, MP (2017) Environmental Science and Pollution Research 24:1854-1861. HERO ID: 3982695

[Less] Polychlorinated biphenyls (PCBs) have been recognized as metabolic disruptors. The liver plays a pivotal . . . [More] Polychlorinated biphenyls (PCBs) have been recognized as metabolic disruptors. The liver plays a pivotal role in detoxification of an organism. Fatty liver results from altered intra-, and extra-hepatic mediators and is associated with increased glucose-related protein 78 (GRP78), commonly used as a marker for endoplasmic reticulum (ER) stress signaling. This pilot study aimed to study the effects of a single exposure on fatty liver metabolic parameters. The objective of the study is to characterize the effects of 3,3',4,4',5-pentachlorobiphenyl (PCB126) on ER stress protein chaperon GRP78 and CCAAT-enhancer-binding protein homologous protein (CHOP) and intra-hepatic mediators such as microsomal triglyceride transfer protein (MTP), sterol regulatory element-binding protein 1c (SREBP1c), and peroxisome proliferator-activated receptor alpha (PPARα), as well as extra-hepatic factors such as non-esterified fatty acid (NEFA) and tumor necrosis factor alpha (TNFα). Hepatic GRP78 mRNA and protein levels, indicating the presence of ER stress, were significantly increased following a single PCB126 exposure in rats. Intra-hepatic mechanisms such as lipoprotein secretion pathway (i.e., MTP), lipogenesis de novo (i.e., SREBP1c), and oxidation (i.e., PPARα) were altered in PCB126-treated rats. In addition, a state of inflammation measured by higher TNFα plasma levels was present in contaminated rats. These data indicate that a single injection of PCB126-modulated expression of GRP78 associated with hepatic ER stress and systemic inflammation in rats.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

A compromised liver alters polychlorinated biphenyl-mediated toxicity

Authors: Wahlang, B; Perkins, JT; Petriello, MC; Hoffman, JB; Stromberg, AJ; Hennig, B (2017) Toxicology 380:11-22. HERO ID: 3982706

[Less] Exposure to environmental toxicants namely polychlorinated biphenyls (PCBs) is correlated with multiple . . . [More] Exposure to environmental toxicants namely polychlorinated biphenyls (PCBs) is correlated with multiple health disorders including liver and cardiovascular diseases. The liver is important for both xenobiotic and endobiotic metabolism. However, the responses of an injured liver to subsequent environmental insults has not been investigated. The current study aims to evaluate the role of a compromised liver in PCB-induced toxicity and define the implications on overall body homeostasis. Male C57Bl/6 mice were fed either an amino acid control diet (CD) or a methionine-choline deficient diet (MCD) during the 12-week study. Mice were subsequently exposed to either PCB126 (4.9mg/kg) or the PCB mixture, Arcolor1260 (20mg/kg) and analyzed for inflammatory, calorimetry and metabolic parameters. Consistent with the literature, MCD diet-fed mice demonstrated steatosis, indicative of a compromised liver. Mice fed the MCD-diet and subsequently exposed to PCB126 showed observable wasting syndrome leading to mortality. PCB126 and Aroclor1260 exposure worsened hepatic fibrosis exhibited by the MCD groups. Interestingly, PCB126 but not Aroclor1260 induced steatosis and inflammation in CD-fed mice. Mice with liver injury and subsequently exposed to PCBs also manifested metabolic disturbances due to alterations in hepatic gene expression. Furthermore, PCB exposure in MCD-fed mice led to extra-hepatic toxicity such as upregulated circulating inflammatory biomarkers, implicating endothelial cell dysfunction. Taken together, these results indicate that environmental pollution can exacerbate toxicity caused by diet-induced liver injury which may be partially due to dysfunctional energy homeostasis. This is relevant to PCB-exposed human cohorts who suffer from alcohol or diet-induced fatty liver diseases.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Anxiety-like behaviors in adulthood are altered in male but not female rats exposed to low dosages of polychlorinated biphenyls in utero

Authors: Gillette, R; Reilly, MP; Topper, VY; Thompson, LM; Crews, D; Gore, AC (2017) Hormones and Behavior 87:8-15. HERO ID: 3982717

[Less] Exposure to polychlorinated biphenyls (PCBs), a class of endocrine-disrupting chemicals, can result . . . [More] Exposure to polychlorinated biphenyls (PCBs), a class of endocrine-disrupting chemicals, can result in altered reproductive behavior in adulthood, especially when exposure occurs during critical periods of brain sexual differentiation in the fetus. Whether PCBs alter other sexually dimorphic behaviors such as those involved in anxiety is poorly understood. To address this, pregnant rat dams were injected twice, on gestational days 16 and 18, with the weakly estrogenic PCB mixture Aroclor 1221 (A1221) at one of two low dosages (0.5mg/kg or 1.0mg/kg, hereafter 1.0 and 0.5), estradiol benzoate (EB; 50μg/kg) as a positive estrogenic control, or the vehicle (3% DMSO in sesame oil). We also conducted a comprehensive assessment of developmental milestones of the F1 male and female offspring. There were no effects of treatment on sex ratio at birth and age at eye opening. Puberty, assessed by vaginal opening in females and preputial separation in males, was not affected in females but was advanced in males treated with A1221 (1.0). Males and females treated with A1221 (both dosages) were heavier in early adulthood relative to controls. The earliest manifestation of this effect developed in males prior to puberty and in females slightly later, during puberty. Anxiety-like behaviors were tested using the light:dark box and elevated plus maze tests in adulthood. In females, anxiety behaviors were unaffected by treatment. Males treated with A1221 (1.0) showed reduced indices of anxiety and increased activity in the light:dark box but not the elevated plus maze. EB failed to replicate the phenotype produced by A1221 for any of the developmental and behavioral endpoints. Collectively, these results indicate that PCBs increase body weight in both sexes, but their effects on anxiety-like behaviors are specific to males. Furthermore, differences between the results of A1221 and EB suggest that the PCBs are likely acting through mechanisms distinct from their estrogenic activity.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

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

Authors: Aly, HA; Alahdal, AM; Nagy, AA; Abdallah, HM; Abdel-Sattar, EA; Azhar, AS (2017) Environmental Toxicology 32:1147-1157. HERO ID: 3983444

[Less] Aroclor 1260 is one of the more representative polychlorinated biphenyls found in biota. This study . . . [More] 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.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Strategy set-shifting and response inhibition in adult rats exposed to an environmental polychlorinated biphenyl mixture during adolescence

Authors: Monaikul, S; Eubig, P; Floresco, S; Schantz, S (2017) Neurotoxicology and Teratology 63:14-23. HERO ID: 3983676

[Less] Converging evidence from studies with animal models and humans suggests that early developmental exposure . . . [More] Converging evidence from studies with animal models and humans suggests that early developmental exposure to polychlorinated biphenyls (PCBs) leads to deficits in cognitive flexibility and inhibitory control. These processes are mediated to a large extent by the prefrontal cortex, thus we examined the effects of PCB exposure during adolescence-a period of robust prefrontal cortical development-on both processes. Specifically, we used operant set-shifting and differential reinforcement of low rates of responding (DRL) tasks to assess cognitive flexibility and response inhibition, respectively. One male and one female pup from each of 14 litters were assigned to each of three treatment groups: 0, 3 or 6mgPCB/kg/day. Rats were dosed orally from postnatal day (PND) 27-50 to capture the whole period of adolescence in rats. At approximately PND 90, they began testing in the set-shifting task which included an initial visual cue discrimination, an extra-dimensional shift to a position discrimination and a reversal of the position discrimination. There were no statistically significant group differences in errors to criterion on visual cue discrimination or on the shift from visual to position discrimination in either males or females. During the position reversal, the 6mg/kg PCB males made significantly fewer errors to reach criterion than control males. The 3mg/kg PCB males showed a trend in the same direction, but this did not reach statistical significance. Interestingly, error analysis revealed that PCB-exposed males made significantly fewer perseverative errors than controls in this phase. No group differences were observed in females. These results suggest a male-specific effect of adolescent PCB-exposure on the reversal phase of the set-shifting task. Following set-shifting, rats progressed to the DRL task in which they were required to withhold responding for a specified period of time (15s) in order to receive a reinforcer. There were no exposure-related group differences in total presses or efficiency ratio in males or in females. In summary, there were subtle sex-specific effects of adolescent PCB exposure on the reversal phase of a set-shifting task, but no effects of exposure on performance on a DRL15 task, suggesting an effect on cognitive flexibility but not response inhibition.