Apoptotic frequency is increased in spermatogenic maturation arrest and hypospermatogenic states

Protective effect of cerium oxide on testicular function and oxidative stress after torsion/detorsion in adult male rats

Testicular torsion (T)/detorsion (D) can cause testicular injury due to the rotation of the spermatic cord and its vessels, therefore it represents an urological emergency that is surgically treated. Oxidative damage occurs in the testis and distant organs because of the overproduction of free radicals and overexpression of proinflammatory cytokines by reperfusion after surgery. Cerium oxide (CeO₂) nanoparticles, a material also known as nanoceria, have regenerative antioxidant properties on oxidative stress. The present study aimed to investigate the effects of nanoceria on testis tissues in testicular T/D in rats. A total of 24 rats were equally and randomly divided into four groups: Control, CeO₂, T/D and CeO2-T/D groups. Left inguinoscrotal incision was performed in the control group. In the CeO₂ group, 0.5 mg/kg CeO₂ was given intraperitoneally 30 min before inguinoscrotal incision. In the T/D group, unilateral testicular T/D was performed through an inguinoscrotal incision and rotating the left testis 720˚ clockwise, which was then left ischemic for 120 min, followed by 120 min of reperfusion. In the CeO₂-T/D group, 0.5 mg/kg CeO₂ was given intraperitoneally 30 min before testicular T/D. At the end of the experiment, testis tissues were removed for histopathological and biochemical examinations. The samples were histologically examined, Glutathione-s transferase (GST), catalase (CAT), paraoxonase (PON) activities and malondialdehyde (MDA) levels were measured via biochemical analysis methods, while the expression levels of p53, Bax and Bcl-2 were detected using immunohistochemistry. The present results revealed statistically significant inter-group differences in PON, CAT and GST activities and MDA levels. GST, CAT and PON activities were significantly higher, whereas MDA levels in the CeO₂-T/D group were significantly lower compared with those in the T/D group. The T/D group had increased Bax and decreased Bcl-2 expression levels in their seminiferous tubules compared with the control and CeO₂ groups. CeO₂ treatment led to downregulation of Bax and upregulation of Bcl-2. The expression of p53 was high in the T/D group compared with that in the control and CeO2 groups, and was upregulated in all germinal cells. However, compared with that in the T/D group, p53 expression was significantly decreased in the CeO₂-T/D group. The testicular injury score significantly increased in the CeO₂-T/D group compared with the control and CeO₂ groups. Rats in the CeO₂-T/D group demonstrated significantly milder tissue lesions compared with those in T/D group. The present findings indicated that nanoceria may protect testis in rats against the harmful effects of T/D. Further studies are required to evaluate how CeO₂ reduces oxidative stress and cell death in testis tissue that underwent T/D-related injury.

Effects of Environmental and Pathological Hypoxia on Male Fertility

Male infertility is a widespread health problem affecting approximately 6%-8% of the male population, and hypoxia may be a causative factor. In mammals, two types of hypoxia are known, including environmental and pathological hypoxia. Studies looking at the effects of hypoxia on male infertility have linked both types of hypoxia to poor sperm quality and pregnancy outcomes. Hypoxia damages testicular seminiferous tubule directly, leading to the disorder of seminiferous epithelium and shedding of spermatogenic cells. Hypoxia can also disrupt the balance between oxidative phosphorylation and glycolysis of spermatogenic cells, resulting in impaired self-renewal and differentiation of spermatogonia, and failure of meiosis. In addition, hypoxia disrupts the secretion of reproductive hormones, causing spermatogenic arrest and erectile dysfunction. The possible mechanisms involved in hypoxia on male reproductive toxicity mainly include excessive ROS mediated oxidative stress, HIF-1α mediated germ cell apoptosis and proliferation inhibition, systematic inflammation and epigenetic changes. In this review, we discuss the correlations between hypoxia and male infertility based on epidemiological, clinical and animal studies and enumerate the hypoxic factors causing male infertility in detail. Demonstration of the causal association between hypoxia and male infertility will provide more options for the treatment of male infertility.

Mkrn2 deficiency induces teratozoospermia and male infertility through p53/PERP-mediated apoptosis in testis

The apoptosis that occurs in the immature testis under physiological conditions is necessary for male germ cell development, whereas improper activation of apoptosis can impair spermatogenesis and cause defects in reproduction. We previously demonstrated that in mice, the makorin-2 (Mkrn2) gene is expressed exclusively in the testis and its deletion leads to male infertility. To understand the potential molecular mechanism, in this study, we found that levels of apoptosis in the testis were abnormally high in the absence of Mkrn2. To identify specific gene(s) involved, we performed digital gene expression profiling (DGE) and pathway analysis via gene set enrichment analysis (GSEA) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, and we found that MKRN2 inhibits p53 apoptosis effector related to PMP22 (PERP) expression and that levels of the protein in sperm samples have an inverse correlation with infertility levels. GSEA additionally indicated that PERP is a negative regulator of spermatogenesis and that its ectopic expression induces male infertility. Further, Gene Expression Omnibus (GEO) dataset analysis showed that p53, upstream of PERP, was upregulated in oligoasthenoteratozoospermia (OAT). These observations suggest that Mkrn2 is crucial for protecting germ cells from excessive apoptosis and implicate Mkrn2-based suppression of the p53/PERP signaling pathway in spermatogenesis and male fertility.

Protective effects of apocynin on damaged testes of rats exposed to methotrexate

Background/aim

Methotrexate (MTX), widely used as a drug in cancer, has many adverse effects on tissues. Apocynin (APO) is a NADPH oxidase inhibitor and is known with many antioxidant properties. In this study, we aimed to evaluate the adverse effects of MTX on testicular tissue and the protective effects of APO at two different doses (20 mg/kg and 50 mg/kg) on MTX-induced testicular damage.

Materials and methods

Fifty adult male Wistar albino rats (8 weeks old and weighing 200–250 g) were divided into five groups of 10 rats each: 1. saline control, 2. dimethyl sulfoxide (DMSO) control, 3. MTX, 4. APO-20 + MTX, and 5. APO-50 + MTX. All injections were performed intraperitoneally. At the end of day 28, all rats were sacrificed under anesthesia. The testes were evaluated histologically and the blood samples were analyzed biochemically.

Results

According to histological and biochemical analyses, there was no significant difference between the DMSO and control groups. In terms of the histological findings, MTX group was significantly the worst affected group compared to the others, and in this group, apoptotic cell number (P = 0.011) was significantly increased in comparison with the control group. Except MTX, there was no significant difference in apoptotic cell number of the other groups compared to the control group. In the MTX group, malondialdehyde (MDA, P = 0.017) and myeloperoxidase (MPO, P < 0.001) levels were significantly increased in tissue and in blood (MDA P < 0.001, MPO P < 0.001), while tissue glutathione (GSH, P < 0.05) and serum testosterone levels (P < 0.01) were decreased compared with the control group. APO + MTX treatment groups exhibited better testis morphology, and apoptotic cells were also significantly decreased compared to MTX group (P < 0.001).

Conclusion

Our results suggest that MTX induced defects on testis via oxidative stress and APO reversed the effects of MTX with its antioxidant properties.

Association of hMSH5 C85T polymorphism with radiation sensitivity of testicular cell lines GC-1, GC-2, TM3, and TM4

BACKGROUND

The hMSH5 C85T polymorphism, which encodes hMSH5 P29S, is associated with individual differences in spermatogenic abnormalities caused by ionizing radiation (IR), but the molecular mechanisms remain unclear.

OBJECTIVES

This manuscript aims to explore the role of hMSH5 C85T polymorphism in IR-induced individual differences in spermatogenic abnormalities.

MATERIAL AND METHODS

We transfected pcDNA-hMSH5^P29S vector into mouse spermatogonia GC-1, mouse spermatocytes GC-2, mouse testicular mesenchymal cells TM3, and mouse testicular support cells TM4. After radiation, we evaluated cell survival with colony formation assay, apoptosis with TUNEL assay and caspase-3 activity assay, DNA damage with comet assay and an in vivo NHEJ activity assay.

RESULTS

Results showed that only spermatocytes GC-2 transfected with pcDNA-hMSH5^P29S vector had significant differences in IR-induced cell survival and apoptosis when compared to that transfected with pcDNA empty vector and pcDNA-wild-hMSH5 vector, while there was no statistical difference in GC-1, TM3, and TM4. In addition, comet assay showed that the DNA damage of GC-2 transfected with pcDNA-hMSH5^P29S vector increased significantly compared to that transfected with pcDNA empty vector and pcDNA-wild-hMSH5 vector after IR. And in vivo NHEJ activity assay showed that the NHEJ activity of GC-2 transfected with pcDNA-hMSH5^P29S vector was statistically higher than that transfected with pcDNA empty vector and pcDNA-wild-hMSH5 vector.

CONCLUSION

Our study indicates that the hMSH5 C85T polymorphism leads to an abnormal increase in apoptosis and lessen the control on error-prone NHEJ of spermatocyte GC-2, thereby altering the difference of radiation sensitivity of spermatogenesis.

Alteration in apoptotic rate of testicular cells and sperms following administration of Bisphenol A (BPA) in Wistar albino rats

The aim of the study was to evaluate the effect of Bisphenol A [BPA] widely used as a plasticizer in the formation of polycarbonate plastics and epoxy resins, exposure causing alteration in apoptosis rate, and protective effect of Vitamin E when supplemented with BPA orally. Adult male Wistar albino rats aged 3 months were randomly divided into seven groups: control (olive oil treated) BPA-treated (dose 5, 50,100 μg/100gmBW) and Vitamin E intervention group (dose 5, 50, 100 μg/100gmBW BPA+ Vitamin E dose 4 mg/100gmBW). Animals were sacrificed 3 months later, and blood and tissue samples were collected. Apoptotic changes were analyzed in epididymal spermatozoa and testis tissue by binding of annexin V apoptotic biomarker. A significant decline in the weight of testis, testosterone level, and sperm count was observed. Histopathological and apoptotic changes were observed in testis tissue. In epididymal sperms, the early apoptotic cells were observed by staining of annexin V-conjugated FITC and PI green fluorescence in spermatozoa head which indicated the damage of membrane and late apoptotic cells. These changes reduced significantly in Vitamin E-treated groups though were not found to be comparable to control animals. All these changes were attributed to disrupted spermatogenesis that would interfere with sperm formation. Thus, the study infers that BPA affects the apoptosis process in the testis and epididymal sperm that would interfere with its function and contribute to infertility, whereas Vitamin E-supplemented dose has a protective effect towards these changes, indicating its role in improving male fertility.

Mammalian sperm nuclear organization: resiliencies and vulnerabilities

Sperm cells are remarkably complex and highly specialized compared to somatic cells. Their function is to deliver to the oocyte the paternal genomic blueprint along with a pool of proteins and RNAs so a new generation can begin. Reproductive success, including optimal embryonic development and healthy offspring, greatly depends on the integrity of the sperm chromatin structure. It is now well documented that DNA damage in sperm is linked to reproductive failures both in natural and assisted conception (Assisted Reproductive Technologies [ART]). This manuscript reviews recent important findings concerning - the unusual organization of mammalian sperm chromatin and its impact on reproductive success when modified. This review is focused on sperm chromatin damage and their impact on embryonic development and transgenerational inheritance.

Interaction of exposure concentration and duration in determining the apoptosis of testis in rats after cigarette smoke inhalation

The effects of differences in smoke concentration and exposure duration in Sprague Dawley rats to determine variation in type and severity of the testis apoptosis were evaluated. The daily dosages were 10, 20 and 30 non-filter cigarettes for a period of 2, 4, 6, 8 and 12 weeks. Mainstream smoke exposure suppressed body weight gain in all regimens. A dose-related increase in plasma nicotine concentration was observed in smoke-exposed groups for 4, 6, 8 and 12 week regimens. Histopathological examination of the exposed groups showed disturbances in the stages of spermatogenesis, tubules atrophying and these appeared to be dose-related. Cytoplasmic caspase-3 immunostaining was detected both in Sertoli cells and germ cells in smoke-exposure groups. An increase in TUNEL-positive cells of testicular cells was observed after 6 weeks of cigarette exposure. The results indicate that cigarette exposure concentration and duration have interaction effect to induce apoptosis in the rat testes.

Varicocele-Induced Infertility in Animal Models

Varicocele is characterized by abnormal tortuosity and dilation of the veins of the pampiniform plexus within the spermatic cord. Although several reports show the mechanisms by which the varicocele exerts its infertility impact, the exact pathophysiology for varicocele-induced inflammation and its relationship with testicular endocrine disruption remain largely unknown. This review article will update previous findings by discussing the pathophysiology of long term-induced varicocele in rats. Testicular endocrine disruption in experimentally-induced varicocele, new findings related to biochemical alterations in germinal epithelium, and sperm cells apoptosis are highlighted. Recent observations show that varicocele down-regulates first and second maturation divisions, results in Leydig and Sertoli cell inflammation, and increases immune cell infiltration in the testes of the rat as an animal model. Ultimately, previous findings of our laboratory have revealed that varicocele decreased sperm motility, viability and severe DNA damage. Damage in sperm significantly lowers the animal’s fertility potential. Varicocele not only exerts its pathologic impact by lowering the testicular antioxidant capacity but it also down-regulates first and second maturation divisions by exerting biochemical alterations such as reducing the intracytoplasmic carbohydrate ratio in germinal epithelium.

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

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

Decreased expression of SAM68 in human testes with spermatogenic defects

OBJECTIVE

To assess the expression patterns of SAM68 in the testes of azoospermic patients with normal and abnormal spermatogenesis.

DESIGN

Retrospective study and in vitro study.

SETTING

University hospital.

PATIENT(S)

Testicular biopsies of azoospermic men with normal spermatogenesis (OAZ; n=20), with maturation arrest at the spermatocyte stage (MA; n=20), and with Sertoli cell-only syndrome (SCOS; n=10).

INTERVENTION(S)

No interventions with patients. Knockdown of Sam68 was performed in the GC-2spd(ts) cell line.

MAIN OUTCOME MEASURE(S)

SAM68 expression was analyzed using quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR), Western blot, and immunohistochemistry analysis in tissues. Moreover, Sam68 was knocked down in GC-2spd(ts) cells. Cell viability was measured using the MTT assay, and the apoptosis rate was detected using flow cytometry with the Annexin V-FITC kit.

RESULT(S)

Using qRT-PCR, the expression level of testicular SAM68 mRNA in MA and SCOS patients was statistically reduced compared with in OAZ patients. In addition, using qRT-PCR, Western blot, and immunohistochemistry analyses, mRNA and protein expressions of SAM68 were absent or barely detectable in testicular tissues in 45% (9 of 20) of patients with MA and in all patients with SCOS. Furthermore, decreased expression of Sam68 suppressed germ cell proliferation and induced apoptosis in transfected GC-2spd(ts) cells.

CONCLUSION(S)

Deficient SAM68 expression was observed in the human testis with MA at the spermatocyte stage and SCOS. These results may offer new perspectives on the molecular basis of abnormal spermatogenesis.

Environmental Tobacco Smoke Exposure during Intrauterine Period, Promotes Caspase Dependent and Independent DNA Fragmentation in Sertoli-Germ Cells

Objectives. To investigate the effect of cigarette smoke exposure during intrauterine period on neonatal rat testis. Methods. Twenty-five rats were randomized to be exposed to cigarette smoke with the Walton Smoking Machine or to room air during their pregnancies. The newborn male rats (n = 21) were grouped as group 1 (n = 15) which were exposed to cigarette smoke during intrauterine life and group 2 (n = 6) which were exposed to room air during intrauterine life. The orchiectomy materials were analyzed with TUNEL immunofluorescent staining for detection of DNA damage. To detect apoptosis, immunohistochemical analyses with caspase-3 were performed. Primary outcomes were apoptotic index and immunohistochemical scores (HSCORES); secondary outcomes were Sertoli-cell count and birth-weight of rats. Results. Sertoli cell apoptosis was increased in group 1 (HSCORE = 210.6 ± 41.9) when compared to group 2 (HSCORE = 100.0 ± 17.8) (P = 0.001). Sertoli cell count was decreased in group 1 (P = 0.043). The HSCORE for the germ cells was calculated as 214.0 ± 46.2 in group 1 and 93.3 ± 10.3 in group 2 (P = 0.001) referring to an increased germ cell apoptosis in group 1. The apoptotic indexes for group 1 were 49.6 ± 9.57 and 29.98 ± 2.34 for group 2 (P = 0.001). The immunofluorescent technique demonstrated increased DNA damage in seminiferous epithelium in group 1. Conclusions. Intrauterine exposure to cigarette smoke adversely affects neonatal testicular structuring and diminishes testicular reserve.

Endogenous EGF maintains Sertoli germ cell anchoring junction integrity and is required for early recovery from acute testicular ischemia/reperfusion injury

Administration of exogenous epidermal growth factor (EGF) improves testicular injury after acute ischemia–reperfusion (IR) stress, but the molecular basis is poorly understood. The role of endogenous EGF in testicular recovery and the underlying intracellular signaling pathways involved were herein investigated. In mice, testicular IR injury significantly enhanced the expression level of endogenousEgfat the very beginning of reperfusion. Expression of EGF receptor (Egfr(ErbB1)) was accordingly upregulated 3 h after reperfusion. Deprivation of majority of circulated EGF by sialoadenectomy aggravated testicular detriment (especially in pachytene spermatocytes), enhanced germ cell apoptosis, and thereafter resulted in impaired meiotic differentiation after IR insult. Mechanistically, endogenous EGF signaling appeared to be indispensable for the proper maintenance of Sertoli germ cells anchoring junction dynamics during the early testicular recovery. We also provided thein vitroevidences in a well-established rat Sertoli germ cell co-cultures model that the pro-survival effect of endogenous EGF on germ cells in response to testicular IR insult is mediated, at least in part, via the phosphatidylinositol 3-kinase/pAkt pathway. Collectively, our results suggest that the augment of endogenous EGF during the early testicular recovery may act on top of an endocrinous cascade orchestrating the intimate interactions between Sertoli cells and germ cells and may operate as indispensable defensive mechanism in response to testicular IR stress. Future studies in this field would shed light on this complicated pathogenesis.

Caspase signalling pathways in human spermatogenesis

PURPOSE

Little is known about the apoptotic mechanisms involved in abnormal spermatogenesis. In order to describe the significance of apoptosis in azoospermia, testicular tissue from abnormal spermatogenesis was analysed.

METHODS

Testicular treatment biopsies were obtained from 27 men. Five presented oligozoospermia, 9 obstructive azoospermia (4 congenital bilateral absence of the vas deferens; 5 secondary azoospermia) and 13 non-obstructive azoospermia (5 hypospermatogenis; 3 maturation arrest; 5 Sertoli-cell-only syndrome). Immunohistochemical staining was performed for active caspases-3, -8 and -9. The presence of active caspases in Sertoli cells and germ cells was analyzed using stereological tools.

RESULTS

Increased active caspase-3 was found in Sertoli-cell-only syndrome. No significant differences were found in maturation arrest. In hypospermatogenesis, primary spermatocytes were the germ cells with higher active caspases. Oligozoospermia and secondary obstruction showed significant differences among germ cells for the presence of all active caspases. In oligozoospermia, spermatogonia presented significant increased active caspase-9 in relation to active caspase-8. In primary obstruction and hypospermatogenesis, germ cells presented significant increased active caspases-3 and -9.

CONCLUSIONS

Results suggest that increased active caspase-3 might be involved in Sertoli-cell-only syndrome etiology. In cases of hypospermatogenesis, intrinsic lesions at the meiotic stage seem to be related to the pathology. In secondary obstruction apoptosis is suggested to be initiated due to extrinsic and intrinsic lesions, whereas in primary obstruction only the intrinsic apoptotic pathway seems to be present. Finally, in oligozoospermic patients spermatogonia death by mitochondrial damage additionally to meiosis malfunctioning, might be on the origin of the decreased sperm output.

Ultrastructure of the seminiferous tubules in oligoasthenoteratozoospermic men associated with varicocele

Varicocele is associated with venous reflux that may cause increased heat and interstitial pressure within the testes, with variable pathological effects on spermatogenesis. This study aimed to study the ultrastructural testicular changes in the seminiferous tubules of 20 infertile severe oligoasthenoteratozoospermia (OAT) men associated with varicocele and five patients with obstructive azoospermia without varicocele as controls. They were subjected to testicular biopsy which was evaluated by transmission electron microscopy. Ultrastructurally, the seminiferous epithelium in the testicular biopsies of infertile severe OAT men associated with varicocele was variably affected in the form of thickening of the peritubular connective tissue, vacuolation of Sertoli cell and germ cell cytoplasm, presence of degenerated and apoptotic cells among the germinal epithelium, altered spermatids and abnormal spermatozoa. It is concluded that varicocele in severe OAT men is associated with ultrastructural changes in the seminiferous tubule.

Apoptosis in the germ line

Apoptosis is a critical process for regulating both the size and the quality of the male and female germ lines. In this review, we examine the importance of this process during embryonic development in establishing the pool of spermatogonial stem cells and primordial follicles that will ultimately define male and female fertility. We also consider the importance of apoptosis in controlling the number and quality of germ cells that eventually determine reproductive success. The biochemical details of the apoptotic process as it affects germ cells in the mature gonad still await resolution, as do the stimuli that persuade these cells to commit to a pathway that leads to cell death. Our ability to understand and ultimately control the reproductive potential of male and female mammals depends upon a deeper understanding of these fundamental processes.

Relationship between caspase activity and apoptotic markers in human sperm in response to hydrogen peroxide and progesterone

Apoptosis plays an essential role in normal spermatogenesis, but deregulations of this biological process, which is closely associated with male infertility, have been found. Whereas calcium homeostasis is a key regulator of cell survival, sustained elevation of intracellular calcium plays a role in apoptosis. The aim of this research was to determine the role of two different calcium mobilizing agents, hydrogen peroxide (H(2)O(2)) and the physiological agonist progesterone, on the apoptosis process of human ejaculated spermatozoa. Translocation of membrane phosphatidylserine was examined with an annexin V binding assay, DNA damage was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL assay) and caspase-3 activity was assessed using a fluorometric assay. After incubation of spermatozoa for 1 h with either 10 microM H(2)O(2) or 20 microM of progesterone, there was a significant increase in both caspase-3 activity and the percentage of annexin V-positive cells. Similarly, the TUNEL results were significantly higher 1 h after incubation with either 10 microM H(2)O(2) or 20 microM of progesterone. In fact, progesterone-treated cells showed a three-fold increase (from 17.6 to 52.9%) of TUNEL-positive cells compared to untreated cells, while H(2)O(2)-treated cells exhibited a two-fold increase (from 17.6 to 37.9%). In sum, our results suggest that spermatozoa treated with calcium mobilizing agents, such as H(2)O(2) and progesterone, seem to undergo an apoptosis process that is dependent on caspase-3 activation.

Programmed cell death in varicocele-bearing testes

Accelerated apoptosis is a significant factor in the pathophysiology of male infertility disorders associated with abnormal spermatogenesis. This study aimed to investigate apoptosis in varicocele-bearing testes. Sixty four men with varicocele (18 fertile and 46 infertile) were studied compared with eight men with obstructive azoospermic as controls. Apoptosis was assessed in testicular biopsy specimens using terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling (TUNEL) method as well as electron microscopy. The results demonstrated that the occurrence of apoptotic changes comprised all types of germ cells but not affecting Sertoli cells. Mean tubular apoptotic indices of fertile or infertile men with varicocele were significantly higher than controls (mean +/- SD 4.55 +/- 1.03%, 6.29 +/- 1.82% versus 2.71 +/- 0.45%, P < 0.05). Mean Leydig cells apoptotic indices of infertile men with varicocele were significantly higher than those of fertile men without varicocele as well as controls (1.18 +/- 0.38%, 0.68 +/- 0.15%, 0.31 +/- 0.21%, P < 0.05). Apoptotic indices were nonsignificantly correlated with Johnsen score, testicular volume or varicocele grade. It is concluded that testicular apoptosis is increased in varicocele-associated men either fertile or infertile who may be implicated in associated spermatogenic dysfunction.

Caspase-3 and VEGF immunopositivity in seminiferous tubule germ cells in cases of obstructive and non-obstructive azoospermia in smokers versus non-smokers

PURPOSE

To investigate immunostaining pattern of caspase-3, an apoptosis marker, and vascular endothelial growth factor (VEGF), an hypoxia marker in testis biopsy specimens collected either from smoking or non-smoking patients with azoospermia.

METHODS

Testis biopsy specimens were obtained from thirty seven non-smoker and thirty eight smoker patients. Using immunochemistry technique, caspase-3 and VEGF were evaluated in all intratubular spermatogenic and interstitial Leydig cells.

RESULT(S)

Caspase-3 expression was significantly increased in germ cells in maturation arrest specimens in smoker azoospermic patients. No statistically significant difference was present between smokers and non-smokers for caspase-3 expression in Sertoli cell. However, the VEGF immunopositive Leydig cells were statistically higher in smokers. There were no differences between groups in terms of germ cell immunopositivity.

CONCLUSION

Our results support the hypothesis that increased apoptosis contributes significantly to impaired spermatogenesis. We conjecture that germ cell apoptosis may be augmented by hypoxic microenvironments and environmental toxicants in smoking azoospermic men.

Insights into male germ cell apoptosis due to depletion of gonadotropins caused by GnRH antagonists

The role of pituitary gonadotropins in the regulation of spermatogenesis has been unequivocally demonstrated, although, the precise mechanism of this regulation is not clearly understood. Previous studies have shown that specific immunoneutralization of LH/testosterone caused apoptotic cell death of meiotic and post-meiotic germ cells while that of FSH resulted in similar death of meiotic cells. In the present study, the death process of germ cells has been characterized by depleting both FSH and testosterone by administering two different potent GnRH antagonists, Cetrorelix and Acyline to both rats and mice. Pro-survival factors like Bcl-2 and Bcl-x/l were unaltered in germ cells due to GnRH antagonist treatment, although a significant increase in several pro-apoptotic markers including Fas and Bax were evident at both protein and RNA levels. This culminated in cytochrome C release from mitochondria and eventually increase in the activity of caspase-8 and caspase-3. These data suggest that both extrinsic and intrinsic apoptotic death pathways are operative in the germ cells death following decrease in FSH and testosterone levels. Multiple injections of GnRH antagonist resulted in complete disappearance of germ cells except the spermatogonial cells and discontinuation of the treatment resulted in full recovery of spermatogenesis. In conclusion our present data suggest that the principal role of FSH and testosterone is to maintain spermatogenic homeostasis by inhibiting death signals for the germ cells.

Involvement of the Fas-Fas ligand system and active caspase-3 in abnormal apoptosis in human testes with maturation arrest and Sertoli cell-only syndrome

OBJECTIVE

To provide evidence that the Fas-mediated apoptotic process may participate in developing hypospermatogenesis, such as maturation arrest (MA) and Sertoli cell-only syndrome (SCO).

DESIGN

Prospective clinical and descriptive study.

SETTING

Hospital-based infertility research laboratory and university laboratory.

PATIENT(S)

Twenty-two testicular biopsy specimens were obtained for routine clinical purposes from 12 men with nonobstructive azoospermia and from 10 men with obstructive azoospermia.

INTERVENTION(S)

In situ terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining was used for detection of apoptosis. Reverse transcription-polymerase chain reaction and immunohistochemical analyses were used for detection of testicular expressions of Fas, Fas ligand (FasL), and caspase-3.

MAIN OUTCOME MEASURE(S)

Apoptotic indices and testicular expressions of apoptosis regulators.

RESULT(S)

Increased apoptosis of germ cells and Sertoli cells was observed in MA and SCO compared with normal spermatogenesis. In testes with MA, increased immunostaining for FasL was observed in the Sertoli cells and Leydig cells, while intense immunostaining of Fas was observed in primary degenerating spermatocytes. Active caspase-3 immunostaining was detected in the cytoplasm of both Sertoli cells and germ cells. In cases of SCO, expression of Fas, FasL, and active caspase-3 was detected both in Sertoli cells and in hyperplastic interstitial cells.

CONCLUSION(S)

The current study demonstrates that the expression of FasL is upregulated in the testes of patients with SCO and MA, which suggests that it may be associated with apoptotic elimination or altered maturation of Fas-expressing germ cells through the activation of caspase-3.

In vivo detection of apoptotic cells in the testis using fluorescence labeled annexin V in a mouse model of testicular torsion

PURPOSE

It is well established that experimental testicular torsion induces germ cell specific apoptosis. Annexin V (BD Pharmingentrade mark) binds phosphatidylserine that becomes exposed on the cell membrane in apoptotic cells. In vivo detection of apoptotic cells with fluorescently labeled annexin V is an emerging technique that we evaluated for detecting apoptotic germ cells in a mouse model of testicular torsion.

MATERIALS AND METHODS

Annexin V labeled with an indocyanine fluorophore (bisfunctional succinimidyl ester of cyanine 5.5) (Amersham, Little Chalfont, United Kingdom) was injected intravenously in mice 18 hours after the repair of unilateral 720-degree testicular torsion for 2 hours. Serial fluorescence images were obtained 21, 24, 28 and 42 hours after torsion repair. Relative fluorophore localization was visualized in vivo using an optical small animal imaging system mounted with a filter in near infrared light. Average fluorescence intensity in torsed and sham testes was quantified in images of testes in situ exposed through an abdominal incision and in ex vivo testes.

RESULTS

A significant increase in fluorescence intensity was found in images of torsed vs sham operated testes. This was seen in ex vivo, exposed and in vivo testes (215%, 250% and 161%, respectively, p <0.05). Bisfunctional succinimidyl ester of cyanine 5.5 conjugated to dehydrogenase, a protein with a size similar to that of annexin V, was used to assess for capillary leakage. It was also more localized to the torsed testis relative to its contralateral sham control whether exposed or ex vivo (174% and 176%, respectively).

CONCLUSIONS

To our knowledge this study demonstrates for the first time the possibility of in vivo near infrared fluorescence imaging of apoptotic germ cells after testicular torsion in mice. It shows important confounding factors that must be considered as this new imaging technique is developed for detecting apoptotic cells in vivo in testes or in any other organ.

From spermatocytes to spermatozoa in an infertile XYY male

Sex chromosome distribution and aneuploidy as well as germ cell degeneration were evaluated in meiotic and post-meiotic cells from an infertile XYY male. Sex chromosome distribution was assessed by multicolour fluorescence in situ hybridization on meiotic preparations. Post-meiotic cell aneuploidy was characterized by a method combining multicolour fluorescence in situ hybridization and immunocytochemistry using the proacrosin-specific monoclonal antibody (mAb 4D4). TUNEL assay was carried out on seminiferous tubules to evaluate germ cell degeneration. At the prophase stage of the first meiotic division, 63.64% of cells at the pachytene stage carried three sex chromosomes. The ratio of X-bearing to Y-bearing spermatids and spermatozoa differed significantly from 1 : 1 with an excess of Y-bearing spermatids and spermatozoa. The frequency of hyperhaploid XY spermatids was increased in the XYY male, as well as the incidence of YY, XY and disomic 18 ejaculated spermatozoa. A preferential elimination of germ cells by apoptosis occurred in spermatocytes I. The persistence of the extra Y chromosome during meiosis of an XYY male is associated with a high rate of spermatocyte I degeneration and a low rate of aneuploid spermatozoa.

TCP10L is expressed specifically in spermatogenic cells and binds to death associated protein kinase-3

The human transcriptional factor T-complex protein 10 like (TCP10L) gene is expressed exclusively in the liver and testis. However, the function of TCP10L in the testis remains unknown. We examined the expression of TCP10L in human testis and found that TCP10L was expressed specifically in the nucleus of spermatogenic cells during spermatogenesis. In addition, we identified death associated protein kinase 3 (DAPK-3/ZIP kinase) as a binding partner for TCP10L by yeast two-hybrid screening, followed with immunoprecipitation and subcellular localization experiments. Mutagenesis study revealed that this interaction was dependant on the leucine zipper motif-containing region. The specific expression pattern of TCP10L and interaction with DAPK-3 implies that TCP10L might play crucially important roles in spermatogenesis through its interaction with DAPK-3.

Experimental Varicocele Induces Testicular Germ Cell Apoptosis in the Rat

PURPOSE

We evaluated the impact of experimentally created varicocele on ipsilateral and contralateral testicular germ cells in the rat.

MATERIALS AND METHODS

Experimental left varicocele was created by partial ligation of the left renal vein in 17 adult male Sprague-Dawley rats. An additional 5 rats that underwent laparotomy and renal vein handling without ligation served as sham surgical controls. Five rats that underwent no surgical or other intervention served as a control group. Rats were sacrificed 7 (5), 14 (5) or 28 (7) days following varicocele creation. Germ cell apoptosis was quantified using a TUNEL assay. The results of this assay are expressed as the number of apoptotic germ cell nuclei per seminiferous tubular cross section. The presence of apoptosis was confirmed by cellular ultrastucture evaluation using transmission electron microscopy.

RESULTS

Control and sham animals were found to have a mean of 0.05 and 0.15 apoptotic germ cells per seminiferous tubular cross section, respectively. Rats sacrificed 7, 14 and 28 days after varicocele creation were found to have 0.15, 0.23 and 0.27 apoptotic germ cells per tubule in the ipsilateral testis, and 0.14, 0.16 and 0.17 apoptotic germ cells per tubule in the contralateral testis, respectively. Compared with control animals a statistically significant increase in the number of apoptotic germ cells per tubular cross section was noted 14 days following varicocele creation in the ipsilateral testis (p <0.05).

CONCLUSIONS

The creation of experimental varicocele generated an increase in germ cell apoptosis in the ipsilateral testis at 14 days compared with control animals.

Deciphering the pathways of germ cell apoptosis in the testis

A growing body of evidence demonstrates that germ cell death both spontaneous (during normal spermatogenesis) and that induced by suppression of hormonal support or increased scrotal temperature occurs via apoptosis. The mechanisms by which these proapoptotic stimuli activate germ cell apoptosis are not well understood. In order to provide some insight, here we report the key molecular components of the effector pathways leading to caspase activation and increased germ cells apoptosis triggered by mildly increased scrotal temperature. Short-term exposure (43 degrees C for 15 min) of the testis to mild heat results, within 6h, in stage- and cell-specific activation of germ cell apoptosis in rats. Initiation of apoptosis was preceded by a redistribution of Bax from a cytoplasmic to paranuclear localization in heat-susceptible germ cells. Such relocation of Bax is further accompanied by sequestration of mitochondria and endoplasmic reticulum (ER) into paranuclear areas, cytosolic translocation of cytochrome c and is associated with activation of the initiator caspase 9 and the executioner caspases 3, 6, and 7, and cleavage of PARP. Furthermore, Bax is co-localized with ER in the susceptible germ cells as assessed by combined two-photon and confocal microscopy and Western blot analyses of fractionated testicular lysates. In additional studies, using gld and lpr(cg) mice, which harbor loss-of-function mutations in Fas-ligand (FasL) and Fas, respectively, we demonstrated that heat-induced germ cell apoptosis is not blocked, thus providing further evidence that the Fas signaling system is dispensable for heat-induced germ cell apoptosis in the testis. Taken together, these results demonstrate that the mitochondria- and possibly also ER-dependent pathways are the key apoptotic pathways for heat induced germ cell death in the testis.

Fas-Fas ligand system as a possible mediator of spermatogenic cell apoptosis in human maturation-arrested testes

To elucidate the mechanism of maturation arrest, known as one of the male infertility, we addressed whether germ cell apoptosis occurs during maturation arrest, and if so, whether Fas and Fas ligand expressions are involved in the apoptosis. By electron microscopy and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL), typical apoptotic features were frequently found around the spermatocytic stage in maturation arrest, compared to that in normal testes. When paraffin-embedded sections reacted with anti-Fas antiserum, staining for Fas was found in the plasma membranes of spermatocytes in the maturation-arrested testes, while no positive spermatogenic cells were seen in the normal testes. On the other hand, positive immunostaining for Fas ligand was restricted to Sertoli cells in the maturation-arrested testes as well as in the normal testes, although the intensity of staining for Fas ligand in normal testicular Sertoli cells was much weaker than that of maturation-arrested ones. Thus, these findings demonstrate that "maturation arrest" is characterized by frequent apoptosis of spermatocytes, and that Fas and Fas ligand staining are associated with a high frequency of apoptosis.

Decreased expression of the heat shock protein hsp70-2 is associated with the pathogenesis of male infertility

OBJECTIVE

To examine the expression of the heat shock protein hsp70-2, and the possible relationship with the pathogenesis of male infertility.

DESIGN

Prospective study.

SETTING

Reproductive testing laboratory in a university hospital.

PATIENT(S)

Men undergoing testicular biopsy during an investigation of subfertility.

INTERVENTION(S)

Testicular tissues were obtained from biopsies of men undergoing infertility evaluation and subdivided into three groups: normal testes, maturational arrest and Sertoli cell-only syndrome. Immunostaining and Western blotting techniques determined expression of the heat shock protein hsp70-2

MAIN OUTCOME MEASURE(S)

Expression of the heat shock protein hsp70-2 in the testes.

RESULT(S)

The experimental data demonstrated that the heat shock protein hsp70-2 was expressed in the normal and maturation arrest testicular specimens. The heat shock protein hsp70-2 was strongly present in the cytoplasm of spermatocytes and spermatides in the adluminal compartment of the seminiferous epithelium in normal testis. However, maturation arrest testis tissue demonstrated light staining in spermatocytes and spermatides, and Sertoli-only specimens demonstrated no staining for the heat shock protein hsp70-2. The Western blotting data showed a 70-kDa heat shock protein in the normal and maturation arrest testicular tissues, but not in the Sertoli-only tissues.

CONCLUSIONS

These results suggest that the heat shock protein hsp70-2 is expressed in spermatocytes and spermatides in normal and maturation arrest tissues. However, the expression of the heat shock protein hsp70-2 was low in maturation arrest, and no heat shock protein hsp70-2 was demonstrated in Sertoli-only specimens. Therefore the decreased expression of the heat shock protein hsp70-2 is associated with the pathogenesis of male infertility.

Analysis of DNA fragmentation, plasma membrane translocation of phosphatidylserine and oxidative stress in human spermatozoa

The objectives of this cross-sectional observational study were: (i) to detect DNA damage and plasma membrane translocation of phosphatidylserine in purified sperm populations of high and low motility, and (ii) to analyse their relationship with the endogenous generation of reactive oxygen species. Ejaculates from infertile men were examined following gradient centrifugation. The main outcome measures were: sperm motion parameters (assessed with a computer analyser), generation of reactive oxygen species (measured by chemiluminescence), DNA damage (detected by terminal deoxynucleotidyl transferase-mediated dUDP nick-end labelling and monoclonal antibody labelling of single-stranded DNA) and translocation of membrane phosphatidylserine (examined with annexin V staining). DNA fragmentation and membrane translocation of phosphatidyl-serine were observed in the fractions with low and high sperm motility in all patients. The fractions with low sperm motility had significantly higher proportion of cells with DNA damage and production of reactive oxygen species than the fractions with high sperm motility (P < 0.005). DNA fragmentation was significantly and positively correlated with the generation of reactive oxygen species (r = 0.42; P = 0.02).

IN CONCLUSION

(i) spermatozoa from infertile men display translocation of membrane phosphatidylserine as diagnosed by annexin V positive staining; (ii) DNA damage (fragmentation and presence of single-stranded DNA) can be detected in ejaculated spermatozoa from infertile men in fractions with low and high sperm motility, and (iii) there is a relationship between DNA damage and oxidative stress.

Demonstration of testicular apoptosis in human male infertility states using a DNA laddering technique

DNA laddering, morphometric analysis, and in-situ end labelling of testis biopsy tissue obtained from azoospermic or severely oligozoospermic men revealed increased apoptosis frequency, implicating a possible role of apoptosis in the pathogenesis of human male infertility.

Decreased expression of the c-kit receptor is associated with increased apoptosis in subfertile human testes

OBJECTIVE

To examine the expression of the c-kit receptor and its ligand, stem cell factor, and their possible relation with apoptosis in infertile men.

DESIGN

Prospective laboratory study.

SETTING

Urology laboratory in a university hospital.

PATIENT(S)

Men undergoing testicular biopsy during an investigation of subfertility.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Expression of the c-kit receptor protein, stem cell factor, and apoptosis in the testes.

RESULT(S)

The c-kit receptor was strongly present in Leydig cells and type A spermatogonia of normal testes, with decreased staining in Leydig cells and type A spermatogonia of testes with maturational arrest, and staining in only Leydig cells of Sertoli cell-only specimens. Stem cell factor was demonstrated in Leydig cells and Sertoli cells in all specimens. Western blotting demonstrated the 150-kd c-kit protein in the normal testes and the testes with maturational arrest, but not in the testes with the Sertoli cell-only pattern. Stem cell factor was expressed in all specimens, with a protein size of 45 kd. Increased apoptosis was demonstrated in type A spermatogonia and spermatocytes of tissue with maturational arrest compared with normal testicular tissue.

CONCLUSION(S)

C-kit receptor expression is decreased in subfertile testicular tissue compared with normal testicular tissue. Stem cell factor expression is present in Leydig cells and Sertoli cells. Increased apoptosis is seen in tissue with maturational arrest compared with normal tissue.