Involvement of Fas system and active caspases in apoptotic signalling in testicular germ cells of ethanol-treated rats

Functional role of autophagy in testicular and ovarian steroidogenesis

Autophagy is an evolutionarily conserved cellular recycling process that maintains cellular homeostasis. Despite extensive research in endocrine contexts, the role of autophagy in ovarian and testicular steroidogenesis remains elusive. The significant role of autophagy in testosterone production suggests potential treatments for conditions like oligospermia and azoospermia. Further, influence of autophagy in folliculogenesis, ovulation, and luteal development emphasizes its importance for improved fertility and reproductive health. Thus, investigating autophagy in gonadal cells is clinically significant. Understanding these processes could transform treatments for endocrine disorders, enhancing reproductive health and longevity. Herein, we provide the functional role of autophagy in testicular and ovarian steroidogenesis to date, highlighting its modulation in testicular steroidogenesis and its impact on hormone synthesis, follicle development, and fertility therapies.

Rats Orally Administered with Ethyl Alcohol for a Prolonged Time Show Histopathology of the Epididymis and Seminal Vesicle Together with Changes in the Luminal Metabolite Composition

Prolonged ethanol (EtOH) consumption is associated with male infertility, with a decreased spermatogenesis rate as one cause. The defective maturation and development of sperm during their storage in the cauda epididymis and transit in the seminal vesicle can be another cause, possibly occurring before the drastic spermatogenesis disruption. Herein, we demonstrated that the cauda epididymis and seminal vesicle of rats, orally administered with EtOH under a regimen in which spermatogenesis was still ongoing, showed histological damage, including lesions, a decreased height of the epithelial cells and increased collagen fibers in the muscle layer, which implicated fibrosis. Lipid peroxidation (shown by malondialdehyde (MDA) levels) was observed, indicating that reactive oxygen species (ROS) were produced along with acetaldehyde during EtOH metabolism by CYP2E1. MDA, acetaldehyde and other lipid peroxidation products could further damage cellular components of the cauda epididymis and seminal vesicle, and this was supported by increased apoptosis (shown by a TUNEL assay and caspase 9/caspase 3 expression) in these two tissues of EtOH-treated rats. Consequently, the functionality of the cauda epididymis and seminal vesicle in EtOH-treated rats was impaired, as demonstrated by a decreases in 1H NMR-analyzed metabolites (e.g., carnitine, fructose), which were important for sperm development, metabolism and survival in their lumen.

Protective effect of Mucuna pruriens (L.) DC. var. pruriens seed extract on apoptotic germ cells in ethanolic male rats

Thai Mucuna pruriens (L.) DC. var pruriens (T-MP) seed containing levodopa (L-DOPA) and antioxidant capacity has been shown to improve sexual behavior and male reproductive parameters in rats treated with ethanol (Eth). However, its protective effect on testicular apoptotic germ cells has never been reported. This study aimed to investigate the potential effects of T-MP seed extract on expressions of caspase, proliferating cell nuclear antigen (PCNA), and dopamine D2 receptor (D2R) proteins in Eth rats. Thirty-six male Wistar rats were divided into four groups (9 animals/group), including control, Eth, T-MP150+Eth, and T-MP300+Eth, respectively. Control rats received distilled water, and Eth rats received Eth (3g/kg BW; 40%v/v). The T-MP groups were treated with T-MP seed extract at a dose of 150 or 300 mg/kg before Eth administration for 56 consecutive days. The results showed that the seminiferous tubule diameter and epithelial height were significantly increased in both T-MP treated groups compared to the Eth group. Additionally, the caspase-9 and -3, and PCNA expressions were decreased, but D2R expression was markedly increased in T-MP groups. It was concluded that T-MP seed extract could protect testicular apoptosis induced by Eth via changes in caspase, PCNA, and D2R protein expressions.

Polymorphisms in the HSF2, LRRC6, MEIG1 and PTIP genes correlate with sperm motility in idiopathic infertility

The aim of this study was to investigate the association of 24 functionally important single nucleotide polymorphisms (SNPs) with male infertility. In this cross-sectional study, we genotyped 24 functionally important single nucleotide polymorphisms in 24 infertility candidate genes in 500 oligo-/astheno-/oligoastheno-/normo-zoospermic infertile men with idiopathic infertility. Sequenom iPlex gold assay was used for genotyping. Sperm count and motility were compared between prevalent genotypes at each test locus. We did not observe any significant difference in the average sperm count between the alternate genotypes for the loci in the KLK3, LRRC6, MEIG1, HSF2, ESR2 and PTIP genes. However, we observed a significant difference in sperm motility between the alternate genotypes for the loci in the LRRC6, MEIG1, HSF2 and PTIP genes. Polymorphisms in the LRRC6 (rs200321595), MEIG1 (rs150031795), HSF2 (rs143986686) and PTIP (rs61752013) genes show association with sperm motility.

Sitagliptin and fucoidan prevent apoptosis and reducing ER stress in diabetic rat testes

Sitagliptin increases the levels of incretin hormones and stimulates a decrease in blood glucose levels, by blocking the DPP4 enzyme. We have very limited information about impact of sitagliptin on male genital system and relationship between sitagliptin/diabetes/ER. Fucoidan can be effective in blood glucose homeostasis. We goal to explain of the effect of sitagliptin and introduce an approach of fucoidan treatment in experimental diabetes in male rats. Fifty-eight Wistar albino rats were divided into C-control group and D-diabetes group: 60 mg/kg streptozotocin intraperitoneal (i.p.); DS group: STZ + 10 mg/kg sitagliptin intragastric (i.g.); DF group: STZ + 100 mg/kg fucoidan i.p.; and DSF group: STZ + 10 mg/kg sitagliptin + 100 mg/kg fucoidan. A significant decrease was detected when DS, DF and DSF groups compared to group D in blood glucose levels, basement membrane thickness and also apoptotic cell/tubule index, pJNK, caspase 3, caspase 12, GRP78, CHOP and DPP4. Sitagliptin and fucoidan have been found to be effective in blood glucose homeostasis and reducing the expression of certain proteins that lead to apoptosis and especially the proteins in the ER stress pathway. Therefore, we think that both sitagliptin and fucoidan can be effective in preventing or eliminating histopathological damages in diabetic testicular tissues, and their treatment effects can be used more.

Beer consumption negatively regulates hormonal reproductive status and reduces apoptosis in Leydig cells in peripubertal rats

Beer is one of the most popular alcoholic beverages consumed by young people. Ethanol intake is associated with harmful effects to the reproductive system. Bioactive compounds present in beer may diminish the toxics effect of ethanol. However, there is still little knowledge about the effect of beer consumption on hormonal regulation of male reproduction in organisms exposed to alcohol after the peripubertal age. Therefore, the aim of this study was to determine the influence of beer intake on plasma reproductive hormones, immunolocalization of cleaved caspase-3 (casp-3), and the level of the neuronal isoform of nitric oxide synthase (nNOS) in Leydig cells (LCs) in adolescent male Wistar rats. The animals, beginning at the age of 30 days, drank beer (10% ethanol; B2 group [2 weeks' exposure] and B4 group [4 weeks' exposure]), 10% ethanol solution (CE2 group [2 weeks' exposure] and CE4 group [4 weeks' exposure]), or water (C2 group [2 weeks' exposure] and C4 group [4 weeks' exposure]). Rats drinking beer for 4 weeks showed higher phenolic acid intake compared to rats drinking beer for 2 weeks. Rats exposed to beer for 4 weeks showed decreased plasma levels of follicle-stimulating hormone (FSH) and 17β-estradiol (E2) (3.173 ng/mL and 11.49 pg/mL, respectively), compared to the CE4 (5.293 ng/mL and 43.912 pg/mL, respectively) and the C4 groups (5.002 ng/mL and 41.121 pg mL, respectively). Expression of cleaved caspase-3 in LCs was lower in the B4 group rats, compared to the CE4 group rats (ID score: 1.676 vs. 2.190). No changes in nNOS expression were observed. Beer consumption revealed a similar negative effect on hormonal regulation of male reproductive function, but lower apoptosis in LCs may be beneficial for steroidogenic activity.

Ethanol-Induced Autophagy in Sertoli Cells Is Specifically Marked at Androgen-Dependent Stages of the Spermatogenic Cycle: Potential Mechanisms and Implications

In a recent study, we reported that acute ethanol exposure enhanced autophagy in Sertoli cells (SCs) of adult rats. However, further research is needed to clarify the specific spermatogenic stage exhibiting the highest autophagic response, the mechanisms behind such specificity, and the related relevance to sperm. This brief report provides results indicating that stages VII⁻VIII (androgen-dependent or spermiation stages) of the spermatogenic cycle exhibited more marked autophagic response in acute-ethanol treated rats (ETRs) than other stages based on suppression of androgen receptor (AR), analysis of microtubule-associated protein 1 light chain 3 (LC3) (an autophagosomal marker) immunostaining in SCs, double labeling of LC3 and lysosomal proteins and electron microscopy. Ultrastructural observations and TUNEL method revealed a notable presence of phagocytosed apoptotic germ cells and retained sperm in SCs of ETRs at these specific stages-a finding rarely observed in control testes. In addition, PTEN-induced putative kinase 1 ( PINK1) (a sensor of mitochondrial damage and mitophagy) and giant lipid droplets were found to have accumulated in SCs of ETRs at same stages. Our data show novel findings indicating that stages VII⁻VIII of the spermatogenic cycle exhibit high levels of autophagy, specifically under stress conditions, as expressed by the term autophagic stages. This stage-specific upregulation of autophagy in SCs may be related to AR suppression, mitochondrial damage, lipid accumulation, and phagocytosis of apoptotic cells. The phenomenon may be an essential part of ensuring the viability of SCs and supporting germ cells in toxic environments.

Murine sperm capacitation, oocyte penetration and decondensation following moderate alcohol intake

Male chronic alcohol abuse causes testicular failure and infertility. We analyzed the effects of moderate sub-chronic alcohol intake on sperm morphology, capacitation, fertilization and sperm head decondensation. CF-1 male mice were administered 15% ethanol in drinking water for 15 days; control mice received ethanol-free water. Similar patterns of tyrosine phosphorylation were observed in capacitated spermatozoa of control and treated males. Percentage of hyperactivation (H) and spontaneous (SAR) and progesterone-induced (IAR) acrosome reaction significantly decreased at 120 and 150 min of capacitation in treated males compared to controls (H: 14.1 ± 2.5 vs 23.7 ± 2.6, P < 0.05; SAR-T120 min: 17.9 ± 2.5 vs 32.9 ± 4.1, P < 0.01; IAR-150 min: 43.3 ± 3.5 vs 73.1 ± 1.1, P < 0.001, n = 6). During in vitro fertilization (2.5, 3.5 and 4.5 h post-insemination), there was an increased percentage of fertilized oocytes (with a decondensed sperm head and one or two pronuclei) in treated males (P < 0.001, n = 7). After 60 min of in vitro decondensation with glutathione plus heparin, the percentage of decondensed sperm heads was significantly higher in treated males than in controls (mean ± s.d.: 57.1 ± 5.6 vs 48.3 ± 4.5, P < 0.05, n = 5). The percentage of morphologically normal sperm heads was significantly decreased in treated males with respect to controls (P < 0.001, n = 9). These results show that short-term moderate alcohol consumption in outbred mice affect sperm morphology, hyperactivation, acrosomal exocytosis, and the dynamics of in vitro fertilization and in vitro sperm nuclear decondensation.

Impact of weight loss on sperm DNA integrity in obese men

The objective of the study was to determine whether weight loss in obese men improves their fertility with respect to DNA fragmentation index and morphology. Collected fertility parameters included DFI and morphology. Body mass index (BMI) was calculated for all patients with comparisons to their fertility parameters before and after weight loss using paired t test and chi-square tests. The mean BMI was significantly higher in group 1, before weight loss (33.18 kg/m2 ), than in group 2, after weight loss (30.43 kg/m2 ). Overall, 53.3% of men had DFI <20% while 43.8% had a DFI between 20% and 40%, and 2.9% of men had DFI >40%. The mean DFI of participants was higher before weight loss (20.2%) and had improved significantly after weight loss (17.5%) (p = <.001). The weight loss had significant positive correlation with percentage of DFI. There was a significant improvement in morphology after weight loss (p = <.05). In one of the largest cohorts of male fertility and obesity, DFI and morphology demonstrated significant relationship with adiposity, possibly contributing to subfertility in this population.

Upregulated Autophagy in Sertoli Cells of Ethanol-Treated Rats Is Associated with Induction of Inducible Nitric Oxide Synthase (iNOS), Androgen Receptor Suppression and Germ Cell Apoptosis

This study was conducted to investigate the autophagic response of Sertoli cells (SCs) to acute ethanol toxicity using in vivo and in vitro models. Adult Wistar rats were intraperitoneally injected with either 5 g/kg ethanol or phosphate-buffered saline (for the control group) and sacrificed 0, 3, 6 and 24 h after injection. Compared to the control group, enhanced germ cell apoptosis was observed in the ethanol-treated rats (ETRs) in association with upregulation of iNOS and reduced expression of androgen receptor protein levels in SCs, which were resistant to apoptosis. Meanwhile, autophagy was upregulated in ETR SCs (peaking at 24 h) compared to the control group, as evidenced by transcription factor EB (TFEB) nuclear translocation, enhanced expression of microtubule-associated protein 1 light chain3-II (LC3-II), lysosome-associated membrane protein-2 (LAMP-2), pan cathepsin protein levels and reduced expression of p62. This upregulation of SC autophagy was confirmed ultrastructurally by enhanced formation of autophagic vacuoles and by immunofluorescent double labelling of autophagosomal and lysosomal markers. Study of cultured SCs confirmed enhanced autophagic response to ethanol toxicity, which was cytoprotective based on decreased viability of SCs upon blocking autophagy with 3-methyladenine (3-MA). The results highlighted the molecular mechanisms of prosurvival autophagy in ETR SCs for the first time, and may have significant implications for male fertility.

Diethylstilbestrol induces oxidative DNA damage, resulting in apoptosis of spermatogonial stem cells in vitro

) in SSCs was detected using p-Nitro Blue Tetrazolium (NBT) assay. The viability of cells after DES treatment was examined in the CCK8 (cell counting kit-8) cytotoxicity assay. The results showed that DES-induced DNA damage causes an increase in intracellular superoxide anions which are reduced by the flavonoid, quercetin. Investigating the molecular mechanisms and biology of SSCs provides a better understanding of spermatogonial stem cell regulation in the testis.

Studies on the characteristics and mechanisms of testicular toxicity induced by Hydroxyurea

OBJECTIVE

Apoptosis plays a dominant role in both spontaneous spermatogenesis and germ cell death. This study was aimed to investigate the functions of related genes in testicular germ cell death induced by Hydroxyurea (HU).

METHOD

Wild-type (WT) and FasL transgenic (TG) DBA/C57BL mice were intraperitoneal injected with 400 mg/kg HU. Twelve hours later, testes were collected. Histomorphology of testis was observed by staining with Periodic Acid Schiff (PAS). Apoptosis was assessed by TUNEL assay. mRNA and protein levels of related genes were evaluated by quantitative RT-PCR and Western blot, respectively.

RESULTS

The 2 × 2 factorial design comparative experiments between the WT and TG mice showed that the TG mice exhibited a higher basal apoptotic index. The basal mRNA levels of Fas and FasL and protein levels of Fas, FasL, Caspase-3, Caspase-8 and Caspase-9 in the TG mice were also higher than that in the WT mice. Twelve hours after injection of HU, the testicular tubules exhibited no significantly morphological changes but apoptosis index remarkably increased in both the WT and TG mice, with the latter having the higher amplitude. Although, HU up-regulated the mRNA of apoptosis-related genes, such as Fas and FasL, in both the TG and WT mice, the increased amplitude was more obvious in the TG mice. By Western blot analysis, apoptosis-related proteins Fas, FasL Caspase-3, Caspase-8 and Caspase-9 were significantly increased in both the WT and TG mice, with the TG mice exhibiting a greater up-regulation.

CONCLUSION

Germ cell apoptosis induced by the HU treatment may be related to the FasL-mediated signal transduction pathway.

Protective effects of propolis on methotrexate-induced testis injury in rat

Propolis is an adhesive substance which is collected and used by honeybees. Propolis is a potent antioxidant and a free radical scavenger. This study was designed to determine whether propolis could protect against dysfunction and oxidative stress induced by methotrexate-induced injury in rat testis. A total of 40 male Wistar albino rats were divided into four groups: group 1 was the untreated control. On the eighth day of the experiment, groups 2 and 3 received single intraperitoneal injections of methotrexate (MTX) at 20mg/kg. Groups 3 and 4 received 100mg/kg/day propolis (by oral gavage) for 15 days by the first day of the experimental protocol. Then the rats were decapitated under anesthesia, and their testes were removed. The histopathological and biochemical analysis along with apoptosis assessment of testis tissues were compared. Immunohistochemical analysis of Heat shock protein-70 (HSP-70) and Proliferating Cell Nuclear Antigen (PCNA) were performed. The phenolic characterization of propolis was performed by Liquid chromatography-mass spectrometry (LC-MS/MS). Methotrexate caused tended to increase in malondialdehyde level and in the number of apoptotic cells; it also caused a decrease in MSTD and JTBS, PCNA and HSP-70 expression and xanthine oxidase levels in group 2. Propolis prevented the rise in malondialdehyde, xanthine oxidase levels and HSP-70 expression and improved testicular morphology and JTBS. It was found that, methorexate gives rise to serious damage in the testes and propolis is a potent antioxidant agent in preventing testicular injury.

Implications of Sertoli cell induced germ cell apoptosis to testicular pathology

After exposure to toxicants, degenerating germ cells represents the most common testicular histopathological alteration, regardless of the mechanism of toxicity. Therefore, deciphering the primary toxicant cellular target and mechanism of action can be extremely difficult. However, most testicular toxicants display a cell-specific and a stage-specific pattern of damage, which is the best evidence for identifying the primary cellular target (i.e. germ cell, Sertoli cell, peritubular myoid cell, or Leydig cell). Some toxicant-induced Sertoli cell injury presents with germ cell apoptosis occurring primarily in spermatocytes in rats in stages XI-XIV, I and II. Although some toxicants result in spermatid degeneration and apoptosis, it is still unclear if spermatid apoptosis is a result of Sertoli cell-selective apoptosis or a direct effect of toxicants on spermatids, therefore if this is seen as the earliest change, one cannot infer the mechanism of apoptosis. This review summarizes some of the distinguishing features of Sertoli cell-induced germ cell apoptosis and the associated mechanisms of cell death to provide the toxicologist observing similar cell death, with evidence about a potential mode of action.

Clinical factors associated with sperm DNA fragmentation in male patients with infertility

OBJECTIVE

The clinical factors associated with sperm DNA fragmentation (SDF) were investigated in male patients with infertility.

MATERIALS AND METHODS

Fifty-four ejaculates from infertile Japanese males were used. Thirty-three and twenty-one were from the patients with varicoceles and idiopathic causes of infertility, respectively. We performed blood tests, including the serum sex hormone levels, and conventional and computer-assisted semen analyses. The sperm nuclear vacuolization (SNV) was evaluated using a high-magnification microscope. The SDF was evaluated using the sperm chromatin dispersion test (SCDt) to determine the SDF index (SDFI). The SDFI was compared with semen parameters and other clinical variables, including lifestyle factors.

RESULTS

The SDFI was 41.3 ± 22.2% (mean ± standard deviation) and did not depend on the cause of infertility. Chronic alcohol use increased the SDFI to 49.6 ± 23.3% compared with 33.9 ± 18.0% in nondrinkers. The SDFI was related to adverse conventional semen parameters and sperm motion characteristics and correlated with the serum FSH level. The SNV showed a tendency to increase with the SDFI. The multivariate analysis revealed that the sperm progressive motility and chronic alcohol use were significant predictors of the SDF.

CONCLUSION

The SCDt should be offered to chronic alcohol users and those with decreased sperm progressive motility.

Autophagy in the endocrine glands

Autophagy is an important cellular process involving the degradation of intracellular components. Its regulation is complex and while there are many methods available, there is currently no single effective way of detecting and monitoring autophagy. It has several cellular functions that are conserved throughout the body, as well as a variety of different physiological roles depending on the context of its occurrence in the body. Autophagy is also involved in the pathology of a wide range of diseases. Within the endocrine system, autophagy has both its traditional conserved functions and specific functions. In the endocrine glands, autophagy plays a critical role in controlling intracellular hormone levels. In peptide-secreting cells of glands such as the pituitary gland, crinophagy, a specific form of autophagy, targets the secretory granules to control the levels of stored hormone. In steroid-secreting cells of glands such as the testes and adrenal gland, autophagy targets the steroid-producing organelles. The dysregulation of autophagy in the endocrine glands leads to several different endocrine diseases such as diabetes and infertility. This review aims to clarify the known roles of autophagy in the physiology of the endocrine system, as well as in various endocrine diseases.

Elevated autophagic sequestration of mitochondria and lipid droplets in steatotic hepatocytes of chronic ethanol-treated rats: an immunohistochemical and electron microscopic study

Ethanol-induced hepatic steatosis may induce the progression of alcoholic liver disease. The involvement of autophagic clearance of damaged mitochondria (mitophagy) and lipid droplets (LDs) (lipophagy) in chronic ethanol-induced hepatic steatosis is not clearly understood. Adult Wistar rats were fed either 5 % ethanol in Lieber-DeCarli liquid diet or an isocaloric control diet for 10 weeks. Light microscopy showed marked steatosis in hepatocytes of ethanol-treated rats (ETRs), which was further revealed by transmission electron microscopy (TEM), where significant numbers of large LDs and damaged mitochondria were detected in steatotic hepatocytes. Moreover, TEM demonstrated that hepatocyte steatosis was associated with greatly enhanced autophagic vacuole (AV) formation compared to control hepatocytes. Mitochondria and LDs were the predominant contents of AVs in steatotic hepatocytes. Immunohistochemistry of LC3, a specific marker of early AVs (autophagosomes), demonstrated an extensive punctate pattern in hepatocytes of ETRs, while LC3 puncta were much less frequent in control hepatocytes. This was confirmed by immunoelectron microscopy (IEM), which showed localization of LC3 to autophagosomes sequestering damaged mitochondria and LDs. In addition, IEM revealed that PINK1 (a sensor of mitochondrial damage and marker of mitophagy) was overexpressed in mitochondria of ETRs. Enhanced autophagic lysosomal activity was evidenced by increased immunolabeling of LAMP-2, a marker of late AVs (autolysosomes) in hepatocytes of ETRs and colocalization of LC3 and lysosomal cathepsins using double immunofluorescence labeling. Increased AVs in hepatocytes of ETRs reflect ethanol toxicity and could represent a possible protective mechanism via stimulation of mitophagy and lipophagy.

Enhanced mitophagy in Sertoli cells of ethanol-treated rats: morphological evidence and clinical relevance

Although chronic ethanol consumption results in Sertoli cell vacuolization and augmented testicular germ cell apoptosis via death receptor and mitochondrial pathways, Sertoli cells are resistant to apoptosis. The aim of this study was to examine whether the activation of autophagy in the Sertoli cells of ethanol-treated rats (ETR) may have a role in their survival. Adult Wistar rats were fed either 5% ethanol in Lieber-DeCarli liquid diet or an isocaloric control diet for 12 weeks. The TUNEL method demonstrated that Sertoli cells were always TUNEL-negative despite the presence of many apoptotic germ cells in ETR, supporting our previous studies. Electron microscopy revealed the presence of large numbers of autophagic vacuoles (AVs) in Sertoli cells of ETR compared to few AVs in control testes. Most of the AVs in Sertoli cells of ETR enveloped and sequestered damaged and abnormally shaped mitochondria, without cytoplasm, indicating mitochondrial autophagy (mitophagy). Immuno-electron microscopy showed the localization of LC3, a specific marker of early AVs (autophagosomes), around AVs sequestering mitochondria in Sertoli cells of ETR. Immunohistochemical staining of LC3 demonstrated a punctate pattern in Sertoli cells of ETR, confirming the formation of autophagosomes, while LC3 puncta were almost absent in control testes. Moreover, increased immunoreactivity of LAMP-2, a lysosomal membrane protein and marker of late AVs (autolysosomes), was mainly observed in Sertoli cells of ETR, with weaker expression in control testes. Via the deletion of pro-apoptotic damaged mitochondria, enhanced Sertoli cell mitophagy in ETR may be an anti-apoptotic mechanism that is essential for spermatogenesis.

Male germ cell apoptosis: regulation and biology

Cellular apoptosis appears to be a constant feature in the adult testis and during early development. This is essential because mammalian spermatogenesis is a complex process that requires precise homeostasis of different cell types. This review discusses the latest information available on male germ cell apoptosis induced by hormones, toxins and temperature in the context of the type of apoptotic pathway either the intrinsic or the extrinsic that may be used under a variety of stimuli. The review also discusses the importance of mechanisms pertaining to cellular apoptosis during testicular development, which is independent of exogenous stimuli. Since instances of germ cell carcinoma have increased over the past few decades, the current status of research on apoptotic pathways in teratocarcinoma cells is included. One other important aspect that is covered in this review is microRNA-mediated control of germ cell apoptosis, a field of research that is going to see intense activity in near future. Since knockout models of various kinds have been used to study many aspects of germ cell development, a comprehensive summary of literature on knockout mice used in reproduction studies is also provided.

[Sperm apoptosis: myth or reality?]

Apoptosis has become a popular biologic concept, for many reasons. From embryonic development to adult tissues, apoptosis is necessary to maintain tissues homeostasis in most organ systems during organogenesis and in the adult. Human spermatogenetic epithelium is also concerned. Dysregulations of this process are involved in many pathologies (leukaemia, auto-immune diseases, etc...), and some forms of male infertility also. Apoptotic features have been found in human semen from infertile patients, and could become useful in order to appreciate semen quality, especially in Assisted Reproductive Technology (ART). Despite numerous studies, some questions remain, especially about meaning of apoptotic damages of spermatozoa.

Impairment of adult male reproductive function in rats exposed to ethanol since puberty

The objective of this work was to evaluate reproductive function in adult male rats exposed to ethanol since puberty. Male Wistar rats, 50 days old, received a liquid diet with 36% of the daily calories derived from ethanol or an isocaloric control diet for 55 days. The ethanol treatment impaired sexual behavior and only 22% of these rats reached ejaculation. The fertility of ethanol-treated animals was significantly reduced, mainly after natural mating. Serum testosterone levels, daily sperm production and sperm count in the epididymis were also significantly diminished after ethanol treatment, associated with an acceleration of the sperm transit time in the cauda epididymidis, decrease in sperm motility and increased percentage of abnormal shaped sperm cells. The results showed that chronic consumption of ethanol beginning at puberty impairs the reproductive function of adult male rats.

Death receptor and mitochondrial pathways are involved in germ cell apoptosis in an experimental model of autoimmune orchitis

BACKGROUND

Studies on experimental autoimmune orchitis (EAO) have helped to elucidate immunological mechanisms involved in testicular damage. We previously demonstrated that EAO is characterized by lymphomononuclear cell infiltrates and apoptosis of spermatocytes and spermatids expressing Fas and TNFR1. The aim of this work was to characterize the pathways involved in germ cell apoptosis in EAO and to determine the involvement of the Bcl-2 protein family in this process.

METHODS AND RESULTS

EAO was induced in rats by immunization with testicular homogenate (TH) and adjuvants, whereas control (C) rats were injected with saline solution and adjuvants. Testis of EAO rats showed procaspase 8 cleavage products (western blot) with high caspase 8 activity. Cytochrome c content increased in the cytosol and decreased in the mitochondrial fraction of testis from EAO rats compared with C, concomitant with increased caspase 9 activity. Bax was mainly expressed in spermatocytes and spermatids and Bcl-2 in basal germ cells (immunohistochemistry). Baxbeta isoform content increased in EAO rat testis compared with C, whereas content of Baxalpha remained unchanged (western blot). However, Baxalpha content decreased in the cytosol and increased in the mitochondrial and endoplasmic reticulum (ER)-enriched fractions of testis from EAO rats compared with C (western blot). Bcl-2 content also increased in the testes of EAO rats.

CONCLUSIONS

Our results demonstrated that extrinsic, mitochondrial and possibly ER pathways are inducers of germ cell apoptosis in EAO and that Bax and Bcl-2 proteins modulate this process.

Effect of lifestyle exposures on sperm aneuploidy

Lifestyle exposures including cigarette smoke, alcohol, and caffeine have all been studied in relationship to male reproductive health. Over the years the focus has primarily been on semen quality and/or fertility. More recently, literature evaluating direct adverse effects of lifestyle exposures on sperm chromosomes and chromatin has grown due to concern that induced damage could be transmitted to offspring causing transgenerational health effects. In this paper we present a new analysis that summarizes published studies of smoking effects on sperm chromosome number and demonstrates a statistically significant increase in sperm disomy among smokers compared to nonsmokers (P < 0.001). In addition, new data on the effect of alcohol intake on sperm chromosome number are presented showing a rate ratio of 1.38 (95% CI 1.2, 1.6) for XY frequency in sperm of alcohol drinkers compared to nondrinkers.

Ontogenesis and cell specific localization of Fas ligand expression in the rat testis

Over the past few years, a number of experimental evidences suggested the involvement of Fas Ligand (FasL) expressing Sertoli cells to induce apoptosis of Fas bearing germ cells. However, the FasL expression during testicular development and its cell specific localization within the testis is still a matter of debate. In the present study, we have monitored FasL expression during rat testis development by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and evaluated cell specific localization of FasL expression, by in situ RT-PCR and immunohistochemistry, on adult rat testis. RT-PCR analysis, performed on total RNA from rat testes obtained from 1 day up to 1-year-old animals, demonstrated the presence of FasL transcripts at all developmental stages examined. In situ RT-PCR analysis clearly indicated the presence of FasL mRNA in Sertoli cells of adult testis, while we could never detect FasL transcripts in germ cells. Immunohistochemistry experiments showed a strong immunostaining for FasL in Sertoli cells of adult testis and again, no immunopositivity was observed in germ cells. In conclusion, our data suggest that FasL expression in rat testis is present from the early postnatal days up to the adult, and the Sertoli cells is the main FasL expressing cell within the seminiferous tubule.

Enhancement of germ cell apoptosis induced by ethanol in transgenic mice overexpressing Fas Ligand

It was suggested that chronic ethanol exposure could result in testicular germ cell apoptosis, but the mechanism is still unclear. In the present study, we use a model of transgenic mice ubiquitously overexpressing human FasL to investigate whether Fas ligand plays a role in ethanol-induced testicular germ cell apoptosis. Both wild-type (WT) mice and transgenic (TG) mice were treated with acute ethanol (20% v/v) by introperitoneal injection for five times. After ethanol injection, WT mice displayed up-regulation of Fas ligand in the testes, which was shown by FITC-conjugated flow cytometry and western blotting. Moreover, TG mice exhibited significantly more apoptotic germ cells than WT mice did after ethanol injection, which was demonstrated by DNA fragmentation, PI staining flow cytometry and TUNEL staining. In addition, histopathological examination revealed that degenerative changes of epithelial component of the tubules occurred in FasL overexpressing transgenic mice while testicular morphology was normal in wild-type mice after acute ethanol exposure, suggesting FasL expression determines the sensitivity of testes to ethanol in mice. In summary, we provide the direct evidences that Fas ligand mediates the apoptosis of testicular germ cells induced by acute ethanol using FasL transgenic mice.

Effects of ethanol on embryonic and neonatal rat testes in organ cultures

Ethanol exposure in adult animals and humans has shown to elicit significant inhibitory effects on the function of male reproduction, but consequences of ethanol exposure on the embryonic and early postnatal testis development are not known. The current study investigated the effect of ethanol on embryonic and neonatal testis development using an organ culture technique. In embryonic day 13 (E13) testis organ cultures, ethanol had no effect on the testicular cord formation, the expression of Müllerian-inhibiting substance (MIS) in Sertoli cells or the number of gonocytes. Similarly, in the ethanol-treated embryonic day 18 (E18) testes, both the number of gonocytes and the expression of GATA-4 and MIS were similar to those from the control testes. In contrast, in postnatal day 3 (P3) testes, ethanol at concentrations of 150 and 200 mM significantly decreased the number of gonocytes without affecting the expression of GATA-4 and MIS in Sertoli cells. This effect was shown to be resulting from the enhanced apoptosis of gonocytes. In addition, ethanol abnormally activated retinoic acid receptor alpha (RARalpha), as indicated by increased nuclear localization of RARalpha with increasing doses of ethanol treatment. These observations suggest that the effect of ethanol on testis varies at different stages during embryonic and neonatal testis development. Furthermore, germ cells may be the main target for the action of ethanol on the early postnatal testis.

Diethylstilbestrol induces rat spermatogenic cell apoptosis in vivo through increased expression of spermatogenic cell Fas/FasL system

The significant role that estrogens play in spermatogenesis has opened up an exciting area of research in male reproductive biology. The realization that estrogens are essential for proper maintenance of spermatogenesis, as well as growing evidence pointing to the deleterious effects of estrogen-like chemicals on male reproductive health, has made it imperative to dissect the role estrogens play in the male. Using a model estrogen, diethylstilbestrol (DES), to induce spermatogenic cell apoptosis in vivo in the male rat, we provide a new insight into an estrogen-dependent regulation of the Fas-FasL system specifically in spermatogenic cells. We show a distinct increase in Fas-FasL expression in spermatogenic cells upon exposure to diethylstilbestrol. This increase is confined to the spermatid population, which correlates with increased apoptosis seen in the haploid cells. Testosterone supplementation is able to prevent DES-induced Fas-FasL up-regulation and apoptosis in the spermatogenic cells. DES-induced germ cell apoptosis does not occur in Fas-deficient lpr mice. One other important finding is that spermatogenic cells are type II cells, as the increase in Fas-FasL expression in the spermatogenic cells is followed by the cleavage of caspase-8 to its active form, following which Bax translocates to the mitochondria and precipitates the release of cytochrome c that is accompanied by a drop in mitochondrial potential. Subsequent to this, activation of caspase-9 occurs that in turn activates caspase-3 leading to the cleavage of poly(ADP-ribose) polymerase. Taken together, the data indicate that estrogen-like chemicals can precipitate apoptotic death in spermatogenic cells by increasing the expression of spermatogenic cell Fas-FasL, thus initiating apoptosis in the same lineage of cells through the activation of the apoptotic pathway chosen by type II cells.

Physiological and pathological cell deaths in the reproductive organs

Apoptosis of testicular germ cells and oocytes and their supporting cells in the gonads occurs at physiological and normal conditions or after exposure to pathological stimuli. Cell-death regulators, including Bcl-2 family members, caspases, Fas and p53 are thought to be involved in these processes. This article reviews the details of the apoptotic machinery in the reproductive organs by describing briefly the abnormal phenotypes observed in transgenic and gene-ablated mice.