Effects of exposure to genistein during pubertal development on the reproductive system of male mice

Prostate histological investigation in rats exposed to bisphenol a and phytochemicals during the perinatal period and subjected to hormonal stimulus in adulthood

Bisphenol A (BPA) is an environmentally dispersed chemical associated with tumor development. Phytochemicals such as indole-3-carbinol (I3C) and genistein (GEN) have chemoprotective effects on tumor cells. Thus, this study aimed to evaluate the prostatic morphological aspects of rats exposed to BPA, GEN, and I3C during the perinatal period and submitted to hormonal stimulus in adulthood. Blood was collected to obtain hormone concentrations. Slides stained with hematoxylin & eosin, and picrosirius were subjected to fractal, stereological, morphometric, and collagen quantification analysis. I3C decreased the plasma dihydrotestosterone levels, and both phytochemicals increased the plasma estrogen levels. Unlike phytochemicals, BPA did not alter any of the parameters evaluated. GEN reduced the epithelial height, while I3C increased the fractal dimension and stromal collagen. Although BPA did not alter the prostate morphology, the phytochemicals provided beneficial effects for the prostate histological organization in adult animals subjected to hormonal stimulus.

The Impact of Endocrine-Disrupting Chemicals in Male Fertility: Focus on the Action of Obesogens

The current scenario of male infertility is not yet fully elucidated; however, there is increasing evidence that it is associated with the widespread exposure to endocrine-disrupting chemicals (EDCs), and in particular to obesogens. These compounds interfere with hormones involved in the regulation of metabolism and are associated with weight gain, being also able to change the functioning of the male reproductive axis and, consequently, the testicular physiology and metabolism that are pivotal for spermatogenesis. The disruption of these tightly regulated metabolic pathways leads to adverse reproductive outcomes. The permanent exposure to obesogens has raised serious health concerns. Evidence suggests that obesogens are one of the leading causes of the marked decline of male fertility and key players in shaping the future health outcomes not only for those who are directly exposed but also for upcoming generations. In addition to the changes that lead to inefficient functioning of the male gametes, obesogens induce alterations that are “imprinted” on the genes of the male gametes, establishing a link between generations and contributing to the transmission of defects. Unveiling the molecular mechanisms by which obesogens induce toxicity that may end-up in epigenetic modifications is imperative. This review describes and discusses the suggested molecular targets and potential mechanisms for obesogenic–disrupting chemicals and the subsequent effects on male reproductive health.

Acute and sub-chronic toxicity of Cajanus cajan leaf extracts

CONTEXT

The leaves of Cajanus cajan (L.) Millsp. (Fabaceae) have diverse bioactivities, but little safety data are reported.

OBJECTIVE

This study examines the toxicological profiles of C. cajan leaf extracts.

MATERIALS AND METHODS

The leaves were extracted by water or 90% ethanol to obtain water or ethanol extract (WEC or EEC). EEC was suspended in water and successively fractionated into dichloroform and n-butanol extracts (DEC and BEC). Marker compounds of the extracts were monitored by high-performance liquid chromatography (HPLC). Kunming mice were administered with a single maximum acceptable oral dose (15.0 g/kg for WEC, EEC and BEC and 11.3 g/kg for DEC) to determine death rate or maximal tolerated doses (MTDs). In sub-chronic toxicity investigation, Sprague-Dawley rats were orally given WEC or EEC at 1.5, 3.0 or 6.0 g/kg doses for four weeks and observed for two weeks after dosing to determine toxicological symptoms, histopathology, biochemistry and haematology.

RESULTS

Flavonoids and stilbenes in the extracts were assayed. In acute toxicity test, no mortality and noted alterations in weight and behavioural abnormality were observed, and the maximum oral doses were estimated as MTDs. In sub-chronic toxicity study, no mortality and significant variances in haematological and biochemical parameters or organ histopathology were observed, but increased kidney weight in 3.0 g/kg WEC- or 3.0 and 6.0 g/kg EEC-treated female rats, and reduced testes and epididymis weight in EEC-treated male rats were recorded. These changes returned to the level of control after recovery period.

CONCLUSION

Acute and sub-chronic toxicity of Cajanus cajan leaf extracts was not observed.

Effects of a soybean milk product on feto-neonatal development in rats

Since estrogenic pollutants and phytoestrogens can cause the disorder of the reproductive system, the effects of a soybean milk product (Vegemil® containing 162 ppm isoflavones) on the feto-neonatal development, including male reproductive function, were investigated. Pregnant rats were fed the soybean milk (5% or 100% in drinking water) from gestational day (GD) 6 to parturition or to post-natal day (PND) 56. Specifically, the rats were divided into 4 groups: the control group (drinking water), the GD5% group (5% soybean milk during only the GD period), the GD-PND5% group (5% soybean milk during the GD and PND periods), and the GD-PND100% group (100% soybean milk instead of water during the GD and PND periods). During the gestational, lactational, and developmental periods, the reproductive and developmental parameters of dams and offspring were observed. Feeding soybean milk did not affect the birth and physical development of both male and female offspring. At PND57, the weights of the testes and epididymides of F1 males significantly increased by feeding a high concentration of the soybean milk (GD-PND100%). In addition, feeding of the soybean milk during both the GD and PND periods (GD-PND5% and GD-PND100%) enhanced the sperm counts and motility. The results indicate that soybean milk is safe for embryos, fetuses, and offspring, and improves the post-generational development of male reproductive function.

THE POTENTIAL OF DIETHYLHEXYL-PHTHALATE AND GENISTEIN TO INDUCE TESTICULAR CHANGES IN RAT'S OFFSPRING

OBJECTIVE

To study the effect of diethylhexyl phthalate (DEHP) alone or in combination with genistein (GEN) on the reproductive system of offspring rats, focus on the induction of reproductive outcomes.

METHOD

180 Wistar rats were divided in 6 groups (30 animals per group): DEHP 250 mg/kg/day group, DEHP 1000 mg/kg/day group, DEHP 2500 mg/kg/day group treated with DEHP 2500 mg/kg/day, DEHP (2500 mg/kg) + GEN (50 mg/kg) group, DEHP (2500 mg/kg) + GEN (500 mg/kg) group and control group treated with the same quantity of corn oil. The differences in sperm quality and reproductive organs were observed.

RESULTS

After DEHP administration we observed an increase in rat's abestrus, metaestrus and all estrus cycle (P < 0.05), a decrease in rat testicle's organ coefficient and relative energy of testis Sertoli cells and an increase in the early, late and total apoptotic rate of testicular Sertoli cells in a dose dependent manner (P < 0.05). When combine DEHP with GEN the sperm density, sperm quality, the cell activity rate and testis tissue's changes will decrease compared with the group that receive only DEHP in a dose dependent manner.

CONCLUSION

DEHP exposure induces cryptorchidism in offspring rats and this is aggravated by adding GEN.

Genistein up-regulates miR-20a to disrupt spermatogenesis via targeting Limk1

Genistein (GEN) is one of the isoflavones that has effect on male reproduction. However, the underlying mechanism remains unknown. miRNAs are a type of small non-coding RNAs that play important roles in spermatogenesis. We measured the GEN levels and miR-17-92 cluster expression in infertile subjects and found that miR-17-92 might be involved in GEN induced abnormal spermatogenesis. To clarify, we fed adult ICR mice with different doses of GEN (0, 0.5, 5, 50 and 250 mg/kg/day) for 35 days to study the underlying mechanism. We found that sperm average path velocity, straight-line velocity and eurvilinear velocity of the mice orally with GEN at 5mg/kg/day were significantly decreased, the expression levels of miR-17 and miR-20a in mice testis were higher in corresponding group. We also found miR-20a was the only miRNA that differentially expressed both in human and mice. By applying bioinformatics methods, Limk1 was predicted to be the target gene of miR-20a that is involved in spermatogenesis. Limk1 were significantly decreased in the corresponding group. Dual-luciferase report assay also proved that miR-20a could directly target Limk1. These results implied that Limk1 might be the target gene of miR-20a that is involved in GEN induced abnormal spermatogenesis.

Phytoestrogens as alternative hormone replacement therapy in menopause: What is real, what is unknown

Menopause is characterized by an altered hormonal status and by a decrease in life quality due to the appearance of uncomfortable symptoms. Nowadays, with increasing life span, women spend one-third of their lifetime under menopause. Understanding menopause-associated pathophysiology and developing new strategies to improve the treatment of menopausal-associated symptoms is an important topic in the clinic. This review describes physiological and hormone alterations observed during menopause and therapeutic strategies used during this period. We critically address the benefits and doubts associated with estrogen/progesterone-based hormone replacement therapy (HRT) and discuss the use of phytoestrogens (PEs) as a possible alternative. These relevant plant-derived compounds have structural similarities to estradiol, interacting with cell proteins and organelles, presenting several advantages and disadvantages versus traditional HRT in the context of menopause. However, a better assessment of PEs safety/efficacy would warrant a possible widespread clinical use.

Phospholipid hydroperoxide glutathione peroxidase gene is regulated via an estrogen and estrogen receptor signaling in cultured mouse fetuses

Although it has been suggested that the transcription of phospholipid hydroperoxide glutathione peroxidase (PHGPx), an essential antioxidant selenoenzyme, may be affected by the estrogen state in mammals, the direct mechanism underlying the regulation of the PHGPx gene by estrogens in mammalian tissues remains to be clearly elucidated. In this study, we evaluated the expression of the PHGPx mRNA in cultured mouse fetuses (embryonic days 8.5-10.5) exposed to 17β-estradiol (E(2); 0.1, 1, 10, 100, and 1,000 ng/ml); estrogen receptor (ER) agonists [propyl pyrazole triol (PPT, an ERα-selective ligand, 1 μl/ml) and diarylpropionitrile (DPN, an ERβ-selective ligand, 1 μl/ml)]; and/or ER antagonist [ICI 182,780 (ICI, 1 μl/ml)] using a whole embryo culture system. E(2)-alone treatment significantly stimulated the expressions of both ERα and ERβ mRNAs in all the cultured fetuses (p < 0.05), although the ERβ mRNA levels were higher than ERα mRNA. PHGPx mRNA expression was significantly increased in all the fetuses treated with E(2) (1-1,000 ng/ml), PPT, and DPN (p < 0.05). Furthermore, pretreatment with ICI completely blocked the E(2)-induced PHGPx mRNA expression in the fetuses. In addition, the mRNA levels of cytosolic GPx, the other intracellular antioxidant selenoenzyme, did not differ significantly from the controls by an exposure to those agents. These results suggest that the PHGPx gene is regulated via an estrogen and ER signal pathway in the cultured mouse fetus.

Endocrine disruptors and Leydig cell function

During the past decades, a large body of information concerning the effects of endocrine disrupting compounds (EDCs) on animals and humans has been accumulated. EDCs are of synthetic or natural origin and certain groups are known to disrupt the action of androgens and to impair the development of the male reproductive tract and external genitalia. The present overview describes the effects of the different classes of EDCs, such as pesticides, phthalates, dioxins, and phytoestrogens, including newly synthesized resveratrol analogs on steroidogenesis in Leydig cells. The potential impact of these compounds on androgen production by Leydig cells during fetal development and in the adult age is discussed. In addition, the possible role of EDCs in connection with the increasing frequency of abnormalities in reproductive development in animals and humans is discussed.

Potential detrimental effects of a phytoestrogen-rich diet on male fertility in mice

Soy and soy-based products are widely consumed by infants and adult individuals. There has been speculation that the presence of isoflavone phytoestrogens in soybean cause adverse effects on the development and function of the male reproductive system. The purpose of this study was to examine the influence of dietary soy and phytoestrogens on testicular and reproductive functions. Male mice were fed from conception to adulthood with either a high soy-containing diet or a soy-free diet. Although adult mice fed a soy-rich diet exhibited normal male behaviour and were fertile, we observed a reduced proportion of haploid germ cells in testes correlating with a 25% decrease in epididymal sperm counts and a 21% reduction in litter size. LH and androgens levels were not affected but transcripts coding for androgen-response genes in Sertoli cells and Gapd-s, a germ cell-specific gene involved in sperm glycolysis and mobility were significantly reduced. In addition, we found that dietary soy decreased the size of the seminal vesicle but without affecting its proteolytic activity. Taken together, these studies show that long-term exposure to dietary soy and phytoestrogens may affect male reproductive function resulting in a small decrease in sperm count and fertility.

Soy, phyto-oestrogens and male reproductive function: a review

There is growing interest in the possible health threat posed by the effects of endocrine disruptors on reproduction. Soy and soy-derived products contain isoflavones that mimic the actions of oestrogens and may exert adverse effects on male fertility. The purpose of this review was to examine the evidence regarding the potential detrimental effects of soy and phyto-oestrogens on male reproductive function and fertility in humans and animals. Overall, there are some indications that phyto-oestrogens, alone or in combination with other endocrine disruptors, may alter reproductive hormones, spermatogenesis, sperm capacitation and fertility. However, these results must be interpreted with care, as a result of the paucity of human studies and as numerous reports did not reveal any adverse effects on male reproductive physiology. Further investigation is needed before a firm conclusion can be drawn. In the meantime, caution would suggest that perinatal phyto-oestrogen exposure, such as that found in infants feeding on soy-based formula, should be avoided.

Soy protein isolates of varying isoflavone content do not adversely affect semen quality in healthy young men

OBJECTIVE

To determine the effects of consumption of soy protein of varying isoflavone content on parameters of semen quality in healthy young men.

DESIGN

Randomized crossover intervention.

SETTING

University campus.

PATIENT(S)

Healthy adult men (age 27.5 ± 5.67 years, body mass index 25.4 ± 3.14 kg/m(2)).

INTERVENTION(S)

Milk protein isolate (MPI), low-isoflavone soy protein isolate (low-iso SPI; 1.64 ± 0.19 mg isoflavones/day, expressed as aglycone equivalents), and high-isoflavone soy protein isolate (high-iso SPI; 61.7 ± 7.35 mg isoflavones/day, expressed as aglycone equivalents) for 57 days each separated by 28-day washout periods.

MAIN OUTCOME MEASURE(S)

Urinary isoflavones were measured from 24-hour urine samples collected on days 54-56 of each treatment period. Semen quality parameters (semen volume, sperm concentration, sperm count, sperm percent motility, total motile sperm count, sperm morphology) were measured from semen samples collected on days 1 and 57 of each treatment period.

RESULT(S)

Urinary isoflavones were significantly higher after consumption of high-iso SPI compared with the low-iso SPI and MPI. Semen parameters, including semen volume, sperm concentration, sperm count, sperm percent motility, total motile sperm count, and sperm morphology, were not significantly affected by consumption of either low- or high-iso SPI compared with MPI.

CONCLUSION(S)

Consumption of soy protein of low or high isoflavone content does not adversely affect semen quality in a sample of healthy adult men.

Dietary red clover (Trifolium pratense) induces oviduct growth and decreases ovary and testes growth in Japanese quail chicks

To determine whether drought-stress alters phytoestrogens in red clover and whether red clover in the diet influences sexual development in Japanese quail, we fed chicks diets containing irrigated or non-irrigated clover. Irrigation altered phytoestrogenic activity of red clover (determined using an in vitro bioassay), with extracts of irrigated clover diet containing more estrogenic activity than extracts of non-irrigated clover diet. Chick growth was negatively correlated with the amount of irrigated or non-irrigated clover in the diet. Dietary red clover also depressed both absolute and relative gonad weights; however, relative oviduct weight was increased by the irrigated diet. Diets did not affect serum vitellogenin. These results reveal a negative influence of drought-stress on phytoestrogenic potency of clover, and that red clover in the diet can inhibit avian growth and development independent of irrigation state. Thus, phytoestrogens may affect reproductive development in wild birds, and environmental stressors may influence levels of phytoestrogens in the field.

Licorice extract does not impair the male reproductive function of rats

The effect of water extract of licorice (Glycyrrhiza uralensis), one of the most widely used medicinal plants in Oriental nations and in Europe, on male reproductive function was investigated in rats. Licorice extract was prepared as in Oriental clinics and orally administered at doses of 500, 1,000 or 2,000 mg/kg, the upper-limit dose (2,000 mg/kg) recommended in the Toxicity Test guideline of the Korea Food and Drug Administration, to 6-week-old male rats for 9 weeks. Licorice extract neither induced clinical signs, nor affected the daily feed consumption and body weight gain. There were no significant changes in testicular weights, gross and microscopic findings, and daily sperm production between vehicle- and licorice-treated animals, in spite of slight decreases in prostate weight and daily sperm production at the high dose (2,000 mg/kg). In addition, licorice did not affect the motility and morphology of sperm, although the serum testosterone level tended to decrease without significant difference, showing a 28.6% reduction in the high-dose (2,000 mg/kg) group. The results suggest that the no observed adverse-effect level of licorice extract is higher than 2,000 mg/kg, the upper-limit dose, and that long-term exposure to licorice might not cause profound adverse effects.

Lindane may modulate the female reproductive development through the interaction with ER-beta: an in vivo-in vitro approach

Lindane (gamma-HCH) is a persistent environmental pollutant that may act as endocrine disrupter, affecting the nervous, immune and reproductive system, possibly through endocrine-mediated mechanisms. Since both estrogen receptors (ER-alpha and -beta) have shown to be target for endocrine disruption, we investigated the role of gamma-HCH on the development of female reproductive system. For an in vivo evaluation of gamma-HCH effects during prenatal period, pregnant CD1 mice were treated p.o. on gestational days 9-16 with 15 mg/kg bw/day of gamma-HCH and vehicle. The in vivo findings in treated F1 pups - in the absence of signs of systemic toxicity - included increase in the absolute and relative and absolute uterus weight revealed on post-natal day 22, earlier vaginal patency and reduced diameters of primary oocytes at fully sexual maturity. No effects on steroid hormone metabolism (aromatase, testosterone catabolism) were observed. Thus, gamma-HCH elicited subtle effects on female reproductive development likely mediated by ER-beta-mediated pathway(s), without a concurrent impairment of steroid hormone metabolism. Furthermore, to verify whether the endocrine interference of gamma-HCH is attributable to stimulation of ER-beta-mediated pathway(s), its effect has been evaluated in vitro on a cell line, LNCaP, expressing only functional ER-beta. In vitro treatments revealed a concentration-related effect on LNCaP cell viability and proliferation. Significantly, the contemporary addition of a pure anti-estrogen, the ER antagonist ICI 182,780, completely reversed gamma-HCH effects indicating an ER-beta-mediated action. Our findings indicate that gamma-HCH may act as endocrine disruptor during the female reproductive system development and ER-beta as a potential target for this compound and other endocrine disrupting chemicals as well.

Expression pattern of cytosolic glutathione peroxidase (cGPx) mRNA during mouse embryogenesis

The selenoprotein cytosolic glutathione peroxidase (cGPx) is ubiquitously distributed in a variety of organs, and its primary function is to protect oxidative damage. To investigate the spatial and temporal expression pattern of cGPx mRNA in embryogenesis, as this has not been studied before, reverse transcription-polymerase chain reaction (RT-PCR) was carried out in a thermal cycler using mouse-specific cGPx primers, and in situ hybridization was performed in whole embryos or embryonic tissues using digoxigenin-labeled mouse cGPx riboprobes. Expression of cGPx mRNA was detected in all the embryos retrieved from embryonic days (EDs) 7.5 to 18.5. On EDs 10.5-12.5, cGPx mRNA was highly expressed in the margin of forelimb and hindlimb buds and dorsally in the cranial neural tube, including the telencephalon, diencephalon, and hindbrain neural tube. On ED 13.5, cGPx mRNA was accumulated especially in vibrissae, forelimb and hindlimb plates, tail, and spinal cord. On EDs 14.5-16.5, cGPx mRNA was found in the developing brain, Rathke's pouch, thymus, lung, and liver. On ED 17.5, the expression of cGPx mRNA was apparent in various tissues such as brain, submandibular gland, vibrissae, heart, lung, liver, stomach, intestine, pancreas, skin, and kidney. In particular, cGPx mRNA was greatly expressed in epithelial linings and metabolically active sites such as whisker follicles, alveolar epithelium of lung, surface epithelium and glandular region of stomach, skin epithelium, and cortex and tubules of kidney. Overall results indicate that cGPx mRNA is expressed in developing embryos, cell-specifically and tissue-specifically, suggesting that cGPx may function to protect the embryo against reactive oxygen species and/or hydroperoxides massively produced by the intracellular or extracellular environment.