Brain-derived neurotrophic factor (BDNF) expression and function in the mammalian reproductive Tract

BACKGROUND

Neurotrophins of the nerve growth factor family are soluble polypeptides that are best known for their role in nerve growth, survival and differentiation in the central nervous system. A growing body of literature shows that neurotrophins and their receptors are also expressed throughout the reproductive tract.

OBJECTIVE AND RATIONALE

Neurotrophins are key regulatory proteins in reproductive physiology during development and throughout adult life. Of the neurotrophins, the literature describing the expression and function of brain-derived neurotrophic factor (BDNF) and its high-affinity receptor, neurotrophin receptor kinase-2 (NTRK2), has been expanding rapidly. We therefore conducted a systematic inductive qualitative review of the literature to better define the role of the BDNF in the reproductive tract. We postulate that BDNF and NTRK2 are central regulatory proteins throughout the reproductive system.

SEARCH METHODS

An electronic search of Medline (PubMed) and Web of Science for articles relating to BDNF and the reproductive system was carried out between January 2018 and February 2019.

OUTCOMES

In the ovary, BDNF expression and levels have been linked with follicle organisation during ovarian development, follicle recruitment and growth and oocyte maturation. In the endometrium, BDNF is involved in cell proliferation and neurogenesis. In contrast, literature describing the role of BDNF in other reproductive tissues is sparse and BDNF-NTRK2 signalling in the male reproductive tract has been largely overlooked. Whilst estradiol appears to be the primary regulator of BDNF expression, we also identified reports describing binding sites for glucocorticoid and myocyte enhancer factor-2, a calcium-response element through activation of an N-methyl-D-aspartate (NMDA) receptor, and aryl hydrocarbon receptor nuclear transporter protein-4 (ARNT) response elements in promoter regions of the BDNF gene. Expression is also regulated by multiple microRNAs and post-translational processing of precursor proteins and intracellular shuttling. BDNF-NTRK2 signalling is modulated through tissue specific receptor expression of either the full-length or truncated NTRK2 receptor; however, the functional importance remains to be elucidated. Dysregulation of BDNF expression and circulating concentrations have been implicated in several reproductive disorders including premature ovarian failure, endometriosis, pre-eclampsia, intra-uterine growth restriction (IUGR) and several reproductive cancers.

WIDER IMPLICATIONS

We conclude that BDNF and its receptors are key regulatory proteins central to gonadal development, ovarian regulation and uterine physiology, as well as embryo and placenta development. Furthermore, dysregulation of BDNF-NTRK2 in reproductive diseases suggests their potential role as candidate clinical markers of disease and potential therapeutic targets.

Melatonin activity and receptor expression in endometrial tissue and endometriosis

STUDY QUESTION

Are melatonin receptors (melatonin receptor 1A (MR1A) and melatonin receptor 1B (MR1B)) expressed in human endometrium and endometriotic tissue, and does melatonin affect endometrial cell proliferation?

SUMMARY ANSWER

Melatonin receptors are expressed in human eutopic endometrium, endometriomas and peritoneal lesions, although to different extents, and melatonin treatment attenuated estradiol-induced endometrial epithelial cell proliferation in culture.

WHAT IS KNOWN ALREADY

Melatonin decreased endometriotic lesion volume in a rat model of endometriosis. Melatonin treatment reduced pain scores in and analgesic use by women with endometriosis.

STUDY DESIGN, SIZE, DURATION

Basic science study using human endometrial tissue and an endometrial epithelial cell line.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Measurement of melatonin receptor expression (mRNA and protein) in women with surgically confirmed endometriosis (endometrioma (n = 20) or peritoneal lesion (n = 11) alone) and women without surgical evidence of endometriosis (control, n = 15). Collection of endometrial and endometriotic tissue samples, gynecologic history and demographic information. Quantification of estradiol (1.0 nM) and melatonin (0.1 nM-1.0 μM) ± estradiol-induced endometrial epithelial cell proliferation in cultures of endometrial epithelial cells (CRL-1671) following 24 and 48 hours of culture.

MAIN RESULTS AND THE ROLE OF CHANCE

MR1A and MR1B were localized by immunohistochemistry in glandular epithelial cells of endometrial biopsies from women with and without endometriosis. Both receptors were expressed in eutopic and ectopic endometrial tissue. mRNA expression of MR1A and MR1B was significantly greater in peritoneal lesions than in either endometriomas or eutopic endometrium. However, protein expression of MR1A was decreased in peritoneal lesions compared to control eutopic endometrium, whereas MR1B expression did not differ between the groups. Melatonin (0.1 nM-1.0 μM) treatment inhibited estradiol (1.0 nM)-induced endometrial epithelial cell proliferation at 48 hours but not 24 hours of culture.

LIMITATIONS, REASONS FOR CAUTION

Beneficial effects of melatonin seen in culture have yet to be comprehensively evaluated in women with endometriosis.

WIDER IMPLICATIONS OF THE FINDINGS

Our data suggest that melatonin may be useful as an adjunct to current endometriosis treatments.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the Canadian Institutes of Health Research (grant MOP142230 to W.G.F.). A.A.M. is supported by a resident research grant through the Physicians Services Incorporated Foundation. The authors have no conflicts of interest.

Maternal exposure to butyl paraben impairs testicular structure and sperm quality on male rats

Parabens are hormonally active chemicals widely used as preservatives in foods and are frequently detected in human fluids and tissues. Therefore, the objective of this study was to determine the effects of maternal butyl paraben (BP) exposure on male sexual development. Pregnant Wistar rats received corn oil (control group), or BP at doses of 10, 100, or 200 mg/kg, subcutaneously, from gestational day 12 until postnatal day 21. Our results demonstrated that developmental BP exposure significantly increased the number of adult Leydig cells and the circulating concentrations of testosterone and attenuated FSH and LH concentrations at 200 mg/kg. BP exposure adversely affected spermatogenesis kinetics at doses of 10 and 200 mg/kg and provoked a decrease in the immunostaining of EsR1 and AR at 200 mg/kg. The sperm motility was impaired at the 10 mg/kg dose, and sperm head abnormalities were increased in all BP dose groups. We suggest that BP impairs testicular structure and function in the rat, affecting sperm quality. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1273-1289, 2017.

Receptors for non-MHC ligands contribute to uterine natural killer cell activation during pregnancy in mice

INTRODUCTION

Activated uterine natural killer (uNK) cells are abundant in early human and mouse decidual basalis. In mice, distinct uNK cell subsets support early endothelial tip cell induction, the pruning of new vessels and initiation of spiral arterial modification. While genetic studies indicate that NK/uNK cell activation via receptors recognizing Class I MHC-derived peptides promotes human pregnancy, roles for other activation receptors expressed by NK cells, such as the aryl hydrocarbon receptor (AHR) and natural cytotoxicity receptors (NCR) are undefined in human or mouse pregnancies.

METHODS

Expression of AHR and NCR1 (ortholog of human NKp46) by gestation day (gd)10.5 mouse uNK cell subsets was measured by quantitative real-time RT-PCR. Early implantation sites from mice lacking expression of either receptor were examined histologically.

RESULTS

Gd10.5 uNK cell subsets, separated by reactivity to Dolichos biflorus agglutinin lectin, differed in relative transcript abundance for Ahr and Ncr1. Quantitative histology revealed that, in comparison to C57BL/6 controls, implant sites from gd10.5 Ahr(-/-) and gd6.5-12.5 UkCa:B6.Ncr1(Gfp/Gfp) mice had normal uNK cell abundance but the uNK cells were smaller than normal and unable to trigger spiral arterial remodeling. Whole mount immunohistochemistry comparisons of viable, gd6.5-8.5 Ncr1(Gfp/Gfp) and C57BL/6 implant sites revealed deficits in implant site angiogenesis and conceptus growth in Ncr1(Gfp/Gfp).

DISCUSSION

In mice, activation of AHR and of NCR1 by endogenous, as yet undefined ligands, contributes to uNK cell activation/maturation and angiogenic functions during early to mid-gestation pregnancy. MHC-independent activation of uNK cells also likely makes critical contributions to human pregnancy success.

Optimization of an MCF7-E3 Cell Proliferation Assay and Effects of Environmental Pollutants and Industrial Chemicals

Environmental contaminants might adversely affect human health by acting as endocrine disruptors and thus need to be identified. Our objective was to optimize the MCF7 cell proliferation assay to screen industrial chemicals for potential oestrogenic effects. Growth conditions, performance of the clone E3 and WT-MCF7 cells and five methods to derive proliferation indices were compared. The E3 cells were further characterized by testing the effects of transforming growth factorbeta (TGFbeta), epidermal growth factor (EGF), insulin, testosterone, the anti-oestrogen ICI 164,384 (ICI) and environmental contaminants with known oestrogenic potential. Industrial chemicals with unknown oestrogenic effects were then tested. As expected, induction of proliferation by estradiol-17beta (E2) was greater and less variable using the clone E3. To generate proliferation indices, the alamarBlue assay had a sensitivity comparable to that of [(3)H]thymidine incorporation ((3)H-TI). The E3 cells were not responsive to EGF (0-100 ng/ml) or insulin (0-313 ng/ml) but their proliferation was decreased (P<0.05) by TGFbeta (45 ng/ml) and testosterone (10(-8)m), which might be typical of highly oestrogen-responsive MCF7 cells. ICI (5x10(-7)m) inhibited the proliferative effects of 10(-10)m E2 and that of 10(-6)m 4-tert-octylphenol (Op) but not the proliferative effect of 10(-5)m Op, suggesting displacement of ICI by Op or induction of oestrogen-receptor independent proliferation. N-oxydiethylene-2-benzothiazole sulfenamide (OBTS) altered (3)H-TI in the MCF7 cells, although not in a dose related manner. OBTS did not induce uterotrophic effects in immature female rats, or any response in a human oestrogen chimeric receptor/reporter gene assay, suggesting that its effects were not mediated through the binding of the oestrogen-receptor. Seven other industrial chemicals were tested and had no effects. In conclusion, the MCF7 cell proliferation assay is one screening tool that permits identification of chemicals with oestrogenic potential which thus require further testing.

Atrazine-induced changes in aromatase activity in estrogen sensitive target tissues

Atrazine (ATR) is a pesticide used widely throughout North America. Although not directly estrogenic, ATR treatment has been shown to increase aromatase activity in tumor cell lines. Thus, it is suggested that ATR can increase local tissue estrogen levels in estrogen sensitive target tissues through increased aromatase activity. Therefore the effect of ATR on aromatase activity was measured in human granulosa-lutein cell cultures, cells that abundantly express aromatase, and endometrial stromal cell (ESC) cultures, cells that do not express aromatase. Aromatase activity was quantified by the tritiated water method and the specificity of the assay was confirmed by co-incubation with 4-hydroxyandrostenedione, an irreversible inhibitor of the catalytic activity of aromatase. Aromatase activity in ATR treated (1-10 microm) granulosa-lutein cells was increased more than 2-fold compared with control cultures. There were no treatment related changes in cellular protein and thus it is suggested that the ATR-induced change in aromatase activity was not due to an increase in cell number. ATR-treatment had no effect on ESC aromatase activity at any concentration tested. Similarly, there was no effect of ATR treatment on human recombinant aromatase activity in our cell-free test system. Therefore it is concluded that microm concentrations of ATR can increase aromatase activity of human granulosa cells but not ESC and this effect is not elicited at the enzyme level.

Fetal and neonatal exposure to nicotine in Wistar rats results in increased beta cell apoptosis at birth and postnatal endocrine and metabolic changes associated with type 2 diabetes

AIMS/HYPOTHESIS

Epidemiological studies report an increased risk of obesity and type 2 diabetes in children born to women who smoked during pregnancy. This study examines the effect of fetal and neonatal exposure to nicotine, the major addictive component of cigarettes, on postnatal growth, adiposity and glucose homeostasis.

METHODS

Female Wistar rats were given either saline (vehicle) or nicotine (1 mg kg(-1) day(-1)) during pregnancy and lactation. Serum and pancreas tissue were collected from the infant rats at birth. Postnatal growth was assessed weekly until the rats reached 26 weeks of age and glucose homeostasis was examined by OGTTs performed at 7 and 26 weeks of age.

RESULTS

Exposure to nicotine resulted in increased postnatal growth and adiposity. Nicotine exposure also resulted in dysglycaemia at 7 and 26 weeks of age. Serum insulin concentrations were decreased in the pups exposed to nicotine at birth. This was associated with increased beta cell apoptosis (pups of saline-treated mothers 8.8+/-1.21% apoptotic beta cells; pups of nicotine-treated mothers 27.8+/-3.1% apoptotic beta cells).

CONCLUSIONS/INTERPRETATION

Fetal and neonatal exposure to nicotine results in metabolic changes in the offspring that are consistent with obesity and type 2 diabetes. We propose that these metabolic changes may be a consequence of the initial insult to the beta cell during fetal life and that this animal model has many characteristics of diabetes in humans.

Benzo-[a]-pyrene increases invasion in MDA-MB-231 breast cancer cells via increased COX-II expression and prostaglandin E2 (PGE2) output

Benzo-[a]-pyrene (B[a]P), a carcinogenic component of cigarette smoke, has been shown to increase both COX-II expression and prostaglandin output in vascular smooth muscle and oral epithelial cells. In addition, invasive breast cancer cells have been reported to over express COX-II and PGE(2). Therefore, the objective of this study was to quantify the effect of increasing B[a]P concentrations on COX-II expression, PGE(2) output, and invasion using MDA-MB-231 cells, an invasive estrogen unresponsive breast cancer cell line. B[a]P significantly increased invasion in MDA-MB-231 cells at concentrations greater than 4 x 10(-8) M. Treatment of MDA-MB-231 cells with Vomitoxin (a selective COX-II inducer) enhanced invasion whereas co-treatment with NS398 (a selective COX-II inhibitor) attenuated B[a]P-induced invasion in MDA-MB-231 cells. Immunohistochemical staining and Western blots demonstrated a significant B[a]P treatment-induced increase in both the number of COX-II immunopositive MDA-MB-231 cells and COX-II protein levels. Moreover, B[a]P-treatment induced a profound (46 fold) increase in PGE(2) production by MDA-MB-231 cells. The aryl hydrocarbon receptor (AhR) antagonists resveratrol (RES) and alpha-naphthaflavone (alpha-NF) had no effect on their own, whereas B[a]P-induced invasion was significantly inhibited by co-treatment with RES and alpha-NF. Our data demonstrate that B[a]P-induced changes in invasion are mediated through augmented COX-II expression and PGE(2) production involving an AhR regulated pathway. Moreover, these results suggest a potential role for the AhR signalling pathway in breast cancer invasion.

Dichlorodiphenylchloroethylene elevates cytosolic calcium concentrations and oscillations in primary cultures of human granulosa-lutein cells

1,1-Dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), a metabolite of DDT (1,1-dichlorodiphenyltrichloroethane), is a persistent hormonally active environmental toxicant that has been found in human serum and follicular fluid. The objective of this study was to determine whether DDE can alter free calcium ion concentrations in the cytosol ([Ca(2+)](cyt)) of human granulosa cells. Changes in [Ca(2+)](cyt) in single cells loaded with Fura-2 were studied using a dynamic digital Ca(2+) imaging system. At a concentration of 100 ng/ml, DDE stimulated small elevations of [Ca(2+)](cyt) accompanied by Ca(2+) oscillations. At 1 microg DDE/ml, there was a biphasic Ca(2+) response with marked elevations of [Ca(2+)](cyt) over time. In Ca(2+)-free medium, cells showed an initial small elevation of [Ca(2+)](cyt), which was magnified after addition of Ca(2+) to the medium. Washing the cells after DDE treatment failed to remove the elevated [Ca(2+)](cyt) and oscillations, both of which were eliminated by addition of EGTA. ATP also induced [Ca(2+)](cyt) elevations and oscillations, and these effects were potentiated when DDE was added. FSH induced transient [Ca(2+)](cyt) elevations, whereas hCG caused a prolonged elevation and marked oscillations in [Ca(2+)](cyt). These results suggest that DDE at concentrations normally found in human tissues induces elevations in [Ca(2+)](cyt) in granulosa-lutein cells. Our data therefore highlight a novel mechanism through which DDE can alter endocrine homeostasis and possibly act as an endocrine toxicant.

Environmental toxicants and human fertility

Globally there is increasing concern that the environment is having a negative impact on human health. Hormone-like activity and endocrine toxicity of environmental toxicants have been documented in the contemporary literature raising concern that exposure to these chemicals could alter human reproductive function and affect fertility. In addition, epidemiological reports of an association between exposure to chemical toxicants in the workplace and adverse reproductive outcomes together with detection of environmental toxicant residues in serum and ovarian follicular fluid, has led to widespread concern that chemical contaminants may be a contributing factor in the pathobiology of idiopathic infertility in the general population. While the epidemiological evidence is equivocal, animal studies provide biological plausibility for a potential association between environmental toxicant exposures and altered reproductive function. Furthermore, cell and organ culture experiments illustrate potential mechanisms of toxicant action on the reproductive system. This review summarizes the evidence linking environmental toxicant exposure and infertility and examines the biological plausibility for this association.

Levels of environmental contaminants in human follicular fluid, serum, and seminal plasma of couples undergoing in vitro fertilization

Environmental chemicals are thought to adversely affect human reproductive function, however there are no studies that have explored the association between failed fertilization and exposure of both partners to environmental contaminants. Therefore, we collected blood and follicular fluid from the female partner and seminal plasma from the male partner of 21 couples attending an in vitro fertilization (IVF) program, in order to determine the extent of the existence of environmental chemicals in these fluids. Any relationship to the outcome of IVF was also considered. Sera and fluids were analysed for a variety of contaminants, including polychlorinated biphenyls, pesticides, cotinine, and the steroids progesterone and estradiol. Of the couples examined, 18 had fertilizations, three of whom became pregnant. There were no fertilizations in three other couples. The contaminants most frequently found in follicular fluid, more than 50% of the samples tested, were p,p'-DDE, mirex, hexachloroethane, 1,2,4-trichlorobenzene, PCB 49, PCB 153, and PCB 180. Cadmium was detected in eight of 21 (38.1%) samples of follicular fluid whereas cotinine was detected in 18 (85.7%). Residue levels of p,p'-DDE, endosulfan I, PCB 99, PCB 138, PCB 153, PCB 180 were quantified in more than 50% of the sera samples examined. Seminal plasma was relatively free of pollutants with mirex being the most frequently detected contaminant found in seven of 21 (33.3%) samples. Mirex could not be detected in the seminal plasma of the husbands whose partner's oocytes failed to fertilize whereas significant levels of mirex were found in the seminal plasma of all couples who had a pregnancy. Cadmium was also found in the follicular fluid of these pregnant subjects. No relationship was found between follicular fluid cotinine in pregnant and non-pregnant subjects. Where identical contaminants were found in both sera and follicular fluids, the levels were about twofold higher in serum and were positively correlated in both fluids. Fertilization was negatively correlated with serum and follicular fluid p,p'-DDE whereas pregnancy was positively correlated with follicular fluid PCB 49. These data reveal that more than 50% of the population of women attending a fertility program have had exposure to environmental chemicals sufficient to produce detectable concentrations in their serum and ovarian follicular fluid. Of the chemical contaminants detected in the serum and follicular fluid of these women, p,p'-DDE was the most frequently detected, had the highest residue levels, and was associated with failed fertilization.

Appendiceal disease in women with endometriosis and right lower quadrant pain

STUDY OBJECTIVE

To evaluate the frequency and range of appendiceal disease in women with endometriosis and right lower quadrant (RLQ) pain, and to estimate the value of preoperative gastrograffin enema (GGE) as a screen for the disease.

DESIGN

Nonrandomized clinical trial (Canadian Task Force classification II-2).

SETTING

University-affiliated hospital with a private practice setting.

PATIENTS

A subpopulation of 65 women from a group of 337 patients undergoing laparoscopy for symptomatic endometriosis.

INTERVENTION

Preoperative GGE was performed whenever possible in these women. At laparoscopy, the appendix was removed if it appeared abnormal or if the preoperative GGE was positive.

MEASUREMENTS AND MAIN RESULTS

Of 65 women (19%) with symptomatic endometriosis and preoperative RLQ pain, 52 (80%) underwent appendectomy as part of surgery. Of these 52 excised appendixes, 39 (75%) had histologically confirmed pathology including appendicitis or periappendicitis, endometriosis, fibrous obliteration, lymphoid hyperplasia, and carcinoid tumor. Preoperative GGE had sensitivity of 74% and specificity of 83% for appendiceal disease. Its positive predictive value was 95% and negative predictive value was 42%. No complications from laparoscopic appendectomy occurred.

CONCLUSION

Disease of the appendix is common in women with endometriosis and RLQ pain. Appendectomy is particularly likely if preoperative GGE is positive.

The effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin on corticotrophin-releasing hormone, arginine vasopressin, and pro-opiomelanocortin mRNA levels in the hypothalamus of the cynomolgus monkey

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a widespread environmental contaminant that has profound deleterious effects on development and reproduction. TCDD may act at one or more levels to alter the hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axes. The objective of this study was to investigate whether TCDD modulates neuroendocrine systems by altering gene expression of arginine vasopressin (AVP), corticotrophin-releasing hormone (CRH), or pro-opiomelanocortin (POMC), which are important neuroregulators of the HPA and HPG axes. Four groups of female cynomolgus monkeys (Macaca fascicularis) were administered daily oral doses of gelatin capsule containing TCDD (0, 1, 5, or 25 ng/kg body weight) mixed with glucose 5 days a week for 1 year. At the end of the dosing period, animals were euthanized and brains were harvested. CRH, AVP, and POMC mRNA levels were semiquantified by in situ hybridization histochemistry on 30-microm coronal sections of the brain. Blood collected on the day of euthanasia was assayed for cortisol and progesterone. CRH mRNA levels in the paraventricular nucleus (PVN) were significantly increased by the 2 higher TCDD doses (5 and 25 ng/kg/day) compared to controls (p < 0.05). There was a trend towards increased AVP mRNA levels in both the supraoptic nucleus (SON) and PVN. No effect of TCDD on POMC was observed. Cortisol levels were significantly increased in TCDD-exposed animals. Progesterone concentrations and menstruation data indicated that TCDD did not interfere with ovulation. We conclude that TCDD stimulated the HPA axis by a central effect involving CRH, but had no effect on the HPG axis at the doses tested.

Subchronic exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin modulates the pathophysiology of endometriosis in the cynomolgus monkey

An increase in the incidence and severity of endometriosis following treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was a serendipitous finding in a reproductive toxicology study in rhesus monkeys. The purpose of this study was to investigate the effects of subchronic exposure to TCDD on the survival and growth of surgically implanted endometrial fragments. Endometrial fragments of equal size (4 x 1 mm(2)) were auto-transplanted to the pelvic cavity of nulliparous cynomolgus monkeys (Macaca fascicularis, n = 23), who were divided into 4 treatment groups and dosed 5 days a week with gelatin capsules containing 0, 1, 5, or 25 ng/kg body weight of TCDD mixed with glucose. Endometrial implant survival was monitored by laparoscopy at intervals of 1, 3, and 6 months. Animals were euthanized at 12 months of treatment in the early to mid luteal phase and the maximal and minimal endometrial implant diameter was measured. Both the maximal and minimal diameters were significantly reduced in the 0.71-ng/kg/day-TCDD dose group, compared to controls, whereas the survival rate was unaffected (20 vs. 16%, respectively). In contrast, exposure to 3.57 and 17.86 ng/kg/day TCDD for 1 year resulted in a significantly higher survival rate of implants (26.7% and 33.3% respectively vs. 16.0%) and significantly larger diameter implants in the 17.86-ng/kg/day dose group only, compared to the control group. Treatment had no effect on circulating gonadal steroid levels or menstrual cycle characteristics. It is concluded that TCDD facilitates the survival of endometrial implants and exerts a bimodal effect on endometrial implant growth.

Reproductive effects of tris(4-chlorophenyl)methanol in the rat

Tris(4-chlorophenyl)methanol (TCPM) is a global contaminant of unknown origin that is structurally related to the endocrine modulating pesticides 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and Dicofol. Therefore, the potential reproductive toxic effects of TCPM were investigated in sexually mature male Sprague Dawley rats (n = 20) treated with 1.0, 10.0 or 100 ppm of TCPM mixed in the diet for 28 days. The calculated TCPM intake was 0.0, 0.1, 1.2 and 12.4 mg/kg/day, respectively. Serum concentrations of follicle stimulating hormone (FSH) in terminal blood samples were significantly (P < 0.02) elevated in the highest dose group compared to the controls. In contrast, dietary exposure to TCPM had no effect on circulating levels of luteinizing hormone (LH), testosterone (T) and the T/LH ratio. Incubation of MCF-7 cells with increasing concentrations of TCPM failed to either induce proliferation or to block the proliferative effect induced by estradiol indicating that TCPM is neither estrogenic or anti-estrogenic. Relative binding affinity studies using androgen receptors from the prostate revealed that TCPM has a binding affinity comparable to 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE), the principle metabolite of DDT. In addition, the calculated Ki (0.62 microM) for TCPM is lower than the reported Ki's for the antiandrogenic pesticides p,p'-DDE and vinclozolin. Although TCPM binds with the androgen receptor in vitro, the absence of both an effect on serum T levels and morphological changes in the testis suggests that the mechanism of action for elevated FSH levels seen in vivo may not involve an antiandrogenic effect of TCPM at the dose level used in this study. The no adverse effect level for reproductive effects of TCPM is 10 ppm which is equivalent to a calculated intake of 1.2 mg/kg/day.

Effects of acute exposure to PCBs 126 and 153 on anterior pituitary and thyroid hormones and FSH isoforms in adult Sprague Dawley male rats

3,3'4,4',5-Pentachlorobiphenyl (PCB 126) and 2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153) were administered to adult male rats in order to identify sensitive indicators of endocrine disruption. We tested the hypothesis that PCB exposure modifies follicle-stimulating hormone (FSH) pituitary isoforms, as well as the pituitary and serum concentrations of FSH, luteinizing hormone (LH), growth hormone, prolactin, and thyroid-stimulating hormone (TSH). Effects on serum levels of thyroxine (T4) and testosterone (T), and prostate androgen receptor content, were also tested. In one experiment, 5 groups of 8 rats each received two i.p. injections, one day apart, of either corn oil or 6.25, 25, 100 or 400 micrograms/kg/day of PCB 126. Decreases (p < 0.05) in the serum concentrations of T4 and LH started at doses of 25 and 100 micrograms/kg/day, respectively. Serum FSH concentrations were reduced (p = 0.07) in the highest dose group. In contrast, pituitary content of FSH and LH increased with PCB-126 doses (p = 0.004, p = 0.002, respectively). Despite changes in reproductive hormones, PCB-126 had no effect on the androgen receptor content of the prostate. The effect of PCB-126 was tested in the hemicastrated rat, and suggested adverse effects on testosterone secretion. To test the effects of PCB exposure on FSH pituitary isoforms, 4 groups of 10 male rats received two i.p. injections, one day apart, of either corn oil, PCB 153 (25 mg/kg/day), estradiol-17 beta (E2; 20 micrograms/kg/day), or PCB 126 (0.1 mg/kg/day). Serum T4 levels were higher (p < 0.01) in the E2 and PCB 153 groups, and slightly reduced in the PCB 126-treated groups, compared to controls. Simultaneous purification of pituitary FSH and TSH isoforms was performed by HPLC, using two chromatofocusing columns in series. In contrast to TSH isoforms, the distribution of FSH isoforms over the chromatography run differed slightly between treatment groups; the amounts of FSH isoform eluted during the pH gradient were lower (p < 0.05) in E2 and PCB 153-treated rats than in control or PCB 126-treated rats. The similarity between the effects of E2 and PCB 153 on T4 and FSH isoforms supports the contention that PCB 153 possesses estrogenic properties. Serum LH and T4 concentrations were the most sensitive and practical endocrine indicators of PCBs 126 and 153 exposure in male rats.

Canadian semen quality: an analysis of sperm density among eleven academic fertility centers

OBJECTIVE

To determine whether sperm quality has declined among Canadian men during the past 13 years and whether there are regional differences in sperm quality.

DESIGN

Retrospective temporal series of cross-sectional studies.

SETTING

University fertility centers across Canada.

PATIENT(S)

Men being investigated as part of the normal infertility work-up.

MAIN OUTCOME MEASURE(S)

Sperm concentrations among all the samples were compared on an annual basis to assess any changes over 13 years from 1984 through 1996.

RESULT(S)

There were regional differences and trends in both up and down directions. Linear regression analysis of the means of each center for each year showed no significant trend. However, when all the samples were analyzed by regression analysis there was a significant downward trend.

CONCLUSION(S)

Linear regression analysis showed a significant downward trend in sperm concentration among 48,968 samples from Canadian men obtained from 1984 through 1996. A significant difference was seen in the mean concentrations between centers, ranging from 48.6 to 104.5 X 10(6)/mL. Secular trends in sperm density are dependent on the statistical method used for analysis.

The effect of photomirex on the in vitro perfused ovary of the rat

Photomirex, a photodegradation product of the insecticide mirex, is an environmental contaminant that has been identified in Great Lakes fish, soil, and human adipose tissue. Because of the potential for human exposure, the present study was designed to investigate the short-term effects of photomirex on the in vitro perfused ovary of the rat. Adult Sprague-Dawley rat ovaries were isolated and perfused for a total of 6 h with Medium 199. Following a 2-h baseline period, 10(-4) M of photomirex was administered to the medium. Control ovaries received medium or DMSO (vehicle control). Significant effects of perfusion and chemical intervention were identified using lactate dehydrogenase enzyme, glucose utilization, lactate, pyruvate, and flow:pressure ratio as markers of toxicity (P < 0.05). Lactate:pyruvate ratio, glutathione, and oxygen consumption did not demonstrate significant effects. Post hoc tests showed that there were significant differences between the DMSO + photomirex group and the control group (M199) using lactate dehydrogenase as a marker of toxicity. Pyruvate concentration was also reduced significantly after perfusion with DMSO + photomirex compared to M199 only and DMSO only (P < 0.05). Histopathologic changes were not discernible by light microscopy. These results suggest that metabolic and respiratory processes of the ovary are acutely sensitive to perturbation with photomirex in the in vitro perfused rat ovary model.

Endocrine disruptors and development of the reproductive system in the fetus and children: is there cause for concern?

Reports of decreased semen quality and increased rates of developmental abnormalities of the male reproductive tract along with increasing incidence of testicular cancer have focused attention on man-made chemicals as potential causative factors. A biologically plausible hypothesis has been advanced which suggests that man-made chemicals act as endocrine disruptors through interaction with the estrogen receptor resulting in altered development of the reproductive tract. Available evidence suggests that this mechanism may play only a minor role in the purported adverse effects described to date. Man-made chemicals, however, may induce adverse health effects through mechanisms independent of the estrogen receptor. Indeed, man-made chemicals have been shown to induce adverse effects on thyroid function and androgen-dependent processes in animal studies. Hence the focus on estrogenic mimics may be too simplistic and alternate mechanisms could be more relevant due to target gland exposure levels and potency of the toxicant. Before it can be concluded that man-made chemicals pose little or no risk to the development of the reproductive tract in the fetus and children it will be necessary to, at the very least, insure that: 1) exposure scenarios include the most sensitive developmental stage, 2) all endocrine targets have been evaluated for potential effects, and 3) the role of environmentally and biologically relevant levels of chemical mixtures in adverse health outcomes have been evaluated. Due to potential for exposure, sensitivity of the developing reproductive tract, suggestive evidence of a possible role of man-made chemicals in developmental abnormalities of the reproductive tract, and the many outstanding research questions, it is concluded that there is sufficient cause for concern.

Chronic lead exposure effects in the cynomolgus monkey (Macaca fascicularis) testis

Although reproductive consequences of high circulating blood lead levels (> or = 60 micrograms/dL) have been reported, potential adverse effects of chronic lead exposure in males that result in low to moderate blood lead levels (10-25 and 26-60 micrograms/dL, respectively) are unknown. Effects of chronic lead exposure to testis ultrastructure were determined in the cynomolgus monkey after oral administration of lead acetate (1500 micrograms/kg BW/day) in a vehicle in the following groups: from birth to 10 years (lifetime), postnatal day 300 to 10 years (postinfancy), and postnatal day 0-400 (infancy); monkeys in the control group received only the vehicle (95% glycerol and 5% distilled water). At age 10 years, circulating lead concentrations in lifetime and postinfancy-dosed monkeys were approximately 35 micrograms/dL, and in control and infancy animals the concentrations were < 1.0 microgram/dL. Sertoli and spermatogenic cells of dosed monkeys from the infancy and lifetime groups revealed injuries. Chronic exposure to lead that results in moderate blood lead concentrations induced persistent ultrastructural alterations in the cynomolgus monkey testis. Results of this study on the primate, following extrapolation to humans, could influence further refining of the impact of environmental lead contamination concentrations vis-à-vis the health of children, adults, and aged human beings.

Interactions between endosulfan and dieldrin on estrogen-mediated processes in vitro and in vivo

There is growing concern that estrogenic chemicals, both natural and human-made, may be causing a variety of reproductive disorders in wildlife and human populations. Recent in vitro data suggest that the interaction between some weakly estrogenic organochlorines, dieldrin, endosulfan, toxaphene, and chlordane, causes a synergistic increase in their estrogenic potency, an effect due to joint action on estrogen receptors (ER). As these studies were conducted using models of estrogen action derived from cells that are not physiologically controlled by estrogens, the relevance of these findings to human health are not clear. The present studies were conducted to examine the interaction between endosulfan and dieldrin in the activation of ER in or extracted from mammalian cells. Endosulfan and dieldrin showed no synergism in displacing 3H-E2 from rat uterine ER or in inducing the proliferation of MCF-7 breast cancer cells, an estrogen-dependent response. Furthermore, endosulfan (0.1 mg per animal per d) or dieldrin (0.1 mg), alone or in combination, injected intraperitoneally daily for 3 d, did not stimulate any uterotrophic activity nor had any effect on pituitary prolactin or other endocrine-related endpoints in immature female rats. These studies demonstrate that these weakly estrogenic compounds do not interact in a synergistic fashion in binding to ER or in activating ER-dependent responses in mammalian tissues or cells. Thus, these results suggest that coexposure to these weakly estrogenic environmental contaminants likely will not cause human reproductive toxicity related to estrogen action.

Morphologic characteristics of endometriosis in the mouse model: application to toxicology

Surgically induced endometriosis in the mouse has been described as a model to investigate the effect of environmental pollutants on the growth of endometriotic implants. The objectives of this study were to evaluate a modified surgical procedure to induce endometriosis and validate the model by comparing the effects of estrogen, 4-chlorodiphenyl ether (4-CDE) as a possible estrogenic contaminant, and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a contaminant with predominantly anti-estrogenic activities, on the growth of endometrial implants. Uterine strips (1.0 x 4.0 mm2) were autotransplanted to multiple sites in the abdomen of sexually mature female B6C3F1 mice (n = 33), which were randomly assigned to the following groups: intact control (n = 4); ovariectomized (OVX, n = 9); OVX and treated with 4-CDE (n = 6); OVX and treated with 17 beta-estradiol (E2, n = 9); and OVX and treated with E2 plus TCDD (n = 5). Endometrial implants survived warm ischemia regardless of implant site and appeared as small clear spherical or ovoid fluid-filled cysts. The diameter of the endometrial cysts in the OVX animals was significantly (p < 0.0001) smaller compared with the intact animals and OVX animals replaced with E2 or 4-CDE. In contrast, TCDD treatment inhibited the growth of endometrial cysts in the presence of estrogen. We conclude that autotransplantation of uterine slices to multiple abdominal sites results in formation of endometriotic cysts that are responsive to estrogen, and that environmental contaminants possess the potential to affect the survival and growth of endometrial cysts. Therefore, we concluded that the mouse endometriosis model described in this paper has applications to investigate the possible role of environmental pollutants in the development of endometriosis.

Reproductive and thyroid hormone levels in rats following 90-day dietary exposure to PCB 28 (2,4,4'-trichlorobiphenyl) or PCB 77 (3,3'4,4'-tetrachlorobiphenyl)

Subchronic exposure to the PCB congener 77 (PCB 77) and 28 (PCB 28) was previously shown to induce histological changes in the thyroid and in the brain biogenic amines levels, suggesting possible effects on thyroid and reproductive hormone levels. Thus, the effects of a 90-day dietary exposure to PCB 28 or 77 on luteinizing hormone, follicle-stimulating hormone, and testosterone concentrations were studied in male rats, as well as the levels of thyroid-stimulating hormone, thyroxine (T4) and uridine diphosphate-glucuronyl transferase (UDP-GT) activity in both genders. Weanling Sprague Dawley rats were randomly distributed into groups of 10 rats and were fed, for the next 13 weeks, purina lab chow containing 50, 500, 5,000 or 50 000 ppb of PCB 28 or 10, 100, 1000, or 10 000 ppb of PCB 77. The serum concentrations of T4 were decreased in rats of both sexes receiving 1000 ppb or more of PCB 77, and was associated with an increased activity of UDP-GT which reached significance only in the females. There was a tendency for the highest dose of PCB 28 also to decrease serum T4 concentrations in the female rats. None of the PCB treatments significantly altered gonadotropin, TSH, or testosterone concentrations. These results suggest that thyroid functions may be more susceptible or adapt less readily than the pituitary gland and the testes to endocrine disruption caused by PCB congeners.

Stimulating effects of 4-chlorodiphenyl ether on surgically induced endometriosis in the mouse

The objectives of this study were to evaluate the effects of repeated injection of 4-chlorodiphenyl ether (4-CDE) on the survival and growth of endometriotic implants. Endometriosis was surgically induced in adult female B6C3F1 mice (n = 25) after ovariectomy. Seven days later the animals were randomly divided into five groups and treated with vehicle alone (corn oil, control), or 20 micrograms/kg/d estrone (positive control), or 10, 75, or 150 mg/kg/d 4-CDE in vehicle for 28 d. The number and size of the endometriotic cysts were recorded and the cysts were then harvested for histology at necropsy 2 d after the last treatment. There were significantly more cysts formed (P < 0.05) in the 150 mg/kg/d 4-CDE group compared to the vehicle-treated control (60 vs. 8%), but not compared to the estrone-treated positive control (90 vs. 60%). Hepatic enzymes were evaluated to confirm exposure and to further clarify the enzymatic route of 4-CDE biotransformation by the liver. In conclusion, the repeated exposure to 4-CDE increased the survival rates of the endometriotic cysts in the ovariectomized mouse, which suggests that 4-CDE mimics estrogen effects on endometriotic tissues because the endometrial tissues are dependent on estrogenic support for survival.

Continuous exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin inhibits the growth of surgically induced endometriosis in the ovariectomized mouse treated with high dose estradiol

The objectives of this study were to evaluate the effects of repeated injection of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the growth of endometriosis and the formation of adhesions in the mouse. Sexually mature female B6C3F1 mice (n = 19) were ovariectomized and subcutaneously implanted with a silastic capsule containing estradiol (E2). Uterine tissues in full thickness (I x I mm2, 5 pieces) from the left uterine horn were surgically autotransplanted to 5 different locations in the peritoneal cavity. One week later the animals were randomly assigned to four groups and treated with: vehicle alone (corn oil). 10.50 or 100 ng/kg/day TCDD for 28 days. Two days after last dose a necropsy was performed to measure the diameter of endometrial implants and to score the adhesions. Endometrial implants were harvested for histology and blood was collected for assessment of E2 levels. The diameter of endometrial implants was significantly smaller in the TCDD treated groups compared to the controls (p < 0.05). Survival of endometrial implants, the formation and scores of adhesions, and serum E2 levels were not significantly different among the dosing groups. Histology of implants showed a significant regression of endometrial tissues in the animals receiving 50 and 100 ng/kg/day TCDD compared to the controls. We conclude that continuous exposure to TCDD resulted in regression of the endometriotic implants in the ovariectomized mice treated with a high dose exogenous F2.

Sperm chromatin structure is altered in cynomolgus monkeys with environmentally relevant blood lead levels

Exposure to lead has been associated with a variety of adverse reproductive outcomes such as spontaneous abortion, impaired fecundity, and sterility. Although decreased sperm counts and serum testosterone levels have been found in men with occupational lead exposure, animal experiments suggest that fertility may be impaired at blood lead levels that have no apparent effect on reproductive hormone levels or sperm concentration. Consequently, this study investigated the effect of chronic lead treatment on semen quality in healthy cynomolgus monkeys aged 15-20 years with mean (+/-SD) blood lead levels of 10 +/- 3 micrograms/dL (range 6-20 micrograms/dL, n = 4) and 56 +/- 49 micrograms/dL (range 22-148 micrograms/dL, n = 7) compared to a reference group with blood lead levels < 1.0 microgram/dL (n = 8). Blood and semen samples were collected once from each monkey in five different months. Serum testosterone levels were determined by radioimmunoassay, and lead effects on chromatin structure were analyzed by flow cytometry. There were no effects of treatment on circulating levels of testosterone or parameters of semen quality such as sperm count, viability, motility, and morphology. However, significant (p < 0.03) treatment-related effects were seen on SD alpha t values in the treated vs control animals. Group comparisons also revealed that the effects of chronic lead exposure were significant (p < 0.05) for both lead-exposed groups compared to the reference group. We conclude that chronic lead exposure alters sperm chromatin structure at blood lead levels relevant to the human population and in the absence of effects on endocrine function and traditional measures of semen quality.

Intrauterine 5-aminolevulinic acid induces selective endometrial fluorescence in the rhesus and cynomolgus monkey

OBJECTIVES

To evaluate the selectivity of endometrial photosensitization after intrauterine 5-aminolevulinic acid administration in nonhuman primates, and to assess acute and chronic systemic toxicity after intravenous (i.v.) delivery of 5-aminolevulinic acid.

METHODS

Ovariectomized cynomolgus monkeys (n = 19) aged 6-18 years and ovariectomized rheusus monkeys (n = 3) aged 9-14 years were used in these studies, 5-aminolevulinic acid at various doses was administered by a transfundal (n = 8), transcervical (n = 3), or i.v. (n = 11) route. Spectrophoto-fluorometric readings and fluorescence microscopy were used to assess 5-aminolevulinic acid-induced photosensitization of uterine tissues; respiration, heart rate, blood biochemistry, and behavior were used to evaluate potential acute and delayed systemic toxicity.

RESULTS

Endometrial fluorescence was achieved in all animals after administration of 5-aminolevulinic acid. Characteristic spectrophotofluorescence peaks of protoporphyrin IX (PpIX) in the endometrium but not myometrium confirmed selective endometrial PpIX production from 5-aminolevulinic acid. A transient (less than 1 week) increase in serum aspartate aminotransferase was observed after systemic instillation of 5-aminolevulinic acid in dosages 24-50-fold greater than that required to induce endometrial photosensitization after intrauterine injection.

CONCLUSIONS

The endometrium but not myometrium in nonhuman primates is capable of converting 5-aminolevulinic acid into protoporphyrin IX. At large doses, systemic 5-aminolevulinic acid causes a transient increase in the serum aspartate aminotransferase level. No other evidence of acute or delayed systemic toxicity was observed.

Subclinical changes in luteal function in cynomolgus monkeys with moderate blood lead levels

The objective of the present study was to investigate luteal function in cynomolgus monkeys (n = 32), aged 15-20 years with blood lead levels (BLLs) in the range of < 3.0 micrograms dl-1 (control, n = 20), 10-15 micrograms dl-1 (low, n = 7) and 25-30 micrograms dl-1 (moderate, n = 5). Sampling was performed daily beginning with day 10 of the menstrual cycle and concluding on the first day of the subsequent menstrual cycle. Circulating levels of oestradiol (E2), progesterone (P4) and 20 alpha-hydroxyprogesterone (20-OHP) were normalized to the day of the ovulatory E2 surge. The area under the concentration curve (AUC) for P4 was significantly lower in monkeys with moderate BLLs compared to the control group (P = 0.04). The number of days for which circulating levels of P4 were greater than 1.0 ng ml-1 were also significantly fewer (P = 0.03) in monkeys with moderate BLLs compared to controls. There was no statistical evidence of a lead effect on circulating levels of E2, 20-OHP or menstrual cycle characteristics. These data suggest that chronic lead exposure suppresses corpora luteal production of P4 in the monkey at circulating BLLs lower than previously reported and relevant to humans with occupational exposure to lead.

The reproductive toxicology of Great Lakes contaminants

The Great Lakes basin is characterized as a heavily populated and industrialized region in which a large number of environmental contaminants have been identified. Both the scientific community and the public have voiced concern that contaminants present in the Great Lakes may pose undue risk to human reproduction. Evidence from animal experiments, wildlife studies, and reports of occupational and accidental human exposures indicate that chemical contaminants can adversely affect reproduction. The purpose of this paper is to review the reproductive toxicity of some of the many contaminants known to be present in the Great Lakes. Since the number of chemicals present in the Great Lakes is far too great for each to be adequately reviewed here, discussion will be limited to those contaminants that have been identified in human serum, ovarian follicular fluid, and semen obtained from people residing in the Great Lakes region. It is concluded that a) the data at present is too limited to support the notion that reproduction, in the general population, has been impaired by exposure to chemicals present in the Great Lakes; b) the lack of data in some cases such as for hexachloroethane and 1,2,4-trichlobenzene does provide reason for concern and underscores the need for further research in this area; and c) the potential for a number of the compounds, including polychlorinated biphenyls (PCBs) and 1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane (DDT), to disrupt endocrine functions suggests that additive or synergistic effects of these compounds may already be causing adverse effects on reproduction in sensitive individuals, which needs to be explored.

Ultrastructural changes in ovarian follicles of monkeys administered hexachlorobenzene

OBJECTIVE

To test hexachlorobenzene (HCB), an environmental pollutant, for its potential toxicity to the ovary.

DESIGN

Nonhuman primates were orally administered the pollutant at doses between 0.01 and 10 mg of HCB/kg of body weight to test viability of ovarian follicles. At the end of dosing period, the monkeys received a compound that contained follicle-stimulating and luteinizing hormones to stimulate development of follicles that would be examined by electron microscopy.

ANIMALS

Twenty, 6- to 13-year-old cynomolgus monkeys were randomly assigned to 5 groups.

PROCEDURE

The HCB, in concentrations of 0.01, 0.1, 1.0, and 10.0 mg/kg, was orally administered with glucose in gelatin capsules for 13 weeks. Monkeys receiving capsules containing glucose only served as controls. After the 13th week, monkeys were given a compound that contained follicle-stimulating and luteinizing hormones daily during days 2 to 7 from the start of menses. On day 8 of the menstrual cycle, 5,000 IU of human chorionic gonadotropin was administered, and 35 to 38 hours later, 1 ovary from each monkey was obtained during laparotomy. Approximately 1-mm cubes of tissue from each ovary were harvested, fixed by immersion in buffered 2% glutaraldehyde, and processed for transmission electron microscopy.

RESULTS

Ultrastructure of ovarian follicles was altered in the monkeys administered HCB. Lesions were observed in the follicles from monkeys given the lowest concentrations of HCB, and comprised condensed mitochondria in the developing ova and follicular cells that contained nuclei with deep indentations and abnormal accumulation of cytoplasmic lipid droplets. Alterations, such as herniation of the ooplasm, degeneration of the follicular cells, and appearance of abnormal spaces between follicular cells were observed in the follicles from monkeys of the 0.1 to 1.0 mg of HCB/kg dosage groups. The most relevant alterations were seen in the mitochondrion, an organelle that appeared to be most sensitive to the compound. Mitochondria were condensed, with abnormal intracristal spaces in the lower-dosage groups, and were markedly degenerated in the 10 mg/kg group. The effect of HCB were dose-related.

CONCLUSION

The HCB is a reproductive system toxicant, and its damaging effects may be a result of augmentation of lipid peroxidation, especially in the primary follicle, which abnormally affects cellular membranes and thus, impairs their permeability.

Alterations in circulating ovarian steroids in hexachlorobenzene-exposed monkeys

Hexachlorobenzene (HCB) is a global pollutant that has been identified in human serum and ovarian follicular fluid, and its effect on ovarian function has not been adequately defined. Thus, the effects of HCB on ovarian steroidogenesis and menstrual cycle characteristics were investigated in cynomolgus monkeys (n = 16) orally dosed by gelatin capsule (0.0, 0.1, 1.0, and 10.0 mg HCB/kg b.wt./d) for 90 d (approximately three menstrual cycles). Analysis of change in menstrual cycle length for each animal revealed a dose-dependent increase (P = 0.02) in cycle length. Ovulatory levels of estradiol (E2) were significantly reduced (P = 0.02) in the highest treatment group. During ovulation induction, the area under the E2 concentration curve (AUC) was significantly (P = 0.03) suppressed in the highest treatment group. Our data demonstrate that HCB treatment, under the conditions of the present study, alters both ovarian function and menstrual cycle characteristics with a no observable adverse effect level of 1.0 mg/kg.

The effects of hexachlorobenzene on circulating levels of adrenal steroids in the ovariectomized rat

Hexachlorobenzene (HCB), is a global pollutant that resists degradation and possesses a propensity to bioaccumulate. However, the effect of HCB on adrenal function remains largely unknown. Thus, circulating levels of adrenal steroids in HCB-exposed (0.0, 1.0, 10.0, or 100.0 mg/kg/day--for 30 days by gavage) adult ovariectomized Sprague-Dawley rats (N = 32) were investigated. A terminal blood sample was collected for HCB residue analysis, and levels of circulating progesterone (P4), corticosterone (CS), and aldosterone (ALD) were quantified. Mean serum CS levels were significantly (P = 0.02) reduced by HCB exposure, starting with the lowest dose group (1.0 mg/kg/day for 30 days), whereas no differences in mean serum P4 and ALD levels were observed. Since it has been argued that the rodent possesses the ability to produce small amounts of cortisol and that levels of this glucocorticoid are altered in pathological states, serum cortisol (C) levels were also measured. Circulating levels of C were significantly lower (P < 0.05) in the highest dose group compared with controls. The presence of C in serum was confirmed by reverse-phase HPLC. These data suggest that even at the lowest dose studied, HCB exposure induces alterations in steroidogenesis of cells of the adrenal cortex inner zone.

Melatonin and steroids in human pre-ovulatory follicular fluid: seasonal variations and granulosa cell steroid production

Follicular fluid samples were obtained from the largest pre-ovulatory follicle of 120 women undergoing in-vitro fertilization and were examined for melatonin by enzyme-linked immunosorbent assay and the steroids oestradiol and progesterone by radioimmunoassay. The concentrations (mean +/- SE) of melatonin (213.4 +/- 18.9 pmol/l) and progesterone (20.1 +/- 1.1 mumol/l) in follicular fluid during the autumn and winter (dark) months were significantly higher than during the spring and summer (light) months, melatonin (138.4 +/- 12.5 pmol/l) and progesterone (11.6 +/- 0.8 mumol/l). By contrast, oestradiol concentrations were significantly lower during the dark months than during the light months (264.7 +/- 44.1 and 661.8 +/- 55.1 nmol/l respectively). There was a positive correlation between follicular fluid melatonin and progesterone concentrations (r = 0.271, P < 0.05, n = 120) and a negative relationship between melatonin and oestradiol (r = -0.254, P < 0.05, n = 120). The effects of melatonin alone and in combination with human chorionic gonadotrophin (HCG) or follicle stimulating hormone (FSH) on steroidogenesis by human granulosa cell culture were also investigated. Melatonin had minimal effects on oestradiol or progesterone production by granulosa cells. Interestingly, the oestradiol response in culture appeared to be different according to the time of the year when harvested. During the light period oestradiol production was enhanced. Melatonin also synergized with HCG in increasing progesterone production on days 6 and 7 after treatment during both light and dark periods. FSH stimulated oestradiol production by the cells on day 2 of culture. Melatonin had no effect on FSH stimulation of oestradiol production. The results of this study suggest that melatonin may be involved in the regulation of steroidogenesis by the human ovaries.

Developmental changes in the gonadotropin releasing hormone neuron of the female rabbit: effects of tamoxifen citrate and pregnant mare serum gonadotropin

Developmental changes in immunostained gonadotropin releasing hormone neurons were demonstrated in female rabbits assigned to the following treatment groups: (i) tamoxifen citrate, 10 mg.kg-1 x day-1, in sesame seed oil (vehicle) (n = 24) or (ii) vehicle alone (control, n = 24) for 108 days; and (iii) 50 IU of pregnant mare serum gonadotropin on postnatal days 22 and 25 (n = 24) or vehicle on nontreatment days. Treatments had no effect on the total number of immunostained cells, but there was a significant (p = 0.0160) developmental shift from cells with smooth processes to rough. Group comparisons revealed that there was a significant (p < 0.001) age-related increase in the number of rough cells in pregnant mare serum treated rabbits between days 25 and 75, indicating an advancement in the shift from smooth to rough cells. Plasma gonadotropin levels, ovarian follicular development, and the developmental shift from smooth to rough cells were markedly suppressed by tamoxifen treatment compared with rabbits of the control group, while no difference in estradiol levels were found. Our results suggest that a developmental shift in gonadotropin releasing hormone cell morphology from smooth to rough precedes sexual maturity in the female rabbit.

Reproductive endocrine effects of chronic lead exposure in the male cynomolgus monkey

The reproductive endocrine effects of chronic lead exposure were investigated in 9 year old male (n = 16) cynomolgus monkeys, orally dosed with lead acetate (1500 micrograms/kg/day) according to the following dosing regimens: continuous exposure from birth onward (lifetime, n = 4), beginning at postnatal day 300 (post-infancy, n = 5) and postnatal days 0 to 400 (infancy, n = 4), or vehicle only (control, n = 3). Altered Sertoli cell function was shown by a significant (P = 0.0286) decrease in the inhibin/follicle stimulating hormone (INH/FSH) ratio in both the lifetime and post-infancy groups compared to the control group. Gonadotropin releasing hormone (GnRH) stimulated levels of luteinizing hormone (LH) were significantly (P = 0.0370) lower in the lifetime group compared to the control group as determined by comparisons of the area under the curve. These data suggest that chronic lead exposure exerts a subtle effect on the pituitary as well as on Sertoli cell function.

Body distribution and endocrine toxicity of hexachlorobenzene (HCB) in the female rat

Hexachlorobenzene (HCB) residue levels in dosed rats (50.0 mg kg-1 body wt.day-1, n = 9) were significantly (P < 0.05) greater in the periovarian fat compared to the thyroid gland. Hexachlorobenzene residue levels were significantly (P < 0.05) greater in the thyroid versus the adrenal and ovary. Ovarian HCB residue levels were greater than those found in the thymus, liver and lung. Serum thyroxin (T4) and the free T4 index (FTI) were significantly (P < 0.05) suppressed in HCB-treated rats compared to the control group (n = 8). In contrast, no significant differences in serum concentrations of oestradiol (E2), progesterone (P4) or percentage triiodothyronine uptake (%T3) were observed, thus suggesting an HCB-induced hypothyroid-like state. In a second experiment, adult female Sprague Dawley rats (n = 16) were dosed as above and superovulated with pregnant mare serum gonadotrophin (PMSG, 10 IU s.c.) and human chorionic gonadotrophin (hCG, 20 IU s.c.). Circulating levels of P4 were significantly (P < 0.05) elevated compared to the control group (n = 8). The %T3 uptake and serum T4 levels were significantly (P = 0.05) suppressed compared to controls. Hexachlorobenzene treatment had no effect on circulating levels of E2 or on the FTI. These results suggest that HCB-induced changes found in the spontaneously cycling rat are augmented by ovulation induction strategies. We also conclude that HCB concentrates in the endocrine tissues in addition to the fat.

Ultrastructure of granulosa lutein cells from rats fed hexachlorobenzene

Corpora lutea from Sprague-Dawley rats that were orally administered 0.0 (control), 1.0, 10.0, and 100.0 mg/kg hexachlorobenzene (HCB) for 21 days were analyzed by electron microscopy. Granulosa lutein cells (GLC) from animals of the 10.0 mg group showed differences from the cells of animals that served as the controls. Golgi complexes and smooth endoplasmic reticulum appeared more conspicuous, possibly due to dilation resulting from hyperactivity. Free polysomes seemed more prominent in the cells of the 10.0 mg group. The GLC architecture from animals of the 1.0 and 100.0 mg groups was similar to that of the corresponding cells in the control group. Since smooth endoplasmic reticulum is involved in the synthesis of steroid hormones, and that free polysomes are engaged in synthesis of cytoplasmic proteins, it is suggested that HCB at a dose of 10.0 mg/kg given for 21 days may alter the synthetic activity of the GLC of the rat.

An ultrasound study of the effect of chronic lead exposure on endometrial cycle changes in the female cynomolgus monkey

The effect of up to 10 years of lead (Pb) exposure (1500 micrograms/kg BW/day) on endometrial cycle changes in adult cynomolgus monkeys (n = 30) were examined by real-time ultrasound. Pb exposure had no effect on peak serum estradiol (E2) or progesterone (P4) concentrations, menstrual cycle length, and endometrial response to gonadal steroids as determined by ultrasound.

Light-related melatonin changes in pituitary response to gonadotropin-releasing hormone during sexual development in the female rabbit

Melatonin levels in the blood of female rabbits were determined from the time of weaning to adulthood in a longitudinal study. Blood samples were taken at 3 h after light onset and 1 h after dark onset and plasma was analysed for melatonin, LH and FSH by radioimmunoassay procedures. The animals were sacrificed on days 25, 32, 39, 51, 72, 91 and 120 days of life and pituitaries removed for in vitro incubation of slices to determine their response to GnRH. Circulating melatonin levels were significantly higher in the dark compared to the light phase and peaked on days 72 and 91 when gonadotropin levels were at a nadir. Melatonin levels on day 120 were lower than those on any other day examined. Basal secretion of LH and FSH by pituitary slices in vitro increased several-fold from day 25 of age to days 51-91 and then decreased by day 120. The pituitary gonadotropin responsiveness to GnRH in vitro was also different: while LH generally increased, FHS accumulation remained constant after GnRH stimulation. These data suggest that the female rabbit pituitary undergoes changes in sensitivity to GnRH during sexual maturation and that the pineal gland may play a role in this process.

Hexachlorobenzene (HCB) suppresses circulating progesterone concentrations during the luteal phase in the cynomolgus monkey

Hexachlorobenzene (HCB) is a known reproductive toxin. However, the full spectrum of its reproductive toxicity is unknown. Consequently, the effect of HCB on serum oestradiol (E2) and progesterone (P4) concentrations during the follicular (days 1-9), periovulatory (days 10-14) and luteal (days 15 to beginning of next menses) phases was investigated in the spontaneously cycling cynomolgus monkey. Adult female cynomolgus monkeys (n = 16) were randomly assigned to one of four treatment groups and orally doses with gelatin capsules containing HCB (0.0, 0.1, 1.0 and 10.0 mg kg-1 body wt. day-1) mixed with glucose. A 10-week acclimitization phase was followed by 13 weeks of dosing. HCB induced a dose-dependent suppression of serum P4 concentrations during the luteal phase. However, circulating levels of P4 were unaffected during the follicular and periovulatory phases of the menstrual cycle. Serum E2 concentrations, body weight, menstrual cycle length and duration of menses were not affected by HCB treatment. The range of menstrual cycle length and duration range of menses, however, were broader in the highest dose group. We conclude that HCB interfers with mechanisms regulating ovarian steroidogenesis and suppresses P4 levels during the luteal phase in the cynomolgus monkey.

Ovarian toxicity of hexachlorobenzene (HCB) in the superovulated female rat

Hexachlorobenzene (HCB) is a persistent environmental contaminant which has been measured in human serum, fat, semen, and follicular fluid. In animal testing HCB has been shown to be a reproductive toxin. Discrepant results were obtained from prior studies concerning the effect of HCB treatment on ovarian steroidogenesis. The current study was designed to assess the impact of HCB on the ovary and gonadal steroid levels in the superovulated rat. Female Sprague-Dawley rats (n = 24) were dosed with HCB (0.0, 1.0, 10.0, or 100.0 mg/kg BW/day) for 21 days. All rats received 10 IU pregnant mare serum gonadotropin (PMSG) s.c. on day 18 of treatment and 15 IU of human chorionic gonadotropin (hCG) on day 20. A terminal blood sample was collected and circulating levels of estradiol (E2) and progesterone. (P4) were determined. Serum concentrations of P4 were significantly (p less than 0.0034) elevated by HCB treatment at all dose levels. Ovarian weights were significantly increased (p less than 0.05) in the lowest dose group only compared to the control group. Serum concentrations of E2, uterine weight, weight gain, and general animal health were not affected by HCB treatment. We conclude that during HCB treatment the rat ovary remains responsive to gonadotropin stimulation. Moreover, it is suggested that HCB effects on ovarian steroidogenesis are indirect.

A prospective analysis of endometrial cycle changes by ultrasound in the female cynomolgus monkey

Endometrial cycle changes in adule female cynomolgus monkeys with normal ovulatory cycles were examined prospectively by real-time ultrasound. Endometrial thickness, as measured by ultrasound, was correlated with cycle day and serum estradiol (E2) and progesterone (P4) levels. We conclude that ultrasound is a reliable method of diagnosis of endometrial cycle stage.

Reproductive toxicity of chronic lead exposure in the female cynomolgus monkey

The effect of chronic lead (Pb) exposure on menstrual function and circulating concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), estradiol (E2) and progesterone (P4) were studied in female nulliparous cynomolgus monkeys (n = 32). Pb acetate (1500 micrograms/kg BW/day) was administered by capsule to monkeys in teh following groups; exposure from birth to 10 years (lifetime, n = 8), postnatal day 300 to 10 years (adolescent, n = 8), and postnatal days 0 to 400 (childhood, n = 8). Monkeys in the control group (n = 8) received gelatin capsules containing the vehicle only. Reproductive assessment of these monkeys was performed between 9 and 10 years, during which time the blood Pb levels in the lifetime and adolescent exposure groups were approximately 35 micrograms/dL. No overt signs of Pb-induced toxicity were found in the general health or menstrual function. However, Pb treatment significantly suppressed circulating levels of LH (P less than 0.042), FSH (P less than 0.041), and E2 (P less than 0.0001) during the menstrual cycle. Pb treatment had no effect on plasma concentrations of P4. These data indicate that chronic Pb exposure results in subclinical suppression of circulating concentrations LH, FSH, and E2 without producing overt signs of menstrual irregularity.

An immunohistochemical study of the GnRH neuron morphology and topography in the adult female rabbit hypothalamus

The morphology and distribution of immunoreactive (GnRH) neural elements in the hypothalamus of the adult nulliparous female rabbit were examined. Approximately 1,000 GnRH cells (range 890-1136) were counted in the right half of the hypothalamus. Two distinct GnRH cell types were observed: GnRH cells with rough or spiny contours accounted for 64% of the total immunoreactive cells, and smooth-contoured cells represented 34% of the total. The majority of immunoreactive neural elements were found in the anterior hypothalamus. GnRH cells and processes were located primarily in the ventral and medial anterior hypothalamus forming an inverted V pattern. Processes were followed from the medial preoptic area and suprachiasmatic nucleus to the infundibular stem. Extrahypothalamic projections of GnRH cells were observed. Immunoreactive fibers were also found to contact the ependymal lining of the third ventricle. It is concluded that two morphologically distinct GnRH cell types exist and have a broad distribution in the rabbit hypothalamus. The functional significance of these cell types requires further study.

Immunoglobulin-mediated hypersensitivity in response to long-term treatment with gonadorelin hydrochloride (Factrel) in a female patient

Recently a patient with severe hypogonadotropic hypogonadism who was given luteinizing hormone-releasing hormone (Factrel) through an infusion pump developed a wheat-and-flare reaction at the sites of injection. Treatment with luteinizing hormone-releasing hormone was discontinued and the immune response was characterized. Skin testing by skin prick test was positive for luteinizing hormone-releasing hormone but negative for vehicle. Radioallergosorbent testing was performed with allergic (patient serum with an elevated serum immunoglobulin E concentration and allergic to inhalant allergens including ragweed pollen) and nonallergic controls. Radioallergosorbent testing was negative for luteinizing hormone-releasing hormone-reactive immunoglobulin E antibodies. Radioimmunoassay of serum of the allergic patient antibody to luteinizing hormone-releasing hormone was positive only for immunoglobulin E. Maximum binding occurred at a dilution of 1:10. Sera from nonallergic and unchallenged patients were negative. It is concluded that this patient developed hypersensitivity reactions caused by IgE antibody to luteinizing hormone-releasing hormone.

Light microscopic study of the hypophyseal angioarchitecture in the rabbit

This study describes the hypophyseal angioarchitecture found in 79 adult New Zealand white rabbits. The pituitary glands and attached hypothalami were removed and carefully processed following routine histological methods, and the vascular organization was studied by light microscopy. Whole mounts of the pituitary median eminence complex were prepared and studied with a binocular dissecting microscope employing transmitted and epi-illumination. Arterial blood was found to be directed primarily to the neurohypophysis by the superior hypophyseal artery (SHA) and the inferior hypophyseal artery (IHA). A direct arterial blood supply was found to the adenohypophysis, but was limited solely to the pars intermedia by branches of the anterior hypophyseal artery (AHA) and the IHA. Capillaries of the pars intermedia were subdivided into an intermediate and a superficial plexus. The superficial plexus was situated between the intermediate plexus and the capillaries of the infundibular process. Capillaries of the superficial plexus did not form anastomoses between themselves, but ramified into the intermediate plexus to form a dense network of anastomosing capillaries that were continuous with capillaries of the pars distalis. A direct arterial blood supply was found only to the superficial plexus.