Effects of continuous and intermittent exposure of lactating mothers to aroclor 1242 on testicular steroidogenic function in the adult male offspring

Degradation of 3,3',4,4'-tetrachlorobiphenyl (PCB77) by dielectric barrier discharge (DBD) non-thermal plasma: Degradation mechanism and toxicity evaluation

Polychlorinated biphenyls (PCBs) are a kind of persistent organic pollutants (POPs) with stable chemical properties which can be enriched in a biological body for a long time. They are often carelessly released into natural environment and thus constantly posing a potential threat to human health. However, because of lack of effective ways of degrading PCBs, researchers are still striving to explore new approaches to remove them from the environment. In this work, we employed atmospheric-pressure non-thermal dielectric barrier discharge (DBD) plasma to treat 3,3',4,4'-tetrachlorobiphenyl (PCB77) in aqueous solution and investigated the removal efficiency under different DBD conditions using different discharging gases. As a result, we showed that He-DBD had the highest removal efficiency with hydroxyl radical playing the major role in the degradation, while O₂-DBD also gave rise to relatively high efficiency with ozone making an important contribution. After 2 min of treatments by He-DBD and O₂-DBD, over 75% of PCB77 was degraded with removal rate of 23.65 mg/L and 22.19 mg/L per minute, respectively. Besides, the toxicological evaluation for the DBD treatment was also provided, confirming that the PCB77 degradation products had negligible biotoxicity. This work therefore provides a new effective approach to treatment of persistent organic pollutants (POPs) in the environment.

Reproductive Function in a Population of Young Faroese Men with Elevated Exposure to Polychlorinated Biphenyls (PCBs) and Perfluorinated Alkylate Substances (PFAS)

Semen quality may be adversely affected by exposure to environmental chemicals such as polychlorinated biphenyls (PCBs) and perfluorinated alkylate substances (PFASs) that are persistent and may act as endocrine disrupting compounds. The aim of this study was to explore whether PCBs or PFASs exposure were associated with abnormalities in semen quality or reproductive hormones in Faroese men. This population based cross-sectional study includes 263 Faroese men (24⁻26 years) who delivered a semen sample for assessment of sperm concentration, total sperm count, semen volume, morphology and motility. A blood sample was drawn and analyzed for reproductive hormones, PCBs and PFASs. Exposure to ∑PCBs and perfluorooctane sulfonate (PFOS) was positively associated with sex hormone-binding globulin (SHBG) and luteinizing hormone (LH). In addition, total testosterone (T) was positively associated with ∑PCB. Both PCBs and PFOS appear to lead to increased SHBG, perhaps mediated via the liver. The higher total T associated with PCB may represent a compensatory adaption to elevated SHBG levels to maintain an unchanged free testosterone concentration. The positive association to LH for both PCBs and PFOS may indicate a direct adverse effect on the testosterone producing Leydig cells.

Impact of low-dose chronic exposure to bisphenol A and its analogue bisphenol B, bisphenol F and bisphenol S on hypothalamo-pituitary-testicular activities in adult rats: A focus on the possible hormonal mode of action

Bisphenol A an estrogen-mimic endocrine disrupting chemical, used to manufacture polycarbonate plastics and epoxy resins with toxic effects for male reproduction. Due to its toxicity, industries have started to replace it with other bisphenols. In this study, the toxicity of BPA analogues (BPB, BPF and BPS) was evaluated in a chronic study. We investigated whether the chronic exposure to low bisphenols doses affects spermatogenesis with outcomes on oxidative stress and male reproductive system. Male rats (22 day old) were exposed to water containing 0.1% ethanol for control or different concentrations of BPA and its analogues BPB, BPF and BPS (5, 25 and 50 μg/L) in drinking water for 48 weeks. Results of the present study showed a significant alteration in the gonadosomatic index (GSI) and relative reproductive organs weights. Oxidative stress in the testis was significantly elevated while sperm motility, Daily sperm production (DSP) and number of sperm in epididymis were reduced. Plasma testosterone, LH and FSH concentrations were reduced and estradiol levels were high in 50 μg/L exposed group. These results suggest that exposure to BPA and its analogues for chronic duration can induce structural changes in testicular tissue and endocrine alterations in the male reproductive system.

Comparative Aspects of Pre- and Postnatal Development of the Male Reproductive System

This review describes pre- and postnatal development of the male reproductive system in humans and laboratory animals, and highlights species differences in the timing and control of hormonal and morphologic events. Major differences are that the fetal testis is dependent on gonadotropins in humans, but is independent of such in rats; humans have an extended postnatal quiescent period, whereas rats exhibit no quiescence; and events such as secretion by the prostate and seminal vesicles, testicular descent, and the appearance of spermatogonia are all prenatal events in humans, but are postnatal events in rats. Major differences in the timing of the developmental sequence between rats and humans include: gonocyte transformation period (rat: postnatal day 0-9; human: includes gestational week 22 to 9 months of age); masculinization programming window (rat: gestational day 15.5-17.5; human: gestational week 9-14); and mini-puberty (rat: 0-6 hr after birth; human: 3-6 months of age). Endocrine disruptors can cause unique lesions in the prenatal and early postnatal testis; therefore, it is important to consider the differences in the timing of the developmental sequence when designing preclinical studies as identification of windows of sensitivity for endocrine disruption or toxicants will aid in interpretation of results and provide clues to a mode of action. Birth Defects Research 110:190-227, 2018. © 2017 Wiley Periodicals, Inc.

The toxic effects of polychlorinated biphenyl (Aroclor 1242) on Tm3 Leydig cells

Polychlorinated biphenyls (PCBs) are ubiquitous and persistent environmental contaminants that disrupt endocrine function in biological systems, especially in the male reproductive system. Previous studies on the reproductive toxicity of PCBs have focused on the impairment of spermatogenesis, disruption of steroidogenesis, decreased sperm number, and infertility. Aroclor 1242 is a commercial mixture with an average of 42% chlorine by weight. The purpose of the present study was to elucidate the hazardous effects of Aroclor 1242 on Leydig cells through an evaluation of cell viability, lipid peroxidation, hydroxyl radicals, H2O2 production, antioxidant enzymes, and steroidogenic enzymes. Leydig cells were exposed to Aroclor 1242 for 24 h under basal and luteinizing hormone-stimulated conditions at different concentrations (ranging from 10−16 M to 10−6 M). After incubation, Leydig cells were measured for cell viability, lipid peroxidation, reactive oxygen species (hydroxyl radical and H2O2), antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase, and glutathione-S-transferase), and steroidogenic enzymes (3β-hydroxysteroid dehydrogenase [HSD] and 17β-HSD). The results showed that cell viability was reduced only at Aroclor 1242 concentrations of 10−6 M and 10−8 M, whereas lipid peroxidation and reactive oxygen species increased relative to the concentration. Furthermore, antioxidant systems and steroidogenesis were interrupted to varying degrees, relative to the concentration. These findings suggest that exposure to Aroclor 1242 at high concentrations may result in detrimental effects to Leydig cell homeostasis. In addition, Aroclor 1242 may impair steroidogenesis, especially testosterone biosynthesis, by inhibiting two important steroidogenic enzymes.

Spermatogenic capacity in fertile men with elevated exposure to polychlorinated biphenyls

BACKGROUND

Endocrine disrupting industrial chemicals, such as polychlorinated biphenyls (PCBs), are suspected to adversely affect male reproductive functions.

OBJECTIVES

The Faroe Islands community exhibits an unusually wide range of exposures to dietary contaminants, and in this setting we examined the possible association between PCB exposure and semen quality and reproductive hormones in fertile Faroese men.

METHODS

Participants in this cross-sectional study include 266 proven fertile men residing in the Faroe Islands. PCB levels and hormone profiles were measured in serum samples taken at the clinical examination that included semen quality parameters.

RESULTS

A significant positive association was seen between serum-PCB and the testosterone/estradiol ratio (p=0.04). In the unadjusted analyses, elevated PCB exposure was associated with increased serum concentrations of SHBG (p=0.01) and FSH (p=0.05). We found no association between the serum PCB concentration and the semen quality variables.

CONCLUSION

In this population of highly exposed fertile men, the current serum-PCB concentration was associated with higher androgen/estrogen ratio. Further studies are needed to establish the findings and further document PCB-associated hormonal effects, any time windows of increased susceptibility, and the role of PCB in sub-fecundity.

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.

Associations between congenital cryptorchidism in newborn boys and levels of dioxins and PCBs in placenta

In animal studies, exposure to dioxins has been associated with disrupted development of the male reproductive system, including testicular maldescent. Some polychlorinated biphenyls (PCBs) have also dioxin-like effects. In addition, one previous case-control study has reported an association between congenital cryptorchidism and colostrum PCB levels. We performed a case-control study to evaluate whether congenital cryptorchidism in boys was associated with increased levels of dioxins or PCBs in placenta reflecting foetal exposure. In addition, associations between placenta levels of these chemicals and reproductive hormone levels in boys at 3 months were studied. Placentas were collected in a Danish-Finnish joint prospective cohort study on cryptorchidism (1997-2001). The boys were examined for cryptorchidism at birth and at 3 months. Altogether, 280 placentas [112 Finnish (56 cases, 56 controls) and 168 Danish (39 cases, 129 controls)] were analysed for 17 toxic polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and 37 PCBs (including 12 dioxin-like PCBs). Infant serum samples taken at 3 months were analysed for reproductive hormones. No significant differences between cases and controls were observed in either country in dioxin WHO-TEq levels (median 9.78 vs. 8.47 pg/g fat, respectively, in Finland, and 11.75 vs. 10.88 pg/g fat in Denmark) or PCB WHO-TEq levels (median 2.12 vs. 2.15 pg/g fat in Finland, 2.34 vs. 2.10 pg/g fat in Denmark) or total-TEq levels (median 11.66 vs. 10.58 pg/g fat in Finland, 13.94 vs. 13.00 pg/g fat in Denmark). Placenta WHO-TEq levels of dioxins were not associated with infant reproductive hormone levels at 3 months. In Finland, PCB WHO-TEq levels in placenta associated positively with infant LH levels. WHO-TEq levels of dioxins and PCBs and total-TEq levels were higher in Danish than Finnish samples. In conclusion, no association between placenta levels of dioxins or PCBs and congenital cryptorchidism was found. Significant country differences in chemical levels were observed.

Nitric oxide signaling as a common target of organohalogens and other neuroendocrine disruptors

Organohalogen compounds such as polychlorinated biphenyls (PCB) and polybrominated diphenyl ethers (PBDE) are global environmental pollutants and highly persistent, bioaccumulative chemicals that produce adverse effects in humans and wildlife. Because of the widespread use of these organohalogens in household items and consumer products, indoor contamination is a significant source of human exposure, especially for children. One significant concern with regard to health effects associated with exposure to organohalogens is endocrine disruption. Toxicological studies on organohalogen pollutants primarily focused on sex steroid and thyroid hormone actions, and findings have largely shaped the way one envisions their disruptive effects occurring. Organohalogens exert additional effects on other systems including other complex endocrine systems that may be disregulated at various levels of organization. Over the last 20 years evidence has mounted in favor of a critical role of nitric oxide (NO) in numerous functions ranging from neuroendocrine functions to learning and memory. With its participation in multiple systems and action at several levels of integration, NO signaling has a pervasive influence on nervous and endocrine functions. Like blockers of NO synthesis, PCBs and PBDEs produce multifaceted effects on physiological systems. Based on this unique set of converging information it is proposed that organohalogen actions occur, in part, by hijacking processes associated with this ubiquitous bioactive molecule. The current review examines the emerging evidence for NO involvement in selected organohalogen actions and includes recent progress from our laboratory that adds to our current understanding of the actions of organohalogens within hypothalamic neuroendocrine circuits. The thyroid, vasopressin, and reproductive systems as well as processes associated with long-term potentiation were selected as sample targets of organohalogens that rely on regulation by NO. Information is provided about other toxicants with demonstrated interference of NO signaling. Our focus on the convergence between NO system and organohalogen toxicity offers a novel approach to understanding endocrine and neuroendocrine disruption that is particularly problematic for developing organisms. This new working model is proposed as a way to encourage future study in elucidating common mechanisms of action that are selected with a better operational understanding of the systems affected.

Environmental influences on human growth and development: historical review and case study of contemporary influences

Over the past 100 years, the study of environmental influences on human physical growth and development has focused on the influences of social and economic factors; family and household characteristics; urbanization/modernization; nutrition; and features of the physical environment such as altitude, temperature and climate. Continuing in this tradition are current investigations into the roles of pollutants and other aspects of the human-made environment in affecting patterns of human growth and development, specifically the timing of sexual maturation and the development of obesity. Some of the methodological problems in conducting such studies are presented, as are results from an ongoing investigation among one Native American community that show relationships of pollutants to sexual maturation, overweight/obesity and thyroid system function which can impact growth and maturation.

Relationships of putative endocrine disruptors to human sexual maturation and thyroid activity in youth

Endocrine disruption has become a significant human health concern, but is difficult to study outside of the laboratory for several reasons including the multiplicity of exposures, the difficulty in assessing each exposure, and the variety of possible outcomes among human populations. This review summarizes our studies of the relationships of measured persistent organic pollutants (PCBs, p,p'-DDE, HCB and mirex), and heavy metals (lead and mercury), to outcomes directly related to thyroid function and sexual maturation. These studies were conducted in a sample of Native American youth from the Akwesasne Mohawk community. The participants were first studied during puberty (10-16.9 years of age) and then at approximately 18 years of age. Results from these studies show that PCB levels are positively related to TSH and negatively to free T4. Further, these effects are conditioned by breastfeeding history. Anti-thyroid peroxidase antibody levels also are related to PCB levels suggesting elevated risk of autoimmune disease among the exposed. Earlier age at menarche is associated with higher PCB levels while risk of delay is associated with higher lead levels. Some evidence that the timing of exposure produces different effects is presented, and the level of exposure in the participants suggests that effects observed may be relevant to a considerable proportion of the US population. Further investigations are warranted to determine effect thresholds and mechanisms.

Early aspects of gonadal sex differentiation in Xenopus tropicalis with reference to an antero-posterior gradient

In an effort to contribute to the development of Xenopus tropicalis as an amphibian model system, we carried out a detailed histological analysis of the process of gonadal sex differentiation and were able to find evidence that gonadal differentiation in X. tropicalis follows an antero-posterior gradient. Although the main reason for the presence of a gradient of sex differentiation is still unknown, this gradient enabled us to define the early events that signal ovarian and testicular differentiation and to identify the undifferentiated gonad structure. Given the various advantages of this emerging model, our work paves the way for experiments that should contribute to our understanding of the dynamics and mechanisms of gonadal sex differentiation in amphibians.

Tilapia larvae Aroclor 1254 exposure: effects on gonads and circulating thyroid hormones during adulthood

Aroclor 1254 a polychlorinated biphenyls (PCBs) mixture, when administrated through the diet, was previously found to inhibit adult tilapia (Oreochromis niloticus) reproduction. Since fish larvae can be more sensitive to contaminants, the objectives of this study were to evaluate in adults the impact in gonad development and in thyroid function of Aroclor 1254 administrated at larvae stages. Aroclor 1254 exposed tilapia presented both ovary and testicular alterations and a decline in T4 plasma concentration while T3 remained unaltered. This work shows exposure to Aroclor 1254 during tilapia early life stages causes a disruption of the reproductive axis that enables reproduction.

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.

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.

Effects of long-term maternal exposure to low doses of PCB126 and PCB153 on the reproductive system and related hormones of young male goats

In this study, female goats were orally exposed to PCB126 or PCB153, at 49 ng/kg body weight per day and 98 microg/kg body weight per day respectively, from gestational day 60 until delivery at approximately day 150. Exposure of the offspring continued via lactation until postnatal day 40. Reproductive toxicity in the male offspring was studied by the evaluation of conventional reproductive endpoints as well as flow cytometric analyses of spermatogenesis and sperm chromatin structure. PCB153-treated animals showed a significant smaller testis diameter in comparison to the control group. Neither of the treated groups showed differences for plasma FSH in comparison to controls. PCB153-treated animals differed significantly from the control group with respect to plasma LH and testosterone levels, whereas PCB126-treated animals only differed from the controls in plasma testosterone concentrations. Neither the PCB126 nor the PCB153 group differed from the controls with respect to the conventional sperm parameters or testis histology. A significant lower ratio of interstitium area to seminiferous tubules area and proportion of diploid testis cells were observed for the PCB153 group. Sperm from PCB153-treated animals showed a significantly higher percentage of sperm with damaged DNA. From the results of the present study it was concluded that PCB153 was able to induce alterations in reproductive endpoints related to the hypothalamic-pituitary-axis as well as to the testis. The effects observed in male kids after a long-term maternal exposure to PCB153 support the concept that exposure to endocrine-disrupting compounds during foetal development may lead to adverse reproductive effects in adult life.

Morphometric Studies on the Testis of Korean Ring-necked Pheasant (Phasianus colchicus karpowi) during the Breeding and Non-breeding Seasons

The purpose of this study was to obtain detailed quantitative information on all cell types in the testis interstitium of Korean ring-necked pheasants and to combine these data with changes in the steroidogenic function of the testis during the breeding and non-breeding seasons. For animals collected during the breeding season, their testis weights, sperm production, serum testosterone levels and leuteinizing hormone (LH)-stimulated testosterone secretion were significantly (p < 0.01) increased compared to the non-breeding season. Testes of the pheasants during the non-breeding season displayed a 98% reduction in testis volume that was associated with a decrease in the absolute volume of seminiferous tubules (98% reduction), tubular lumen (100%), interstitium (90%), blood vessels (84%), lymphatic spaces (97%), Leydig cells (79%), mesenchymal cells (51%) and myoid cells (61%) compared to the breeding season. The numbers of Leydig cells, mesenchymal cells and myoid cells per testis in the breeding season were much higher than in the non-breeding season. Although the mean volume of a Leydig cell was 74% lower in the non-breeding season, the mean volumes of myoid and mesenchymal cells remained unchanged. These results demonstrate that there are striking differences in the testicular structure of the Korean ring-necked pheasant during the breeding and non-breeding seasons. Every structural parameter of the Leydig cell was positively correlated with both testosterone serum levels and LH-stimulated testosterone secretion. The correlation of changes in hormonal status with the morphometric alterations of Leydig cells suggests that the Korean-ring necked pheasant may be used as a model to study structure-function relationships in the avian testis.

Effects of maternal exposure to 3,3',4,4',5-pentachlorobiphenyl (PCB126) or 3,3',4,4',5,5'-hexachlorobiphenyl (PCB169) on testicular steroidogenesis and spermatogenesis in male offspring rats

On days 7-21 of gestation, Sprague-Dawley rats were orally administered 3 or 30 mug/kg/d of 3,3',4,4',5-pentachlorobiphenyl (PCB126) or 3,3',4,4',5,5'-hexachlorobiphenyl (PCB169) daily. Their male offspring were autopsied at 3, 6, and 15 weeks after birth to investigate the effects of the 2 polychlorinated biphenyls (PCBs) on spermatogenesis and steroidogenesis in their testes. PCB treatment caused a decrease in the area ratio of 3beta-hydroxysteroid dehydrogenase (HSD)-expressing cells (Leydig cells)/testis at 3 weeks after birth. When PCB126 was administered to pregnant rats, the plasma testosterone levels in their offspring were decreased at 3 weeks. The expression levels of P450scc, 3beta-HSD, and P450(17alpha) mitochondrial RNAs (mRNAs) were unchanged, although the StAR (steroidogenic acute regulatory protein) mRNA expression level was increased at 6 weeks. On the other hand, when PCB169 was administered, plasma testosterone levels were decreased at 3 and 6 weeks and were increased at 15 weeks. Plasma luteinizing hormone (LH) levels were decreased at 6 weeks, and plasma follicle-stimulating hormone (FSH) levels were increased at 15 weeks. The expression levels of 3beta-HSD and P450(17alpha) were increased, and the mRNA level of 5alpha-reductase 1 was decreased at 15 weeks. PCB169 treatment suppressed the conversion of round spermatids between stages VII and VIII. These results indicate that in utero and lactational exposure to PCB126 or PCB169 decreases plasma testosterone levels in 3-week-old rats, with no change in the expression levels of the mRNAs of enzymes, and that PCB169 inhibits testicular steroid synthesis more strongly than PCB126. PCB169 greatly altered the concentration of testosterone, indicating a stronger inhibitory effect on spermatogenesis. Low testosterone and LH levels in prenatally PCB169-exposed rats until 6 weeks after birth presumably retard the functional differentiation of testicular Leydig cells; however, the increased testosterone levels at 15 weeks suggest that Leydig cells in PCB-exposed rats are virtually mature by the 15th week.

The inhibitory effects of polychlorinated biphenyl Aroclor 1254 on Leydig cell LH receptors, steroidogenic enzymes and antioxidant enzymes in adult rats

Polychlorinated biphenyls (PCBs) are global pollutants of major concern to human and animal reproductive health. The present study has examined the impact of Aroclor 1254 exposure on oxidative stress and testicular Leydig cell function. Adult albino male rats of the Wistar strain were dosed for 30 days with daily intraperitoneal injections of 2 mg/kg Aroclor 1254 or vehicle (corn oil). One day after the last treatment, animals were euthanized and blood collected for the assay of serum testosterone and estradiol. Testes were removed and Leydig cells were isolated for the assay of luteinizing hormone (LH) receptors, steroidogenic enzymes cytochrome P450 side chain cleavage enzyme (P450 scc), 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and 17beta-hydroxysteroid dehydrogenase (17beta-HSD). Cellular antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR), and glutathione-S-transferase (GST) were also assayed. Lipid peroxidation (LPO) and reactive oxygen species (ROS) were quantified. Results showed that Aroclor 1254 exposure lowered serum testosterone and estradiol levels. Leydig cell LH receptor density, activities of the steroidogenic enzymes P450 scc, 3beta-HSD, 17beta-HSD, antioxidant enzymes SOD, CAT, GPX, GR, and GST were significantly diminished whereas, LPO and ROS significantly elevated. Taken together, these results suggest that inefficient LH receptors, steroidogenic enzymes and antioxidant enzymes are possible mechanisms by which Aroclor 1254 treatment disrupts Leydig cell steroidogenesis.

Environmental pollutant Aroclor 1242 (PCB) disrupts reproduction in adult male rhesus monkeys (Macaca mulatta)

Adult male rhesus monkeys (Macaca mulatta) were given oral treatment of either Aroclor 1242 or vehicle (corn oil and glycerol) at a dose of 200 microg/kg body wt/day for 6 months to investigate the effects of the pollutant on plasma testosterone and the morphology of testes and accessory glands. Aroclor 1242 treatment significantly decreased testicular size and testosterone levels in plasma and adversely affected spermatogenic activity by disrupting epithelial organization. All components of the germinal epithelium were greatly reduced. The spermatogonia were either hypertrophied or had shrunken vesiculated cytoplasm with distorted mitochondria and nuclear pyknosis. Changes were milder in the Sertoli cells, where nuclear infoldings were reduced. Characteristic features of treated Leydig cells were the presence of electron-dense and electron-opaque zones, appearing as plaques, cell membrane abnormalities, and high variability in nuclear shape and heterochromatin distribution. All the Aroclor 1242-treated accessory glands contained more connective tissue than their vehicle-treated counterparts. The epithelium contained many layers of irregularly shaped necrotic cells possessing stereocilia in the epididymides, either hypochromic and hypertrophied or hyperchromic and hypotrophied cells in the prostate and shrunken cuboidal cells with elongated nuclei in the seminal vesicles. In conclusion, Aroclor 1242 treatment causes severe structural alterations on gonads and accessory organs in adult male rhesus monkeys, and these effects could be mediated through both estrogen and Ah receptors.

Postnatal exposure of 2,2',3,3',4,6'-hexachlorobiphenyl and 2,2',3,4',5',6-hexachlorobiphenyl on sperm function and hormone levels in adult rats

Polychlorinated biphenyls (PCBs) are known to affect reproductive system in animals and in accidentally or occupationally exposed humans. Information is lacking on effects of non-dioxin like chlorinated biphenyls (CB) congeners on male reproduction. The aim of this study is to determine whether treatment of postnatal non-dioxin like CB congeners affects sperm function and hormone levels in rats. Male Sprague-Dawley rats received either 2,2',3,3',4,6'-hexachlorobiphenyls (CB 132) or 2,2',3,4',5',6-hexachlorobiphenyls (CB 149) by ip injection of 9.6 or 96 mg/kg at day 21. At 16 weeks, the animals were sacrificed; sperm quality and hormone levels were measured. Body weight, testis and cauda epididymis weights, sperm counts, ROS generation, acrosome reaction rate, serum thyroxine (T(4)), free T(4) and testosterone (TT) concentrations were unaffected. However, treatment of CB 132 and CB 149 caused decreases in sperm motility, curvilinear velocity (VCL), average path velocity (VAP), straight-line velocity (VSL), amplitude of lateral head displacement (ALH) and beat cross frequency (BCF). Serum triiodothyronine (T(3)) level was significantly decreased in CB 132 9.6 mg/kg dose group compared with the controls. On the other hand, a significant decrease was found in free T(3) concentration both in 96 mg/kg of CB 132 and CB 149 groups. In summary, this study showed that CB 132 and CB 149 affects serum levels of triiodothyronine as well as sperm motility, velocity and capability of penetrating oocytes. The mechanism of action and potential effects on human warrant further investigation.