Chronic cyclophosphamide exposure alters the profile of rat sperm nuclear matrix proteins

Protective effect of propolis on the antioxidant enzymes activities, characteristics of epididymal spermatozoa and histopathological structure of testis from rats treated with cyclophosphamide

El objetivo de este estudio fue evaluar el posible efecto terapéutico del propóleo sobre la peroxidación lipídica testicular inducida por ciclofosfamida (CP) y sobre los cambios asociados en los parámetros espermatológicos en los espermatozoides epididimarios y la estructura histopatológica de los testículos de rata. Las ratas se separaron aleatoriamente en 4 grupos con 7 ratas en cada grupo. Se formaron grupos como; 1.er grupo: grupo control (ratas no tratadas), 2.º grupo: grupo tratado con propóleo, 3.er grupo: grupo tratado con CP y 4.º grupo: grupo tratado con CP+propóleo. Se administró propóleo a las ratas en una dosis de 200 mg·kg bw -1 mediante alimentación forzada durante 7 días (d). Se administró CP a las ratas en una dosis única de 150 mg·kg pc -1 por vía intraperitoneal. La administración de propóleo se inició 2 días antes de la administración de CP y continuó durante 7 días. Niveles de malondialdehído (MDA) y glutatión reducido (GSH), actividades de catalasa (CAT), glutatión peroxidasa (GSH-Px), glutatión S-transferasa (GST) y superóxido dismutasa (SOD), parámetros espermatológicos, peso de los órganos reproductivos. y se determinó la estructura histopatológica. En comparación con el grupo de control, los niveles de MDA y las actividades de SOD aumentaron significativamente; Si bien las actividades de CAT y GST disminuyeron, no se encontraron cambios en los niveles de GSH ni en las actividades de GSH-Px en el grupo CP. En el grupo tratado con CP, hubo una disminución en la motilidad de los espermatozoides del epidídimo, la densidad de los espermatozoides en los espermatozoides del epidídimo y el peso de los testículos, la próstata, el epidídimo y la vesícula seminal; mientras que hubo un aumento en la proporción de espermatozoides anormales en comparación con el grupo de control en los espermatozoides epididimarios. El propóleo normalizó los parámetros bioquímicos y espermatológicos en los espermatozoides epididimarios. El examen histopatológico del tejido testicular mostró que los cambios histopatológicos más significativos, como restos celulares, invaginación y degeneración, ocurrieron en el grupo CP. En la patogénesis de la toxicidad testicular inducida por la PC puede desempeñar un papel el deterioro del equilibrio oxidante-antioxidante y el propóleo puede reducir los efectos secundarios graves de las alteraciones inducidas por la PC.

The hepato- and neuroprotective effect of gold Casuarina equisetifolia bark nano-extract against Chlorpyrifos-induced toxicity in rats

BACKGROUND

The bark of Casuarina equisetifolia contains several active phytoconstituents that are suitable for the biosynthesis of gold nanoparticles (Au-NPs). These nanoparticles were subsequently evaluated for their effectiveness in reducing the toxicity induced by Chlorpyrifos (CPF) in rats.

RESULTS

Various hematological and biochemical measurements were conducted in this study. In addition, markers of oxidative stress and inflammatory reactions quantified in liver and brain tissues were evaluated. Histopathological examinations were performed on both liver and brain tissues. Furthermore, the native electrophoretic protein and isoenzyme patterns were analyzed, and the relative expression levels of apoptotic genes in these tissues were determined. The hematological and biochemical parameters were found to be severely altered in the group injected with CPF. However, the administration of Au-C. equisetifolia nano-extract normalized these levels in all treated groups. The antioxidant system markers showed a significant decrease (P ≤ 0.05) in conjunction with elevated levels of inflammatory and fibrotic markers in both liver and brain tissues of the CPF-injected group. In comparison, the pre-treated group exhibited a reduction in these markers when treated with the nano-extract, as opposed to the CPF-injected group. Additionally, the nano-extract mitigated the severity of histopathological lesions induced by CPF in both liver and brain tissues, with a higher ameliorative effect observed in the pre-treated group. Electrophoretic assays conducted on liver and brain tissues revealed that the nano-extract prevented the qualitative changes induced by CPF in the pre-treated group. Furthermore, the molecular assay demonstrated a significant increase in the relative expression of apoptotic genes in the CPF-injected rats. Although the nano-extract ameliorated the relative expression of these genes compared to the CPF-injected group, it was unable to restore their values to normal levels.

CONCLUSION

Our results demonstrated that the nano-extract effectively reduced the toxicity induced by CPF in rats at hematological, biochemical, histopathological, physiological, and molecular levels, in the group pre-treated with the nano-extract.

Protective effects of pomegranate (Punica granatum) and its main components against natural and chemical toxic agents: A comprehensive review

BACKGROUND

Different chemical toxicants or natural toxins can damage human health through various routes such as air, water, fruits, foods, and vegetables.

PURPOSE

Herbal medicines may be safe and selective for the prevention of toxic agents due to their active ingredients and various pharmacological properties. According to the beneficial properties of pomegranate, this paper summarized the protective effects of this plant against toxic substances.

STUDY DESIGN

In this review, we focused on the findings of in vivo and in vitro studies of the protective effects of pomegranate (Punica granatum) and its active components including ellagic acid and punicalagin, against natural and chemical toxic agents.

METHODS

We collected articles from the following databases or search engines such as Web of Sciences, Google Scholar, Pubmed and Scopus without a time limit until the end of September 2022.

RESULTS

P. granatum and its constituents have shown protective effects against natural toxins such as aflatoxins, and endotoxins as well as chemical toxicants for instance arsenic, diazinon, and carbon tetrachloride. The protective effects of these compounds are related to different mechanisms such as the prevention of oxidative stress, and reduction of inflammatory mediators including tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), cyclooxygenase-2(COX-2) and nuclear factor ĸB (NF-ĸB) as well as the modulation of apoptosis, mitogen-activated protein kinase (MAPK) signaling pathways and improvement of liver or cardiac function via regulation of enzymes.

CONCLUSION

In this review, different in vitro and in vivo studies have shown that P. granatum and its active constituents have protective effects against natural and chemical toxic agents via different mechanisms. There are no clinical trials on the protective effects of P. granatum against toxic agents.

Curcumin nanocrystals attenuate cyclophosphamide-induced testicular toxicity in mice

The cancer therapy using cyclophosphamide (CP) has been associated with adverse effects on the testicular function that raises concerns about the future fertility potential among cancer survivors. Curcumin, a polyphenol, has shown to possess a plethora of biological functions including tissue protective effects. In the present study, we investigated the protective effects of curcumin nanocrystals (NC) in mitigation of CP-induced testicular toxicity. Healthy adult (8-10 week) and prepubertal (2 week) male Swiss albino mice were injected with a single dose of CP (200 mg/kg) intraperitoneally (i.p). NC (4 mg/kg, i.p.) was administered every alternate day, for 35 days in adult mice while, a single dose of NC was injected intraperitoneally to prepubertal mice 1 h prior to CP. Administration of multiple doses of NC ameliorated CP-induced testicular toxicity in adult mice, which was evident from the improved sperm functional competence, sperm chromatin condensation, seminiferous tubule architecture and decreased apoptosis in testicular cells. Further, administration of NC 1 h prior to CP in prepubertal mice modulated the expression of genes pertaining to proliferation, pluripotency, DNA damage and DNA repair in spermatogonial cells at 24 h after the treatment. Overall, these results suggest that NC could be a promising chemoprotective agent, which can have potential application in male fertility preservation.

Regulatory Potential of Long Non-Coding RNAs (lncRNAs) in Boar Spermatozoa with Good and Poor Freezability

Long non-coding RNAs (lncRNAs) are suggested to play an important role in the sperm biological processes. We performed de novo transcriptome assembly to characterize lncRNAs in spermatozoa, and to investigate the role of the potential target genes of the differentially expressed lncRNAs (DElncRNAs) in sperm freezability. We detected approximately 4007 DElncRNAs, which were differentially expressed in spermatozoa from boars classified as having good and poor semen freezability (GSF and PSF, respectively). Most of the DElncRNAs were upregulated in boars of the PSF group and appeared to significantly affect the sperm's response to the cryopreservation conditions. Furthermore, we predicted that the potential target genes were regulated by DElncRNAs in cis or trans. It was found that DElncRNAs of both freezability groups had potential cis- and trans-regulatory effects on different protein-coding genes, such as COX7A2L, TXNDC8 and SOX-7. Gene Ontology (GO) enrichment revealed that the DElncRNA target genes are associated with numerous biological processes, including signal transduction, response to stress, cell death (apoptosis), motility and embryo development. Significant differences in the de novo assembled transcriptome expression profiles of the DElncRNAs between the freezability groups were confirmed by quantitative real-time PCR analysis. This study reveals the potential effects of protein-coding genes of DElncRNAs on sperm functions, which could contribute to further research on their relevance in semen freezability.

Protective Effect of Vitamin C and Zinc as an Antioxidant Against Chemotherapy-Induced Male Reproductive Toxicity

Treatment with anticancer drugs such as cyclophosphamide can harm the male reproductive system. Vitamin C and zinc are micronutrients with antioxidant activity and are the essential components of semen. Therefore, this study aimed to evaluate whether cyclophosphamide-exposed mice can recover from fertility with vitamin C and zinc therapy.

In this experimental study, fifty male mice were divided into five groups. Groups 1-4 received cyclophosphamide (100 mg/kg, once a week for eight weeks). Also, group 2 received zinc (200 mg/kg), group 3 received vitamin C (300 mg/kg), group 4 received zinc and vitamin C (200 mg/kg and 300 mg/kg, respectively), five times per week for eight weeks, and group 5 received normal saline once a week and water five days a week for eight weeks. The data collected were statistically analyzed using SPSS 22.

Results showed a significant increase in mount latency and a significant decrease in the number of sperms in the cyclophosphamide group compared to the control group. However, mount latency has been significantly decreased in mice treated with cyclophosphamide plus zinc compared to the cyclophosphamide group. The study also showed that the sperm count in the group that received cyclophosphamide and zinc had been increased compared to the cyclophosphamide group; the other treatments have decreased mount latency and increased the sperm count compared to the group treated with cyclophosphamide but not significantly. The Tubule Differentiation Index showed an increase in the cyclophosphamide-Zinc-Vitamin C group in comparison with the cyclophosphamide group.

The current study showed that zinc could improve cyclophosphamide-induced toxicity of the reproductive system in male mice.

Evaluation of the Biological Efficiency of Silver Nanoparticles Biosynthesized Using Croton tiglium L. Seeds Extract against Azoxymethane Induced Colon Cancer in Rats

BACKGROUND

Colorectal cancer (CRC) is considered as the most common type of gastrointestinal cancers. Chemotherapy became limited due to the adverse side effects. Therefore, the most effective Croton tiglium extract was selected to be incorporated by silver nanoparticles (Ag-NPs) then evaluated against colon cancer induced by azoxymethane (AOM) in rats.

METHODS

Different hematological and biochemical measurements were quantified in addition to markers of oxidative stress. Specific tumor and inflammatory markers were assayed. Colonic tissues were examined histopathologically in addition to immunohistochemistry (IHC). Native proteins and isoenzymes patterns were electrophoretically assayed beside expression of Tumor Protein P53 (TP53) and Adenomatous Polyposis Coli (APC) genes in colonic tissues.

RESULTS

It was found that AOM caused significant (P≤0.05) elevation in the hematological and biochemical measurements. C. tiglium nano-extract restored these measurements to normalcy. Tumor and inflammatory markers elevated significantly (P≤0.05) in sera of AOM induced colon cancer group in addition to increasing peroxidation products with decline in antioxidant enzymes activities in colon tissues. Nano-extract restored these measurements to normalcy in post-treated group. Histopathological study revealed that nano-extract minimized severity of inflammatory reactions in all nano-extract treated groups and prevented  anti-Keratin 20 antibody expression in post-treated group. The lowest similarity index (SI%) values were noticed with electrophoretic protein (SI=71.43%), lipid (SI=0.00%) and calcium (SI=75.00%) moieties of protein patterns, catalase (SI=85.71%), peroxidase (SI=85.71%), α-esterase (SI=50.00%) and β-esterase (SI=50.00%) isoenzymes in colon cancer group. Furthermore, AOM altered the relative quantities of total native bands. The nano-extract prevented the alterations that occurred qualitatively in nano-extract post-treated group and quantitatively in all nano-extract treated groups. Levels of TP53 and APC gene expression increased in AOM injected group and nano-extract restored their levels to normalcy in the post-treated group.

CONCLUSION

C. tiglium nano-extract exhibited ameliorative effect against the biochemical and molecular alterations induced by AOM in nano-extract post-treated group.

Glutathione compartmentalization and its role in glutathionylation and other regulatory processes of cellular pathways

Glutathione is considered the major non-protein low molecular weight modulator of redox processes and the most important thiol reducing agent of the cell. The biosynthesis of glutathione occurs in the cytosol from its constituent amino acids, but this tripeptide is also present in the most important cellular districts, such as mitochondria, nucleus, and endoplasmic reticulum, thus playing a central role in several metabolic pathways and cytoprotection mechanisms. Indeed, glutathione is involved in the modulation of various cellular processes and, not by chance, it is a ubiquitous determinant for redox signaling, xenobiotic detoxification, and regulation of cell cycle and death programs. The balance between its concentration and redox state is due to a complex series of interactions between biosynthesis, utilization, degradation, and transport. All these factors are of great importance to understand the significance of cellular redox balance and its relationship with physiological responses and pathological conditions. The purpose of this review is to give an overview on glutathione cellular compartmentalization. Information on its subcellular distribution provides a deeper understanding of glutathione-dependent processes and reflects the importance of compartmentalization in the regulation of specific cellular pathways. © 2018 BioFactors, 45(2):152-168, 2019.

Immunosuppressants and Male Reproduction

Prolonged use of immunosuppressant medications is occasionally seen in infertile men with chronic inflammatory conditions; autoimmune disorders; or an organ or hematopoietic stem cell transplant. Chronic inflammation impacts negatively on male reproductive endpoints, so immunosuppressant therapy can produce improvements. Corticosteroids have been used to treat antisperm antibodies and even as an empirical treatment for male infertility in general. Trials of these methods have provided mixed results on semen quality and fertility, with improvement, no change and negative effects reported by different investigators. In a substantial number of observational studies, patients on long-term therapy with prednisone for chronic inflammatory disease, testosterone levels were lower compared to untreated controls, though randomized controlled trials have not been conducted. Similarly decreases in testosterone have been reported in men receiving corticosteroids to minimize transplant rejection; however, most were treated with multiple immunosuppressive medications that may have contributed to this effect. A large number of trials of healthy men treated with corticosteroids have shown some disruption in reproductive hormone levels, but other studies reported no effect. Studies in monkeys, rats (at human equivalent dose), cattle, sheep, and horses have shown endocrine disruption, including low testosterone with dexamethasone treatment. Of the cytostatic immunosuppressives, which have high potential for cellular damage, cyclophosphamide has received the most attention, sometimes lowering sperm counts significantly. Methotrexate may decrease sperm numbers in humans and has significant negative impacts in rodents. Other chemotherapeutic drugs used as immunosuppressants are likely to impact negatively on male fertility endpoints, but few data have been collected. The TNF-α Inhibitors have also received little experimental attention. There is some evidence that the immunophilin modulators: cyclosporine, sirolimus, and everolimus cause endocrine disruption and semen quality impairment. As we review in this chapter, results in experimental species are concerning, and well-designed studies are lacking for the effects of these medications on reproductive endpoints in men.

Zinc Transport Differs in Rat Spermatogenic Cell Types and Is Affected by Treatment with Cyclophosphamide

Adequate zinc levels are required for proper cellular functions and for male germ cell development. Zinc transport is accomplished by two families of zinc transporters, the ZIPs and the ZnTs, that increase and decrease cytosolic zinc levels, respectively. However, very little is known about zinc transport in the testis. Furthermore, whether cytotoxic agents such as cyclophosphamide (CPA), a known male germ cell toxicant, can affect zinc transport and homeostasis is unknown. We examined zinc transporter expression and zinc transport in pachytene spermatocytes (PS) and round spermatids (RS) in a normal state and after exposure to CPA. We observed differences in the expression of members of the ZnT and ZIP families in purified populations of PS and RS. We also observed that RS accumulate more zinc over time than PS. The expression of many zinc binding genes was altered after CPA treatment. Interestingly, we found that the expression levels of ZIP5 and ZIP14 were increased in PS from animals treated daily with 6 mg/kg CPA for 4 wk but not in RS. This up-regulation led to an increase in zinc uptake in PS but not in RS from treated animals compared to controls. These data suggest that CPA treatment may alter zinc homeostasis in male germ cells leading to an increased need for zinc. Altered zinc homeostasis may disrupt proper germ cell development and contribute to infertility and effects on progeny.

The effects of chemotherapy with bleomycin, etoposide, and cis-platinum on telomeres in rat male germ cells

Co-administration of bleomycin, etoposide, and cis-platinum (BEP) has increased the 5-year survival rate of testis cancer patients to over 90%; however, this treatment induces chemotoxic effects on male germ cells. Treatment of male rats with BEP, using a similar schedule to that used in man, affects reproductive organ weights and sperm count, motility, and DNA integrity, as well as pup survival rates. Telomeres, specialized structures at the termini of chromosomes, play an important role in the maintenance of genetic stability. In previous studies, we demonstrated, using a spermatogonial cell line, that cis-platinum and bleomycin damage telomeres and that cis-platinum also inhibits telomerase activity. Our objective here was to test the hypothesis that in vivo exposure to the BEP regimen used to treat testis cancer targets telomeres in the male germ line. Adult male Brown Norway rats received chronic treatment with a BEP regimen. DNA double strand breaks were increased significantly in zygotene germ cells, as assessed by γ-H2AX immunofluorescence. Interestingly, treatment with this BEP regimen increased γ-H2AX foci in the telomere region of zygotene spermatocytes, but not in other germ cell types, such as pachytene cells, round spermatids, or elongating spermatids. Mean telomere lengths were reduced in zygotene, pachytene, round spermatid, elongating spermatid and cauda epididymal spermatozoa compared with the saline control group. Thus, telomere lengths did not recover during germ cell development. These studies demonstrate that BEP treatment is associated with an effect on telomeres.

Double-stranded DNA breaks hidden in the neutral Comet assay suggest a role of the sperm nuclear matrix in DNA integrity maintenance

We used a mouse model in which sperm DNA damage was induced to understand the relationship of double-stranded DNA (dsDNA) breaks to sperm chromatin structure and to the Comet assay. Sperm chromatin fragmentation (SCF) produces dsDNA breaks located on the matrix attachment regions, between protamine toroids. In this model, epididymal sperm induced to undergo SCF can religate dsDNA breaks while vas deferens sperm cannot. Here, we demonstrated that the conventional neutral Comet assay underestimates the epididymal SCF breaks because the broken DNA ends remain attached to the nuclear matrix, causing the DNA to remain associated with the dispersion halo, and the Comet tails to be weak. Therefore, we term these hidden dsDNA breaks. When the Comet assay was modified to include an additional incubation with sodium dodecyl sulfate (SDS) and dithiothreitol (DTT) after the conventional lysis, thereby solubilizing the nuclear matrix, the broken DNA was released from the matrix, which resulted in a reduction of the sperm head halo and an increase in the Comet tail length, exposing the hidden dsDNA breaks. Conversely, SCF-induced vas deferens sperm had small halos and long tails with the conventional neutral Comet assay, suggesting that the broken DNA ends were not tethered to the nuclear matrix. These results suggest that the attachment to the nuclear matrix is crucial for the religation of SCF-induced DNA breaks in sperm. Our data suggest that the neutral Comet assay identifies only dsDNA breaks that are released from the nuclear matrix and that the addition of an SDS treatment can reveal these hidden dsDNA breaks.

Alfa-lipoic acid protects testosterone secretion pathway and sperm quality against 4-tert-octylphenol induced reproductive toxicity

The protective effect of α-lipoic acid (LA) (50 mg/kg bw) against 4-tert-octylphenol (OP) (50 mg/kg bw) induced reproductive toxicity in male rats was studied. LA was injected 1h prior to OP administration three times a week. OP caused significant increase in oxidative stress in hypothalamus and epididymal sperm, disturbed hormonal levels in serum, decreased sperm quality, increased DNA fragmentation and loss of 35 and 95 kDa proteins in sperm, as well as elevated proliferating index in testis. LA protected against oxidative stress through promoting the levels of glutathione and glutathione-S-transferase in hypothalamus and sperm. In addition, LA prevented the decrease in testosterone, dehydroepiandrosterone sulfate, 3β-hydroxysteroid dehydrogenase, and inhibited the elevations in sex-hormone-binding globulin levels and showed normal sperm quality. LA modulated proliferation of germ cell, protected against DNA fragmentation and maintained membrane protein organization in the sperm. In conclusion, LA normalized oxidative stress and protected testosterone synthesis pathway across hypothalamus-testicular axis and sperm quality indicating its defensive influence against OP-induced oxidative reproductive dysfunction in male rats.

Exposure to bleomycin, etoposide, and cis-platinum alters rat sperm chromatin integrity and sperm head protein profile

Testicular cancer, currently the most common cancer affecting men of reproductive age, is one of the most curable malignancies due to the progress made in the early diagnosis and effective treatment of this disease. The coadministration of bleomycin, etoposide, and cis-platinum (BEP) has brought the 5-yr survival rate of testis cancer patients to over 90%. However, this treatment results in reproductive chemotoxic effects. We assessed the effect of BEP treatment on sperm chromatin integrity and sperm head protein profiles of adult male Brown Norway rats following 9 wk of treatment with BEP and in animals treated for 9 wk and then subjected to a 9-wk recovery period. Both the susceptibility of DNA to denaturation and the number of strand breaks were significantly increased in mature sperm following 9 wk of treatment with BEP; proteomic analysis revealed that the expression of several proteins, including HSP90AA1 and HSP90B1, was markedly affected. Following a 9-wk recovery period, mature sperm did not show significant DNA damage, indicating that repair had potentially occurred. Interestingly, the protamination level of the sperm of these animals was significantly decreased, while histones HIST1H1D (H1.2), HIST1H4B (H4), HIST2H2AA3 (H2A1), and HIST1H2BA (H2B1A) were concomitantly up-regulated; this was not observed in the sperm immediately following 9 wk of treatment. Thus, there are persistent effects on proteins in sperm heads from the cauda epididymidis 9 wk posttreatment, in the absence of DNA strand breaks. We suggest that these effects on the sperm head proteome may contribute to long-lasting adverse effects in the progeny of BEP-exposed males.

The activation of DNA damage detection and repair responses in cleavage-stage rat embryos by a damaged paternal genome

Male germ cell DNA damage, after exposure to radiation, exogenous chemicals, or chemotherapeutic agents, is a major cause of male infertility. DNA-damaged spermatozoa can fertilize oocytes; this is of concern because there is limited information on the capacity of early embryos to repair a damaged male genome or on the fate of these embryos if repair is inadequate. We hypothesized that the early activation of DNA damage response in the early embryo is a critical determinant of its fate. The objective of this study was to assess the DNA damage response and mitochondrial function as a measure of the energy supply for DNA repair and general health in cleavage-stage embryos sired by males chronically exposed to an anticancer alkylating agent, cyclophosphamide. Male rats were treated with saline or cyclophosphamide (6 mg/kg/day) for 4 weeks and mated to naturally cycling females. Pronuclear two- and eight-cell embryos were collected for immunofluorescence analysis of mitochondrial function and biomarkers of the DNA damage response: γH2AX foci, 53BP1 reactivity, and poly(ADP-ribose) polymer formation. Mitochondrial activities did not differ between embryos sired by control- and cyclophosphamide-exposed males. At the two-cell stage, there was no treatment-related increase in DNA double-strand breaks; by the eight-cell stage, a significant increase was noted, as indicated by increased medium and large γH2AX foci. This was accompanied by a dampened DNA repair response, detected as a decrease in the nuclear intensity of poly(ADP-ribose) polymers. The micronuclei formed in cyclophosphamide-sired embryos contained large γH2AX foci and enhanced poly(ADP-ribose) polymer and 53BP1 reactivity compared with their nuclear counterparts. Thus, paternal cyclophosphamide exposure activated a DNA damage response in cleavage-stage embryos. Furthermore, this damage response may be useful in assessing embryo quality and developmental competence.

The Sperm Centrosome: Its Role and Significance in Nature and Human Assisted Reproduction

In humans and other non-rodent mammalian species, the sperm's centriole-centrosome complex is an essential component for successful fertilization and serves as template for all centrioles during subsequent cell divisions, embryo development, divisions of most adult somatic cells, as well as in primary cilia formation and functions. Dysfunctions of this complex can be causes for infertility, developmental disorders, and play a role in various adulthood diseases. While assisted reproductive technology (ART) has been able to overcome sperm motility dysfunctions by employing intracytoplasmic sperm injection (ICSI), we currently do not yet have therapies to overcome dysfunctions of the centriole-centrosome complex although several lines of investigations have addressed the causes for centriole-centrosome dysfunctions and implications for sperm aster formation and union of the parental genomes. The present review highlights the importance of the centriole-centrosome complex and its significance for fertilization and embryo development.

Non-genetic contributions of the sperm nucleus to embryonic development

Recent data from several laboratories have provided evidence that the newly fertilized oocyte inherits epigenetic signals from the sperm chromatin that are required for proper embryonic development. For the purposes of this review, the term epigenetic is used to describe all types of molecular information that are transmitted from the sperm cell to the embryo. There are at least six different forms of epigenetic information that have already been established as being required for proper embryogenesis in mammals or for which there is evidence that it may do so. These are (i) DNA methylation; (ii) sperm-specific histones, (iii) other chromatin-associated proteins; (iv) the perinuclear theca proteins; (v) sperm-born RNAs and, the focus of this review; and (vi) the DNA loop domain organization by the sperm nuclear matrix. These epigenetic signals should be considered when designing protocols for the manipulation and cryopreservation of spermatozoa for assisted reproductive technology as necessary components for effective fertilization and subsequent embryo development.

The sperm nucleus: chromatin, RNA, and the nuclear matrix

Within the sperm nucleus, the paternal genome remains functionally inert and protected following protamination. This is marked by a structural morphogenesis that is heralded by a striking reduction in nuclear volume. Despite these changes, both human and mouse spermatozoa maintain low levels of nucleosomes that appear non-randomly distributed throughout the genome. These regions may be necessary for organizing higher order genomic structure through interactions with the nuclear matrix. The promoters of this transcriptionally quiescent genome are differentially marked by modified histones that may poise downstream epigenetic effects. This notion is supported by increasing evidence that the embryo inherits these differing levels of chromatin organization. In concert with the suite of RNAs retained in the mature sperm, they may synergistically interact to direct early embryonic gene expression. Irrespective, these features reflect the transcriptional history of spermatogenic differentiation. As such, they may soon be utilized as clinical markers of male fertility. In this review, we explore and discuss how this may be orchestrated.

Paternal exposure to cyclophosphamide affects the progression of sperm chromatin decondensation and activates a DNA damage response in the prepronuclear rat zygote

Spermatozoon decondensation in the zygote leads to the initiation of chromatin remodeling during which protamines are removed and replaced with maternal histones. We hypothesize that damage to male germ cells induced by paternal exposure to cyclophosphamide may alter the timing of spermatozoal decondensation and the pattern of chromatin remodeling in the prepronuclear rat zygote. A specific order of sperm decondensation was observed, starting at the posterior end, proceeding to the ventral sides, followed by the tip, and finally the midbody region of the sperm head nucleus; subgroups of partially decondensed type a sperm nuclei were defined as types a1, a2, a3, and a4. Based on their frequencies relative to controls, paternal exposure to cyclophosphamide accelerated the timing of spermatozoal decondensation. Two distinct patterns of chromatin remodeling were observed for totally decondensed (type b) and recondensing (type c) sperm nuclei: H4K12ac showed a homogenous staining, whereas H3S10ph displayed a ring-like staining around the sperm nucleus; the distribution of these posttranslationally modified histones was not affected by cyclophosphamide exposure. In contrast, paternal cyclophosphamide treatment increased the number of gammaH2AX foci found in decondensing sperm nuclei. Small foci were significantly increased in type a2 and a3 nuclei, whereas a significant increase in the numbers of large foci was found in type b and c nuclei. This increase in gammaH2AX foci in the decondensing male genome suggests that damage recognition and repair pathways are initiated in prepronuclear rat zygotes. Thus, exposure of male rats to chronic low doses of cyclophosphamide accelerates spermatozoal decondensation and leads to the activation of gammaH2AX recognition of DNA damage in the male genome of the prepronuclear zygote.

Toxic effect of cyclophosphamide on sperm morphology, testicular histology and blood oxidant-antioxidant balance, and protective roles of lycopene and ellagic acid

In this study, the toxic effect of cyclophosphamide (CP) on sperm morphology, testicular histology and blood oxidant-antioxidant balance, and protective roles of lycopene (LC) and ellagic acid (EA) were investigated. For this purpose, 48 healthy, adult, male Sprague-Dawley rats were divided into six groups; eight animals in each group. The control group was treated with placebo. LC, EA and CP groups were given alone LC (10 mg/kg/every other day), EA (2 mg/kg/every other day) and CP (15 mg/kg/week) respectively. One of the last two groups received CP + LC, and the other treated with CP + EA. All treatments were maintained for 8 weeks. At the end of the treatment period, morphological abnormalities of sperm, plasma malondialdehyde (MDA) levels and glutathione (GSH) levels, and GSH-peroxidase (GSH-Px), catalase (CAT) and superoxide dismutase (SOD) activities in erythrocytes, and testicular histopathological changes were examined. CP administration caused statistically significant increases in tail and total abnormality of sperm, plasma MDA level and erythrocyte SOD activity, and decreases in erythrocyte CAT activity, diameters of seminiferous tubules, germinal cell layer thickness and Johnsen's Testicular Score along with degeneration, necrosis, immature germ cells, congestion and atrophy in testicular tissue. However, LC or EA treatments to CP-treated rats markedly improved the CP-induced lipid peroxidation, and normalized sperm morphology and testicular histopathology. In conclusion, CP-induced lipid peroxidation leads to the structural damages in spermatozoa and testicular tissue of rats, and also LC or EA have a protective effect on these types of damage.

Antiperoxidative and anti-apoptotic effects of lycopene and ellagic acid on cyclophosphamide-induced testicular lipid peroxidation and apoptosis

The present study was conducted to investigate the possible protective effects of lycopene (LC) and ellagic acid (EA) on cyclophosphamide (CP)-induced testicular and spermatozoal toxicity associated with the oxidative stress and apoptosis in male rats. Forty-eight healthy adult male Sprague-Dawley rats were divided into six groups of eight rats each. The control group was treated with placebo; the LC, EA and CP groups were given LC (10 mg kg–1), EA (2 mg kg–1) and CP (15 mg kg–1), respectively, alone; the CP+LC group was treated with a combination of CP (15 mg kg–1) and LC (10 mg kg–1); and the CP+EA group was treated with a combination of CP (15 mg kg–1) and EA (2 mg kg–1). All treatments were maintained for 8 weeks. At the end of the treatment period, bodyweight and the weight of the reproductive organs, sperm concentration and motility, testicular tissue lipid peroxidation, anti-oxidant enzyme activity and apoptosis (i.e. Bax and Bcl-2 proteins) were determined. Administration of CP resulted in significant decreases in epididymal sperm concentration and motility and significant increases in malondialdehyde levels. Although CP significantly increased the number of Bax-positive (apoptotic) cells, it had no effect on the number of Bcl-2-positive (anti-apoptotic) cells compared with the control group. However, combined treatment of rats with LC or EA in addition to CP prevented the development of CP-induced lipid peroxidation and sperm and testicular damage. In conclusion, CP-induced lipid peroxidation leads to structural and functional damage, as well as apoptosis, in spermatogenic cells of rats. Both LC and EA protect against the development of these detrimental effects.

Memoirs of an insult: sperm as a possible source of transgenerational epimutations and genetic instability

Male transgenerational epigenetic effects have been discovered in the discipline of mouse radiation genetics, using genetic and non-genetic readouts. The mechanism to explain the origin of the transmission of epigenetic and genetic instability is still unknown. In a search for a hypothesis that could satisfy the data, we propose that regulation of chromosome structure in the germline, by the occupancy of matrix/scaffold associated regions, contains molecular memory function. The male germline is strikingly dynamic as to chromatin organization. This could explain why experience of irradiation stress leaves a persistent mark in the male germline only. To be installed, such memory requires both S-phase and chromatin reorganization during spermatogenesis and in the zygote, that likely also involves reorganization of loop domains. By this reorganization, another layer of information is added, needed to accommodate early embryonic development. Observations point at the involvement of DNA repair as inducer of transgenerational epigenetic modulation. Nuclear structure, chromatin composition and loop domain organization are aspects of human sperm variability that in many cases of assisted reproduction is increased due to inclusion of more incompletely differentiated/maturated sperm nuclei. Adjustment of loop domains in early embryo development can be anticipated and zygotic and cleavage stage S-phase repair activity will have to deal with potential paternal DNA lesions. Therefore, by changing male nucleus structure due to reproduction from impaired spermatogenesis, the transgenerational information content could be changed as well. We discuss aspects of male reproductive performance in the context of this hypothesis.

Do heat stress and deficits in DNA repair pathways have a negative impact on male fertility?

In Europe up to one in four couples experience difficulty conceiving and in half of these cases the problem has been attributed to sub or infertility in the male partner. The development of assisted reproductive technologies (ART) such as in vitro fertilization and intra-cytoplasmic spermatozoa injection has allowed some such couples to achieve a pregnancy. Concerns have been raised over the increasing use of ART not least because of the discovery of elevated levels of DNA damage in sperm from subfertile men. The impact of damaged DNA originating in the male germ line is poorly understood, but is thought to contribute to early pregnancy loss (recurrent miscarriage), placental problems and have a long-term impact on the health of the offspring. DNA repair is essential for meiotic recombination and correction of DNA damage in germ cells and proteins involved in all the major repair pathways are expressed in the testis. In this review, we will consider evidence that the production of sperm containing damaged DNA can be the result of suboptimal DNA repair and/or a mild environmental insult, such as heat stress, and how studies in mice may give us insight into the origins and consequences of DNA damage in human sperm.