Experimental cryptorchidism induces testicular germ cell apoptosis by p53-dependent and -independent pathways in mice

Heat wave exposure and semen quality in sperm donation volunteers: A retrospective longitudinal study in south China

BACKGROUND

Previous studies have suggested an association between non-optimum ambient temperature and decreased semen quality. However, the effect of exposure to heat waves on semen quality remains unclear.

METHODS

Volunteers who intended to donate sperm in Guangdong provincial human sperm bank enrolled. Heat waves were defined by temperature threshold and duration, with a total of 9 definitions were employed, specifying daily mean temperature exceeding the 85th, 90th, or 95th percentile for at least 2, 3, or 4 consecutive days. Residential exposure to heat waves during 0-90 days before ejaculation was evaluated using a validated gridded dataset on ambient temperature. Association and potential windows of susceptibility were evaluated and identified using linear mixed models and distributed lag non-linear models.

RESULTS

A total of 2183 sperm donation volunteers underwent 8632 semen analyses from 2018 to 2019. Exposure to heat wave defined as daily mean temperature exceeding the 95th percentile for at least 4 consecutive days (P95-D4) was significantly associated with a 0.11 (95% confidence interval [CI]: 0.03, 0.18) ml, 3.36 (1.35, 5.38) × 106/ml, 16.93 (7.95, 25.91) × 106, and 2.11% (1.4%, 2.83%) reduction in semen volume, sperm concentration, total sperm number, and normal forms, respectively; whereas exposure to heat wave defined as P90-D4 was significantly associated with a 1.98% (1.47%, 2.48%) and 2.08% (1.57%, 2.58%) reduction in total motility and progressive motility, respectively. Sperm count and morphology were susceptible to heat wave exposure during the early stage of spermatogenesis, while sperm motility was susceptible to exposure during the late stage.

CONCLUSION

Heat wave exposure was significantly associated with a reduction in semen quality. The windows of susceptibility during 0-90 days before ejaculation varied across sperm count, motility, and morphology. Our findings suggest that reducing heat wave exposure before ejaculation may benefit sperm donation volunteers and those attempting to conceive.

Effects of electroacupuncture at ST36 and BL20 on the diabetic rat testis

OBJECTIVE

We aimed to evaluate the effects of electroacupuncture (EA) at ST36 and BL20 on the testicular tissues in a rat model of diabetes and to explore the mechanisms of action.

METHODS

A total of 34 male Sprague-Dawley rats were allocated to a control group (n = 10), diabetes (D) group (n = 12) or diabetes + acupuncture (DA) group (n = 12). To model diabetes, rats in groups D and DA received an intraperitoneal injection of a single dose of 35 mg/kg streptozotocin (STZ) dissolved in citrate buffer (pH = 4.5; 0.1 M) after 2 weeks of high-fat diet administration. Under xylazine/ketamine anesthesia, stainless steel needles (30 mm × 0.25 mm) were inserted bilaterally at ST36 and BL20. The needles were connected to an EA device via cables, and EA was applied for 30 min (15 Hz frequency and 0.2-1 mA intensity) twice a week for 5 weeks.

RESULTS

The effects of EA at ST36 and BL20 on blood glucose levels and body weight, biochemical parameters, histopathological, morphometric and immunohistochemical findings, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) analysis were evaluated. A significant decrease was detected in DA versus D groups in blood glucose levels, basement membrane thickness and apoptotic cell/tubule indices. In addition, there was a significant increase in the Johnsen scores, seminiferous tubule diameters, serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH) and testosterone, proliferation indices, and sex hormone-binding globulin (SHBG) and insulin-like peptide 3 (INSL3) immunoreactivities.

CONCLUSION

EA had multiple positive effects on blood glucose homeostasis and testicular structure/function in this rat model of diabetes. EA may be effective at preventing or eliminating histopathological damage in the diabetic testis.

Testicular heat stress, a historical perspective and two postulates for why male germ cells are heat sensitive

Herein, we compare the different experimental regimes used to induce testicular heat stress and summarise their impact on sperm production and male fertility. Irrespective of the protocol used, scrotal heat stress causes loss of sperm production. This is first seen 1-2 weeks post heat stress, peaking 4-5 weeks thereafter. The higher the temperature, or the longer the duration of heat, the more pronounced germ cell loss becomes, within extreme cases this leads to azoospermia. The second, and often underappreciated impact of testicular hyperthermia is the production of poor-quality spermatozoa. Typically, those cells that survive hyperthermia develop into morphologically abnormal and poorly motile spermatozoa. While both apoptotic and non-apoptotic pathways are known to contribute to hyperthermic germ cell loss, the mechanisms leading to formation of poor-quality sperm remain unclear. Mechanistically, it is unlikely that testicular hyperthermia affects messenger RNA (mRNA) abundance, as a comparison of four different mammalian studies shows no consistent single gene changes. Using available evidence, we propose two novel models to explain how testicular hyperthermia impairs sperm formation. Our first model suggests aberrant alternative splicing, while the second model proposes a loss of RNA repression. Importantly, neither model requires consistent changes in RNA species.

Unraveling the harmful effect of oxidative stress on male fertility: A mechanistic insight

Male infertility is a widely debated issue that affects males globally. There are several mechanisms involved. Oxidative stress is accepted to be the main contributing factor, with sperm quality and quantity affected by the overproduction of free radicals. Excess reactive oxygen species (ROS) cannot be controlled by the antioxidant system and, thus, potentially impact male fertility and hamper sperm quality parameters. Mitochondria are the driving force of sperm motility; irregularities in their function may lead to apoptosis, alterations to signaling pathway function, and, ultimately, compromised fertility. Moreover, it has been observed that the prevalence of inflammation may arrest sperm function and the production of cytokines triggered by the overproduction of ROS. Further, oxidative stress interacts with seminal plasma proteomes that influence male fertility. Enhanced ROS production disturbs the cellular constituents, particularly DNA, and sperms are unable to impregnate the ovum. Here, we review the latest information to better understand the relationship between oxidative stress and male infertility, the role of mitochondria, the cellular response, inflammation and fertility, and the interaction of seminal plasma proteomes with oxidative stress, as well as highlight the influence of oxidative stress on hormones; collectively, all of these factors are assumed to be important for the regulation of male infertility. This article may help improve our understanding of male infertility and the strategies to prevent it.

Seasonal Expression of Gonadotropin Genes in the Pituitary and Testes of Male Plateau Zokor (Eospalax baileyi)

The gonadotropins, luteinizing hormone (LH) and follicle stimulating hormone (FSH), are glycoprotein hormones in the hypothalamic-pituitary-gonadal (HPG) axis and regulate mammalian reproduction. The expression of these genes in the plateau zokor (Eospalax baileyi) is poorly understood. We characterized the immunolocalization of the luteinizing hormone receptor (LHR) and follicle stimulating hormone receptor (FSHR) in the testes and evaluated the positive immunohistochemical results and the relative mRNA expression of gonadotropin genes. During the non-breeding season (September), the relative testes weight and the seminiferous tubule diameter were significantly reduced. All germ cell types were observed during the breeding season (May), whereas only spermatogonia were observed during the non-breeding season. LHR was present in the Leydig cells whereas FSHR was present in the Sertoli cells. The mean optical density was higher during the breeding season. The mRNA expression of LHβ and FSHβ was lower in the pituitary but LHR and FSHR genes expression were higher in the testes during the breeding season. These data elucidate the expression of gonadotropin genes in the HPG axis of the male plateau zokor and suggest that gonadotropins play a vital role in the regulation of seasonal breeding.

Damaged male germ cells induce epididymitis in mice

Epididymitis can be caused by infectious and noninfectious etiological factors. While microbial infections are responsible for infectious epididymitis, the etiological factors contributing to noninfectious epididymitis remain to be defined. The present study demonstrated that damaged male germ cells (DMGCs) induce epididymitis in mice. Intraperitoneal injection of the alkylating agent busulfan damaged murine male germ cells. Epididymitis was observed in mice 4 weeks after the injection of busulfan and was characterized by massive macrophage infiltration. Epididymitis was coincident with an accumulation of DMGCs in the epididymis. In contrast, busulfan injection into mice lacking male germ cells did not induce epididymitis. DMGCs induced innate immune responses in epididymal epithelial cells (EECs), thereby upregulating the pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β), as well as the chemokines such as monocyte chemotactic protein-1 (MCP-1), monocyte chemotactic protein-5 (MCP-5), and chemokine ligand-10 (CXCL10). These results suggest that male germ cell damage may induce noninfectious epididymitis through the induction of innate immune responses in EECs. These findings provide novel insights into the mechanisms underlying noninfectious epididymitis, which might aid in the diagnosis and treatment of the disease.

Protective effects of crocin on acrylamide-induced testis damage

Exposure to acrylamide (Ac) through food is almost inevitable and this kind of toxicity may cause lifelong harm. In present study, we researched effects of Crocin (Cr) on testis histopathology in Ac-induced testis of rats. Adult male rats were grouped as: group 1, 1 ml saline only; group 2, 50 mg/kg Cr only; group 3, 25 mg/kg Ac only and group 4, 25 mg/kg Ac + 50 mg/kg Cr. All administrations were given as 1 ml/day by gavage for 21 days. It was found that Ac adversely influenced the levels of FSH, testosterone and LH in the blood serum; malondialdehyde (MDA), total antioxidant status (TOS), oxidative stress index (OSI)/ glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), total antioxidant status (TAS) oxidant/antioxidant parameters in testis tissue (p < .01) and the histopathological parameters like Johnson's score, seminiferous tubule diameter, seminiferous epithelial height and H-score for caspase-3 immunoreactivity. In contrary, Cr treatment resulted in increase in testosterone, follicle stimulating hormone (FSH), luteinizan hormone (LH) levels and SOD, CAT, GSH, TAS levels (p < .01) and improved all the histopathological changes. In conclusion, Cr has a promising protective potential against Ac-caused toxic damages in testicular tissue.

Amelioration of heat stress-induced damage to testes and sperm quality

Heat stress (HS) occurs when temperatures exceed a physiological range, overwhelming compensatory mechanisms. Most mammalian testes are ∼4-5 °C cooler than core body temperature. Systemic HS or localized warming of the testes affects all types of testicular cells, although germ cells are more sensitive than either Sertoli or Leydig cells. Increased testicular temperature has deleterious effects on sperm motility, morphology and fertility, with effects related to extent and duration of the increase. The major consequence of HS on testis is destruction of germ cells by apoptosis, with pachytene spermatocytes, spermatids and epididymal sperm being the most susceptible. In addition to the involvement of various transcription factors, HS triggers production of reactive oxygen species (ROS), which cause apoptosis of germ cells and DNA damage. Effects of HS on testes can be placed in three categories: testicular cells, sperm quality, and ability of sperm to fertilize oocytes and support development. Various substances have been given to animals, or added to semen, in attempts to ameliorate heat stress-induced damage to testes and sperm. They have been divided into various groups according to their composition or activity, as follows: amino acids, antibiotics, antioxidant cocktails, enzyme inhibitors, hormones, minerals, naturally produced substances, phenolic compounds, traditional herbal medicines, and vitamins. Herein, we summarized those substances according to their actions to mitigate HS' three main mechanisms: oxidative stress, germ cell apoptosis, and sperm quality deterioration and testicular damage. The most promising approaches are to use substances that overcome these mechanisms, namely reducing testicular oxidative stress, reducing or preventing apoptosis and promoting recovery of testicular tissue and restoring sperm quality. Although some of these products have considerable promise, further studies are needed to clarify their ability to preserve or restore fertility following HS; these may include more advanced sperm analysis techniques, e.g. sperm epigenome or proteome, or direct assessment of fertilization and development, including in vitro fertilization or breeding data (either natural service or artificial insemination).

Surgery-induced cryptorchidism induces apoptosis and autophagy of spermatogenic cells in mice

Cryptorchidism, characterized by the presence of one (unilateral) or both (bilateral) undescended testes, is a common male urogenital defect. Cryptorchidism can lead to male infertility, testicular cancer being the most extreme clinical symptom, as well as psychological issues of the inflicted individual. Despite this, both knowledge about the aetiology of cryptorchidism and the mechanism for cryptorchidism-induced male infertility remain limited. In this present study, by using an artificial cryptorchid mouse model, we investigated the effects of surgery-induced cryptorchidism on spermatogenic cells and seminiferous epithelial cycles. We found that surgery-induced cryptorchidism led to a reduced testicular weight, aberrant seminiferous epithelial cycles and impaired spermatogenesis characterized by degenerating spermatogenic cells. We also observed multinucleated giant cells after surgery-induced cryptorchidism. Transmission electron microscopy, terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) and western blot assays demonstrated cryptorchidism-induced apoptosis of spermatogenic cells. Moreover, we identified the occurrence of autophagy in germ cells after surgery-induced cryptorchidism. Interestingly, apoptosis and autophagy were synchronous, suggestive of their synergetic roles in promoting germ cell death. Our results provide novel insights into the cryptorchidism-induced male infertility, thereby contributing to the development of male contraceptive strategies as well as treatment options for male infertility caused by cryptorchidism.

Seasonal Changes of Serum Gonadotropins and Testosterone in Men Revealed by a Large Data Set of Real-World Observations Over Nine Years

Environmental rhythmicity is able to affect the hypothalamic-pituitary-gonadal axis in several animals to achieve reproductive advantages. However, conflicting results were obtained when assessing the environmental-dependent rhythmicity on reproductive hormone secretion in humans. This study was designed to evaluate seasonal fluctuations of the main hormones involved in the hypothalamic-pituitary-gonadal axis in men, using a big data approach. An observational, retrospective, big data trial was carried out, including all testosterone, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) measurements performed in a single laboratory between January 2010 and January 2019 using Chemiluminescent Microparticle Immunoassay. Subjects presenting any factor interfering with the hypothalamic-pituitary-gonadal axis were excluded. The trend and seasonal distributions were analyzed using autoregressive integrated moving average (ARIMA) models. A total of 12,033 data, accounting for 7,491 men (mean age 47.46 ± 13.51 years, range 18-91 years) were included. Testosterone serum levels (mean 5.34 ± 2.06 ng/dL, range 1.70-15.80 ng/dL) showed a seasonal distribution with higher levels in summer and a direct correlation to environmental temperatures and daylight duration. LH levels (mean 4.64 ± 2.54 IU/L, range 1.00-15.00 IU/L) presented 2 peaks of secretion in autumn and spring, independently from environmental parameters. FSH levels (mean 5.51 ± 3.24 IU/L) did not show any seasonal distribution. A clear seasonal fluctuation of both LH and testosterone was demonstrated in a large cohort of adult men, although a circannual seasonality of hypothalamic-pituitary-gonadal hormones in humans could be not strictly evolutionarily required. Testosterone seasonality seems independent from LH fluctuations, which could be regulated by cyclic central genes expression, and more sensible to environmental temperatures and daylight duration.

Altered miRNA profile in testis of post-cryptorchidopexy patients with non-obstructive azoospermia

BACKGROUND

Cryptorchidism is one of the most common causes of non-obstructive azoospermia (NOA) leading to male infertility. Despite various medical approaches been utilised, many patients still suffer from infertility. MicroRNAs (miRNAs) play vital roles in the progress of spermatogenesis; however, little is known about the miRNA expression profile in the testes. Therefore, the miRNA profile was assessed in the testis of post-cryptorchidopexy patients.

METHODS

Three post-cryptorchidopexy testicular tissue samples from patients aged 23, 26 and 28 years old and three testis tissues from patients with obstructive azoospermia (controls) aged 24, 25 and 36 years old were used in this study. Next-generation sequencing (NGS) was used to perform the miRNA expression profiling. Quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) assays were subsequently used to confirm the results of several randomly-selected and annotated miRNAs.

RESULTS

A series of miRNAs were found to be altered between post-cryptorchidopexy testicular tissues and control tissues, including 297 downregulated and 152 upregulated miRNAs. In the subsequent qRT-PCR assays, the expression levels of most of the selected miRNAs (9/12, P < 0.05) were consistent with the results of NGS technology. Furthermore, signal transduction, adaptive immune response and biological regulation were associated with the putative target genes of the differentially-expressed miRNAs via GO analysis. In addition, oxidative phosphorylation, Parkinson's disease and ribosomal pathways were shown to be enriched using KEGG pathway analysis of the differentially-expressed genes.

CONCLUSIONS

This study provides a global view of the miRNAs involved in post-cryptorchidopexy testicular tissues as well as the altered expression of miRNAs compared to control tissues, thus confirming the vital role of miRNAs in cryptorchidism.

Dose-dependent photochemical/photothermal toxicity of indocyanine green-based therapy on three different cancer cell lines

The Food and Drug Administration-approved Indocyanine Green can be used as a photosensitizer to kill cancer cells selectively. Although indocyanine green is advantageous as a photosensitizer in terms of strong absorption in the near-infrared region, indocyanine green-based cancer treatment is still not approved as a clinical method. Some reasons for this are aggregation at high concentrations, rapid clearance of the photosensitizer from the body, low singlet oxygen quantum yield, and the uncertainty concerning its action mechanism. This in vitro study focuses on two of these points: "what is the cell inhibition mechanism of indocyanine green-based therapy?" and "how the dose-dependent aggregation problem of indocyanine green alters its cell inhibition efficiency?" The following experiments were conducted to provide insight into these points. Nontoxic doses of indocyanine green and near-infrared laser were determined. The aggregation behavior of indocyanine green was verified through experiments. The singlet oxygen quantum yield of indocyanine green at different concentrations were calculated. Various indocyanine green and energy densities of near-infrared light were applied to prostate cancer, neuroblastoma, and colon cancer cells. An MTT assay was performed at the end of the first, second, and third days following the treatments to determine the cell viability. Temperature changes in the medium during laser exposure were recorded. ROS generation following the treatment was verified by using a Total Reactive Oxygen Species detection kit. An apoptosis detection test was performed to establish the cell death mechanism and, finally, the cellular uptakes of the three different cells were measured. According to the results, indocyanine green-based therapy causes cell viability decrease for three cancer cell lines by means of excessive reactive oxygen species production. Different cells have different sensitivities to the therapy possibly because of the differentiation level and structural differences. The singlet oxygen generation of indocyanine green decreases at high concentrations because of aggregation. Nevertheless, better cancer cell killing effect was observed at higher photosensitizer concentrations. This result reveals that the cellular uptake of indocyanine green was determinant for better cancer cell inhibition.

The contribution of p53 and Y chromosome long arm genes to regulation of apoptosis in mouse testis

Apoptosis of excessive or defective germ cells is a natural process occurring in mammalian testes. Tumour suppressor protein p53 is involved in this process both in developing and adult male gonads. Its contribution to testicular physiology is known to be modified by genetic background. The aim of this study was to evaluate the combined influence of the p53 and Y chromosome long arm genes on male germ cell apoptosis. Knockout of the transformation related protein 53 (Trp53) gene was introduced into congenic strains: B10.BR (intact Y chromosome) and B10.BR-Ydel (Y chromosome with a deletion in the long arm). The level of apoptosis in the testes of 19-day-old and 3-month-old male mice was determined using the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate in situ nick-end labelling (TUNEL) method. The study revealed that although p53 is involved in germ cell apoptosis in peripubertal testes, this process can also be mediated by p53-independent mechanisms. However, activation of p53-independent apoptotic pathways in the absence of the p53 protein requires engagement of the multicopy Yq genes and was not observed in gonads of B10.BR-Ydel-p53-/- males. The role of Yq genes in the regulation of testicular apoptosis seems to be restricted to the initial wave of spermatogenesis and is not evident in adult gonads. The study confirmed, instead, that p53 does participate in spontaneous apoptosis in mature testes.

Ghrelin modulates testicular damage in a cryptorchid mouse model

Cryptorchidism or undescended testis (UDT) is a common congenital abnormality associated with increased risk for developing male infertility and testicular cancer. This study elucidated the effects of endogenous ghrelin or growth hormone secretagogue receptor (GHSR) deletion on mouse reproductive performance and evaluated the ability of ghrelin to prevent testicular damage in a surgical cryptorchid mouse model. Reciprocal matings with heterozygous/homozygous ghrelin and GHSR knockout mice were performed. Litter size and germ cell apoptosis were recorded and testicular histological evaluations were performed. Wild type and GHSR knockout adult mice were subjected to creation of unilateral surgical cryptorchidism that is a model of heat-induced germ cell death. All mice were randomly separated into two groups: treatment with ghrelin or with saline. To assess testicular damage, the following endpoints were evaluated: testis weight, seminiferous tubule diameter, percentage of seminiferous tubules with spermatids and with multinucleated giant cells. Our findings indicated that endogenous ghrelin deletion altered male fertility. Moreover, ghrelin treatment ameliorated the testicular weight changes caused by surgically induced cryptorchidism. Testicular histopathology revealed a significant preservation of spermatogenesis and seminiferous tubule diameter in the ghrelin-treated cryptorchid testes of GHSR KO mice, suggesting that this protective effect of ghrelin was mediated by an unknown mechanism. In conclusion, ghrelin therapy could be useful to suppress testicular damage induced by hyperthermia, and future investigations will focus on the underlying mechanisms by which ghrelin mitigates testicular damage.

Molecular and Cellular Mechanisms of Apoptosis during Dissociated Spermatogenesis

Apoptosis is a tightly controlled process by which tissues eliminate unwanted cells. Spontaneous germ cell apoptosis in testis has been broadly investigated in mammals that have an associated spermatogenesis pattern. However, the mechanism of germ cell apoptosis in seasonally breeding reptiles following a dissociated spermatogenesis has remained enigmatic. In the present study, morphological evidence has clearly confirmed the dissociated spermatogenesis pattern in Pelodiscus sinensis. TUNEL and TEM analyses presented dynamic changes and ultrastructural characteristics of apoptotic germ cells during seasonal spermatogenesis, implying that apoptosis might be one of the key mechanisms to clear degraded germ cells. Furthermore, using RNA-Seq and digital gene expression (DGE) profiling, a large number of apoptosis-related differentially expressed genes (DEGs) at different phases of spermatogenesis were identified and characterized in the testis. DGE and RT-qPCR analysis revealed that the critical anti-apoptosis genes, such as Bcl-2, BAG1, and BAG5, showed up-regulated patterns during intermediate and late spermatogenesis. Moreover, the increases in mitochondrial transmembrane potential in July and October were detected by JC-1 staining. Notably, the low protein levels of pro-apoptotic cleaved caspase-3 and CytC in cytoplasm were detected by immunohistochemistry and western blot analyses, indicating that the CytC-Caspase model might be responsible for the effects of germ cell apoptosis on seasonal spermatogenesis. These results facilitate understanding the regulatory mechanisms of apoptosis during spermatogenesis and uncovering the biological process of the dissociated spermatogenesis system in reptiles.

Curcumin ameliorates high‑fat diet‑induced spermatogenesis dysfunction

Curcumin, a type of natural active ingredient, is derived from rhizoma of Curcuma, which possesses antioxidant, antitumorigenic and anti-inflammatory activities. The present study aimed to investigate whether treatment with curcumin reduced high-fat diet (HFD)-induced spermatogenesis dysfunction. Sprague-Dawley rats fed a HFD were treated with or without curcumin for 8 weeks. The testis/body weight, histological analysis and serum hormone levels were used to evaluate the effects of curcumin treatment on spermatogenesis dysfunction induced by the HFD. In addition, the expression levels of apoptosis associated proteins, Fas, B-cell lymphoma (Bcl)-xl, Bcl-associated X protein (Bax) and cleaved-caspase 3, were determined in the testis. The results of the present study suggested that curcumin treatment attenuated decreased testis/body weight and abnormal hormone levels. Morphological changes induced by a HFD were characterized as atrophied seminiferous tubules, decreased spermatogenetic cells and interstitial cells were improved by curcumin treatment. In addition, curcumin treatment reduced apoptosis in the testis, and decreased expression of Fas, Bax and cleaved-caspase 3, as well as increased expression of Bcl-xl. In conclusion, the present study revealed that curcumin treatment reduced HFD-induced spermatogenesis dysfunction in male rats.

Effects of whole-body heat on male germ cell development and sperm motility in the laboratory mouse

This study investigated the effects of high temperatures on male germ cell development and epididymal sperm motility of laboratory mice. In Experiment 1, adult males (n = 16) were exposed to whole-body heat of 37–38°C for 8 h day–1 for 3 consecutive days, whereas controls (n = 4) were left at 23–24°C. In Experiment 2, adult mice (n = 6) were exposed to 37–38°C for a single 8-h period with controls (n = 6) left at 23–24°C. Experiment 2 was conducted as a continuation of previous study that showed changes in spermatozoa 16 h after exposure to heat of 37–38°C for 8 h day–1 for 3 consecutive days. In the present study, in Experiment 1, high temperature reduced testes weights 16 h and 14 days after exposure, whereas by Day 21 testes weights were similar to those in the control group (P = 0.18). At 16 h, 7 and 14 days after exposure, an increase in germ cell apoptosis was noticeable in early and late stages (I–VI and XI–XII) of the cycle of the seminiferous epithelium. However, apoptosis in intermediate stages (VII–X) was evident 16 h after heat exposure (P < 0.05), without any change at other time periods. By 21 days, there were no significant differences between heat-treated groups and controls. Considerably more caspase-3-positive germ cells occurred in heat-treated mice 16 h after heat exposure compared with the control group (P < 0.0001), whereas 8 h after heat in Experiment 2, sperm motility was reduced with a higher percentage of spermatozoa showing membrane damage. In conclusion, the present study shows that whole-body heat of 37–38°C induces stage-specific germ cell apoptosis and membrane changes in spermatozoa; this may result in reduced fertility at particular times of exposure after heating.

Active vitamin D deficiency mediated by extracellular calcium and phosphorus results in male infertility in young mice

We used mice with targeted deletion of 25-hydroxyvitamin D-1 α-hydroxylase [1α(OH)ase(-/-)] to investigate whether 1,25(OH)2D3 deficiency results in male infertility mediated by 1,25(OH)2D3 or extracellular calcium and phosphorus. Male 1α(OH)ase(-/-) and their wild-type littermates fed either a normal diet or a rescue diet from weaning were mated at 6-14 wk of age with female wild-type mice on the same diet. The fertility efficiency of females was analyzed, and the reproductive phenotypes of males were evaluated by histopathological and molecular techniques. Hypocalcemic and hypophosphatemic male 1α(OH)ase(-/-) mice on a normal diet developed infertility characterized by hypergonadotropic hypogonadism, with downregulation of testicular calcium channels, lower intracellular calcium levels, decreased sperm count and motility, and histological abnormalities of the testes. The proliferation of spermatogenic cells was decreased with downregulation of cyclin E and CDK2 and upregulation of p53 and p21 expression, whereas apoptosis of spermatogenic cells was increased with upregulation of Bax and p-caspase 3 expression and downregulation of Bcl-xl expression. When serum calcium and phosphorus were normalized by the rescue diet, the defective reproductive phenotype in the male 1α(OH)ase(-/-) mice, including the hypergonadotropic hypogonadism, decreased sperm count and motility, histological abnormalities of testis, and defective spermatogenesis, was reversed. These results indicate that the infertility seen in male 1,25(OH)2D3-deficient mice is not a direct effect of active vitamin D deficiency on the reproductive system but is an indirect effect mediated by extracellular calcium and phosphorus.

Causes, effects and molecular mechanisms of testicular heat stress

The process of spermatogenesis is temperature-dependent and occurs optimally at temperatures slightly lower than that of the body. Adequate thermoregulation is imperative to maintain testicular temperatures at levels lower than that of the body core. Raised testicular temperature has a detrimental effect on mammalian spermatogenesis and the resultant spermatozoa. Therefore, thermoregulatory failure leading to heat stress can compromise sperm quality and increase the risk of infertility. In this paper, several different types of external and internal factors that may contribute towards testicular heat stress are reviewed. The effects of heat stress on the process of spermatogenesis, the resultant epididymal spermatozoa and on germ cells, and the consequent changes in the testis are elaborated upon. We also discuss the molecular response of germ cells to heat exposure and the possible mechanisms involved in heat-induced germ cell damage, including apoptosis, DNA damage and autophagy. Further, the intrinsic and extrinsic pathways that are involved in the intricate mechanism of germ cell apoptosis are explained. Ultimately, these complex mechanisms of apoptosis lead to germ cell death.

Quinestrol induces spermatogenic apoptosis in vivo via increasing pro-apoptotic proteins in adult male mice

The effects of quinestrol on spermatogenesis were investigated in adult male mice by daily intragastric administration of quinestrol with various doses of 5, 10, 50 and 100mg/kg body weight for 10 days. The sperm counts declined while the number of abnormal spermatozoa went up in mice treated with quinestrol. The testicular weight and seminiferous tubular area gradually declined with increasing dosages of quinestrol to 50 and 100mg/kg. Rarefied germ cells showed irregular distributions in the seminiferous tubules of mice treated with 50 and 100mg/kg quinestrol. Apoptosis was highly pronounced in spermatogonia, spermatocytes, spermatids and Leydig cells. Antioxidant enzyme activities - superoxide dismutase and glutathione peroxidase - as well as total antioxidant capacity significantly reduced, while malondialdehyde contents increased. The number of germ cells expressing caspase-3, p53, Bax and FasL significantly increased whereas cells expressing Bcl-2 significantly decreased in groups treated with 50 and 100mg/kg quinestrol compared with the control. The concentration of nitrogen monoxidum also increased significantly under these dosages. The results suggest that quinestrol stimulates oxidative stress to induce apoptosis in spermatogenic cells through the mitochondrial and death receptor pathways in adult male mice.

Redox reactions in mammalian spermatogenesis and the potential targets of reactive oxygen species under oxidative stress

Reduction-oxidation (Redox) reactions are ubiquitous mechanisms for vital activities in all organisms, and they play pivotal roles in the regulation of spermatogenesis as well. Here we focus on 3 redox-involved processes that have drawn much recent attention: the regulation of signal transduction by reactive oxygen species (ROS) such as hydrogen peroxide, oxidative protein folding in the endoplasmic reticulum (ER), and sulfoxidation of protamines during sperm chromatin condensation. The first 2 of these processes are emerging topics in cell biology and are applicable to most living cells, which includes spermatogenic cells. The roles of ROS in signal transduction have been elucidated in the last 2 decades and have received broad attention, most notably from the viewpoint of the proper control of mitotic signals. Redox processes in the ER are important because this is the organelle where secretory and membrane proteins are synthesized and proceed toward their functional structure, so that malfunction of the ER affects not only the involved cells but also the accepting cells of the secreted proteins in multicellular organisms. Sulfoxidation is the third of these processes, and the sulfoxidation of chromatin is a unique process in sperm maturation. During recent sulfoxidase research, GPX4 has emerged as a promising enzyme that plays essential roles in the production of fertile sperm, but the involvement of other redox proteins is also becoming evident. Because the molecules involved in the redox reactions are prone to oxidation, they can be sensitive to oxidative damage, which makes them potential targets for antioxidant therapy.

Ghrelin is a suppressor of testicular damage following experimentally induced cryptorchidism in the rat

BACKGROUND

Cryptorchidism is associated with increased level of reactive oxygen species and lipid peroxidation. This study was undertaken to examine the possible ghrelin ability in attenuation of testicular damage in response to elevated temperature.

METHODS

Thirty male rats were subdivided into sham-operated, cryptorchidism-saline and cryptorchidism-ghrelin group. Bilateral cryptorchidism was induced in groups 2 and 3, surgically. The animals in group 3 were given ghrelin for 7 days and all testes were taken for biochemical and photomicrograph analysis.

RESULTS

Glutathione peroxidase activity and glutathione content significantly promoted on day 7 in the cryptorchid rats treated by ghrelin. Catalase activity was higher in the ghrelin-exposed animals than the cryptorchidism-saline group on both experimental days. Although superoxide dismutase activity was elevated by ghrelin treatment on both days, it did not differ significantly. By contrast, significant reduction was observed in thiobarbituric acid reactive substances concentrations following ghrelin administration on day 7. Moreover, ghrelin could improve histopathological scores of the testes, and diminished formation of giant cells and tubular vacuolization.

CONCLUSIONS

These findings indicate for the first time the novel evidence of ghrelin antioxidant properties in attenuation of rat testicular injury following experimentally induced cryptorchidism.

Influence of the temperature and the genotype of the HSP90AA1 gene over sperm chromatin stability in Manchega Rams

The present study addresses the effect of heat stress on males' reproduction ability. For that, we have evaluated the sperm DNA fragmentation (DFI) by SCSA of ejaculates incubated at 37 °C during 0, 24 and 48 hours after its collection, as a way to mimic the temperature circumstances to which spermatozoa will be subject to in the ewe uterus. The effects of temperature and temperature-humidity index (THI) from day 60 prior collection to the date of semen collection on DFI were examined. To better understand the causes determining the sensitivity of spermatozoa to heat, this study was conducted in 60 males with alternative genotypes for the SNP G/C-660 of the HSP90AA1 promoter, which encode for the Hsp90α protein. The Hsp90α protein predominates in the brain and testis, and its role in spermatogenesis has been described in several species. Ridge regression analyses showed that days 29 to 35 and 7 to 14 before sperm collection (bsc) were the most critical regarding the effect of heat stress over DFI values. Mixed model analyses revealed that DFI increases over a threshold of 30 °C for maximum temperature and 22 for THI at days 29 to 35 and 7 to 14 bsc only in animals carrying the GG-660 genotype. The period 29-35 bsc coincide with the meiosis I process for which the effect of the Hsp90α has been described in mice. The period 7-14 bsc may correspond with later stages of the meiosis II and early stages of epididymal maturation in which the replacement of histones by protamines occurs. Because of GG-660 genotype has been associated to lower levels of HSP90AA1 expression, suboptimal amounts of HSP90AA1 mRNA in GG-660 animals under heat stress conditions make spermatozoa DNA more susceptible to be fragmented. Thus, selecting against the GG-660 genotype could decrease the DNA fragmentation and spermatozoa thermal susceptibility in the heat season, and its putative subsequent fertility gains.

Oxidative stress and redox regulation of gametogenesis, fertilization, and embryonic development

Oxidative stress caused by elevated reactive oxygen species (ROS) is one of the predominant causes of both male and female infertility. Oxidative stress conditions cause either cell death or senescence by oxidation of cellular molecules including nucleic acid, proteins, and lipids. It is particularly important to minimize oxidative stress when in vitro fertilization is performed for the purpose of assisted reproduction. The problems associated with assisted reproductive technology are becoming evident, and it is now the time to clarify its mechanisms and cope with them. On the other hand, the beneficial roles of ROS, such as intracellular signaling, have become evident. The antithetical functions of ROS make it more difficult to overcome the problems caused by oxidative stress. Despite the difficulty in understanding mammalian reproduction, the mechanisms and problems can be gradually unveiled by advanced technology such as genetic modification of animals.

Heat stress response of male germ cells

The vast majority of mammalian testes are located outside the body cavity for proper thermoregulation. Heat has an adverse effect on mammalian spermatogenesis and eventually leads to sub- or infertility. Recent studies have provided insights into the molecular response of male germ cells to high temperatures. Here, we review the effects of heat on male germ cells and discuss the mechanisms underlying germ cell loss and impairment. We also discuss the role of translational control in male germ cells as a potential protective mechanism against heat-induced germ cell apoptosis.

Damaged spermatogenic cells induce inflammatory gene expression in mouse Sertoli cells through the activation of Toll-like receptors 2 and 4

Testicular inflammation, including noninfectious inflammatory responses in the testis, may impair male fertility. Mechanisms underlying the initiation of noninfectious testicular inflammation are poorly understood. In the current study, we demonstrate that damaged spermatogenic cell products (DSCPs) induce expression of various inflammatory mediators, including TNF-α, IL-1β, IL-6, and macrophage chemotactic protein 1 (MCP-1), in Sertoli cells. Notably, the DSCP-induced inflammatory gene expression was significantly reduced by knockout Toll-like receptor (TLR)2 or TLR4, and abolished by double knockout TLR2 and TLR4 (TLR2(-/-)TLR4(-/-)). MCP-1 secreted by Sertoli cells after stimulation with DSCPs promotes macrophage migration. We also provide evidence that busulfan-induced spermatogenic cell damages in vivo upregulate TNF-α and MCP-1 expression in Sertoli cells, and facilitate macrophage infiltration into the testis in wild-type mice. These phenomena were not observed in TLR2(-/-)TLR4(-/-) mice. Data indicate that DSCPs induce inflammatory gene expression in Sertoli cells via the activation of TLR2 and TLR4, which may initiate noninfectious inflammatory responses in the testis. The results provide novel insights into the mechanisms underlying damaged spermatogenic cell-induced testicular inflammation.

Heat-Induced Apoptosis of Mouse Meiotic Cells Is Suppressed by Ectopic Expression of Testis-Specific Calpastatin

Calpastatin is a naturally occurring inhibitor of calpain, a protease involved in apoptotic cell death. A testis-specific isoform of calpastatin (tCAST) has been identified that is transcribed in haploid germ cells but not in spermatocytes. To investigate the possible function(s) of tCAST, we tested the hypothesis that the ectopic expression of calpastatin in spermatocytes would suppress the death of these cells in response to an apoptosis-inducing stimulus in vivo. To this end, the 5'-flanking region of the mouse ldhc gene was linked to tCAST, and transgenic mice were generated. Immunohistochemical analysis revealed that, in contrast to control sections in which the signal for tCAST was seen in round spermatids, intense staining was visualized in pachytene spermatocytes in the transgenic animals, indicating that the strategy we used to generate the transgenic animals resulted in the ectopic expression of tCAST in spermatocytes. We then tested the effect of a short period of heating on germ cell apoptosis in the testes of wild-type and transgenic mice. Pachytene spermatocytes were the major germ cell type seen to undergo apoptosis after heat treatment. There were no differences in the number of apoptotic germ cells per seminiferous tubule between wild-type and tCAST transgenic control mice; thus, there was no apparent effect of the transgene on normal apoptosis. Heating resulted in increased numbers of TUNEL-positive germ cells in both wild-type and tCAST transgenic mice, as well as increased testicular DNA fragmentation. Heating the tCAST transgenic mouse testes resulted in significantly fewer apoptotic cells per seminiferous tubule than in wild-type mice at both 8 and 24 hours after treatment. Thus, as hypothesized, the ectopic expression of tCAST in pachytene spermatocytes suppressed germ cell apoptosis.

Testicular cancer and cryptorchidism

The failure of testicular descent or cryptorchidism is the most common defect in newborn boys. The descent of the testes during development is controlled by insulin-like 3 peptide and steroid hormones produced in testicular Leydig cells, as well as by various genetic and developmental factors. While in some cases the association with genetic abnormalities and environmental causes has been shown, the etiology of cryptorchidism remains uncertain. Cryptorchidism is an established risk factor for infertility and testicular germ cell tumors (TGCT). Experimental animal models suggest a causative role for an abnormal testicular position on the disruption of spermatogenesis however the link between cryptorchidism and TGCT is less clear. The most common type of TGCT in cryptorchid testes is seminoma, believed to be derived from pluripotent prenatal germ cells. Recent studies have shown that seminoma cells and their precursor carcinoma in situ cells express a number of spermatogonial stem cell (SSC) markers suggesting that TGCTs might originate from adult stem cells. We review here the data on changes in the SSC somatic cell niche observed in cryptorchid testes of mouse models and in human patients. We propose that the misregulation of growth factors' expression may alter the balance between SSC self-renewal and differentiation and shift stem cells toward neoplastic transformation.

Expression and function analysis of metallothionein in the testis of stone crab Charybdis japonica exposed to cadmium

Metallothionein (MT) participates in metallic homeostasis and detoxification in living animals. Previous studies have focused mainly on the functions of MT in vertebrates, but the functions of MT during spermiogenesis in invertebrates remain unclear. In order to investigate the functions of MT during spermiogenesis in the Japanese stone crab (Charybdis japonica), we identified the C. japonica MT complete cDNA sequence from the total RNA of the testis using RT-PCR and RACE. The 587 bp MT cDNA contains: an 80 bp 5' untranslated region, a 333 bp 3' untranslated region, and a 174 bp open reading frame. MT has 57 amino acids including 19 cysteines. The protein alignment between MT sequences of C. japonica and other crabs shows a high similarity and a strong identity in cysteine residues vital for the metal-binding affinity of MT. After the cadmium (Cd) exposure, the testis displays both abnormal morphology and MT mRNA expression both of which indicate a sensitive response of testis MT to Cd. Therefore, we suggest that MT is an excellent biomarker candidate for evaluating Cd pollution.

Overexpression of human SPATA17 protein induces germ cell apoptosis in transgenic male mice

SPATA17 is a new testis-specific-expressed gene that is involved in Spermatogenesis process. Previous studies show that SPATA17 was involved in acceleration of cell apoptosis in GC-1 cell lines. To further investigate specific roles of SPATA17 in Spermatogenesis in vivo, we generated transgenic mice in which the human SPATA17 gene was expressed specifically in spermatocytes using the human phosphoglycerate kinase 2 (PGK2) promoter. The SPATA17 transgenic mice did not show any significant defect in gross testicular anatomy as well as in fertility. However, a significant increase was observed in defective spermatogenic cells, such as apoptotic cells in the SPATA17 transgenic mice. These results revealed that elevated production of the SPATA17 protein disturbed the normal development of male germ cells.

The apoptotic function analysis of p53, Apaf1, Caspase3 and Caspase7 during the spermatogenesis of the Chinese fire-bellied newt Cynops orientalis

BACKGROUND

Spontaneous and stress-induced germ cell apoptosis during spermatogenesis of multicellular organisms have been investigated broadly in mammals. Spermatogenetic process in urodele amphibians was essentially like that in mammals in spite of morphological differences; however, the mechanism of germ cell apoptosis in urodele amphibians remains unknown. The Chinese fire-belly newt, Cynops orientalis, was an excellent organism for studying germ cell apoptosis due to its sensitiveness to temperature, strong endurance of starvation, and sensitive skin to heavy metal exposure.

METHODOLOGY/PRINCIPAL FINDINGS

TUNEL result showed that spontaneous germ cell apoptosis took place in normal newt, and severe stress-induced apoptosis occurred to spermatids and sperm in response to heat shock (40°C 2 h), cold exposure (4°C 12 h), cadmium exposure (Cd 36 h), and starvation stress. Quantitative reverse transcription polymerase chain reactions (qRT-PCR) showed that gene expression of Caspase3 or Caspase7 was obviously elevated after stress treatment. Apaf1 was not altered at its gene expression level, and p53 was significantly decreased after various stress treatment. Caspase assay demonstrated that Caspase-3, -8, -9 enzyme activities in newt testis were significantly elevated after heat shock (40°C 2 h), cold exposure (4°C 12 h), and cadmium exposure (Cd 36 h), while Caspase3 and Caspase8 activities were increased with Caspase9 significantly decreased after starvation treatment.

CONCLUSIONS/SIGNIFICANCE

Severe germ cell apoptosis triggered by heat shock, cold exposure, and cadmium exposure was Caspase3 dependent, which probably involved both extrinsic and intrinsic pathways. Apaf1 may be involved in this process without elevating its gene expression. But starvation-induced germ cell apoptosis was likely mainly through extrinsic pathway. p53 was probably not responsible for stress-induced germ cell apoptosis in newt testis. The intriguing high occurrence of spermatid and sperm apoptosis probably resulted from the sperm morphology and unique reproduction policy of Chinese fire-belly newt, Cynops orientalis.

Semen quality parameters and embryo lethality in mice deficient for Trp53 protein

Trp53 is a protein which is able to control semen parameters in mice, but the extent of that control depends on the genetic background of the mouse strain. Males from C57BL/6Kw, 129/Sv, C57BL×129 -p53+/+ (wild type controls) and C57BL×129-p53-/- (mutants) strains were used in the study, and histology and light microscopy were applied to evaluate the influence of genetic background and Trp53 (p53) genotype on testes morphology and semen quality in male mice. We showed that sperm head morphology, maturity and tail membrane integrity were controlled only by the genetic background of C57BL/6Kw and 129/Sv males, while testes weight and sperm concentration depended on both the genetic background and p53 genotype. Cell accumulation in seminiferous tubules may be responsible for heavier testes of p53-deficient males. In addition, to examine the effect of sex and p53 genotype on embryo lethality, pairs of control (C57BL×129-p53+/+) and heterozygous (C57BL×129-p53+/-) mice were examined. Before day 7 post coitum (dpc), female and male embryos were equally resorbed in both crosses types. After 7 dpc, preferential female embryo lethality in the heterozygote pairs was responsible for the skewed sex ratio in their progeny. Also, mutant female and male newborns were underrepresented in the litters of the heterozygous breeding pairs.

Spermatogenesis in cryptorchidism

Cryptorchidism or undescended testis is the most frequent congenital abnormality in newborn boys. The process of testicular descent to the scrotum is controlled by hormones produced in Leydig cells, insulin-like3, and androgens. Variation in genetic and environmental factors might affect testicular descent. A failure of spermatogenesis and germ cell apoptosis resulting in infertility as well as an increased risk of neoplastic transformation of germ cell are the direct consequences of cryptorchidism in adulthood.

Is p53 controlling spermatogenesis in male mice with the deletion on the Y chromosome?

The aim of the study was to evaluate the influence of the chromosome Y structure and Trp53 genotype on semen quality parameters. Mice with partial deletion of the Y chromosome (B10.BR-Ydel) have severely altered sperm head morphology when compared with males that possess the complete Y chromosome (B10.BR). Control males from B10.BR and B10.BR-Ydel mice, and mutant males from B10.BR-p53−/− and B10.BR-Ydel-p53−/− experimental groups were used. We assessed testis weight, sperm head abnormalities, viability of spermatozoa (eosin test), percentage of motile and immature sperm, and performed a hypo-osmotic test to detect abnormal tail membrane integrity. Sperm morphology and maturation were controlled by the genes within the deleted region of the Y chromosome. Testis weight was higher in the mutants than in the control males, possibly due to cell accumulation in Trp53-deficient males as the concentration of sperm was significantly increased in the mutants. An elevated percentage of abnormal sperm was noted in B10.BR-p53−/− and B10.BR-Ydel-p53−/− male mice. We suggest that, in Trp53-deficient mice, the sperm cells that escape apoptosis are the ones that have abnormal morphology. The only sperm quality parameter affected by the interplay between Trp53 and chromosome Y genes was sperm motility, which was elevated in B10.BR-p53−/− males, but remained unchanged in B10.BR-Ydel-p53−/− males.

Redox regulation of fertilisation and the spermatogenic process

Oxidative stress is one of the major causes of male infertility; it damages spermatogenic cells, the spermatogenic process and sperm function. Recent advances in redox biology have revealed the signalling role of reactive oxygen species (ROS) that are generated by cells. While highly reactive oxidants, such as the hydroxyl radical, exert largely deleterious effects, hydrogen peroxide can feasibly serve as a signal mediator because it is moderately reactive and membrane permeable and because it can oxidize only limited numbers of functional groups of biological molecules. The amino acid side chain most sensitive to oxidation is cysteine sulphydryl, which is commonly involved in the catalysis of some enzymes. Although the reactivity of cysteine sulphhydryl is not very high in ordinary proteins, some phosphatases possess a highly reactive sulphydryl group at their catalytic centre and are thereby oxidatively inactivated by transiently elevated hydrogen peroxide levels after extracellular stimuli and under certain environmental conditions. Peroxiredoxins, in turn, show moderate hydrogen peroxide-reducing activity, and their role in the modulation of ROS-mediated signal transduction in ordinary cells, mediated by protecting phosphatases from oxidative inactivation, has attracted much attention. Although knowledge of the signalling role of ROS in the male reproductive system is limited at present, its significance is becoming a focal issue. Here, we present a review of the emerging signalling role of hydrogen peroxide in testes.

DOES ORCHIDOPEXY REVERT THE HISTOLOGICAL ALTERATIONS IN EPIDIDYMAL AND VAS DEFERENS CAUSED BY CRYPTORCHIDISM?

Cryptorchidism is a pathological condition in which the testicles are retained in the abdominal cavity, resulting in atrophic seminiferous tubules. Some gross structural abnormalities and histological altercations have been described in the epididymis and vas deferens in humans with cryptorchidic testes. Orchidopexy surgery restores testicular spermatogenesis in experimental and clinical procedures, but it is still unclear whether histological changes in the epididymis and vas deferens caused by cryptorchidism may be reverted by orchidopexy. The aim of this study was to evaluated the histological changes in the epididymis and vas deferens following experimental uni- bilateral cryptorchidism in mature and immature mice, and to determine whether altercations could be reversed by orchidopexy. Young and adult C57 BL6 mice were randomized into three groups: control mice, bi/unilaterally cryptorchidic mice and bilaterally cryptorchidic mice with orchidopexy. After evaluation of testis, epididymis and vas deferens, there were no histological alterations in contralateral epididymis of mice unilaterally cryptorchidic. Ipsilateral epididymis of unilaterally cryptorchidic mice and epididymis from bilaterally cryptorchidic mice showed significant histological alterations. Orchuidopexy resorted normal spermatogenesis and the histological features of epididymis. It would appear that persistent male infertility clinically observed after orchidopexy could not be related to histological alteration in the testis and epididymis. Development and maintenance of the vas deferens seems to be controlled independently of the epididymis since it was not altered by cryptorchidism condition.

A single, mild, transient scrotal heat stress causes hypoxia and oxidative stress in mouse testes, which induces germ cell death

Spermatogenesis is a temperature-dependent process, and increases in scrotal temperature can disrupt its progression. We previously showed that heat stress causes DNA damage in germ cells, an increase in germ cell death (as seen on TUNEL staining), and subfertility. The present study evaluated the stress response in mouse testes following a single mild transient scrotal heat exposure (40 degrees C or 42 degrees C for 30 min). We investigated markers of three types of stress response, namely, hypoxia, oxidative stress, and apoptosis. Heat stress caused an increase in expression of hypoxia-inducible factor 1 alpha (Hif1a) mRNA expression and translocation of HIF1A protein to the germ cell nucleus, consistent with hypoxic stress. Increased expression of heme oxygenase 1 (Hmox1) and the antioxidant enzymes glutathione peroxidase 1 (GPX1) and glutathione S-transferase alpha (GSTA) was consistent with a robust oxidative stress response. Germ cell death was associated with an increase in expression of the effector caspase cleaved caspase 3 and a decrease in expression of the protein inhibitor of caspase-activated DNase (ICAD). Reduced expression of ICAD contributes to increased activity of caspase-activated DNase and is consistent with the increased rates of DNA fragmentation that have been detected previously using TUNEL staining. These studies confirmed that transient mild testicular hyperthermia results in temperature-dependent germ cell death and demonstrated that elevated temperature results in a complex stress response, including induction of genes associated with oxidative stress and hypoxia.

Induction of apoptosis involving multiple pathways is a primary response to cyclin A1-deficiency in male meiosis

The meiotic arrest in male mice null for the cyclin A1 gene (Ccna1) was associated with apoptosis of spermatocytes. To determine whether the apoptosis in spermatocytes was triggered in response to the arrest at G2/M phase, as opposed to being a secondary response to overall disruption of spermatogenesis, we examined testes during the first wave of spermatogenesis by terminal deoxynucleotidyl transferase-mediated deoxyuridinetriphosphate nick end-labeling (TUNEL) staining. We observed enhanced apoptosis coinciding with the arrest point in postnatal day 22 tubules, with no overt degeneration. Along with activation of caspase-3, an increase in the levels and change of subcellular localization of Bax protein was observed in cyclin A1-deficient spermatocytes, which coincided with the detection of apoptosis. As p53 is implicated in the activation of Bax-mediated cell death, we generated mice lacking both cyclin A1 and p53. Although the absence of p53 did not rescue the meiotic arrest, there was a decrease in the number of apoptotic cells in the double-mutant testes. This finding suggested that p53 may be involved in the process by which the arrested germ cells are removed from the seminiferous tubules but that other pathways function as well to ensure removal of the arrested spermatocytes.

The New Function of Two Ubiquitin C-Terminal Hydrolase Isozymes as Reciprocal Modulators of Germ Cell Apoptosis

Ubiquitination is required throughout all developmental stages of mammalian spermatogenesis. The two ubiquitin C-terminal hydrolase (UCH) enzymes, UCH-L1 and UCH-L3, deubiquitinate ubiquitin-protein conjugates and control the cellular balance of ubiquitin. These two UCH isozymes have 52% amino acid identity and share significant structural similarity. A new function of these two closely related UCH enzymes during spermatogenesis which is associated with germ cell apoptosis has been analyzed. Apoptosis, in general, is thought to be partly regulated by the ubiquitin-proteasome system. During spermatogenesis, apoptosis controls germ cell numbers and eliminates defective germ cells to facilitate testicular homeostasis. In this paper, I review the distinct function of the two UCH isozymes in the testis of gad and Uchl3 knockout mice, which are strongly but reciprocally expressed during spermatogenesis. In addition, the importance of UCHL1-dependent apoptosis for normal spermatogenesis and sperm quality control is discussed.

LPS-induced transient testicular dysfunction accompanied by apoptosis of testicular germ cells in mice

The aim of this study was to clarify effects of inflammation on spermatogenesis in LPS-administered mice. ICR mice were treated by intraperitoneal injection for 7 days with either physiological saline (control) or 0.1 mg lipopolysaccharide (LPS)/kg body weight/day. Control mice were killed at 24 h after the last injection and the LPS-treated group after 24 h or 1, 3, or 5 weeks. Sperm concentration and motility in the cauda epididymis were examined as well as immunohistochemical localization of Fas and FasL and germ cell apoptosis. Sperm concentration and motility markedly fluctuated in LPS-treated mice. Increase of apoptotic cells was common in all post-LPS treatment groups, with a peak at 24 h after LPS injection. In contrast to the lack of Fas immunoreactivity in control testes, LPS-treated groups demonstrated Fas in many germ cells, especially in spermatocytes and spermatids. Immunoreactivity for FasL, on the other hand, was positive for some Sertoli cells, Leydig cells, and germ cells in both control and LPS-treated groups at all time points. The results suggest that the Fas/FasL system mediates apoptosis of germ cells in LPS-treated mice testes. LPS-administered mice thus provide a good experimental model for the study of transient disruption of spermatogenesis.

HtrA2 is up-regulated in the rat testis after experimental cryptorchidism

AIM

The aim of the present study was to elucidate the role of high temperature requirement A2 (HtrA2) in germ cell loss in the heat-stressed testis.

METHODS

We examined the expression of HtrA2, caspase-9 activity and proteolytic activity of HtrA2 in the rat testis, and their in vivo responses to experimental cryptorchid treatment.

RESULTS

Northern analysis revealed the expression of HtrA2 mRNA peaked at days 1 and 7 after cryptorchid treatment. While expression of HtrA2 mRNA was seen in the spermatogonium, spermatocytes and some spermatids in normal adult rat testis, experimental cryptorchidism treatment resulted in a marked increase in its signal intensity in spermatocytes and some spermatids, and the layers of spermatogonium and early primary spermatocytes became negative at days 1 and 7 after the treatment. However, the spermatogonium, Sertoli cells and interstitial cells appeared to have strong intensities at days 14, 28 and 56 after the treatment. Western analysis revealed the expression of HtrA2 protein peaked at day 2 coinciding with the increase of positive spermatogonium, the appearance of protein-positive interstitial cells, and day 28 coinciding with the reappearance of protein-positive interstitial cells. Caspase-9 activity peaked at day 2 and HtrA2 proteolytic activity peaked at day 28. Consequently, the first peak of HtrA2 mRNA expression was followed by the peak of caspase-9 activity and the second peak was followed by the peak of proteolytic activity; however, the second peak of mRNA expression had considerable chronological difference from that of the protein.

CONCLUSION

These findings suggest the probabilities that the heat stress results in germ cell death by a caspase-independent manner with the elevation of HtrA2 proteolytic activity, as well as a caspase-dependent manner with the elevation of caspase-9 activity.