Estrogen-induced spermatogenic cell apoptosis occurs via the mitochondrial pathway: role of superoxide and nitric oxide

Intragastric exposure of rats to silver nanoparticles modulates the redox balance and expression of steroid receptors in testes

Nanosilver (AgNPs) is popular nanomaterials used in food industry that makes gastrointestinal tract an essential route of its uptake. The aim of the presented study was to assess the effects of intragastric exposure to AgNPs on redox balance and steroid receptors in the testes of adult Fisher 344 rats. The animals were exposed to 20 nm AgNPs (30 mg/kg bw/day, by gavage) for 7 and 28 days compared to saline (control groups). It was demonstrated that 7-day AgNPs administration resulted in increased level of total antioxidant status (TAS), glutathione reductase (GR) activity, lower superoxide dismutase activity (SOD), decreased glutathione (GSH) level and GSH/GSSG ratio, as well as higher estrogen receptor (ESR2) and aromatase (Aro) protein expression in Leydig cells compared to the 28-day AgNPs esposure. The longer-time effects of AgNPs exposition were associated with increased lipid hydroperoxidation (LOOHs) and decreased SOD activity and androgen receptor protein level. In conclusion, the present study demonstrated the adverse gastrointestinally-mediated AgNPs effects in male gonads. In particular, the short-term AgNPs exposure impaired antioxidant defence with concurrent effects on the stimulation of estrogen signaling, while the sub-chronic AgNPs exposition revealed the increased testicle oxidative stress that attenuated androgens signaling.

Molecular insights into Sertoli cell function: how do metabolic disorders in childhood and adolescence affect spermatogonial fate?

Male infertility is a major public health concern globally with unknown etiology in approximately half of cases. The decline in total sperm count over the past four decades and the parallel increase in childhood obesity may suggest an association between these two conditions. Here, we review the molecular mechanisms through which obesity during childhood and adolescence may impair future testicular function. Several mechanisms occurring in obesity can interfere with the delicate metabolic processes taking place at the testicular level during childhood and adolescence, providing the molecular substrate to hypothesize a causal relationship between childhood obesity and the risk of low sperm counts in adulthood.

Obesity and male fertility disorders

Often associated with obesity, male infertility represents a widespread condition that challenges the wellbeing of the couple. In this article, we provide a comprehensive and critical analysis of studies exploring the association between obesity and male reproductive function, to evaluate the frequency of this association, and establish the effects of increased body weight on conventional and biofunctional sperm parameters and infertility. In an attempt to find possible molecular markers of infertility in obese male patients, the numerous mechanisms responsible for infertility in overweight/obese patients are reviewed in depth. These include obesity-related functional hypogonadism, insulin resistance, hyperinsulinemia, chronic inflammation, adipokines, irisin, gut hormones, gut microbiome, and sperm transcriptome. According to meta-analytic evidence, excessive body weight negatively influences male reproductive health. This can occurr through a broad array of molecular mechanisms. Some of these are not yet fully understood and need to be further elucidated in the future. A better understanding of the effects of metabolic disorders on spermatogenesis and sperm fertilizing capacity is very useful for identifying new diagnostic markers and designing therapeutic strategies for better clinical management of male infertility.

Seasonal variations of testis anatomy and of G-coupled oestrogen receptor 1 expression in Gerbillus gerbillus

The gerbil, Gerbillus gerbillus, a nocturnal desert rodent of northern Africa, exhibits a seasonal reproductive cycle with marked anatomical and behavioural shifts between breeding season and resting season. The aim of this study is to investigate key elements involved in these seasonal changes, specifically in males: the histology of the testis as well as the expression of the G-protein-coupled oestrogen receptor 1 (GPER1) in the testis. During the breeding season, the seminiferous tubules were full of spermatozoa, and their epithelium contained germinal cells embedded in Sertoli cells. Amidst tubules, well-developed Leydig cells were observed around blood vessels, with peritubular myoid cells providing structural and dynamic support to the tubules. GPER1 was largely expressed throughout the testis. Notably, Leydig cells, spermatogonia and spermatocytes showed strong immunohistochemical signals. Sertoli cells, spermatozoa and peritubular myoid cells were moderately stained. During the resting season, spermatogenesis was blocked at the spermatocyte stage, spermatids and spermatozoa were absent and the interstitial space was reduced. The weight of the testis decreased significantly. At this stage, GPER1 was found in Leydig cells, spermatocytes and peritubular myoid cells. Sertoli cells and spermatogonia were not marked. Overall, the testis of the gerbil, Gerbillus gerbillus, has undergone noticeable histological, cellular and weight changes between seasons. In addition, the seasonal expression pattern of GPER1, with pronounced differences between resting season and breeding season, indicates that this receptor is involved in the regulation of the reproductive cycle.

Oxidative stress-induced apoptosis and autophagy: Balancing the contrary forces in spermatogenesis

Spermatogenesis is a complex process in the testis and is a cornerstone of male infertility. The abundance of unsaturated fatty acid and high cell division rate make male germs cells prone to DNA deterioration. ROS-mediated oxidative stress triggers DNA damage, autophagy, and apoptosis in male germ cells, which are critical causative factors that lead to male infertility. The complex connection and molecular crosstalk between apoptosis and autophagy is seen at multifaceted levels that interconnect the signaling pathways of these two processes. Multilevel interaction between apoptosis and autophagy is a seamless state of survival and death in response to various stressors. Interaction between multiple genes and proteins such as the mTor signaling pathway, Atg12 proteins, and the death adapter proteins, such as Beclin 1, p53, and Bcl-2 family proteins, validates such a link between these two phenomena. Testicular cells being epigenetically different from somatic cells, undergo numerous significant epigenetic transitions, and ROS modulates the epigenetic framework of mature sperm. Epigenetic deregulation of apoptosis and autophagy under oxidative stress conditions can cause sperm cell damage. The current review recapitulates the current role of prevailing stressors that generate oxidative stress leading to the induction of apoptosis and autophagy in the male reproductive system. Considering the pathophysiological consequences of ROS-mediated apoptosis and autophagy, a combinatorial approach, including apoptosis inhibition and autophagy activation, a therapeutic strategy to treat male idiopathic infertility. Understanding the crosslink between apoptosis and autophagy under stress conditions in male germ cells may play an essential role in developing therapeutic strategies to treat infertility.

Lycopene Alleviates Titanium Dioxide Nanoparticle-Induced Testicular Toxicity by Inhibiting Oxidative Stress and Apoptosis in Mice

PURPOSE

The research was carried out to investigate the possible ameliorative effect of lycopene on TiO₂ NPs-induced male reproductive toxicity and explore the possible mechanism.

METHODS

Ninety-six healthy male Institute of Cancer Research (ICR) mice were equally divided into eight groups (control group, 50 mg/kg TiO₂ NPs group, 5 mg/kg LYC group, 20 mg/kg LYC group, 40 mg/kg LYC group, 50 mg/kg TiO₂ NPs + 5 mg/kg LYC group, 50 mg/kg TiO₂ NPs + 20 mg/kg LYC group, 50 mg/kg TiO₂ NPs + 40 mg/kg LYC group), and the mice were treated by intragastric administration every day for 30 days in this research. Sperm parameters, testicular histopathology, oxidant and antioxidant enzymes, and cell apoptosis-related protein expression in the testicular tissue were analyzed.

RESULTS

The results showed that TiO₂ NPs exposure significantly decreased sperm count and motility, and TiO₂ NPs also increased sperm malformation in the epididymis; these characteristics were improved when co-administration with LYC. Testicular histopathological lesions like disorder of germ cells arrange, detachment, atrophy, and vacuolization were observed after TiO₂ NPs exposure, and these abnormalities were effectively ameliorated by co-administration with LYC. Oxidative stress was induced by TiO₂ NPs exposure as evidenced by increased the level of MDA and decreased the activity of SOD as well as the level of anti-O₂^-, and these alterations were effectively prevented by co-administration with LYC. LYC also alleviated TiO₂ NPs-induced germ cell apoptosis by inhibiting mitochondrial apoptotic pathway, as shown by the upregulation of Bcl-2, the downregulation of Bax, Cleaved Caspase 3, and Cleaved Caspase 9.

CONCLUSION

LYC could ameliorate TiO₂ NPs-induced testicular damage via inhibiting oxidative stress and apoptosis, which could be used to alleviate the testicular toxicity associated with TiO₂ NPs intake.

Apoptosis and blood-testis barrier disruption during male reproductive dysfunction induced by PAHs of different molecular weights

The association between polycyclic aromatic hydrocarbons (PAHs) and male reproductive dysfunction has attracted increasing attention. The purpose of this study was to compare the male reproductive toxicity of multiple PAHs and to investigate the underlying molecular mechanisms. TM4 cells (mouse testicular Sertoli cells, SCs) were treated with benzo(a)pyrene (BaP), pyrene (Py), fluoranthene (Fl) and phenanthrene (Phe) (0, 0.1, 1, 10, 50, or 100 μM) for varying time points (4, 12, 24, or 48 h), and male C57BL/6 mice were administered BaP and Py (0, 10, 50, or 100 mg/kg body weight) for 14 days based on the cell experimental results. Histopathological examination, western blotting, ELISA, biochemical assays, RT-PCR, flow cytometry, JC-1 staining and trans-epithelium electrical resistance (TEER) measurements were used to assess apoptosis, blood-testis barrier (BTB) integrity, intracellular calcium ([Ca²⁺]_i) concentrations and oxidative stress (OS). The results revealed that the mRNA levels and enzymatic activities of CYP450 and GST family members; levels of ROS, MDA, cleaved caspase 3 (c-caspase 3), caspase 9, Bax, and cytochrome C (CytC); and numbers of TUNEL-positive cells were significantly increased by BaP and Py, while levels of AhR, GSH, SOD, CAT, Bcl-2 and ΔΨm were decreased. Additionally, BaP and Py notably interfered with tight junctions (TJs) and adherens junctions (AJs) in the BTB. Intriguingly, BaP, but not Py, induced [Ca²⁺]_i overload and gap junction (GJ) destruction. There was no dramatic effect of Fl and/or Phe on any of the above parameters except that slight cytotoxicity was observed with higher doses of Fl. Collectively, these findings showed that BaP and Py elicited SC apoptosis and BTB disruption involving mitochondrial dysfunction and OS, but [Ca²⁺]_i fluctuation and GJ injury were only observed with BaP-induced reproductive toxicity. The male reproductive toxicity of the selected PAHs was ranked in the order of BaP > Py > Fl > Phe.

Beneficial impact of Nesfatin-1 on reproductive dysfunction induced by nicotine in male rats: Possible modulation of autophagy and pyroptosis signaling pathways

This study was conducted to explore the beneficial impact of nesfatin-1 on reproductive dysfunction induced by nicotine (NT) in male rats with possible modulation of autophagy and pyroptosis signaling pathways. This research was performed on 40 Wistar male rats. They were distributed into four groups: control, normal+nesfatin-1, NT, and NT+nesfatin-1. At the end of the experimental period, the serum was separated for assay of testosterone, FSH and LH. Also, sperm parameters were determined. Histopathological examination of testicular tissue and immunohistochemical analysis was done for mammalian target of rapamycin, AMP-activated protein kinase, and mitogen-activated protein kinases including phosphorylated extracellular signal regulated kinase and phosphorylated cJun N-terminal kinase. Relative gene expression was determined for testicular nucleotide oligomerization domain (NOD)-like receptors proteins and Caspase-1, and autophagy markers including microtubule-associated protein 1 light chain 3 alpha and Beclin-1. Also, the following testicular parameters were assayed: 3β-hydroxysteroid dehydrogenase, 17β-hydroxysteroid dehydrogenase, malondialdehyde, superoxide dismutase activity, catalase, glucose-6 phosphate dehydrogenase, reactive oxygen species, caspase-3 activity, IL-1β, IL-18, mitochondrial transmembrane potential and Complex-I activity. The results revealed that the normal+nesfatin-1 group showed insignificant changes as compared to the control group. Meanwhile, the NT group exhibited prominent reproductive dysfunction in male rats. On the other hand, in the NT+nesfatin-1 group nesfatin-1 notably attenuated this reproductive dysfunction as evidenced by improvement of hormonal assay, sperm parameters, histopathological picture, immunohistochemical evaluation and real time relative gene expressions. In conclusion: Nesfatin-1 alleviated the impairment of male reproductive functions induced by NT via enhancement of autophagy pathways, suppression of pyroptosis, apoptosis, mitochondrial dysfunction and ROS production. Thus nesfatin-1 may offer a novel protective or therapeutic access for treating male infertility.

Environmental Factors-Induced Oxidative Stress: Hormonal and Molecular Pathway Disruptions in Hypogonadism and Erectile Dysfunction

Hypogonadism is an endocrine disorder characterized by inadequate serum testosterone production by the Leydig cells of the testis. It is triggered by alterations in the hypothalamic–pituitary–gonadal axis. Erectile dysfunction (ED) is another common disorder in men that involves an alteration in erectile response–organic, relational, or psychological. The incidence of hypogonadism and ED is common in men aged over 40 years. Hypogonadism (including late-onset hypogonadism) and ED may be linked to several environmental factors-induced oxidative stresses. The factors mainly include exposure to pesticides, radiation, air pollution, heavy metals and other endocrine-disrupting chemicals. These environmental risk factors may induce oxidative stress and lead to hormonal dysfunctions. To better understand the subject, the study used many keywords, including “hypogonadism”, “late-onset hypogonadism”, “testosterone”, “erectile dysfunction”, “reactive oxygen species”, “oxidative stress”, and “environmental pollution” in major online databases, such as SCOPUS and PUBMED to extract relevant scientific information. Based on these parameters, this review summarizes a comprehensive insight into the important environmental issues that may have a direct or indirect association with hypogonadism and ED in men. The study concludes that environmental factors-induced oxidative stress may cause infertility in men. The hypothesis and outcomes were reviewed critically, and the mechanistic approaches are applied through oxidant-sensitive pathways. This study also provides reccomendations on future therapeutic interventions and protective measures against such adverse environmental factors-induced hypogonadism and ED.

Testicular Testosterone and Estradiol Concentrations and Aromatase Expression in Men with Nonobstructive Azoospermia

CONTEXT

Spermatogenesis is strictly regulated by the intratesticular hormonal milieu, in which testosterone (T) and estradiol (E2) play pivotal roles. However, the optimal expression of aromatase and intratesticular T (ITT) and E2 (ITE2) levels are unknown.

OBJECTIVE

To investigate ITT/ITE2 and aromatase expression in men with nonobstructive azoospermia (NOA) and to elucidate the roles of aromatase in spermatogenesis, as determined based on sperm retrieval by microdissection testicular sperm extraction (micro-TESE).

DESIGN AND SETTING

A retrospective study at a reproductive center using serum, testicular specimens, and intratesticular fluid.

PATIENTS

Seventy-six men with NOA, including 4 men who received 3 months of anastrozole administration prior to micro-TESE, and 18 men with obstructive azoospermia.

INTERVENTIONS

Testicular aromatase expression was evaluated using immunohistochemistry and quantitative reverse transcription-polymerase chain reaction (RT-PCR). Intratesticular T and ITE2 levels were determined using liquid chromatography-tandem mass spectrometry.

RESULTS

Aromatase was mainly located in Leydig cells, and the levels of its transcript and protein expression levels were increased in men with NOA. No correlation was observed between serum T/E2 and ITT/ITE2 levels, whereas significant associations were observed between decreased ITT and increased ITE2, aromatase expression, and sperm retrieval. Treatment with anastrozole increased the ITT/ITE2 ratio and decreased aromatase expression.

CONCLUSIONS

A close association between the expression of aromatase in Leydig cells and ITT/ITE2 was shown. Leydig cell aromatase is a factor that is independently correlated with spermatogenesis, and aromatase inhibitors may open a therapeutic window by increasing ITT/ITE2 in selected patients.

Effects of PM2.5 exposure on reproductive system and its mechanisms

With the development of human society, haze has become an important form of air pollution. Haze is a mixture of fog and haze, and the main component of haze is fine particulate matter (PM_2.5), which is the most important indicator of composite air pollution. Epidemiological studies proved that PM_2.5 can break through the respiratory mucosal barrier and enter the human body, causing pathological effects on multiple systems of the body. In the past, people put more attention to PM_2.5 in the respiratory system, cardiovascular system, nervous system, etc, and relatively paid less attention to the reproductive system. Recent studies have shown that PM_2.5 will accumulate in the reproductive organs through blood-testis barrier, placental barrier, epithelial barrier and other barriers protecting reproductive tissues. In addition, PM_2.5 can disrupt hormone levels, ultimately affecting fertility. Prior studies have shown that oxidative stress, inflammation, apoptosis, and the breakdown of barrier structures are now considered to contribute to reproductive toxicity and may cause damage at the molecular and genetic levels. However, the exact mechanism remains to be elucidated. Our review aims to provide an understanding of the pathological effects of PM_2.5 on reproductive system and the existing injury mechanism.

Use of Parabens (Methyl and Butyl) during the Gestation Period: Mitochondrial Bioenergetics of the Testes and Antioxidant Capacity Alterations in Testes and Other Vital Organs of the F1 Generation

Since the mid-1920s, parabens have been widely used as antimicrobial preservatives in processed foods and beverages, pharmaceuticals, and cosmetic products. Paraben use continues to generate considerable controversy, both in the general population and in the scientific community itself. The primary purpose of our study was to determine whether parabens (methyl and butyl at concentrations of 100 and 200 mg/kg body weight by subcutaneous injection) during pregnancy of adult female Wistar rats can have an impact on the F1 generation. As far as we know, we are the first to demonstrate that using parabens during pregnancy has negative repercussions on the mitochondrial bioenergetics and antioxidant activity of testicular germ cells in the F1 generation. Our study showed that there was a 48.7 and 59.8% decrease in the respiratory control index with 100 and 200 mg/kg of butylparaben, respectively. Cytochrome c oxidase activity was significantly inhibited (45 and 51%) in both groups. In addition, 200 mg/kg butylparaben promoted a marked decrease in citrate synthase activity, indicating that mitochondrial content decreased in the germ cells, especially spermatocytes and spermatids. Mitochondrial ROS production increased in groups exposed to parabens in a concentration-dependent manner, especially the butyl one (102 and 130%). The groups exposed to butylparaben showed an increase in superoxide dismutase (SOD) and catalase (CAT) activities, while glutathione reductase (GR) and glutathione S-transferase (GST) decreased. With methylparaben, only differences in SOD and GR were observed; for the latter, this only occurred with the highest concentration. The glutathione (GSH)/glutathione disulfide (GSSG) ratio did not undergo any significant change. However, there was a considerable increase in hydroperoxide content in animals exposed to butylparaben, with 100 and 200 mg/kg resulting in 98.6 and 188% increase, respectively. Furthermore, several other organs also showed alterations in antioxidant capacity due to paraben use. In summary, our study demonstrates that paraben use during pregnancy will cause severe changes in the mitochondrial bioenergetics and antioxidant capacity of testicular germ cells and the antioxidant capacity of several other F1 generation organs.

Estradiol and reproduction in the South American toad Rhinella arenarum (Amphibian, Anura)

Rhinella arenarum is a South American toad with wide geographic distribution. Testes of this toad produce high amount of androgens during the non reproductive season and shift steroid synthesis from androgens to 5α-pregnanedione during the breeding. In addition, plasma estradiol (E₂) in males of this species shows seasonal variations but, since testes of R. arenarum do not express aromatase, the source of plasma E₂ remained unknown for several years. However, the Bidder's organ (BO), a structure located at one pole of each testis, is proposed to be the main source of E₂ in male's toads since it expresses several steroidogenic enzymes and is able to produce E₂ from endogenous substrates throughout the year. In addition, there were significant correlations between plasma E₂ and total activity of BO aromatase, and between plasma E₂ and the amount of hormone produced by the BO in vitro. In the toad, apoptosis induced by in vitro treatment with E₂ was mostly detected in spermatocytes during the breeding and in spermatids during the post-reproductive season, suggesting that this steroid has an important role in controlling spermatogenesis. However, in vitro treatment with E₂ had no effect on proliferation. This evidence suggests that the mechanism of action of E₂ on amphibian spermatogenesis is complex and more studies are necessary to fully understand the role of estrogens regulating the balance between cellular proliferation and apoptosis. In addition, in R. arenarum in vitro studies suggested that E₂ has no effect on CypP450c17 protein levels or enzymatic activity, while it reduces 3β-hydroxysteroid dehydrogenase/isomerase (3β-HSD/I) activity during the post reproductive season. As well, E₂ regulates FSHβ mRNA expression all over the year suggesting a down regulation process carried out by this steroid. The effect on LHβ mRNA is dual, since during the reproductive season estradiol increases the expression of LHβ mRNA while in the non-reproductive season it has no effect. In conclusion, the effect of E₂ on gonadotropins and testicular function is complex, not clearly understood and probably varies depending on the species. The aim of the current article is to review evidence on reproductive endocrinology and on the role of estradiol regulating reproduction in amphibians, with emphasis on the South American species Rhinella arenarum.

Delineating the regulation of estrogen and androgen receptor expression by sex steroids during rat spermatogenesis

Estrogen receptors (ERα and β) and androgen receptor (AR) regulate various critical processes during spermatogenesis. Since spermatogenesis is very sensitive to hormonal stimuli and perturbations, it is important to understand the regulation of expression of these receptors by sex steroid hormones. Although many studies have reported deregulation of steroid receptors on endocrine disruption, there is no consensus on the regulation of their expression by steroid hormones during spermatogenesis, and a lack of clear understanding of the mechanism of regulation. Here, we evaluated the receptor expressions in a well-established exogenous estradiol administration model. We then investigated the mechanisms by which the individual receptors regulate their expression by binding to the respective hormone response elements upstream of these receptor genes. By further employing in vitro and in vivo models of ER and AR stimulation or antagonism, we delineated their regulation in a receptor subtype-specific manner. Our results indicate that ERα positively regulates expression of both the ERs; whereas, ERβ and AR negatively regulate expression of both ERβ and AR by direct binding to upstream regulatory regions. The perturbations in the levels of steroid receptors could be an important factor contributing to spermatogenic defects and male sub-fertility after estradiol and ER agonist treatment. Our study delineates the direct contribution of the individual steroid receptors in the regulation of their own expression.

2.45 GHz microwave radiation induced oxidative and nitrosative stress mediated testicular apoptosis: Involvement of a p53 dependent bax-caspase-3 mediated pathway

Deleterious effects of MW radiation on the male reproduction are well studied. Previous reports although suggest that 2.45 GHz MW irradiation induced oxidative and nitrosative stress adversely affects the male reproductive function but the detailed molecular mechanism occurring behind it has yet to be elucidated. The aim of present study was to investigate the underlying detailed pathway of the testicular apoptosis induced by free radical load and redox imbalance due to 2.45 GHz MW radiation exposure and the degree of severity along with the increased exposure duration. Twelve-week old male mice were exposed to 2.45 GHz MW radiation [continuous-wave (CW) with overall average Power density of 0.0248 mW/cm² and overall average whole body SAR value of 0.0146 W/kg] for 2 hr/day over a period of 15, 30, and 60 days. Testicular histology, serum testosterone, ROS, NO, MDA level, activity of antioxidant enzymes, expression of pro-apoptotic proteins (p53 and Bax), anti-apoptotic proteins (Bcl-2 and Bcl-x_L ), cytochrome-c, inactive/active caspase-3, and uncleaved PARP-1 were evaluated. Findings suggest that 2.45 GHz MW radiation exposure induced testicular redox imbalance not only leads to enhanced testicular apoptosis via p53 dependent Bax-caspase-3 mediated pathway, but also increases the degree of apoptotic severity in a duration dependent manner.

17β-Estradiol induces cyto-genotoxicity on blood cells of common carp (Cyprinus carpio)

17β-Estradiol, a natural hormone present at high concentrations in aquatic ecosystems, affects and modifies endocrine function in animals. In recent years research workers have expressed concern over its potential effects on aquatic organisms; however, little is known about its capacity to induce genetic damage or the pro-apoptotic effects of such damage on fish. Therefore, this study aimed to evaluate 17β-estradiol-induced cyto-genotoxicity in blood cells of the common carp Cyprinus carpio exposed to different concentrations (1 ng, 1 μg and 1 mg L^-1). Peripheral blood samples were collected and evaluated by comet assay, micronucleus test, determination of caspase-3 activity and TUNEL assay at 12, 24, 48, 72 and 96 h of exposure. Increases in frequency of micronuclei, TUNEL-positive cells and caspase-3 activity were observed, particularly at the highest concentration. In contrast, the comet assay detected significant increases at 24 and 96 h with the 1 μg and 1 ng L^-1 concentrations respectively. The set of assays used in the present study constitutes a reliable early warning biomarker for evaluating the toxicity induced by this type of emerging contaminants on aquatic species.

The In Vitro Impact of the Herbicide Roundup on Human Sperm Motility and Sperm Mitochondria

Toxicants, such as herbicides, have been hypothesized to affect sperm parameters. The most common method of exposure to herbicides is through spraying or diet. The aim of the present study was to investigate the effect of direct exposure of sperm to 1 mg/L of the herbicide Roundup on sperm motility and mitochondrial integrity. Sperm samples from 66 healthy men who were seeking semen analysis were investigated after written informed consent was taken. Semen analysis was performed according to the World Health Organization guidelines (WHO, 2010). Mitochondrial integrity was assessed through mitochondrial staining using a mitochondria-specific dye, which is exclusively incorporated into functionally active mitochondria. A quantity of 1 mg/L of Roundup was found to exert a deleterious effect on sperm’s progressive motility, after 1 h of incubation (mean difference between treated and control samples = 11.2%) in comparison with the effect after three hours of incubation (mean difference = 6.33%, p < 0.05), while the relative incorporation of the mitochondrial dye in mitochondria of the mid-piece region of Roundup-treated spermatozoa was significantly reduced compared to relative controls at the first hour of incubation, indicating mitochondrial dysfunction by Roundup. Our results indicate that the direct exposure of semen samples to the active constituent of the herbicide Roundup at the relatively low concentration of 1 mg/L has adverse effects on sperm motility, and this may be related to the observed reduction in mitochondrial staining.

Hsd3b2 associated in modulating steroid hormone synthesis pathway regulates the differentiation of chicken embryonic stem cells into spermatogonial stem cells

Steroid hormones regulate differentiation of various types of cell during embryogenesis. Testosterone is one of the androgens that bind to receptors to regulate gene expression and promote spermatogenesis. Our results showed that testosterone, as a product of steroid hormones synthesis pathway, could facilitate the differentiation of embryonic stem cells (ESCs) into spermatogonial stem cells (SSCs). The analysis of the steroid hormones synthesis pathway demonstrated that 3beta-hydroxysteroid dehydrogenase2 (Hsd3b2) plays a major role in the synthesis of testosterone. In the absence of Hsd3b2, the expression of downstream genes such as Cyp1a1, Ugt1a1, and Hsd17b7 was not maintained. This reduction is probably due to the down-regulation of the steroid hormones synthesis pathway. Furthermore, qRT-PCR, immunofluorescence, and flow cytometry analysis confirmed that the steroid hormones synthesis pathway could facilitate the differentiation of ESCs. Altogether, these results lead to a model in which Hsd3b2 regulates ESCs differentiation via modulating the activity of steroid hormones synthesis pathway.

Interactions between oestrogen and 1α,25(OH)2-vitamin D3 signalling and their roles in spermatogenesis and spermatozoa functions

Oestrogens and 1α,25(OH)₂-vitamin D₃ (1,25-D₃) are steroids that can provide effects by binding to their receptors localised in the cytoplasm and in the nucleus or the plasma membrane respectively inducing genomic and non-genomic effects. As confirmed notably by invalidation of the genes, coding for their receptors as tested with mice with in vivo and in vitro treatments, oestrogens and 1,25-D₃ are regulators of spermatogenesis. Moreover, some functions of ejaculated spermatozoa as viability, DNA integrity, motility, capacitation, acrosome reaction and fertilizing ability are targets for these hormones. The studies conducted on their mechanisms of action, even though not completely elicited, have allowed the demonstration of putative interactions between their signalling pathways that are worth examining more closely. The present review focuses on the elements regulated by oestrogens and 1,25-D₃ in the testis and spermatozoa as well as the interactions between the signalling pathways of both hormones.

Seasonal variations of aromatase and estrogen receptors expression in the testis of free-ranging sand rats

An increasing number of studies revealed the importance of estrogen in male reproduction. However, most research was conducted in laboratory rodents subjected to standardized environmental conditions. Therefore, seasonal regulations of estrogen pathways remain poorly understood under natural conditions. Using immunohistochemistry, the expression of several molecules involved in the functioning of testis (i.e. 17-β estradiol [E2], P450 aromatase, estrogen receptors ESR1, ESR2, and GPER1 [also known as GPR30]) were investigated in free-ranging fat sand rats, Psammomys obesus, during the breeding and resting seasons. Leydig cells showed a strong immunoreactivity for aromatase in the testis sampled during the breeding season only; however, E2, ESR1, ESR2 and GPER1 were present during both seasons. Sertoli cells showed a positive signal for E2 and ESR2 during the breeding season; though, all molecules, except GPER1, were present during the resting season. Spermatogonia were reactive for E2, ESR2 and GPER1 during the breeding season and for ESR1 and GPER1 during the resting season. During both seasons, spermatocytes-I presented a moderate reactivity for E2, ESR1, ESR2 and a strong reactivity for GPER1; aromatase was detected during the resting season only. Spermatids and spermatozoa were present exclusively during breeding season and were reactive for all molecules; except round spermatids that were negative for aromatase. The functioning of the testis depends on finely tuned stimulation and inhibition systems. Our results suggest that differential expression of aromatase, ESR1, ESR2, and GPER1 across cells types is involved in the seasonal activation/inactivation cycle of spermatogenesis in a free-ranging species.

Disturbed testicular expression of the estrogen-metabolizing enzymes CYP1A1 and COMT in infertile men with primary spermatogenic failure: possible negative implications on Sertoli cells

Estradiol (E₂ ) is normally metabolized to hydroxyestradiols and methoxyestradiols by CYP1A1, CYP1B1 and COMT. However, an altered production of these metabolites by a disturbed expression of these enzymes is associated with reproductive and non-reproductive pathologies. In vitro studies suggest that increased hydroxyestradiols and methoxyestradiols intratesticular generation is related to male infertility, but no studies have explored whether infertile men have a disturbed testicular expression of the enzymes that generate these E₂ metabolites. The aim of this study was to assess CYP1A1, CYP1B1 and COMT testicular expression at mRNA and protein level in men with spermatogenic impairment. Seventeen men with primary spermatogenic failure (13 with Sertoli cell-only syndrome and four with maturation arrest) and nine controls with normal spermatogenesis were subjected to testicular biopsy. mRNA was quantified using real-time RT-PCR and protein expression was evaluated using western blot and immunohistochemistry followed by integrated optic density analysis. Besides, the effects of hydroxyestradiols and methoxyestradiols on testosterone-induced transcriptional activity were evaluated in TM4 cells using a luciferase reporter assay system. Our results show that patients with Sertoli cell-only syndrome had significantly elevated COMT expression at the mRNA level, higher COMT immunoreactivity in their seminiferous tubules and increased protein expression of the soluble COMT isoform (S-COMT), whereas patients with maturation arrest had significantly elevated CYP1A1 mRNA levels and higher CYP1A1 immunoreactivity in interstitial space. Finally, 2-hydroxyestradiol decreased testosterone-induced transcriptional activity in Sertoli cells in vitro. In conclusion, male infertility is related to disturbed testicular expression of the enzymes responsible for producing hydroxyestradiols and/or methoxyestradiols. If these changes are related with increased intratesticular hydroxyestradiols and methoxyestradiols concentrations, they could elicit an impaired Sertoli cell function. Our results suggest CYP1A1 and COMT as new potential targets in treating male infertility.

Chapter 5 Slow Freezing of Human Sperm

Cryopreservation of human spermatozoa is a highly efficient procedure for managing male fertility, and much of its successful application seems to have a crucial impact on the reproductive outcome of assisted reproduction technologies. Here, we present, explain, and describe the slow freezing method for preserving human spermatozoa, which is currently the most commonly used freezing technique in most clinical andrology laboratories.

17β-estradiol modifies human spermatozoa mitochondrial function in vitro

BACKGROUND

It is assumed that spermatozoa are target cells for estrogens however, the mechanism of their action is not fully understood. The aim of this study was to investigate the influence of 17β-estradiol (E2) on the human spermatozoa mitochondrial function.

METHODS

The effects on spermatozoa of E2 at final concentrations of 10(-10), 10(-8) and 10(-6) M were studied regarding the following phenomena: (1) kinetics of intracellular free calcium ions changes (using Fluo-3), (2) mitochondrial membrane potential ΔΨm (using JC-1 fluorochrome), (3) production of superoxide anion in mitochondria (using MitoSOX RED dye), (4) spermatozoa vitality (propidium iodide staining) and (5) phosphatidylserine membrane translocation (staining with annexin V marked with fluorescein).

RESULTS

E2 initiated rapid (within a few seconds) dose dependent increase of intracellular free calcium ions concentration. E2 was changing the mitochondrial membrane potential: 10(-8) M initiated significant increase of percentage of high ΔΨm spermatozoa while the 10(-6) M induced significant decrease of high ΔΨm cells. In spermatozoa stimulated with E2 10(-6) M a significant increase of mitochondrial superoxide anion level was observed. 2 h incubation of spermatozoa with E2 did not alter cells vitality nor stimulated phosphatidylserine membrane translocation, for all three doses.

CONCLUSIONS

17β-estradiol affected the human spermatozoa mitochondrial function. E2 in low concentration improved while in high concentration might deteriorate mitochondrial function.

Benzo(a)pyrene Induced p53 Mediated Male Germ Cell Apoptosis: Synergistic Protective Effects of Curcumin and Resveratrol

Benzo(a)pyrene (B(a)P) is an environmental toxicant that induces male germ cell apoptosis. Curcumin and resveratrol are phytochemicals with cytoprotective and anti-oxidative properties. At the same time resveratrol is also a natural Aryl hydrocarbon Receptor (AhR) antagonist. Our present study in isolated testicular germ cell population from adult male Wistar rats, highlighted the synergistic protective effect of curcumin and resveratrol against B(a)P induced p53 mediated germ cell apoptosis. Curcumin-resveratrol significantly prevented B(a)P induced decrease in sperm cell count and motility, as well as increased serum testosterone level. Curcumin-resveratrol co-treatment actively protected B(a)P induced testicular germ cell apoptosis. Curcumin-resveratrol co-treatment decreased the expression of pro-apoptotic proteins like cleaved caspase 3, 8 and 9, cleaved PARP, Apaf1, FasL, tBid. Curcumin-resveratrol co-treatment decreased Bax/Bcl2 ratio, mitochondria to cytosolic translocation of cytochrome c and activated the survival protein Akt. Curcumin-resveratrol decreased the expression of p53 dependent apoptotic genes like Fas, FasL, Bax, Bcl2, and Apaf1. B(a)P induced testicular reactive oxygen species (ROS) generation and oxidative stress were significantly ameliorated with curcumin and resveratrol. Curcumin-resveratrol co-treatment prevented B(a)P induced nuclear translocation of AhR and CYP1A1 (Cytochrome P4501A1) expression. The combinatorial treatment significantly inhibited B(a)P induced ERK 1/2, p38 MAPK and JNK 1/2 activation. B(a)P treatment increased the expression of p53 and its phosphorylation (p53 ser 15). Curcumin-resveratrol co-treatment significantly decreased p53 level and its phosphorylation (p53 ser 15). The study concludes that curcumin-resveratrol synergistically modulated MAPKs and p53, prevented oxidative stress, regulated the expression of pro and anti-apoptotic proteins as well as the proteins involved in B(a)P metabolism thus protected germ cells from B(a)P induced apoptosis.

Differential roles of estrogen receptors, ESR1 and ESR2, in adult rat spermatogenesis

Estrogens, through their receptors, play an important role in regulation of spermatogenesis. However, the precise role of the estrogen receptors (ESR1 and ESR2) has been difficult to determine as in vivo estradiol treatment would signal through both the ESRs. Hence we had developed in vivo selective ESR agonist administration models in adult male rats to decipher the individual roles of the ESRs. Treatment with both ESR1 and ESR2 agonists decreased sperm counts after 60 days of treatment. The present study aimed to delineate the precise causes of decreased sperm counts following treatment with the two ESR agonists. Treatment with ESR1 agonist causes an arrest in differentiation of round spermatids into elongated spermatids, mainly due to down-regulation of genes involved in spermiogenesis. ESR2 agonist administration reduces sperm counts due to spermiation failure and spermatocyte apoptosis. Spermiation failure observed is due to defects in tubulobulbar complex formation because of decrease in expression of genes involved in actin remodelling. The increase in spermatocyte apoptosis could be due to increase in oxidative stress and decrease in transcripts of anti-apoptotic genes. Our results suggest that the two ESRs regulate distinct aspects of spermatogenesis. ESR1 is mainly involved with regulation of spermiogenesis, while ESR2 regulates spermatocyte apoptosis and spermiation. Activation of estrogen signaling through either of the receptors can affect their respective processes during spermatogenesis and lead to low sperm output. Since many environmental estrogens can bind to the two ESRs with different affinities, these observations can be useful in understanding their potential effects on spermatogenesis.

Estrogens down-regulate the stem cell factor (SCF)/c-KIT system in prostate cells: Evidence of antiproliferative and proapoptotic effects

The development of prostate cancer (PCa) is intimately associated with the hormonal environment, and the sex steroids estrogens have been implicated in prostate malignancy. However, if some studies identified estrogens as causative agents of PCa, others indicated that these steroids have a protective role counteracting prostate overgrowth. The tyrosine kinase receptor c-KIT and its ligand, the stem cell factor (SCF), have been associated with the control of cell proliferation/apoptosis and prostate carcinogenesis, and studies show that estrogens regulate their expression in different tissues, though, in the case of prostate this remains unknown. The present study aims to evaluate the role of 17β-estradiol (E2) in regulating the expression of SCF/c-KIT in human prostate cell lines and rat prostate, and to investigate the consequent effects on prostate cell proliferation and apoptosis. qPCR, Western Blot, and immuno(cito)histochemistry analysis showed that E2-treatment decreased the expression of SCF and c-KIT both in human prostate cells and rat prostate. Furthermore, the diminished expression of SCF/c-KIT was underpinned by the diminished prostate weight and reduced proliferation index. On the other hand, the results of TUNEL labelling, the increased activity of caspase-3, and the augmented expression of caspase-8 and Fas system in the prostate of E2-treated animals indicated augmented apoptosis in response to E2. The obtained results demonstrated that E2 down-regulated the expression of SCF/c-KIT system in prostate cells, which was associated with antiproliferative and proapoptotic effects. Moreover, these findings support the protective role of estrogens in PCa and open new perspectives on the application of estrogen-based therapies.

Effect of estradiol on apoptosis, proliferation and steroidogenic enzymes in the testes of the toad Rhinella arenarum (Amphibia, Anura)

Estrogens inhibit androgen production and this negative action on amphibian steroidogenesis could be related to the regulation of steroidogenic enzymes. Estrogens are also involved in the regulation of amphibian spermatogenesis by controlling testicular apoptosis and spermatogonial proliferation. The Bidder's organ (BO) is a structure characteristic from the Bufonidae family and in adult males of Rhinella arenarum it is one of the main sources of plasma estradiol (E2). The purpose of this study is to analyze the effect of E2 on testicular steroidogenic enzymes, apoptosis and proliferation in the toad R. arenarum. For this purpose, testicular fragments were treated during 24h with or without 2 or 20nM of E2. After treatments, the activities of cytochrome P450 17α-hydroxylase-C17-20 lyase (CypP450c17) and 3β-hydroxysteroid dehydrogenase/isomerase (3β-HSD/I) were measured by the transformation of radioactive substrates into products, and CypP450c17 expression was determined by Western blot analysis. Apoptosis in testicular sections was detected with a commercial fluorescent kit based on TUNEL method, and proliferation was evaluated by BrdU incorporation. Results indicate that E2 has no effect on CypP450c17 protein levels or enzymatic activity, while it reduces 3β-HSD/I activity during the post reproductive season. Furthermore, although E2 has no effect on apoptosis during the pre and the post reproductive seasons, it stimulates testicular apoptosis during the reproductive season, mostly in spermatocytes. Finally, E2 has no effect on testicular proliferation all year long. Taken together, these results suggest that E2 is involved in the regulation of testicular steroidogenesis and spermatogenesis.

Oestrogens as apoptosis regulators in mammalian testis: angels or devils?

In the mammalian testis, spermatogenesis is a highly coordinated process of germ cell development, which ends with the release of ‘mature’ spermatozoa. The fine regulation of spermatogenesis is strictly dependent on sex steroid hormones, which orchestrate the cellular and molecular events underlying normal development of germ cells. Sex steroids actions also rely on the control of germ cell survival, and the programmed cell death by apoptosis has been indicated as a critical process in regulating the size and quality of the germ line. Recently, oestrogens have emerged as important regulators of germ cell fate. However, the beneficial or detrimental effects of oestrogens in spermatogenesis are controversial, with independent reports arguing for their role as cell survival factors or as apoptosis-inducers. The dual behaviour of oestrogens, shifting from ‘angels to devils’ is supported by the clinical findings of increased oestrogens levels in serum and intratesticular milieu of idiopathic infertile men. This review aims to discuss the available information concerning the role of oestrogens in the control of germ cell death and summarises the signalling mechanisms driven oestrogen-induced apoptosis. The present data represent a valuable basis for the clinical management of hyperoestrogenism-related infertility and provide a rationale for the use of oestrogen-target therapies in male infertility.

New insights into male (in)fertility: the importance of NO

Infertility is a global problem that is on the rise, especially during the last decade. Currently, infertility affects approximately 10-15% of the population worldwide. The frequency and origin of different forms of infertility varies. It has been shown that reactive oxygen and nitrogen species (ROS and RNS) are involved in the aetiology of infertility, especially male infertility. Various strategies have been designed to remove or decrease the production of ROS and RNS in spermatozoa, in particular during in vitro fertilization. However, in recent years it has been shown that spermatozoa naturally produce a variety of ROS/RNS, including superoxide anion radical (O2 (⋅-)), hydrogen peroxide and NO. These reactive species, in particular NO, are essential in regulating sperm capacitation and the acrosome reaction, two processes that need to be acquired by sperm in order to achieve fertilization potential. In addition, it has recently been shown that mitochondrial function is positively correlated with human sperm fertilization potential and quality and that NO and NO precursors increase sperm motility by increasing energy production in mitochondria. We will review the new link between sperm NO-driven redox regulation and infertility herein. A special emphasis will be placed on the potential implementation of new redox-active substances that modulate the content of NO in spermatozoa to increase fertility and promote conception.

Quinestrol induces spermatogenic apoptosis in vivo via increasing pro-apoptotic proteins in adult male mice

The effects of quinestrol on spermatogenesis were investigated in adult male mice by daily intragastric administration of quinestrol with various doses of 5, 10, 50 and 100mg/kg body weight for 10 days. The sperm counts declined while the number of abnormal spermatozoa went up in mice treated with quinestrol. The testicular weight and seminiferous tubular area gradually declined with increasing dosages of quinestrol to 50 and 100mg/kg. Rarefied germ cells showed irregular distributions in the seminiferous tubules of mice treated with 50 and 100mg/kg quinestrol. Apoptosis was highly pronounced in spermatogonia, spermatocytes, spermatids and Leydig cells. Antioxidant enzyme activities - superoxide dismutase and glutathione peroxidase - as well as total antioxidant capacity significantly reduced, while malondialdehyde contents increased. The number of germ cells expressing caspase-3, p53, Bax and FasL significantly increased whereas cells expressing Bcl-2 significantly decreased in groups treated with 50 and 100mg/kg quinestrol compared with the control. The concentration of nitrogen monoxidum also increased significantly under these dosages. The results suggest that quinestrol stimulates oxidative stress to induce apoptosis in spermatogenic cells through the mitochondrial and death receptor pathways in adult male mice.

Disruption of Sertoli cell vimentin filaments in prepubertal rats: an acute effect of butylparaben in vivo and in vitro

Parabens are p-hydroxybenzoic acid ester compounds widely used as preservatives in foods, cosmetics, toiletries and pharmaceuticals. We have recently shown that butylparaben induces spermatogenic cell apoptosis in prepubertal rats. We have conducted the present study for further information. Three-week-old male Sprague-Dawley rats (n=8) were given a single oral dose of 1,000 mg/kg butylparaben. The rats were sacrificed under anesthesia at 3, 6 and 24h after administration and their testes were collected for histopathological and immunohistochemical examination. Results showed a gradual collapse of Sertoli cell vimentin filaments and decreased actin staining intensity without accompanying changes in the pattern of tubulin expression, while spermatogenic cells became separated from the basement membrane and sloughed into the lumen in the butylparaben-treated rats, compared to the controls. To determine the direct effects of butylparaben on Sertoli cells, primary Sertoli cell cultures with and without butylparaben treatment were examined. Toluidine blue staining in butylparaben treated-cultured Sertoli cells showed an increased number and size of vacuoles in their cytoplasm. In agreement with the in vivo experiment, the in vitro study also clearly demonstrated disruption of vimentin filaments in Sertoli cells after butylparaben treatment. Considering both our present and previous reports, we can speculate that butylparaben-induced disruption of Sertoli cell vimentin filaments may lead to precocious release of spermatogenic cells from underlying Sertoli cells, and the released cells may undergo apoptosis owing to loss of support provided by the Sertoli cells.

Single administration of butylparaben induces spermatogenic cell apoptosis in prepubertal rats

Parabens are p-hydroxybenzoic acid ester compounds widely used as preservatives in foods, cosmetics, toiletries and pharmaceuticals. Some parabens, including butylparaben, exert an estrogenic activity as determined by in vitro estrogen receptor assay and in vivo uterotrophic assay, and adversely affect endocrine secretion and male reproductive function. We conducted a research study to evaluate the acute effects of butylparaben on testicular tissues of prepubertal rats. Three-week-old male rats (n=8) were given a single dose of 1000mg/kg butylparaben. The rats were sacrificed under anesthesia at 3, 6 and 24h after administration, and their testes were collected for histopathological examination. The study revealed progressive detachment and sloughing of spermatogenic cells into the lumen of the seminiferous tubules at 3h, and this effect was enhanced at 6h after administration. Thin seminiferous epithelia and wide tubular lumina were seen at 24h in the butylparaben-treated group, compared to the control. In order to clarify whether sloughed spermatogenic cells underwent apoptosis, TUNEL assay was carried out. We found a significant increase in the number of apoptotic spermatogenic cells in all the treated groups, compared to the controls and a maximal number of apoptotic cells were detected at 6h after administration. In semithin sections, apoptotic cells were easily detected by their prominent basophilia and condensed chromatin, mainly found in spermatocytes. Ultrastructurally, the condensed chromatin and shrunken cytoplasm and nucleus, hallmarks of apoptotic cell death, were observed in butylparaben-treated groups. These observations lead us to postulate that butylparaben, similar to other estrogenic compounds, also induces spermatogenic cell apoptosis.

Quercetin supplementation restores testicular function and augments germ cell survival in the estrogenized rats

Quercetin, as a flavonoid, has been recognized to possess dual properties of an oxidant and antioxidant as well. The role of quercetin (QC), as an antioxidant in countering estradiol-3-benzoate (EB) induced adverse effects and germ cell apoptosis in adult rat testis was presently investigated. Adult rats received EB (0.075 mg/rat/5th day) alone or EB+QC (15 mg/kg bw/alternate day) simultaneously for 30 days. Revival of spermatogenesis following QC intervention was associated with a significant restoration in serum and intra-testicular levels of testosterone. Decline in lipid peroxidation and simultaneous improvement in the activities of superoxide dismutase, catalase and glutathione s-transferase were very much evident. Identically, total antioxidant capacity and glutathione demonstrated a marked improvement. QC augmented germ cell survival leading to a decrease in cell apoptosis. Expression of downstream apoptotic markers, caspase-3 and poly-ADP-ribose polymerase (PARP) presented a significant reduction. Down regulation with respect to upstream markers, caspase-8 and -9, Fas, FasL, Bax, and p53 was similarly observed. Taken together, the above findings indicate that with the dose presently used quercetin with its antioxidant and antiestrogenic properties restored testicular function leading to revival of spermatogenesis. It also augmented germ cell survival primarily mediated through downregulation in the expressions of upstream, downstream and other markers in the pathways of metazoan apoptosis.

Propolis attenuates doxorubicin-induced testicular toxicity in rats

Doxorubicin (Dox), an effective anticancer agent, can impair testicular function leading to infertility. The present study aimed to explore the protective effect of propolis extract on Dox-induced testicular injury. Rats were divided into four groups (n=10). Group I (normal control), group II received propolis extract (200 mg kg(-1); p.o.), for 3 weeks. Group III received 18 mg kg(-1) total cumulative dose of Dox i.p. Group IV received Dox and propolis extract. Serum and testicular samples were collected 48 h after the last treatment. In addition, the effects of propolis extract and Dox on the growth of solid Ehrlich carcinoma in mice were investigated. Dox reduced sperm count, markers of testicular function, steroidogenesis and gene expression of testicular 3β-hydroxysteroid dehydrogenase (3β-HSD), 17β-hydroxysteroid dehydrogenase (17β-HSD) and steroidogenic acute regulatory protein (StAR). In addition, it increased testicular oxidative stress, inflammatory and apoptotic markers. Morphometric and histopathologic studies supported the biochemical findings. Treatment with propolis extract prevented Dox-induced changes without reducing its antitumor activity. Besides, administration of propolis extract to normal rats increased serum testosterone level coupled by increased activities and gene expression of 3ß-HSD and 17ß-HSD. Propolis extract may protect the testis from Dox-induced toxicity without reducing its anticancer potential.

Molecular mechanism of 17α-ethinylestradiol cytotoxicity in isolated rat hepatocytes

17α-Ethinylestradiol (17-EE) is used in formulations of contraceptives and hormone replacement therapy because it is an estradiol derivative. However, it has been associated with an increase in the risk of liver cancers and injury. The carcinogenic properties of 17-EE are similar to that of other estrogens, but the molecular mechanism of liver injury is still unclear. It is important to identify any secondary toxic mechanisms that can be used to prevent or treat the toxicity. The LC50 of 17-EE toward isolated rat hepatocytes was determined to be 150 ± 8 μmol/L. Accelerated cytotoxicity mechanism screening (ACMS) techniques using isolated rat hepatocytes showed that CYP1A inhibitors decreased cytotoxicity, whereas tyrosinase increased toxicity; this suggests that the toxic mechanism involved is the oxidation of 17-EE. A hepatocyte inflammation model also increased 17-EE-induced mitochondrial toxicity, as well as the formation of ROS and H2O2. Cytotoxicity was increased when inhibitors of quinone reduction, catechol-O-methylation, glucuronidation, glutathione conjugation, and sulfation were co-incubated with 17-EE. The hepatocytes could be rescued with antioxidants and quinone trapping agents, thereby suggesting a role for quinoid moiety induced oxidative stress in 17-EE induced cytotoxicity. These mechanisms for 17-EE hepatotoxicity could provide a new perspective for the treating 17-EE-induced liver injury.

Hormonal control of Sertoli cell metabolism regulates spermatogenesis

Hormonal regulation is essential to spermatogenesis. Sertoli cells (SCs) have functions that reach far beyond the physical support of germ cells, as they are responsible for creating the adequate ionic and metabolic environment for germ cell development. Thus, much attention has been given to the metabolic functioning of SCs. During spermatogenesis, germ cells are provided with suitable metabolic substrates, in a set of events mediated by SCs. Multiple signaling cascades regulate SC function and several of these signaling pathways are hormone-dependent and cell-specific. Within the seminiferous tubules, only SCs possess receptors for some hormones rendering them major targets for the hormonal signaling that regulates spermatogenesis. Although the mechanisms by which SCs fulfill their own and germ cells metabolic needs are mostly studied in vitro, SC metabolism is unquestionably a regulation point for germ cell development and the hormonal control of these processes is required for a normal spermatogenesis.

Nitric oxide mediated effects on reproductive toxicity caused by carbon disulfide in male rats

This study investigated nitric oxide (NO) mediation of carbon disulfide (CS(2)) toxicity that compromised male rat spermatogenesis and endocrine function. Rats were exposed to multiple levels of CS(2) concentration (0, 50, 250, 1250 mg/m(3)). A 1250 mg/m(3) CS(2)+sodium nitroprusside (SNP) group and a 1250 mg/m(3) CS(2)+NG-monomethyl-L-arginine (L-NMMA) group were established to explore the role of NO in mediating CS(2) toxicity. NO concentrations, NO synthase (NOS) activity, and sex hormone levels were measured, and sperm characteristics were observed and analyzed. Our data show that CS(2) exposure decreased: NOS activity; tissue NO concentrations; serum levels of gonadotropin-releasing hormones, luteinizing hormones, and testosterone; and sperm count and activity. In contrast, increased serum follicle-stimulating hormone concentrations and teratospermia were observed with CS(2) exposure. SNP reduced some of the toxic effects of CS(2), while L-NMMA treatment showed no effect. The results suggests that NO mediates compromised reproductive system function caused by CS(2) exposure.