Estrogen receptor, calcium mobilization and rat sperm motility

Co-culture of sperm with sertoli cells can improve IVF outcomes by increasing sperm motility in mice

The micro-environment of spermatogenesis is important for the improvement of in vitro fertilization (IVF). Therefore, developing a co-culture system may be valuable to improve the rate of IVF. In this study, we aimed to investigate the secretions of testicular sertoli cells (SCs) to find whether it can improve the micro-environment of IVF, by which promote the efficiency of fertilization in mice. The results showed that the motility of sperms in CCSCF group (sperms co-culture with SCs) was significantly promoted and the rate of fertilization were significantly increased compared with the CTR group (control group: sperms not co-culture with SCs). Moreover, we found that the estrogen concentrations, the expression of estrogen receptor (ER) and the phosphorylation of AMPK in sperms were higher in the CCSCF group than in CTR group. In all, our results indicated that SCs co-cultured with sperms can improve the motility of sperms, E2 secreted by SCs can increase Ca²⁺ level in the intracellular and the level of phosphorylation of AMPK through Ca-MKKβ in sperms.

Missing Information from the Estrogen Receptor Puzzle: Where Are They Localized in Bull Reproductive Tissues and Spermatozoa?

Estrogens are steroid hormones that affect a wide range of physiological functions. The effect of estrogens on male reproductive tissues and sperm cells through specific receptors is essential for sperm development, maturation, and function. Although estrogen receptors (ERs) have been studied in several mammalian species, including humans, they have not yet been described in bull spermatozoa and reproductive tissues. In this study, we analyzed the presence of all types of ERs (ESR1, ESR2, and GPER1) in bull testicular and epididymal tissues and epididymal and ejaculated spermatozoa, and we characterize them here for the first time. We observed different localizations of each type of ER in the sperm head by immunofluorescent microscopy. Additionally, using a selected polyclonal antibody, we found that each type of ER in bull sperm extracts had two isoforms with different molecular masses. The detailed detection of ERs is a prerequisite not only for understanding the effect of estrogen on all reproductive events but also for further studying the negative effect of environmental estrogens (endocrine disruptors) on processes that lead to fertilization.

Estrogens in Male Physiology

Estrogens have historically been associated with female reproduction, but work over the last two decades established that estrogens and their main nuclear receptors (ESR1 and ESR2) and G protein-coupled estrogen receptor (GPER) also regulate male reproductive and nonreproductive organs. 17β-Estradiol (E2) is measureable in blood of men and males of other species, but in rete testis fluids, E2 reaches concentrations normally found only in females and in some species nanomolar concentrations of estrone sulfate are found in semen. Aromatase, which converts androgens to estrogens, is expressed in Leydig cells, seminiferous epithelium, and other male organs. Early studies showed E2 binding in numerous male tissues, and ESR1 and ESR2 each show unique distributions and actions in males. Exogenous estrogen treatment produced male reproductive pathologies in laboratory animals and men, especially during development, and studies with transgenic mice with compromised estrogen signaling demonstrated an E2 role in normal male physiology. Efferent ductules and epididymal functions are dependent on estrogen signaling through ESR1, whose loss impaired ion transport and water reabsorption, resulting in abnormal sperm. Loss of ESR1 or aromatase also produces effects on nonreproductive targets such as brain, adipose, skeletal muscle, bone, cardiovascular, and immune tissues. Expression of GPER is extensive in male tracts, suggesting a possible role for E2 signaling through this receptor in male reproduction. Recent evidence also indicates that membrane ESR1 has critical roles in male reproduction. Thus estrogens are important physiological regulators in males, and future studies may reveal additional roles for estrogen signaling in various target tissues.

The in vitro effect of nonylphenol, propranolol, and diethylstilbestrol on quality parameters and oxidative stress in sterlet (Acipenser ruthenus) spermatozoa

The sturgeon is a highly endangered fish mostly due to over-fishing, habitat destruction, and water pollution. Nonylphenol (NP), propranolol (PN), and diethylstilbestrol (DES) are multifunctional xenobiotic compounds used in a variety of commercial and industrial products. The mechanism by which these xenobiotic compounds interfere with fish reproduction is not fully elucidated. This study assessed the effect of NP, PN, and DES on motility parameters, membrane integrity, and oxidative/antioxidant status in sterlet Acispenser ruthenus spermatozoa. Spermatozoa were incubated with several concentrations of target substances for 1h. Motility rate and velocity of spermatozoa decreased in the presence of xenobiotics in a dose-dependent manner compared with controls. A significant decrease in membrane integrity was recorded with exposure to 5μM of NP, 25μM of PN, and 50μM of DES. After 1h exposure at higher tested concentrations NP (5-25μM), PN (25-100μM), and DES (50-200μM), oxidative stress was apparent, as reflected by significantly higher levels of protein and lipid oxidation and significantly greater superoxide dismutase activity. The results demonstrated that NP, PN, and DES can induce reactive oxygen species stress in fish spermatozoa, which could impair sperm quality and the antioxidant defence system and decrease the percentage of intact sperm cells.

Capacitation and acrosome reaction differences of bovine, mouse and porcine spermatozoa in responsiveness to estrogenic compounds

Background

Endocrine disruptors are exogenous substance, interfere with the endocrine system, and disrupt hormonal functions. However, the effect of endocrine disruptors in different species has not yet been elucidated. Therefore, we investigated the possible effects of 17ß-estradiol (E2), progesterone (P4), genistein (GEN) and 4-tert-octylphenol (OP), on capacitation and the acrosome reaction in bovine, mouse, and porcine spermatozoa. In this in vitro trial, spermatozoa were incubated with 0.001-100 μM of each chemical either 15 or 30 min and then assessed capacitation status using chlortetracycline staining.

Results

E2 significantly increased capacitation and the acrosome reaction after 30 min, while the acrosome reaction after 15 min incubation in mouse spermatozoa. Simultaneously, capacitation and the acrosome reaction were induced after 15 and 30 min incubation in porcine spermatozoa, respectively. Capacitation was increased in porcine spermatozoa after 15 min incubation at the lowest concentration, while the acrosome reaction was increased in mouse spermatozoa after 30 min (P <0.05). E2 significantly increased the acrosome reaction in porcine spermatozoa, but only at the highest concentration examined (P <0.05). P4 significantly increased the acrosome reaction in bovine and mouse spermatozoa treated for 15 min (P <0.05). The same treatment significantly increased capacitation in porcine spermatozoa (P <0.05). P4 significantly increased capacitation in mouse spermatozoa treated for 30 min (P <0.05). GEN significantly increased the acrosome reaction in porcine spermatozoa treated for 15 and 30 min and in mouse spermatozoa treated for 30 min (P <0.05). OP significantly increased the acrosome reaction in mouse spermatozoa after 15 min (P <0.05). Besides, when spermatozoa were incubated for 30 min, capacitation and the acrosome reaction were higher than 15 min incubation in E2 or GEN. Furthermore, the responsiveness of bovine, mouse and porcine spermatozoa to each chemical differed.

Conclusions

In conclusion, all chemicals studied effectively increased capacitation and the acrosome reaction in bovine, mouse, and porcine spermatozoa. Also we found that both E2 and P4 were more potent than environmental estrogens in altering sperm function. Porcine and mouse spermatozoa were more responsive than bovine spermatozoa.

Do photoperiod and endocrine disruptor 4-tert-octylphenol effect on spermatozoa of bank vole (Clethrionomys glareolus)?

Photoperiod is an environmental signal that controls physiology and behavior of all organisms. Bank voles, which are seasonal breeders, are stimulated to reproduce by the long photoperiod associated with spring and summer. To date, physiology of bank vole spermatozoa has not been explored, although they constitute an interesting model for examining the relationship between photoperiod and xenoestrogen on spermatozoa function. In an attempt to evaluate the acute effect of 4-tert-octylphenol (OP) an in vitro system was used. Spermatozoa isolated from the cauda epididymidies of long-day (LD; 18 h light: 6 h darkness) and short-day (SD; 6 h light: 18 h darkness) bank voles were treated with two OP concentrations (10(-4) M and 10(-8)M, respectively). OP-treated spermatozoa were used for the examination of motility parameters (computer-assisted semen analyzer CEROS), acrosome integrity (Commassie blue staining), cAMP production (immunoenzymatic assay) and cell viability (flow-cytometry analysis). The study revealed the photoperiod-dependent effect of short OP-treatment on motility parameters of vole spermatozoa. In LD spermatozoa, an increase of velocities: (curvilinear velocity [VCL], average path velocity [VAP] straight line velocity [VSL]) and head activity (amplitude of the lateral head displacement, [ALH]) was found. Interestingly, in SD spermatozoa opposite effect on VCL, VAP, VSL and ALH was observed, however only after treatment with 10(-4)M OP. The dose-dependent influence of OP upon acrosome integrity, as well as cAMP levels, in relation to the reproductive status of voles was observed. Moreover, OP exposure affected spermatozoa morphology rather than spermatozoa viability.

Xenoestrogenic chemicals effectively alter sperm functional behavior in mice

Xenoestrogenic compounds (XCs) can disrupt endogenous hormone function and affect sperm function by binding to receptors on sperm membrane. Albeit spermatozoa are potentially a useful model for screening estrogenic activities of endocrine disruptors, high-quality in vitro test system that examination of the XCs effects on sperm function is required. The objective of this study was to compare the effects of XCs (genistein and 4-tert-octylphenol) to those of steroids (estrogen and progesterone) and heparin on in vitro capacitation and acrosome reaction (AR) in mouse spermatozoa. Mouse spermatozoa were incubated with various concentrations (0.001-100 μM) of each chemical for 15 or 30 min, and then capacitation and AR were assessed using chlortetracycline. All chemicals studied effectively alter capacitation and/or AR in mouse spermatozoa with different manner. Therefore, we believed that our system will provide a good in vitro model system to characterize the physiological effect of XCs especially when compared with steroids.

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.

Involvement of signaling pathways in bovine sperm motility, and effect of ergot alkaloids

There is evidence that ergot alkaloids can directly interact with mammalian spermatozoa affecting sperm functions. Ergot alkaloids exert their toxic or pharmaceutical effects through membrane receptor-mediated activities. This study investigated the signaling pathways involved in the in vitro inhibitory effects of both ergotamine (ET) and dihydroergotamine (DEHT) on the relative motility of bovine spermatozoa using specific inhibitors. Motile bovine spermatozoa were prepared using a Percoll gradient and incubated with ergot alkaloids with and without signaling pathway inhibitors. Co-incubation of ET or DHET with 100 microM prazosin (alpha 1-adrenergic receptor inhibitor) decreased (p < 0.05) relative motility of spermatozoa when compared with controls. In addition, preincubation of spermatozoa with 10 or 20 microM prazosin and DHET also reduced (p < 0.05) the number of motile spermatozoa. Relative sperm motility (motility of treated spermatozoa normalized to control sperm motility) was increased (p < 0.05) when co-incubations included ET and yohimbine (alpha 2-adrenergic receptor inhibitor); conversely, co-incubation of yohimbine (100 microM) and DHET decreased (p < 0.05) the percentage of motile spermatozoa when compared with controls. Pertussis toxin and cholera toxin (effectors of inhibitory and stimulatory G-proteins, respectively) altered (p < 0.05) relative sperm motility in a concentration dependent manner; however, co-incubation of pertussis or cholera toxin with ergot alkaloids had no interactive (p = 0.83) effects on the relative motility of spermatozoa. Co-incubation of Rp-cAMP (a membrane-permeable cAMP inhibitor) with 50 microM DHET had no effect (p > 0.05) on relative sperm motility; whereas, the co-incubation of 22.4 or 44.8 microM Rp-cAMP with 50 microM ET increased (p < 0.05) the percentage of motile spermatozoa when compared with 0 or 224 microM Rp-cAMP (49%, 65%, 59%, and 54%, respectively, for 0, 22.4, 44.8, and 224 microM of Rp-cAMP. An interaction between BAPTA-AM (a chelator of intracellular calcium) and alkaloids also impacted (p < 0.05) relative sperm motility. Generally, co-incubating spermatozoa with BAPTA-AM and ET increased the percentage of motile spermatozoa; however, co-incubation with DHET decreased relative sperm motility except with 41 microM BAPTA-AM. Collectively, these observations suggest that ET and DHET decreased the percentage of motile bovine spermatozoa via alpha adrenergic receptors. However, the second messenger systems involved with ergot alkaloid inhibition of relative motility of bovine spermatozoa remain to be elucidated.

Assessment of short-term exposure to nonylphenol in Japanese medaka using sperm velocity and frequency of motile sperm

Nonylphenol is one of the compounds believed to cause endocrine disruption and affect sperm quality in mammals. However, there is little information on its effects on sperm motility in fish or other forms of wildlife. We examined the effects of nonylphenol on the motility of spermatozoa of medaka (Oryzias latipes) using an in vitro bioassay. Sperm was activated in aqueous media containing no nonylphenol (solvent control, 0.1% ethanol) or 1 or 100 micromol/L nonylphenol and immediately loaded into a sperm motility observation chamber. The ratio of motile spermatozoa and their swimming speeds were analyzed by computer-assisted image analysis at 30 and 60 s after activation. A decrease in swimming speed or the ratio of motile spermatozoa was observed in spermatozoa exposed for 60 s to 100 micromol/L nonylphenol. Our results suggest that nonylphenol causes a reduction in sperm viability in teleost fish in the short period between ejaculation and fertilization.

Cytochrome P450arom, androgen and estrogen receptors in pig sperm

BACKGROUND

Androgens and estrogens are crucial for mammalian sperm differentiation but their role in biology of mature male gamete is not still defined. The expression of proteins involved in the biosynthesis and action of these steroid hormones has been demonstrated in human spermatozoa, but very few data have been reported in mature sperm from non human species. The purpose of the current study was to investigate the expression of aromatase (P450arom), estrogen (ERalpha/ERbeta) and androgen (AR) receptors in ejaculated spermatozoa of pig.

METHODS

The immunfluorescence experiments were carried out treating pig sperm with anti-P450arom, anti-ERalpha, anti-ERbeta and anti-AR as primary antibodies, while Texas-Red/FITC conjugated IgG were applied as secondary antibodies. Furthermore, Western blot analysis was performed on sperm lysates.

RESULTS

Aromatase was immunolocalized in the sperm tail, ERalpha and AR were localised in the sperm midpiece, while ERbeta was confined in the acrosomal region of the male gamete. Immunoblots detected a ~52 kDa aromatase band, a ~110 kDa AR band, a ~67 kDa ERalpha and two ERbeta bands, at ~50 kDa and ~59 kDa.

CONCLUSION

This is the first report demonstrating that pig ejaculated spermatozoa express aromatase, estrogen and androgen receptors with a differential intra-cellular localization revealing a species-specific expression pattern. Therefore, pig sperm could be considered as a potential estrogen source while the different hormone cellular sites suggest distinct roles of androgens and estrogens in pig sperm physiology.

Suppression of endogenous estrogen during development affects porcine epididymal sperm maturation

Estrogen plays an important role in male reproduction, critical for sustained fertility in some species. Reducing estrogen's interaction with its receptor(s) in monkey and mouse models is associated with reduced sperm motility and, in some cases, documented elimination of sperm fertilizing ability, suggesting that normal epididymal function may be estrogen dependent. The objective of these experiments was to evaluate the effects of reduced endogenous estrogen on development of epididymal function in the pig, a species in which males have very high levels of endogenous estrogen. Letrozole, a potent inhibitor of estrogen synthesis, was administered to neonatal boars from 1 week of age and markedly suppressed estrogen production. Epididymal function assessed as acquisition of sperm fertilizing ability (in vitro fertilization of zona-free oocytes) was reduced in Letrozole-treated animals at 24 and 28 weeks of age (23% and 30% fertilization, respectively compared with 37% and 54% in vehicle controls) but had recovered by 32 weeks of age. Cauda epididymal sperm numbers were reduced in treated animals (35% of control values at 20 weeks of age) but appeared to be recovering at 32 weeks of age. Reduction of endogenous estrogen had no effect on other aspects of epididymal function (percentage of motile sperm, sperm motion parameters, sperm head morphometrics, or ability of sperm to undergo an acrosome reaction). Reducing endogenous estrogen during postnatal development appears to have transient effects on porcine epididymal function. These transient effects suggest that the pig, with its high endogenous estrogen, may respond differently than other species to reduced estrogen synthesis.

Effects of tamoxifen citrate on gene expression during nuclear chromatin condensation in male rats

AIM

To evaluate the effects of tamoxifen citrate on gene expression during nuclear chromatin condensation in male rats.

METHODS

The effects of an oral dose of 0.4 kg/(kg.d) tamoxifen citrate on rates of in vitro chromatin decondensation, acridine orange (AO) dye uptake, concentration of thiol-groups, levels and/or expression of transition proteins 1, 2 (TP1, TP2), protamine 1 (P1), cyclic AMP response element modulator-tau (CREMtau), androgen-binding protein (ABP) and cyclic adenosine 3',5' monophosphate (cAMP) were evaluated after 60 days of exposure in adult male rats. Controls received the vehicle.

RESULTS

Tamoxifen citrate enhanced the rates of chromatin decondensation, increased AO dye uptake and reduced free thiols in caput epididymal sperms and reduced the levels of TP1, TP2, P1, and CREMtau in the testis, while cAMP was unaffected. P1 deposition was absent in the sperm. The transcripts of TP1, TP2 were increased, of P1 and ABP decreased, while those of CREMtau unaffected in the testis.

CONCLUSION

Tamoxifen citrate reduced caput epididymal sperm chromatin compaction by reducing the testicular levels of proteins TP1, TP2 and P1 and the CREMtau involved in chromatin condensation during spermiogenesis. Tamoxifen citrate affects the expression of these genes at both the transcriptional and post-transcriptional levels.

Reproductive toxicity assessment of lasofoxifene, a selective estrogen receptor modulator (SERM), in male rats

BACKGROUND

Lasofoxifene is a nonsteroidal selective estrogen receptor modulator (SERM) with greater than 100-fold selectivity against all other steroid receptors and is a potentially superior treatment for postmenopausal osteoporosis. The purpose of this study was to evaluate the effects of lasofoxifene on male reproduction in rats in light of the known effects of estrogen modulating compounds on male reproductive ability.

METHODS

Lasofoxifene was administered to adult male rats at doses of 0.1, 1, 10, and 100 mg/kg for 66-70 consecutive days. After 28 days of dosing, male rats were cohabited with untreated female rats. Female rats were euthanized on gestation day 14 and a uterine examination was carried out for evaluation of reproductive parameters and embryo viability. Male rats were euthanized after 66-70 days of dosing and epididymal sperm motility and concentration were assayed. The testes, epididymides, prostate, and seminal vesicles were weighed and microscopically examined.

RESULTS

The duration of cohabitation was increased for 100 mg/kg males by 0.7 days. The number of males copulating and the number of implantation sites produced per copulation were reduced in the 10 and 100 mg/kg groups. Weights of the seminal vesicles and epididymides were reduced for all groups, although the testes weight and epididymal sperm motility and concentration were not affected by treatment. There were no microscopic findings in the male reproductive tissues.

CONCLUSION

The changes in male fertility and reproductive tissue weights after exposure to lasofoxifene are consistent with those previously described for estrogen receptor-modulating compounds.

17beta-Estradiol and environmental estrogens significantly affect mammalian sperm function

BACKGROUND

Compounds with estrogenic activity can affect reproductive function in mammals. This study investigated possible effects of 17beta-estradiol (E(2)) and three weakly estrogenic environmental estrogens on mammalian sperm capacitation and fertilizing ability in vitro.

METHODS

Uncapacitated and capacitated mouse sperm suspensions were incubated for 30 min in the presence of E(2), genistein (Gen), 8-prenylnaringenin (8-PN) and nonylphenol (NP), and then assessed using chlortetracycline (CTC) fluorescence analysis. In addition, treated uncapacitated sperm suspensions were tested for changes in fertilizing ability.

RESULTS

In uncapacitated cells, E(2) at >or=1 micromol/l and Gen, 8-PN and NP at >or=0.001 micromol/l, significantly stimulated capacitation and acrosome reactions. Hydroxytamoxifen (an estrogen antagonist) did not inhibit responses to any of these compounds. In capacitated cells, E(2) had no effect, but the other three compounds significantly stimulated acrosome reactions. Added to uncapacitated suspensions, 10 micromol/l E(2), 0.1 micromol/l Gen and 0.1 micromol/l 8-PN all significantly stimulated sperm fertilizing ability ( approximately 76% oocytes fertilized) compared with untreated control sperm ( approximately 36%).

CONCLUSIONS

This study provides the first evidence that E(2) and environmental estrogens can significantly stimulate mammalian sperm capacitation, acrosome reactions and fertilizing ability, with the environmental estrogens being much more potent than E(2). The inability of hydroxytamoxifen to block these responses suggests that classical estrogen receptors may not be involved. Whether these responses have effects on fertility in vivo remains to be determined, along with the mechanisms of action involved.