Estrogens in male germ cells

The biosynthesis of steroids and the production of spermatozoa are two major functions of the mammalian testis which are tightly controlled by gonadotropins and numerous locally produced factors. Among these are the estrogens that are produced within the seminiferous epithelium via the irreversible transformation of androgens (C19) into estrogens (C18) by aromatase. We have recently reported that male germ cells are the new source of estrogens in the testis. For instance, estrogen receptors (ER) are found mainly in spermatids that give rise to spermatozoa. Moreover, it is noteworthy that GPR 30 (a transmembrane ER) induces rapid responses after estradiol binding, which, in turn, modulates cyclins and proapoptotic factors (e.g., BAX) to affect germ cell cycle progression and apoptosis. In summary, at least in the animal species that were studied thus far, germ cells are the major source and the target of estrogens, affecting normal male gonadal development and spermatogenesis, in particular spermiogenesis. These findings have also shed new light on the possible adverse effects of endocrine disruptors having estrogenic activities that can cause abnormal development of the male genital tract.

Disruption of nongenomic testosterone signaling in a model of spinal and bulbar muscular atrophy

As one of the nine hereditary neurodegenerative polyQ disorders, spinal and bulbar muscular atrophy (SBMA) results from a polyQ tract expansion in androgen receptor (AR). Although protein aggregates are the pathological hallmark of many neurodegenerative diseases, their direct role in the neurodegeneration is more and more questioned. To determine the early molecular mechanisms causing motor neuron degeneration in SBMA, we established an in vitro system based on the tetracycline-inducible expression of normal (AR20Q), the mutated, 51 glutamine-extended (AR51Q), or polyQ-deleted (AR0Q) AR in NSC34, a motor neuron-like cell line lacking endogenous AR. Although no intracellular aggregates were formed, the expression of the AR51Q leads to a loss of function characterized by reduced neurite outgrowth and to a toxic gain of function resulting in decreased cell viability. In this study, we show that both AR20Q and AR51Q are recruited to lipid rafts in response to testosterone stimulation. However, whereas testosterone induces the activation of the c-jun N-terminal kinase/c-jun pathway via membrane-associated AR20Q, it does not so in NSC34 expressing AR51Q. Phosphorylation of c-jun N-terminal kinase plays a crucial role in AR20Q-dependent survival and differentiation of NSC34. Moreover, c-jun protein levels decrease more slowly in AR20Q- than in AR51Q-expressing NSC34 cells. This is due to a rapid and transient inhibition of glycogen synthase kinase 3α occurring in a phosphatidylinositol 3-kinase-independent manner. Our results demonstrate that the deregulation of nongenomic AR signaling may be involved in SBMA establishment, opening new therapeutic perspectives.

Estrogens: new players in spermatogenesis

Aromatase that irreversibly transforms androgens into estrogens is present in the smooth endoplasmic reticulum of nearly all cell types in the mammalian testis. In rodents, all testicular cells except for myoid cells express aromatase activity. We have demonstrated the presence of the functional aromatase (transcript or protein, and biological activity) in adult rat germ cells including pachytene spermatocytes and round spermatids. We have also demonstrated estrogen output from these cells equivalent to that of Leydig cells. Unlike androgen receptors, which are localized mainly in testicular somatic cells, estrogen receptors are present in both somatic and germ cells in the testis. Moreover, we have recently described the rapid membrane effects of estrogens (via G protein-coupled receptor [GPER]) in purified rat germ cells. On the basis of various experimental models, in vitro studies and clinical data, it can be concluded that estrogens play an essential role in male reproduction, specifically in the development of spermatozoa.

17β-Estradiol regulates cyclin A1 and cyclin B1 gene expression in adult rat seminiferous tubules

Spermatogenesis, which is the fundamental mechanism allowing male gamete production, is controlled by several factors, and among them, estrogens are likely concerned. In order to enlighten the potential role of estrogen in rat spermatogenesis, seminiferous tubules (ST) from two groups of seminiferous epithelium stages (II-VIII and IX-I) were treated with either 17β-estradiol (E(2)) agonists or antagonists for estrogen receptors (ESRs). In this study, we show that cyclin A1 and cyclin B1 gene expression is controlled by E(2) at a concentration of 10(-9) M only in stages IX-I. This effect is mimicked by a treatment with the G-protein coupled estrogen receptor (GPER) agonist G1 and is abolished by treatment with the ESR antagonist ICI 182 780. Moreover, using letrozole, a drug that blocks estrogen synthesis, we demonstrate that these genes are under the control of E(2) within rat ST. Thus, germ cell differentiation may be regulated by E(2) which acts through ESRs and GPER, expressed in adult rat ST.

Role of estrogens in spermatogenesis

Aromatase converts irreversibly androgens into estrogens and is present in the endoplasmic reticulum of various cells of mammalian testes ; at least in rodents, all testicular cells except peritubular cells express aromatase. In testis, high affinity estrogen receptors, ERalpha and/or ERbeta, together with a membrane rapid effect recently described, mediate the effects of estrogens. From the experimental models, in vitro studies and data collected in patients, it is now demonstrated that estrogens play an important role in the testis of vertebrates. At least it is supported by the widespread distribution of estrogen receptors in the testicular cells and the simultaneous presence of a biologically active aromatase in all germ cells (especially in meiotic and post-meiotic stages). Thus the role of estrogens (intracrine, autocrine and / or paracrine) in spermatogenesis (proliferation, apoptosis, survival and maturation) and more generally, in male reproduction is now evidenced, and much more complex than previously predicted.

Role of estrogens in spermatogenesis

Aromatase converts irreversibly androgens into estrogens and is present in the endoplasmic reticulum of various cells of mammalian testes ; at least in rodents, all testicular cells except peritubular cells express aromatase. In testis, high affinity estrogen receptors, ERalpha and/or ERbeta, together with a membrane rapid effect recently described, mediate the effects of estrogens. From the experimental models, in vitro studies and data collected in patients, it is now demonstrated that estrogens play an important role in the testis of vertebrates. At least it is supported by the widespread distribution of estrogen receptors in the testicular cells and the simultaneous presence of a biologically active aromatase in all germ cells (especially in meiotic and post-meiotic stages). Thus the role of estrogens (intracrine, autocrine and / or paracrine) in spermatogenesis (proliferation, apoptosis, survival and maturation) and more generally, in male reproduction is now evidenced, and much more complex than previously predicted.

Effect of methanol extract of Basella alba L. (Basellaceae) on the fecundity and testosterone level in male rats exposed to flutamide in utero

We evaluated the effect of the methanol extract of Basella alba (MEBa) on testosterone level and fecundity/fertility in male rats exposed in utero to flutamide - an androgen receptor antagonist. For this purpose, 1.5- and 2.5 -month-old male rats exposed in utero to flutamide were treated with the MEBa (1 mg kg(-1) ) for 2 and 1 month respectively. Five days before the end of treatment, rats were housed with females to assess their fecundity/fertility. Thereafter, rats were sacrificed and blood collected for the quantification of testosterone. Flutamide-exposed male rats showed a decrease in their ano-genital distance (AGD, P < 0.05) and were infertile. In normal (methylcellulose-exposed) animals, MEBa provoked an increase in testosterone level in 1.5- (P < 0.008) and 2.5 -month-old rats (P < 0.01) concomitantly with the improvement in their fecundity by 25%. In flutamide-exposed male rats, MEBa increased testosterone level in 1.5 -month-old rats (P < 0.001) without any effect on their fecundity; while in 2.5- month-old rats, MEBa did not affect the testosterone level but improved fecundity (by 25%) and fertility (P < 0.001). This study demonstrated the positive effect of MEBa to enhance fecundity/fertility in normal male rats and in rats exposed to the antiandrogen flutamide during their foetal life.

Therapeutic effects of soy isoflavones on α-amylase activity, insulin deficiency, liver-kidney function and metabolic disorders in diabetic rats

Natural estrogens have demonstrated a wide variety of biological activities, which makes them a good candidate for the treatment of diabetes. In vitro, this study evidenced that isoflavones enhanced insulin secretion and inhibited α-amylase activity. In vivo, the findings indicated that soy isoflavones stimulated insulin secretion, increased the hepatic glycogen content and suppressed blood glucose level. The soy isoflavones were also protected hepatic-kidney functions showed by the significant increase in superoxide dismutase, catalase and glutathione peroxidase activities and the decrease in thiobarbituric acid reactive substances, total bilirubin, creatinine and transaminases content. Moreover, soy isoflavones induced a decrease in LDL-cholesterol and triglycerides and an increase in HDL-cholesterol in plasma and liver. Overall, the findings of the current study indicate that soy isoflavones exhibit attractive properties and can, therefore, be considered a promising candidate for future application as alternative therapeutic agents, particularly in the development of anti-diabetic and hypolipidaemic drugs.

Effects of the methanol extract of Basella alba L (Basellaceae) on steroid production in Leydig cells

In this study, Leydig cells were purified from 70 day-old Sprague Dawley male rats and incubated with 10 and 100 μg/mL of methanol extract of Basella alba (MEBa) for 4 hours followed by the evaluation of cell viability, steroid (testosterone and estradiol) production, and the level of aromatase mRNA. Results showed that MEBa did not affect Leydig cell viability. At the concentration of 10 μg/mL, MEBa significantly stimulated testosterone and estradiol production (p < 0.01 and p < 0.03, respectively), and enhanced aromatase mRNA level (p < 0.04). These observations suggest that MEBa directly stimulated testosterone, estradiol and aromatase mRNA levels in isolated Leydig cells.

Regulation of aromatase expression by 1α,25(OH)2 vitamin D3 in rat testicular cells

It is well known that the vitamin D endocrine system is involved in physiological and biochemical events in numerous tissues, especially gut, bone and kidney but also testis. Therefore, in this study the effect and mechanisms of action of 1α,25(OH)2 vitamin D3 (1,25D) on aromatase gene expression in immature rat Sertoli cells were evaluated. Vitamin D receptor transcripts were present in immature Sertoli cells as well as in adult testicular germ cells and somatic cells. The treatment of immature Sertoli cells with 100 nM 1,25D increased the amount of aromatase transcript, mainly in 30-day-old rats. The protein kinase A (PKA) blocker, H89, partially inhibited the 1,25D effect. The stimulation of aromatase gene expression in 30-day-old Sertoli cells by the agonist 1α,25(OH)2 lumisterol3, and the suppression of the 1,25D effect by the antagonists 1β,25(OH)2 vitamin D3 and (23S)-25-dehydro-1α (OH)-vitamin D3-26,23-lactone suggested, besides a genomic effect of 1,25D, the existence of non-genomic activation of the membrane-bound vitamin D receptor involving the PKA pathway.

Immunomodulatory, beta-cell, and neuroprotective actions of fenugreek oil from alloxan-induced diabetes

Immunological disorders and nephropathy are among the most frequent and serious complications of diabetes mellitus. This shows that fewer infiltrated inflammatory cells evidenced by reverted back to near the normal value of white blood cell, mean corpuscular volume, and lymphocytes counts as interleukin-6 in pancreas. Also, fenugreek oil significantly improved blood glucose levels, glucose intolerance, and insulin sensitivity compared to the diabetic group. The pancreatic islet and less beta-cells damage were observed after the administration of fenugreek oil to diabetic rats. Moreover, diabetic rats showed low activities of superoxide dismutase, catalase, glutathione peroxidase, and reduced glutathione content in kidney, which were restored to near normal levels by treatment with fenugreek oil. The increased levels of lipid peroxidation, creatinine, albumin, and urea in diabetic rats decreased significantly in diabetic rats treated with fenugreek oil. Diabetic rats treated with fenugreek oil restored almost a normal architecture of pancreas and kidney. In conclusion, this study reveals the efficacy of fenugreek oil in the amelioration of diabetes, hematological status, and renal toxicity which may be attributed to its immunomodulatory activity and insulin stimulation action along with its antioxidant potential.

Gper and ESRs are expressed in rat round spermatids and mediate oestrogen-dependent rapid pathways modulating expression of cyclin B1 and Bax

Spermatogenesis is a precisely controlled and timed process, comprising mitotic divisions of spermatogonia, meiotic divisions of spermatocytes, maturation and differentiation of haploid spermatids giving rise to spermatozoa. It is well known that the maintenance of spermatogenesis is controlled by gonadotrophins and testosterone, the effects of which are modulated by a complex network of locally produced factors, including oestrogens. However, it remains uncertain whether oestrogens are able to activate rapid signalling pathways directly in male germ cells. Classically, oestrogens act by binding to oestrogen receptors (ESRs) 1 and 2. Recently, it has been demonstrated that rapid oestrogen action can also be mediated by the G-protein-coupled oestrogen receptor 1 (Gper). The aim of the present study was to investigate ESRs and Gper expression in primary cultures of adult rat round spermatids (RS) and define if oestradiol (E2) is able to activate, through these receptors, pathways involved in the regulation of genes controlling rat RS apoptosis and/or maturation. In this study, we demonstrated that rat RS express ESR1, ESR2 and Gper. Short-time treatment of RS with E2, the selective Gper agonist G1 and the selective ESR1 and ERβ agonists, 4,4',4"-(4-propyl-[1H]pyrazole-1,3,5-triyl) trisphenol (PPT) and 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN), respectively, determined activation of Extra-cellular signal-regulated kinase (ERK1/2) through the involvement of epidermal growth factor receptor transactivation. In addition, we investigated the effects of ESRs and Gper pathway activation on factors involved in RS maturation. Expression of cyclin B1 mRNA was downregulated by E2, G1 and PPT, but not by DPN. A concomitant and inverse regulation of the pro-apoptotic factor Bax mRNA expression was observed in the same conditions, with DPN being the only one determining an increase in this factor expression. Collectively, these data demonstrate that E2 activates, through ESRs and Gper, pathways involved in the regulation of genes controlling rat RS apoptosis and differentiation such as cyclin B1 and Bax.

Oestrogens and spermatogenesis

The role of oestrogens in male reproductive tract physiology has for a long time been a subject of debate. The testis produces significant amounts of oestrogenic hormones, via aromatase, and oestrogen receptors (ERs)alpha (ESR1) and ERbeta (ESR2) are selectively expressed in cells of the testis as well as the epididymal epithelium, depending upon species. This review summarizes the current knowledge concerning the presence and activity of aromatase and ERs in testis and sperm and the potential roles that oestrogens may have in mammalian spermatogenesis. Data show that physiology of the male gonad is in part under the control of a balance of androgens and oestrogens, with aromatase serving as a modulator.

Age- and cell-related gene expression of aromatase and estrogen receptors in the rat testis

Spermatogenesis is a complex and coordinated process leading to the formation of spermatozoa. This event, which is under the control of numerous endocrine and paracrine factors, seems to also be controlled by estrogens which exert their effects via nuclear estrogen receptors (ESRs) ESR1 and ESR2. Estrogens are synthesized by aromatase which is biologically expressed in the rat testis. The objective of our study was to clarify the gene expression patterns of aromatase and ESRs according to age and in the two compartments of the adult rat testis. In the adult, transcripts of aromatase vary according to the germ cell type and to the stages of seminiferous epithelium, a maximum being observed at stage I. The ESR1 gene is highly expressed in the adult testis and in stages from VIIc-d to XIV. Moreover, both ESR mRNA levels are higher in purified round spermatids than in pachytene spermatocytes, suggesting a putative role of estrogens in the haploid steps of spermatogenesis. The variability of the results in the expression of both ESRs led us to explore the putative presence of variants in the rat testis. Concerning ESR1, we have shown the presence of the full-length form and of one isoform with exon 4 deleted. For ESR2, besides the wild type, three isoforms were observed: one with exon 3 deleted, another with an insertion of 54 nucleotides, and the last one with both modifications. Therefore, the stage-regulated expression of aromatase and ESR1 genes in the rat testis suggests a likely role of estrogens in spermatogenesis.

Potential protective effect on key steroidogenesis and metabolic enzymes and sperm abnormalities by fenugreek steroids in testis and epididymis of surviving diabetic rats

The current study showed that the daily oral treatment of fenugreek steroids, designated F(steroids), to diabetic rats during 30 days demonstrated a significant (p < 0.05) decrease of blood glucose level and a considerable increase of the area of insulin-immunoreactive beta-cells in diabetic rats. Interestingly, this study showed that F(steroids) potentially unregulated the key steroidogenesis enzymes such as 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoA reductase), malic enzyme, 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and glucose-6-phosphate dehydrogenase (G6P-DH) activities as cholesterol rate in testis, which considerably enhanced testosterone and estradiol levels in the plasma of surviving diabetic rats. More interestingly, F(steroids) obviously prevented the alteration of the key carbohydrate enzymes such as hexokinase and pyruvate kinase activities as well as testicular glycogen and seminal fructose contents in surviving diabetic rats. Furthermore, F(steroids) administration to surviving diabetic rats significantly decreased the sperm shape abnormality and improved the sperm count. Above all, the potential protective action of reproductive systems was approved by the histological study of testis and epididymis.

Aromatase, oestrogens and human male reproduction

In most mammalian species aromatase is encoded by a single gene (Cyp19), which contains 18 exons, nine of them being translated. In man, the presence of a biologically active aromatase and oestrogen receptors (ERalpha and ERbeta) has been reported in Leydig cells, and also in immature germ cells and ejaculated spermatozoa. Concerning aromatase, the amount of transcript and enzymatic activity are decreased in immotile compared with motile sperm. We have amplified aromatase mRNA by real-time polymerase chain reaction in spermatozoa from asthenospermic, teratospermic and asthenoteratospermic men and recorded, respectively, 44, 52 and 67 per cent decreases of the amount of transcripts compared with fertile donors. A high degree of correlation (r = -0.64) between the abnormal spermatozoa (especially microcephaly and acrosome malformations) and aromatase/GAPDH transcript ratio has been observed. Idiopathic infertility is a wide health problem and no treatment is currently available. In humans, even if the role of oestrogens in spermatogenesis is still a matter of debate, the observations of decreased sperm number and motility in men genetically deficient in aromatase, together with our data and those reported in the literature, may suggest a role for aromatase/oestrogens not only during the development and maintenance of spermatogenesis but also in the final maturation of spermatozoa.

17 beta-estradiol activates rapid signaling pathways involved in rat pachytene spermatocytes apoptosis through GPR30 and ER alpha

Aim of the present study was to investigate whether estrogens were able to directly activate rapid signaling pathways controlling spermatogenesis in rat pachytene spermatocytes (PS). Classically, estrogens act by binding to estrogen receptors (ERs) alpha and beta. Recently, it has been demonstrated that rapid estrogen action can also be activated through the G-protein-coupled receptor (GPR)-30. Herein, we demonstrated that rat PS express ER alpha, ER beta and GPR30. Treatment of PS with estradiol (E2), the selective GPR30 agonist G1 and the selective ER alpha agonist PPT determined activation of ERK1/2 which are part of GPR30 signaling cascade. ERK1/2 activation in response to E2 and G1 was correlated to an increased phosphorylation of c-Jun. All treatments failed to induce these responses in the presence of EGFR inhibitor AG1478, ERK inhibitor PD98059 and ER inhibitor ICI182780. mRNA expression of cell cycle regulators cyclin A1 and B1 was downregulated by E2 and G1 while an up-regulation of proapoptotic factor Bax was observed in the same conditions. These data demonstrate that E2, working through both ER alpha and/or GPR30, activates in PS the rapid EGFR/ERK/c-Jun pathway, modulating the expression of genes involved in the balance between cellular proliferation and apoptosis.

Aromatase gene expression in immature rat Sertoli cells: age-related changes in the FSH signalling pathway

Aromatase, the enzyme responsible for the transformation of androgens into oestrogens, is encoded by the cyp19 gene expressed in the testis. The aim of the present study was to analyse the evolution of aromatase gene expression under FSH control in rat Sertoli cells between 10 and 30 days post partum, corresponding to the end of the proliferative period of Sertoli cells, establishment of the blood–testis barrier and acquisition of the mature phenotype. The maximum stimulatory effect of FSH on aromatase gene expression was obtained in 20-day-old rat Sertoli cells, compared with cells from 10- and 30-day-old rats, in parallel with the differentiation of Sertoli cells. Using two effectors of the protein kinase A pathway (i.e. forskolin and dibutyryl-cAMP) revealed differential effects between cells from rats aged 20 and 30 days, implying the involvement of another signalling pathway. Experiments using the specific phosphatidylinositol 3-kinase (PI3-K) inhibitor LY294002 revealed that PI3-K is strongly involved in FSH-induced aromatase expression in Sertoli cells from both 20- and 30-day-old rats. In vivo, this decrease could be explained by a negative effect exerted by germ cells because, in coculture, aromatase gene expression in 20-day-old Sertoli cells is greatly diminished.

Inhibitory effect of estrogens, phytoestrogens, and caloric restriction on oxidative stress and hepato-toxicity in aged rats

OBJECTIVE

To investigate the protective effect of 17beta-estradiol (E2), peganum harmala extract (PHE) administration and calorie restriction (CR) treatment (60%) on oxidative stress and hepato-toxicity in aged rats.

METHODS

Eighteen months old animals that were treated at the age of 12 months were divided into 4 groups: normal control group with free access to food, E2 treatment group, PHE treatment group and CR treatment group of the food given to control group. Six male rats at the age of 4 months were used as a reference group.

RESULTS

Aging significantly decreased superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and increased lactate deshydrogenase (LDH), gamma-glytamyl transferase (GGT), phosphatase alkalines (PAL), aspartate and lactate transaminase (AST and ALT) activities in the liver. Aging also induced an increased lipid peroxidation level, histological changes and a decreased E2 level. However, treatment with E2, PHE, and CR increased 17beta-estradiol, and decreased hepatic dysfunction parameters and lipid peroxidation as well as histological changes in the liver of aged rats.

CONCLUSION

The antioxidant and hepatoprotective activity of PHE and CR is possibly attributed to its ability to increase E2 level, which as an antioxidant, acts as a scavenger of ROS. Further studies on the pharmaceutical functions of E2 in males may contribute to its clinical application.

Medicinal plants as potential male anti-infertility agents: a review

For millions of couples, the inability to have a child is a personal tragedy and a large proportion of childless people are confronted with social stigmatization (blame) and personal frustration. Formerly assigned to women, infertility of a couple is nowadays equitably distributed between the two sexes. Among the methods used to treat male infertility problems, medicinal plants have been used empirically as extracts, decoctions, fractions or semi-purified compounds. These herbal products are used in the treatment of a dysfunctioning of the libido, sexual asthenia, erection, and sperm disorders. Pharmacological activities of many of these plants have been shown in vitro using cells, in vivo (on laboratory animals) and human studies. For instance, extracts of Panax ginseng, Panax quinquefolius and Lepidium meyenii have shown positive effects on sexual desire; while extracts of Astragalus membranaceus, Asparagus racemous, Withania somnifera, Andrographis paniculata and Acanthopanax senticosus improved sperm parameters. Plants provide a treatment option that is affordable and available for infertile couples, and phytotherapy is an essential form of treatment in our health system. However, herbal products are still anarchically used in many regions and countries, and a great proportion of medicinal plants used traditionally to solve male reproductive disorders have not yet been scientifically evaluated. Therefore in this review, we have summarized most of the data dealing with the effects of plant extracts on mammalian reproductive functions.

Positive effects of green tea on hepatic dysfunction, lipid peroxidation and antioxidant defence depletion induced by cadmium

Cadmium (Cd) is a highly toxic environmental and industrial cumulative pollutant that affects many organs, especially the liver. The present study was designed to evaluate the antioxidant effect of green tea on cadmium-induced hepatic dysfunction and oxidative stress in rats. Adult male Wistar rats were administered cadmium by injection of 20 micromoles/kg bw/every 3 days for six months. This study revealed significant (p < 0.05) liver dysfunction, lipid peroxidation and a decline in antioxidant enzyme activities in the liver of cadmium-treated rats compared to control animals. Compared to control rats, the activities of lactate dehydrogenase (LDH), gammaglutamyl transferase (GGT), acid phosphatase (PAC), phosphatase alkaline (PAL), as well as bilirubin and thiobarbituric acid-reactive substances (TBARs), were significantly (p < 0.05) increased in Cd-treated rats. Moreover, antioxidant enzyme activities, such as superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase, were significantly (p < 0.05) decreased in the liver of cadmium-treated rats. The oral administration of 5% aqueous green tea extract, along with cadmium treatment for six months, caused a significant (p < 0.05) improvement in cadmium-induced toxicity by significantly decreasing (p < 0.05) the activities of enzymatic markers of liver dysfunction (LDH, GGT, PAC, PAL activities, as well as the bilirubin rate). Indeed, green tea extract significantly increased (p < 0.05) antioxidant enzymatic activities (SOD, Catalase, GPX) in rat liver, compared to those given cadmium alone. Thus, the oral administration of green tea, along with cadmium significantly (p < 0.05) improves cadmium-induced liver dysfunction and stress oxidant in rats' liver.

Protective effects of estrogens and caloric restriction during aging on various rat testis parameters

AIM

To investigate the effects of 17beta-estradiol (E2), Peganum harmala extract (PHE) and caloric restriction (CR) on various testis parameters during aging.

METHODS

Twelve month-old male rats were treated for 6 months with either E2 or PHE, or submitted to CR (40%).

RESULTS

Our results show that estrogens and CR are able to protect the male gonad by preventing the decrease of testosterone and E2 levels as well as the decrease of aromatase and estrogen receptor gene expressions. Indeed, E2, PHE and CR treatments induced an increase in the superoxide dismutase activities and decreased the activity of testicular enzymes: gamma-glutamyl transferase, alkaline phosphatase, lactate deshydrogenase as well as the aspartate and lactate transaminases in aged animals. In addition, the testicular catalase and gluthatione peroxidase activities were enhanced in E2, PHE and CR-treated rats compared to untreated animals at 18 months of age. Moreover, the positive effects of estradiol, PHE and CR were further supported by a lower level of lipid peroxidation. Recovery of spermatogenesis was recorded in treated rats.

CONCLUSION

Besides a low caloric diet which is beneficial for spermatogenesis, a protective antioxydant role of estrogens is suggested. Estrogens delay testicular cell damage, which leads to functional senescence and, therefore, estrogens are helpful in protecting the reproductive functions from the adverse effects exerted by reactive oxygen species (ROS) produced in large quantities in the aged testis.

Aromatase expression in the normal human adult adrenal and in adrenocortical tumors: biochemical, immunohistochemical, and molecular studies

OBJECTIVE

The aromatase enzyme catalyzes the final stage of estrogen biosynthesis pathway from androgens. Its expression in the adrenal is poorly studied except for the rare estrogen-producing adrenocortical tumors. In order to further characterize aromatase expression in the adrenal, we evaluated the aromatase enzyme activity, Cyp19a1 gene expression level, and promoter utilization in normal adrenal tissues and in adrenocortical secreting tumors.

DESIGN AND METHODS

Six normal adult adrenals (NA), 2 feminizing adrenal tumors (FT), 10 cortisol-producing adenomas with overt (CS, n=4) or sub-clinical Cushing syndrome (SCS, n=6) and 3 aldosterone-producing adenomas (APA) were studied. Tissue aromatase activity was determined by the tritiated ((3)H)-water method. Total aromatase mRNA were measured by a competitive RT-PCR. Promoter regions PII and PI.4-derived transcripts were also studied in NA, FT, and other steroid-producing tumors by a semi-quantitative comparative RT-PCR. Immunofluorescence analysis was performed in normal human adrenal tissues.

RESULTS

Aromatase activity was detected in NA tissues and in all tumor subtypes, at high levels in both FT. In NA, aromatase immunofluorescence was detected in the cytoplasm of steroidogenic cells, mainly from zona reticularis. Compared with NA, aromatase transcript levels were similar in CS and APA, lower in SCS and similar or higher in FT. Promoter analysis suggested predominant PII utilization in NA, APA, and SCS, but similar PII and PI.4 utilization in CS tumors.

CONCLUSION

Aromatase is expressed at similar levels in normal adrenal and in adrenocortical tumors, but at variably high levels in FT. Different promoter utilization patterns are found among tumor subtypes.

Hyperglycaemia, stress oxidant, liver dysfunction and histological changes in diabetic male rat pancreas and liver: protective effect of 17 beta-estradiol

Oxidative stress is thought to play a crucial role in the pathogenesis of chronic diabetic complications. We investigated the protective effects of 17 beta-estradiol (E2) on alloxan-induced stress oxidant, hepatic dysfunction and histological changes in male rats liver and pancreas. Our results showed that 17 beta-estradiol could attenuate the increase of blood glucose in plasma and normalise the hepatic glycogen level. In addition, E2 enhanced superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) (by 207, 52 and 72%, respectively, as compared to diabetic rats), reduced lipid peroxidation in the hepatic tissue (by 54%) and improved the liver dysfunction parameters by the significant decrease of gamma-glytamyl transferase (GGT), phosphatases alkalines (PAL), lactate deshydrogenase (LDH) and aspartate and lactate transaminases (AST and ALT) activities which increased in diabetic rats. Moreover, 17 beta-estradiol treatment in diabetic rats protects against alloxan-induced pancreatic beta-cells and hepatic cells damages.

Protective effect of 17beta-estradiol on oxidative stress and liver dysfunction in aged male rats

In aging liver oxidative stress increases due to the decrease in antioxidant bio-molecules such as estrogens which can be modified by hormonal replacement therapy (HRT). With this in mind, we hypothesized that age-related decline in steroidogenesis may be associated with the impairment of the antioxidant defense cells in liver, the increase in lipid peroxidation, hepatic dysfunction and histological changes; estrogens prevent all these changes induced by aging. 17beta-estradiol treatment was initiated in 12 month-old Wistar rats, and continued until 18 months of age. Our results showed that 17beta-estradiol (E2) level in the serum of the aged untreated rats was reduced by -32% in 18 month-old rats compared to the young animals (4-month-old). The superoxide dismutase (SOD), catalase (CAT), and gluthatione peroxidase (GPX) activities were reduced by -47, -46, and -29% respectively in old rat liver. In addition, the TBARs in liver and hepatic dysfunction parameters in plasma such as gamma-glutamyl transferase (GGT), phosphatase alkalin (PAL) as well as bilirubin level increased significantly in old rats, and histological changes were investigated. In E2-treated rats, protective effects were observed. Indeed, 17beta-estradiol attenuates all changes induced by aging. The 17beta-estradiol level was higher in old E2-treated rats compared to the control rats. Moreover, the SOD, CAT and GPX activities were higher by +28, +15, and +11% respectively. This anti-aging effect of estrogens was clarified by a lower level of lipid peroxidation and liver dysfunction parameters as well as by histological observation.

Estrogens and male reproduction: a new concept

The mammalian testis serves two main functions: production of spermatozoa and synthesis of steroids; among them estrogens are the end products obtained from the irreversible transformation of androgens by a microsomal enzymatic complex named aromatase. The aromatase is encoded by a single gene (cyp19) in humans which contains 18 exons, 9 of them being translated. In rats, the aromatase activity is mainly located in Sertoli cells of immature rats and then in Leydig cells of adult rats. We have demonstrated that germ cells represent an important source of estrogens: the amount of P450arom transcript is 3-fold higher in pachytene spermatocytes compared to gonocytes or round spermatids; conversely, aromatase activity is more intense in haploid cells. Male germ cells of mice, bank voles, bears, and monkeys express aromatase. In humans, we have shown the presence of a biologically active aromatase and of estrogen receptors (alpha and ss) in ejaculated spermatozoa and in immature germ cells in addition to Leydig cells. Moreover, we have demonstrated that the amount of P450arom transcripts is 30% lower in immotile than in motile spermatozoa. Alterations of spermatogenesis in terms of number and motility of spermatozoa have been described in men genetically deficient in aromatase. These last observations, together with our data showing a significant decrease of aromatase in immotile spermatozoa, suggest that aromatase could be involved in the acquisition of sperm motility. Thus, taking into account the widespread localization of aromatase and estrogen receptors in testicular cells, it is obvious that, besides gonadotrophins and androgens, estrogens produced locally should be considered to be physiologically relevant hormones involved in the regulation of spermatogenesis and spermiogenesis.

Protective effects of Peganum harmala extracts on thiourea-induced diseases in adult male rat

Cancers and hepatoprotective prevention using traditional medicines have attracted increasing interest. The aim of our study was to characterize the putative protective effects of ethanol and chloroform extracts of Peganum harmala on thiourea-induced diseases in adult male rat. We seek to determine the effects of these plant extracts on body weight, thyroid and endocrine cancer parameters. In addition the putative hepatoprotective effect was checked by the determination of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities and the bilirubin level in the blood. Our data show that ethanol and chloroform extracts of Peganum harmala protected the animal against the carcinogenic effects induced by thiourea since neuron-specific enolase (NSE) and thyroglobulin (TG) levels were back to the normal range. In addition, the observed-hepatocytotoxicity after thiourea treatment was greatly reduced (AST and ALT activities were respectively 270 IU/l and 60 IU/l and in the same order of magnitude as in the untreated rats) as well as the bilirubin levels (6 micromol/l) especially for animals receiving the choroform preparation. Therefore we may suggest that extracts of Peganum harmala are efficient to reduce the toxicity induced by thiourea in male rat as far as the above parameters are concerned.

Relationship between chromatin organization, mRNAs profile and human male gamete quality

Spermiogenesis is a complex process leading to the formation of motile spermatozoa characterized by a highly stable chromatin compaction that transfers the paternal genome into the oocyte. It is commonly held that these haploid cells are devoid of transcriptional and translational activities and that the transcripts represent remnants of stored mRNAs. Recently, the chromatin organization of mature spermatozoa has been revisited as a double nucleoprotamine-nucleohistone structure possessing less-condensed regions sensitive to nuclease activity, which could be implicated in the expression of genes involved in the early embryo development. The existence of a complex population of mRNAs in human sperm is well-documented, but their role is not yet elucidated. Evidence for a latent transcriptional capacity and/or a potential de novo translation in mature spermatozoa from fertile men are essential for understanding the last steps of sperm maturation, such as capacitation and acrosome reaction. As such, we have documented the relationship between sperm quality and the distribution of sperm RNAs by showing divergent levels of transcripts encoding for proteins involved in either nuclear condensation (protamines 1 and 2) or in capacitation (eNOS and nNOS, c-myc) or in motility and sperm survival (aromatase) between low and high motile sperm issued from the same sample. Therefore, analyzing the profile of mRNAs could be helpful either as a diagnostic tool for evaluating male fertility after spermatogenesis or for prognosis use for fertilization.

RNA dynamics of fertile and infertile spermatozoa

The presence of a complex population of mRNAs in human mature spermatozoa is well documented; among them, transcripts of aromatase and ERs (oestrogen receptors) have been described but their significance is not clear. Therefore, to clarify the role of this complex population of mRNAs in human ejaculated sperm, we have isolated on discontinuous density gradients two main fractions from the same sample: high- and low-motile spermatozoa. The levels of different transcripts coding for molecules involved in nuclear condensation [Prm-1 (protamine 1) and Prm-2], capacitation [eNOS (endothelial nitric oxide synthase), nNOS (neuronal nitric oxide synthase), c-myc], motility and sperm survival (aromatase) have been assessed using semi-quantitative RT (reverse transcriptase)-PCR. The viability of sperm as well as the percentage of apoptosis were identical in high- and low-motile fractions. No significant change in the c-myc/Prm-2 ratio between the two populations of spermatozoa was observed. Conversely the amount of Prm-1 mRNA was significantly higher in low-motile than in high-motile fraction; in most of the high-motile sperm samples analysed, eNOS and nNOS transcripts were undetectable, whereas they were observed in low-motile sperm. Moreover, a partial or complete disappearance of c-myc transcripts was observed after capacitation. As to the aromatase expression, a significant decrease in the amount of transcripts in immotile sperm fraction was recorded in all samples studied. To conclude, analysing mRNA profiles in humans could be helpful either as a diagnostic tool to evaluate male fertility, since they reflect spermatogenesis gene expression, and/or a prognosis value for fertilization, since these RNAs are delivered to oocytes.

Three promoters PII, PI.f, and PI.tr direct the expression of aromatase (cyp19) gene in male rat germ cells

Aromatase is the key enzyme responsible for the irreversible transformation of androgens into estrogens. It is encoded by the cyp19 gene and is expressed in the mammalian testis under the control of the proximal promoter PII. Since both somatic and germ cells contain a biologically active aromatase, we looked for the existence of other promoters that may direct the expression of aromatase in adult rat germ cells. Besides the promoter II, we have shown the presence of transcripts derived from the brain promoter PI.f in spermatogonia-preleptotene spermatocytes (G-PL), pachytene spermatocytes (PS), and round spermatids (RS). A new aromatase cDNA has been isolated by 5'-rapid amplification of cDNA ends that we named I.tr (testis rat). The I.tr transcripts are found in all the testicular cell populations studied with a greater expression in PS. Because of the utilization of these three promoters in the adult rat testis, we studied their putative involvement according to the age. At 10 days, aromatase expression was very low and then strongly increased between 10 and 20 days, with a preferential activation of PII and PI.tr. Transcripts coming from PI.f were found starting from 20 days onwards. The new promoter PI.tr, localized between promoters PI.f and PII, is devoid of a TATA box but contains a transcriptional initiator (Inr) and putative regulatory sequences. Therefore, the identification of the specific trans-activating factors should bring some enlightenments to understand the regulation of these three promoters in germ cells especially according to their stage of development.

Gonadal expression of aromatase and estrogen receptor alpha genes in two races of Tunisian mice and their hypofertile hybrids

House mice (Mus musculus domesticus) in Tunisia consists of two races, one carries the 40-acrocentric standard karyotypes and the other one is a robertsonian race (2n=22) homozygous for nine centric fusions (Rb). The F1 hybrids between the two chromosomal races showed a significant decrease in reproductive success and litter size. Such results can be related to the formation of meiotic trivalent in the hybrids leading to the production of viable aneuploid gametes and post-zygotic elimination of embryos due to chromosomal non disjunction events at meiosis. Moreover, testicular histology of F1 and backcross males showed in some cases a breakdown in spermatogenesis. In both females and males, androgens but also estrogens play an important role in gametogenesis. In this study, we have studied aromatase and estrogen receptor alpha (ERalpha) gene expression in the gonads of the two parental races and their chromosomal hybrids. The results showed that aromatase and ERalpha mRNAs are expressed in hybrid males of inter-racial crosses (female22Rb x male40Std and female40Std x male22Rb) and in hybrid females of inter-racial crosses (female22Rb x male40Std) as in the two parental races. However, in hybrid females of inter-racial crosses (female40Std x male22Rb) the amount of aromatase transcripts decreased sharply suggesting that this gene is involved in the breakdown of hybrid fertility in females, but not in males. However, in hybrid males, a putative post-translational modification of this enzyme, in terms of activity, should be verified.