In vitro tests for essential sperm functions using the phyto-oestrogen genistein as a test substance

Expression of estrogen receptors, PELP1, and SRC in human spermatozoa and their associations with semen quality

Sperm cells are target cells for both estrogens and xenoestrogens. Due to the specific structure of spermatozoa, these hormonal compounds may act on sperm in a non-genomic mechanism only. However, the ESR-mediated signaling pathways are still poorly understood. In this study, we obtained 119 samples from male participants of Caucasian descent who donated semen for standard analysis. We analyzed gene expression of estrogen receptors (ESR1 and ESR2) and their coregulators-proline-, glutamic acid-, and leucine-rich protein 1 (PELP1), and cellular kinase c-Src (SRC). RNA level was established using reverse-transcribed RNA as a template, followed by a polymerase chain reaction. Proteins' presence was confirmed by western blot and immunocytochemistry techniques. "Normal" values of semen parameters were defined as follows: > 32% sperm with progressive motility, > 4% sperm cells with normal morphology, > 15 × 10⁶ sperm per mL, > 58% live spermatozoa and leukocyte amount < 10⁶ cells per mL, according to WHO 2010 reference. Semen parameters that deviated from these "normal" values were labeled as "abnormal". Gene expression ratios revealed significant, moderate, and negative correlations for ESR1/ESR2 and weak, negative ESR2/PELP1 correlations in the subgroup of patients with abnormal values of semen parameters. In addition, SRC/PELP1 was moderately and positively correlated in the subgroup with parameters within the reference values established by WHO 2010. Our study showed that both PELP1 scaffolding protein and SRC kinase might influence semen quality via ESRs. It seems that not the expression of a single gene may affect the sperm quality, but more gene-to-gene mutual ratio. Characterization of estrogen-signaling pathway-related genes' modulated expression in sperm cells could aid in better understanding sperm biology and quality.

Phytoestrogens: A Review of Their Impacts on Reproductive Physiology and Other Effects upon Grazing Livestock

Legume crops and pastures have a high economic value in Australia. However, legume species commonly used for grazing enterprises have been identified to produce high concentrations of phytoestrogens. These compounds are heterocyclic phenolic, and are similar in structure to the mammalian estrogen, 17β-estradiol. The biological activity of the various phytoestrogen types; isoflavones, lignans and coumestans, are species-specific, although at concentrations of 25 mg/kg of dry matter each of the phytoestrogen types affect reproductive functions in grazing livestock. The impacts upon fertility in grazing livestock such as cattle and sheep, vary greatly over length of exposure time, age and health of animal and the stress stimuli the plant is exposed to. More recently, research into the other effects that phytoestrogens may have upon metabolism, immune capacity and growth and performance of grazing livestock has been conducted. Potential new benefits for using these phytoestrogens, such as daidzein and genistein, have been identified by observing the stimulation of production in lymphocytes and other antibody cells. Numerous isoflavones have also been recognized to promote protein synthesis, increase the lean meat ratio, and increase weight gain in cattle and sheep. In Australia, the high economic value of legumes as pasture crops in sheep and cattle production enterprises requires proactive management strategies to mitigate risk associated with potential loss of fertility associated with inclusion of pasture legumes as forages for grazing livestock.

Inventorization and Consensus Analysis of Ethnoveterinary Medicinal Knowledge Among the Local People in Eastern India: Perception, Cultural Significance, and Resilience

Livestock is the main backbone of the rural economy of an agriculture-based country like India. To mitigate the economic loss due to livestock’s poor performance and illness, folk phytotherapy for livestock healthcare is still actively practiced in India. Literature survey revealed that the laterite region of eastern India, characterized by its cultural, ethnic, and biological diversities, as well as topographical uniqueness, lacks comprehensive information on ethnoveterinary medicinal knowledge. The objective of the present study includes documentation of traditional knowledge of ethnoveterinary medicine (EVM) from the northern laterite region in eastern India. Ethnoveterinary medicinal data were collected using a semi-structured questionnaire, free listing, and focus group discussions. The factor for informants’ consensus (Fic), fidelity level (FL), and cultural value (CV) index have been employed for quantitative analyses. Jaccard index (JI) was used to check the knowledge similarity. Altogether, 1,234 citations were made by 132 participants. In total, 232 recorded ethnomedicinal species are used for preparing 306 remedies to treat 79 health disorders of livestock. Recorded species are distributed in 92 families, and Fabaceae is identified as the most medicinally diversified. Uses of 24 angiospermic taxa, one pteridophyte, and two fungal species were exclusively new to the existing inventory of Indian traditional ethnoveterinary medicine. In 20 disease categories, the informant consensus (Fic) value ranges from 0.4 to 0.83. According to the FL value and use-mention factor, 23 EVM plants have been identified as the most important species in the respective disease categories. Value of CV index highlighted nine species as culturally most significant (CV ≥ 0.0025 and frequency of citation ≥20) in the laterite region of eastern India. A large extent of recorded data are quite worthy for the Indian folk veterinary medicinal repository. A handful of new data reported here and statistically justified culturally most significant species will provide the golden opportunity for bioprospecting research.

The Role of Selected Natural Biomolecules in Sperm Production and Functionality

Emerging evidence from in vivo as well as in vitro studies indicates that natural biomolecules may play important roles in the prevention or management of a wide array of chronic diseases. Furthermore, the use of natural compounds in the treatment of male sub- or infertility has been proposed as a potential alternative to conventional therapeutic options. As such, we aimed to evaluate the effects of selected natural biomolecules on the sperm production, structural integrity, and functional activity. At the same time, we reviewed their possible beneficial or adverse effects on male reproductive health. Using relevant keywords, a literature search was performed to collect currently available information regarding molecular mechanisms by which selected natural biomolecules exhibit their biological effects in the context of male reproductive dysfunction. Evidence gathered from clinical trials, in vitro experiments and in vivo studies suggest that the selected natural compounds affect key targets related to sperm mitochondrial metabolism and motion behavior, oxidative stress, inflammation, DNA integrity and cell death. The majority of reports emphasize on ameliorative, stimulating and protective effects of natural biomolecules on the sperm function. Nevertheless, possible adverse and toxic behavior of natural compounds has been indicated as well, pointing out to a possible dose-dependent impact of natural biomolecules on the sperm survival and functionality. As such, further research leading to a deeper understanding of the beneficial or adverse roles of natural compounds is necessary before these can be employed for the management of male reproductive dysfunction.

The non-genomic effects of endocrine-disrupting chemicals on mammalian sperm

Exposure to toxicants present in the environment, especially the so-called endocrine-disrupting chemicals (EDCs), has been associated with decreased sperm quality and increased anomalies in male reproductive organs over the past decades. Both human and animal populations are continuously exposed to ubiquitous synthetic and natural-occurring EDCs through diet, dermal contact and/or inhalation, therefore potentially compromising male reproductive health. Although the effects of EDC are likely induced via multiple genomic-based pathways, their non-genomic effects may also be relevant. Furthermore, spermatozoa are transcriptionally inactive cells that can come in direct contact with EDCs in reproductive fluids and secretions and are therefore a good model to address non-genomic effects. This review thus focuses on the non-genomic effects of several important EDCs relevant to mammalian exposure. Notably, EDCs were found to interfere with pre-existing pathways inducing a panoply of deleterious effects to sperm function that included altered intracellular Ca2+oscillations, induction of oxidative stress, mitochondrial dysfunction, increased DNA damage and decreased sperm motility and viability, among others, potentially jeopardizing male fertility. Although many studies have used non-environmentally relevant concentrations of only one compound for mechanistic studies, it is important to remember that mammals are not exposed to one, but rather to a multitude of environmental EDCs, and synergistic effects may occur. Furthermore, some effects have been detected with single compounds at environmentally relevant concentrations.

Effect of genistein added to bull semen after thawing on pronuclear and sperm quality

The aim of this research was to study the effect of different genistein treatments on bull sperm after thawing on pronuclear formation after in vitro fertilization (IVF) and on different sperm quality variables. Three experiments were performed. In Experiment 1, three treatments (Control, sperm incubation for 1h at 37 °C with or without genistein) and two sperm concentrations during IVF (1 or 3 × 10(6)sperm/mL) were evaluated to study the influence of genistein on pronuclear formation (PNF). Sperm incubation for 1h before IVF reduced PNF regardless of sperm concentration. However, after sperm incubation and with 3 × 10(6)sperm/mL in IVF, the genistein treatment group had greater fertilization rates than the untreated group. In Experiment 2, six treatments plus the control group were performed to study the effect of genistein (presence or not) and incubation conditions (30 min at 37 °C, 1h at 27 °C or at 37 °C) on PNF using 3 × 10(6)sperm/mL for IVF. When incubation time was reduced to 30 min, PNF rate from the genistein treatment group was no different from either the control group or in the group in which incubation occurred for 1h at 27 °C. In Experiment 3, the effect of several genistein treatments (control; genistein treatment for 30 min of incubation at 37 °C; genistein treatment for 1h of incubation at 27 °C) on sperm motility, viability and DNA fragmentation were evaluated. Genistein did not improve sperm motility and, depending on the experimental group or time, it either reduced or had no effect on sperm motility. Genistein treatment did not improve sperm viability after 5h of incubation. However, genistein treatment for 1h at 27 °C decreased sperm DNA fragmentation compared with the control group after 5h of sperm incubation. In conclusion, the treatment of bull sperm with genistein for 1h at 27 °C could decrease sperm DNA fragmentation, although PNF rate after IVF and sperm motility were reduced.

Effect of genistein on acrosome reaction and zona pellucida binding independent of protein tyrosine kinase inhibition in bull

AIM

To investigate if the phytoestrogen, genistein, affects essential functions of cryopreserved bovine spermatozoa.

METHODS

The effect of genistein upon motility was assessed by computer-assisted motion analysis. Hemizona assay was performed to detect the ability of spermatozoa binding to the zona pellucida. The inducibility of the acrosome reaction using progesterone and ZP3-6 peptide was analysed by fluorescein-conjugated Pisum sativum agglutinin (FITC-PSA)/Hoechst 33258 double staining. Capacitation after incubation with genistein was assessed by the chlortetracycline (CTC) assay. Immunoblots showed the pattern of protein tyrosine phosphorylation of cryopreserved bovine spermatozoa.

RESULTS

Immunodetection of tyrosine-phosphorylated proteins showed that genistein did not affect tyrosine phosphorylation in cryopreserved bovine spermatozoa. However, genistein significantly reduced the progesterone- and ZP3-6 peptide-mediated induction of the acrosome reaction and led to a dose-dependent inhibition of sperm-zona pellucida binding; while sperm motility and capacitation were not affected by this phytoestrogen, as indicated by computer-assisted sperm motion analysis and the CTC assay, respectively.

CONCLUSION

Our results suggest that in cryopreserved bovine spermatozoa, genistein affects a protein tyrosine phosphorylation-independent signal transduction pathway that is involved in sperm capacitation, the acrosome reaction and sperm-zona pellucida binding.

Influence of tris(4-chlorophenyl)methanol, non-ortho PCB 77 and gamma-hexachlorocyclohexane on human sperm function in vitro

In recent years, there has been growing concern that environmental pollutants in general, and organochlorines in particular, adversely affect male fertility. Therefore, we investigated the effects of tris(4-chlorophenyl)methanol (TCPM), non-ortho PCB 77 and gamma-hexachlorocyclohexane (gamma-HCH, lindane) on human sperm functions in vitro. Human spermatozoa from healthy donors were washed in human tubular fluid medium containing 1% human serum albumin, filtered through glass wool and exposed to different concentrations of TCPM, PCB 77 or gamma-HCH. After incubation for 5 h at 37 degrees C and 5% CO(2), sperm vitality and the percentage of living acrosome-reacted spermatozoa were examined using triple stain technique. Total sperm motility was evaluated by computer-assisted sperm analysis (Stroemberg-Mika) after 5 h. For TCPM, total motility was additionally measured after 18 and 40 h. Different concentrations of PCB 77 and gamma-HCH did not alter the percentage of spontaneous living acrosome-reacted spermatozoa, vitality and total motility. TCPM dose-dependently altered sperm motility, vitality and acrosome reaction. The percentage of living acrosome-reacted spermatozoa was increased at overtly toxic concentrations. Therefore, it is suggested that unspecific acrosomal loss has been induced by degenerative processes. In conclusion, even high concentrations of PCB 77 and gamma-HCH did not affect human sperm functions in vitro. Only very high cytotoxic TCPM concentrations modulated spontaneous acrosome reaction and total motility. Therefore, in vivo effects on human sperm function seem to be unlikely. However, individual susceptibility has to be considered and little is known about additive and possible synergistic effects as other environmental pollutants with similar potencies have been found in the human male and female reproductive tract.

The effect of oestradiol, progesterone and heparin on bovine spermatozoa function after thawing

The present experiment was designed to determine the effects of various biologically active substances, such as oestradiol (OE), progesterone (P4) and heparin (Hep) alone or in combination on sperm plasma membrane scrambling, capacitation and acrosome reaction (AR) of post-thaw bovine spermatozoa. Spermatozoa were incubated for 180 min in capacitation medium supplemented with (i) 1 mug/ml OE; (ii) 1 mug/ml P4; (iii) 1 mug/ml OE and 1 mug/ml P4; (iv) 1 mug/ml OE and 5 mug/ml Hep; (v) 1 mug/ml P4 and 5 mug/ml Hep; (vi) 1 mug/ml OE, 1 mug/ml P4 and 5 mug/ml Hep. At predetermined time intervals aliquots were taken to assess sperm plasma membrane scrambling, or capacitation (AR induced by lysophosphatidylcholine) in spermatozoa. The second experiment was aimed to study the effects of OE, P4 and OE/P4 as potential inducers of AR in Hep-capacitated spermatozoa. Plasma membrane scrambling was assessed by a flow cytometer, using Merocyanine staining. Acrosomal status and viability of spermatozoa were evaluated under epifluorescence microscope with Ethidium homodimer-1/peanut agglutinin fluorescein isothiocyanate staining method (EthD-1/PNA-FITC). The results show that OE, P4 and a combination of OE/P4 at concentrations used did not affect sperm viability. Heparin significantly (p < 0.001) increased sperm plasma membrane scrambling of OE and P4-treated spermatozoa. P4 significantly affected the rate of sperm capacitation (p < 0.001) and AR (p < 0.05), but OE expressed membrane-stabilizing properties (p < 0.05). It can be concluded that in frozen-thawed bovine spermatozoa OE presents plasma membrane stabilizing properties that can be abolished by Hep, but not by P4. Progesterone possesses capacitating and AR-inducing properties in frozen-thawed bovine spermatozoa that can be alleviated by OE.

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

Genistein, a soybean-originated isoflavone, is widely consumed by humans for putative beneficial health effects but its estrogenic activity may affect adversely the development of the male reproductive system. Twenty-one days old ICR mice weaned from dams fed with a casein-based AIN-76A diet during gestation and lactation were exposed to genistein (2.5 and 5.0 mg/kg/day, p.o.) for 5 weeks. 17beta-Estradiol (7.5 microg/kg/day) and corn oil were used for the positive and negative vehicle controls, respectively. The animals were fed the casein-based AIN-76A diet throughout the experiment. There were no significant differences in body weights of mice between the genistein groups and the negative control group. No significant differences in relative reproductive organ weights were found among all experimental groups. Sperm counts in epididymis and testes were slightly decreased in the genistein-exposed groups compared with control group. Sperm motile characteristics in genistein-exposed groups were slightly higher than those of the control group. Levels of phospholipid hydroxide glutathione peroxidase mRNA in the testis, epididymis, and prostate of mice exposed to genistein or estradiol were significantly higher than those of the controls (P<0.05). Exposure to genistein caused hyperplasia of Leydig cells in the testis and a slight increase of interstitial fibroblasts in the epididymis, while estradiol treatment caused severe damage to the testis and epididymis. These results suggest that dietary uptake of genistein during the juvenile period may affect male reproductive development, resulting in a slight decrease in sperm count, but with an increase in sperm motion quality.

Effects of exposure to genistein and estradiol on reproductive development in immature male mice weaned from dams adapted to a soy-based commercial diet

Genistein, a soybean-originated isoflavone, is widely consumed by humans for putative beneficial health effects but its estrogenic activity may adversely affect the development of male reproductive system. Twenty one-day-old ICR mice weaned from dams fed with a soybean-based diet throughout gestation and lactation were exposed by gavage to genistein (2.5 mg/kg b.w./day) or 17beta-estradiol (7.5 microg/kg b.w./day) for five weeks. Corn oil was used as a negative control. The animals were fed with a casein-based AIN-76A diet throughout the experimental periods. There were no significant differences in body and organ weights of mice among experimental groups. No significant differences in sperm counts and sperm motile characteristics were found between control and genistein groups. Treatment of 17beta-estradiol caused a significant decrease in prostate weight and epididymal sperm counts compared to the control (p<0.05). The levels of phospholipid hydroxide glutathione peroxidase in the testis and prostate of mice exposed to genistein or 17beta-estradiol were significantly higher than that of the control mice (p<0.05). 17beta-estradiol treatment caused degeneration and apoptosis of germ cells in the testis, depletion and degeneration in the epididymal epithelium, and hyperplasia of mucosal fold region in the prostate of mice. Genistein treatment did not cause any lesion in the testis, epididymis, and prostate. These results suggest that dietary uptake of genistein during juvenile period may not affect male reproductive development and functions.

In vitro and in vivo comparison of egg yolk-based and soybean lecithin-based extenders for cryopreservation of bovine semen

Semen diluents containing egg yolk as a cryoprotectant may pose hygienic risks and are difficult to standardize. Although a new generation of semen diluents free of animal ingredients is available, egg yolk-containing extenders are still widely used for cryopreserving semen. We compared the effects of using different extenders on bovine sperm function in vitro and on fertility in vivo. A soy lecithin extender (SL; AndroMed) and an egg yolk-containing (TRIS-EY) extender were tested. No differences (P>0.05) were detected between the two extenders for sperm-zona pellucida binding capacity (HZI=115+/-13). Assessment of the inducibility of the acrosome reaction with progesterone showed no differences (P>0.05) between extenders for live acrosome-reacted sperm (15+/-2.36 and 14.42+/-2.02%, respectively, for SL and TRIS-EY). However, post-thaw sperm motility was significantly lower (P<0.05) when semen was extended in the TRIS-EY diluent. Field trials revealed that nonreturn rates of SL-extended semen showed significantly higher insemination success (P<0.0001) compared with the nonreturn rates for the TRIS-EY extender (70.45 and 67.85%, respectively). We suggest that consistent with quality standards that should be required for cryoprotectant media and because of the superior quality of the egg yolk-free extender, a defined soybean lecithin-containing diluter might be the better choice as a semen extender in the future.

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.