Signaling Pathways for Germ Cell Death in Adult Cynomolgus Monkeys (Macaca fascicularis) Induced by Mild Testicular Hyperthermia and Exogenous Testosterone Treatment1

Synergistic protective effects of 3,4-dihydroxyphenylglycol and hydroxytyrosol in male rats against induced heat stress-induced reproduction damage

Testicular heat stress disrupts spermiogenesis and damages testicular tissue. The study aims to assess 3,4-dihydroxyphenylglycol (DHPG) and hydroxytyrosol (HT) from olive oil as antioxidants to reduce heat-induced testicular damage. Seven groups of 35 male rats were used. Group I got normal saline. Group 2 had HS (43 °C for 20 min/day) and normal saline for 60 days. Groups 3-7 had HS and DHPG/HT doses (0.5 mg/kg DHPG, 1 mg/kg DHPG, 5 mg/kg HT, 0.5 mg/kg DHPG + 5 mg/kg HT, and 1 mg/kg DHPG + 5 mg/kg HT). The evaluation included tests on testicular tissue, sperm quality, oxidative status, gene activity, and fertility after 60 days. After DHPG and HT treatment, sperm motility, viability, and plasma membrane functionality, as well as levels of total antioxidant capacity (TAC), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT), and Bcl-2 gene expression, and in vivo fertility indexes increased. Meanwhile, abnormal morphology and DNA damage decreased, along with levels of glutathione (GSH), nitric oxide (NO), and malondialdehyde (MDA), and Bax, caspase-3, and caspase-9 gene expression, compared to the HS group. The study found that DHPG and HT have a more substantial synergistic effect when used together, improving reproductive health.

Ameliorative effects of omega-3 and omega-6 on spermatogenesis, testicular antioxidant status and in vivo fertility index in heat-stressed rats

The current study aimed to investigate the use of omega-6 (ω6) or omega-3 (ω3) in reducing heat-induced damage to the testicles. This is due to the known detrimental effects of heat and the potential protective properties of ω6 and ω3. In the study, 48 male rats were divided into eight groups, each containing 6 rats. Group I (control) received normal saline. Group 2 was exposed to high temperatures (43 °C for 20 min/day) and also received normal saline for 60 days. Groups 3-7 underwent identical HS conditions and received varying doses of ω6 or ω3 (0.5 mg/kg DHPG, 1 mg/kg DHPG, 5 mg/kg HT, 0.5 mg/kg DHPG + 5 mg/kg HT, and 1 mg/kg DHPG + 5 mg/kg HT), respectively. After 60 days, various tests were conducted on the testicular tissue, sperm quality, oxidative status, gene activity, and in vivo fertility indexes to evaluate the effects of the treatments. Treatment with ω6 and ω3 could reduce abnormal morphology and DNA damage while increasing total and progressive motility, characteristics motility, viability, and plasma membrane functional impairment compared with HS-exposed groups. Antioxidant status levels in testicular tissue were improved after administration of ω6 and ω3. Furthermore, after receiving ω6 and ω3, there were significantly lower expression levels of P53 and Caspase-3 and significantly higher expression levels of Bcl-2 compared to the HS-exposed group. Furthermore, the results showed that administration of ω6 and ω3 to rats exposed to HS could increase their in vivo fertility indexes compared to the group not exposed to HS. According to our data, all doses of ω6 and ω3 (particularly doses of ω6-1.25 and ω3-300) can improve the testicular damage, testicular antioxidant defense mechanism, regulate germ cell apoptosis, and increase in vivo fertility indexes.

The protective impact of curcumin, vitamin D and E along with manganese oxide and Iron (III) oxide nanoparticles in rats with scrotal hyperthermia: Role of apoptotic genes, miRNA and circRNA

BACKGROUND

Infertility is one of the major factors affecting most people around the world. Short-term exposure to high temperatures can cause hyperthermia, which is one of the causes of male infertility. The aim of this study was to investigate the protective effect of curcumin, vitamins D and E along with Iron (III) oxide nanoparticles (Fe2O3-NPs) and manganese oxide nanoparticles (MnO2-NPs) on semen parameters and its effect on miRNA21 and circRNA0001518 expression.

MATERIAL AND METHODS

In this study, the lower part of the rat was exposed to 43 °C for 5 weeks every other day for 5 weeks. Then the animals were killed. Tissue samples were collected for sperm parameters analysis, and tissue samples were taken for evaluation of apoptosis levels in germ cells, and RNA extraction in order to examine the expression of Bax, Bcl-2, miRNA, and CircRNA genes.

RESULTS

The results of this study showed that administration of curcumin, vitamin D, and vitamin E with Fe2O3-NPs and MnO2-NPs can improve the parameters of semen, Bax gene expression, Bcl-2 as well as miRNA and CircRNA in rats with testicular hyperthermia. In addition, curcumin by reducing the toxicity of Fe2O3 nanoparticles was able to reduce its negative effects and also reduce apoptosis in germ cells. This decrease in apoptosis was attributed to decreased Bcl-2 gene expression and increased expression of Bax, miRNA-21, and circRNA0001518.

CONCLUSION

All the results of this study confirmed that Fe2O3-NPs and Mno2-NPs containing antioxidants or vitamins are useful in improving fertility in rats due to scrotal hyperthermia. Although Fe2O3-NPs and Mno2-NPs containing both antioxidants and vitamins had a greater effect on improving fertility and reducing the toxic effects of nanoparticles.

Effect of Dietetic Obesity on Testicular Transcriptome in Cynomolgus Monkeys

Obesity is a metabolic disorder resulting from behavioral, environmental and heritable causes, and can have a negative impact on male reproduction. There have been few experiments in mice, rats, and rabbits on the effects of obesity on reproduction, which has inhibited the development of better treatments for male subfertility caused by obesity. Nonhuman primates are most similar to human beings in anatomy, physiology, metabolism, and biochemistry and are appropriate subjects for obesity studies. In this investigation, we conducted a transcriptome analysis of the testes of cynomolgus monkeys on high-fat, high-fructose, and cholesterol-rich diets to determine the effect of obesity on gene expression in testes. The results showed that the testes of obese monkeys had abnormal morphology, and their testes transcriptome was significantly different from that of non-obese animals. We identified 507 differentially abundant genes (adjusted p value < 0.01, log2 [FC] > 2) including 163 up-regulated and 344 down-regulated genes. Among the differentially abundant genes were ten regulatory genes, including IRF1, IRF6, HERC5, HERC6, IFIH1, IFIT2, IFIT5, IFI35, RSAD2, and UBQLNL. Gene ontology (GO) and KEGG pathway analysis was conducted, and we found that processes and pathways associated with the blood testes barrier (BTB), immunity, inflammation, and DNA methylation in gametes were preferentially enriched. We also found abnormal expression of genes related to infertility (TDRD5, CLCN2, MORC1, RFX8, SOHLH1, IL2RB, MCIDAS, ZPBP, NFIA, PTPN11, TSC22D3, MAPK6, PLCB1, DCUN1D1, LPIN1, and GATM) and down-regulation of testosterone in monkeys with dietetic obesity. This work not only provides an important reference for research and treatment on male infertility caused by obesity, but also valuable insights into the effects of diet on gene expression in testes.

The IL-27 component EBI-3 and its receptor subunit IL-27Rα are essential for the cytoprotective action of humanin on male germ cells†

Humanin (HN) is a mitochondrial-derived peptide that protects many cells/tissues from damage. We previously demonstrated that HN reduces stress-induced male germ cell apoptosis in rodents. HN action in neuronal cells is mediated through its binding to a trimeric cell membrane receptor composed of glycoprotein 130 (gp130), IL-27 receptor subunit (IL-27R, also known as WSX-1/TCCR), and ciliary neurotrophic factor receptor subunit (CNTFR). The mechanisms of HN action in testis remain unclear. We demonstrated in ex-vivo seminiferous tubules culture that HN prevented heat-induced germ cell apoptosis was blocked by specific anti-IL-27R, anti-gp130, and anti-EBI-3, but not by anti-CNTFR antibodies significantly. The cytoprotective action of HN was studied by using groups of il-27r-/- or ebi-3-/- mice administered the following treatment: (1) vehicle; (2) a single intraperitoneal (IP) injection of HN peptide; (3) testicular hyperthermia; and (4) testicular hyperthermia plus HN. We demonstrated that HN inhibited heat-induced germ cell apoptosis in wildtype but not in il-27r-/- or ebi-3-/- mice. HN restored heat-suppressed STAT3 phosphorylation in wildtype but not il-27r-/- or ebi-3-/- mice. Dot blot analyses showed the direct interaction of HN with IL-27R or EBI-3 peptide. Immunofluorescence staining showed the co-localization of IL-27R with HN and gp130 in Leydig cells and germ cells. We conclude that the anti-apoptotic effects of HN in mouse testes are mediated through interaction with EBI-3, IL-27R, and activation of gp130, whereas the role of CNTFR needs further studies. This suggests a multicomponent tissue-specific receptor for HN in the testis and links HN action with the IL-12/IL-27 family of cytokines.

The role of miR-128-3p through MAPK14 activation in the apoptosis of GC2 spermatocyte cell line following heat stress

BACKGROUND

MicroRNAs play a crucial role in the regulation of spermatogenesis. For example, miR-128-3p expression is known to decrease significantly after testicular hyperthermia, but the regulatory effect of this change on the spermatogenesis damage caused by heat stress remains unclear.

OBJECTIVES

This study aimed to verify whether the target gene of miR-128-3p is MAPK14, which affects spermatogenic cell proliferation and apoptosis under testicular hyperthermia.

MATERIALS AND METHODS

Mouse testis and GC2 spermatocyte cell line heat stress models were established. miR-128-3p expression before and after heat stress was analyzed by reverse transcription polymerase chain reaction. MAPK14 and p-MAPK14 expression was detected by Western blot, and cell apoptosis was analyzed by Annexin V-FITC/PI. Subsequently, miR-128-3p inhibitors and mimics were used to interfere with spermatocytes before and after heat stress, respectively, for correlation detection.

RESULTS

Compared with the control group, the heat stress group showed decreased miR-128-3p expression, increased p-MAPK14 expression, and decreased cell proliferation activity. In the GC2-spd cell line in vitro, miR-128-3p inhibitors were found to upregulate p-MAPK14 expression, reduce cell proliferation activity, and increase apoptosis, consistent with the results obtained in the heat treatment alone. Furthermore, miR-128-3p mimics transfected in the GC2 cells after heat stress reduced p-MAPK14 expression, alleviated the decrease in cell proliferation, and decreased the apoptosis level.

CONCLUSIONS

The downregulation of miR-128-3p expression plays an important role in spermatogenesis damages after testicular hyperthermia, which is probably attributable to the activation of the MAPK signaling pathway. Downregulated miR-128-3p expression induces the apoptosis and inhibits the proliferation of spermatogenic cells by promoting MAPK14 phosphorylation.

Temperature-induced testicular germ cell loss and recovery in Nile tilapia Oreochromis niloticus

Water temperature is a critical external factor influencing gonadal development in fish. This research aimed to study the impact of elevated temperature on testicular germ cell survival and reproductive capacity of Nile tilapia. Male Nile tilapia were exposed to high temperatures of either 36 (HT1) or 37 °C (HT2) for 3000 degree-days (DD) and thereafter returned to the control temperature of 27 °C (CT) for 2200 DD. The deleterious effects on testicular germ and somatic cells were observed histologically, characterised by vacuolisation, atrophy and the loss of spermatogenic cells in testes with a more severe impact of HT2 compared to HT1. Interestingly, serum 11-ketotestosterone (11-KT) and testosterone (T) levels tended to be higher during the heat treatments than CT. Expression levels of germline-specific genes piwil1, piwil2 and nanos2 and Bcl-2 family genes, bcl-xLb and baxa were significantly reduced during the heat treatment compared to CT, more so in the HT2, while the levels of nanos3 and gfra1 transcripts were only significantly reduced in HT2, implying a significant loss of spermatogonial stem cell (SSC) and spermatogonia in HT2. The effect of HT2 is further evidenced by the significantly reduced sperm density and fertilisation rate compared to CT and HT1 at the end of the recovery period but complete sterility was not induced by HT2. Overall, the present study showed significant effects of HT2 on germ cell survival with histological changes in testes, reduced milt quality, increased 11-KT, and decreased expression of germline-specific genes, SSC marker genes and Bcl-2 family genes in testes which could therefore be potential target genes for sterilisation by genome editing.

The humanin analogue (HNG) prevents temozolomide-induced male germ cell apoptosis and other adverse effects in severe combined immuno-deficiency (SCID) mice bearing human medulloblastoma

Subfertility is a major concern of long-term cancer survivors at the reproductive age. We have previously demonstrated that a potent humanin analogue, HNG, protected chemotherapy-induced apoptosis in germ cells but not cancer cells in a metastatic melanoma allograft model. In this study, we utilized severe combined immuno-deficiency (SCID) mice bearing human medulloblastoma to study the effect of HNG in Temozolomide (TMZ) induced male germ cell apoptosis and white blood cell (WBC) suppression. Human medulloblastoma DAOY cells were injected subcutaneously into the right flank of male SCID mice. Three weeks later, groups of tumor-bearing mice received one of the following treatments: vehicle, HNG, TMZ, or TMZ + HNG. 24 h after last injection, the tumors weights, complete blood counts, liver and spleen weights, male germ cell apoptosis was assessed. HNG did not affect TMZ's significant anti-tumor action. HNG significantly prevented TMZ-induced germ cell apoptosis and attenuated the suppressed total WBC and granulocyte counts in SCID mice with or without TMZ treatment. HNG also attenuated TMZ-induced body weight loss and decrease of spleen and liver weights. In conclusion, HNG ameliorated TMZ-induced germ cell apoptosis; WBC and granulocytes loss; and decreased body/organ weights without compromising the TMZ's anti-cancer action on medulloblastoma xenografts in SCID mice.

Developmental and molecular responses of buffalo (Bubalus bubalis) cumulus–oocyte complex maturedin vitrounder heat shock conditions

To investigate the effects of physiologically relevant heat shock during oocyte maturation, buffalo cumulus–oocyte complexes (COCs) were cultured at 38.5°C (control) or were exposed to 39.5°C (T1) or 40.5°C (T2) for the first 6 h ofin vitromaturation (IVM), followed by 38.5°C through the next 18 h/IVM and early embryonic development up to the blastocyst stage. Gene expression analysis was performed on selected target genes (HSF-1,HSF-2,HSP-70,HSP-90,BAX,p53,SOD1,COX1,MAPK14) in denuded oocytes and their isolated cumulus cells resulting from control COCs as well as from COCs exposed to a temperature of 39.5°C (T1). The results indicated that heat shock significantly (P< 0.01) decreased the maturation rate in T1 and T2 cells compared with the control. Afterin vitrofertilization (IVF), cleavage rate was lower (P< 0.01) for oocytes exposed to heat stress, and the percentage of oocytes arrested at the 2- or 4-cell stage was higher (P< 0.01) than that of the control. The percentage of oocytes that developed to the 8-cell, 16-cell or blastocyst stage was lower (P< 0.01) in both T1 and T2 groups compared with the control group. mRNA expression levels for the studied genes were decreased (P< 0.05) in treated oocytes (T1) except forHSP-90andHSF-1, which were increased. In cumulus cells isolated from COCs (T1), the expression for the target genes was upregulated except forBAX, which was downregulated. The results of this study demonstrated that exposure of buffalo oocytes to elevated temperatures for 6 h severely compromised their developmental competence and gene expression.

Effect of Heat Stress on Sperm DNA: Protamine Assessment in Ram Spermatozoa and Testicle

Sperm DNA fragmentation is considered one of the main causes of male infertility. The most accepted causes of sperm DNA damage are deleterious actions of reactive oxygen species (ROS), defects in protamination, and apoptosis. Ram sperm are highly prone to those damages due to the high susceptibility to ROS and to oxidative stress caused by heat stress. We aimed to evaluate the effects of heat stress on the chromatin of ejaculated and epididymal sperm and the activation of apoptotic pathways in different cell types in ram testis. We observed higher percentages of ejaculated sperm with increased chromatin fragmentation in the heat stress group; a fact that was unexpectedly not observed in epididymal sperm. Heat stress group presented a higher percentage of spermatozoa with DNA fragmentation and increased number of mRNA copies of transitional protein 1. Epididymal sperm presented greater gene expression of protamine 1 on the 30th day of the spermatic cycle; however, no differences in protamine protein levels were observed in ejaculated sperm and testis. Localization of proapoptotic protein BAX or BCL2 in testis was not different. In conclusion, testicular heat stress increases ram sperm DNA fragmentation without changes in protamination and apoptotic patterns.

Pectinase-treated Panax ginseng protects heat stress-induced testicular damage in rats

Testicular hyperthermia is well studied to cause impaired spermatogenesis. In the present study, the protective effect of enzymatically modified (pectinase-treated) Panax ginseng (GINST) against intermittent sub-chronic heat stress-induced testicular damage in rats was investigated. Male Sprague-Dawley rats were divided into four groups: normal control (NC), heat-stressed control (HC), heat-stressed plus GINST-100 mg/kg/day (HG100) and heat-stressed plus GINST-200 mg/kg/day (HG200) treatment groups. GINST (100 and 200 mg/kg/day) was mixed separately with a regular pellet diet and was administered orally for 8 weeks starting from 1 week before heat exposure. Parameters such as organ weight, blood chemistry, sperm kinetic values, expression of antioxidant enzymes, spermatogenesis molecules and sex hormone receptors levels were measured. Data revealed that kidney and epididymis weight were significantly (P < 0.05) decreased with heat stress and recovered by GINST treatment. Further, the altered levels of blood chemistry panels and sperm kinetic values in heat stress-induced rats were attenuated when GINST was administered (P < 0.05). Furthermore, the expression levels of antioxidant-related enzymes (GSTM5 and GPX4), spermatogenesis-related proteins (CREB1 and INHA) and sex hormone receptors (androgen receptor, luteinizing hormone receptor and follicle-stimulating hormone receptor) were reduced by heat stress; however, GINST treatment effectively ameliorated these changes. In conclusion, GINST was effective in reducing heat-induced damage in various male fertility factors in vivo and has considerable potential to be developed as a useful supplement in improving male fertility.

Germ cell apoptosis and expression of Bcl-2 and Bax in porcine testis under normal and heat stress conditions

The aim of this study was to examine whether an elevated ambient temperature (37-40°C) had an effect on the apoptosis of germ cells and the expression of Bcl-2 and Bax in porcine testis. Six boars were used. Three boars were subjected to an elevated ambient temperature (37-40°C, 7days, 3h per day) as a heat stress (HS) group. The other 3 boars were kept in a room temperature house (20-27°C) as a control group. All boars were castrated and the testes were harvested. TUNEL assay was used for the detection of apoptotic cells. Immunohistochemistry, Western blotting and quantitative real-time PCR were used to analyze protein and mRNA levels of Bcl-2 and Bax in response to heat treatment. The results showed that apoptotic signals increased under heat stress conditions compared with the control (P<0.01), and the cell types most affected by heat treatment were spermatocytes and spermatids. In both the control and experimental groups, Bcl-2 was expressed in the cytoplasm and nucleus of spermatogonia, spermatocytes and differentiating spermatids and Bcl-2 preferentially localized close to the seminiferous tubule's luminal surface in late spermatocytes and spermatids. Compared with the control group, the expression levels of Bcl-2 protein and mRNA significantly increased in heat treatment group, while the expression levels of Bax protein and mRNA did not show significant changes between the control and experimental group. Low to moderate Bax immunoreactivity staining was observed in all kinds of germ cells in the control group. Strong staining was observed in spermatogonia, and low to moderate Bax staining was observed in spermatocytes and spermatids. A redistribution of Bax from a cytoplasmic to perinuclear or nuclear localization could be observed in the spermatogonia, spermatocytes and spermatids obtained in the heat treated group. These results showed that elevated ambient temperatures induced germ cell apoptosis. In response to heat stress, the expression of Bcl-2 increased and a redistribution of Bax from a cytoplasmic to a perinuclear or nuclear localization. This indicates that Bcl-2 and Bax may be involved in regulation of germ cell apoptosis induced by heat stress in boars.

Iridoid glycoside from Cornus officinalis ameliorated diabetes mellitus-induced testicular damage in male rats: Involvement of suppression of the AGEs/RAGE/p38 MAPK signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Cornus officinalis (CO) has been widely used as a traditional Chinese medicine for treating diabetes mellitus (DM) and its complications. Iridoid glycoside from C. officinalis (IGCO) can resist apoptosis, hyperglycemia, oxidation and so on. The aim of this study was to investigate the therapeutic effects of IGCO on DM-induced testicular damage through inhibition of the AGEs/RAGE/p38 MAPK signaling pathway.

MATERIALS AND METHODS

A DM model of male Wistar rats was induced with streptozotocin injection (30mg/kg, i.p.) and high-fat diet. The DM rats were administrated with IGCO at low and high doses (15 and 30mg/kg, p.o.) for 12 weeks. Testicular damage was evaluated by estimating relative testicular weights, testicular pathohistology, sperm count, live sperm rate, endogenous sex hormone level and activity of testicular marker enzymes. Besides, general diabetic symptoms, renal function, oxidative stress parameters and testicular apoptosis marker were also determined. Finally, the mechanism was explored based on the AGEs/RAGE/p38 MAPK pathway.

RESULTS

IGCO effectively mitigated the general symptoms of DM rats including weight loss, polydipsia, polyphagia, polyuria, elevated blood glucose level and low serum insulin level. Nourishing the kidney evidently, IGCO reduced serum creatinine, urea nitrogen and urine protein excretion, and also markedly protected against DM-induced testicular damage by increasing testis/body weight ratio and live sperm rate, improving the histomorphology of testes, upregulating testosterone, LH, FSH and GnRH levels and preventing the decrease of testicular marker enzymes LDH, ACP and γ-GT. Moreover, IGCO showed considerable anti-oxidative and anti-apoptotic effects, which downregulated the increase of ROS and MDA levels, restored SOD and CAT activities, and decreased spermatogenic cell apoptosis and Bax/Bcl-2 ratio. In the end, the increased AGEs, RAGE and p-p38 MAPK protein levels in DM rats were also reversed by IGCO significantly.

CONCLUSIONS

The kidney tonic IGCO well protected DM rats from testicular damage, which may be related to suppression of the AGEs-RAGE-p38 MAPK pathway.

MicroRNA profiles in a monkey testicular injury model induced by testicular hyperthermia

To characterize microRNAs (miRNAs) involved in testicular toxicity in cynomolgus monkeys, miRNA profiles were investigated using next‐generation sequencing (NGS), microarray and reverse transcription‐quantitative real‐time‐PCR (RT‐qPCR) methods. First, to identify organ‐specific miRNAs, we compared the expression levels of miRNAs in the testes to those in representative organs (liver, heart, kidney, lung, spleen and small intestine) obtained from naïve mature male and female monkeys (n = 2/sex) using NGS analysis. Consequently, miR‐34c‐5p, miR‐202‐5p, miR‐449a and miR‐508‐3p were identified to be testicular‐specific miRNAs in cynomolgus monkeys. Next, we investigated miRNA profiles after testicular–hyperthermia (TH) treatment to determine which miRNAs are involved in testicular injury. In this experiment, mature male monkeys were divided into groups with or without TH‐treatment (n = 3/group) by immersion of the testes in a water bath at 43 °C for 30 min for 5 consecutive days. As a result, TH treatment induced testicular injury in all animals, which was characterized by decreased numbers of spermatocytes and spermatids. In a microarray analysis of the testis, 11 up‐regulated (>2.0 fold) and 13 down‐regulated (<0.5 fold) miRNAs were detected compared with those in the control animals. Interestingly, down‐regulated miRNAs included two testicular‐specific miRNAs, miR‐34c‐5p and miR‐449a, indicating their potential use as biomarkers for testicular toxicity. Furthermore, RT‐qPCR analysis revealed decreased expression levels of testicular miR‐34b‐5p and miR‐34c‐5p, which are enriched in meiotic cells, reflecting the decrease in pachytene spermatocytes and spermatids after TH treatment. These results provide valuable insights into the mechanism of testicular toxicity and potential translational biomarkers for testicular toxicity. Copyright © 2016 The Authors. Journal of Applied Toxicology published by John Wiley & Sons Ltd.

In this study, we identified 4 testicular‐specific miRNAs, miR‐34c‐5p, miR‐202‐5p, miR‐449a, and miR‐508‐3p based on next‐generation sequencing of miRNAs from representative organs obtained from naïve mature cynomolgus monkeys. Next, miRNAs were profiled in a model of testicular injury induced by testicular hyperthermia. Microarray and PCR analyses revealed down‐regulation of miR‐34c‐5p in the testis, which is enriched in meiotic cells, reflecting decreased numbers of pachytene spermatocytes and spermatids by the treatment.

The effects of humanin and its analogues on male germ cell apoptosis induced by chemotherapeutic drugs

Human (HN) prevents stress-induced apoptosis in many cells/tissues. In this study we showed that HN ameliorated chemotherapy [cyclophosphamide (CP) and Doxorubicin (DOX)]-induced male germ cell apoptosis both ex vivo in seminiferous tubule cultures and in vivo in the testis. HN acts by several putative mechanisms via binding to: an IL-12 like trimeric membrane receptor; BAX; or insulin-like growth factor binding protein-3 (IGFBP-3, a proapoptotic factor). To understand the mechanisms of HN on male germ cell apoptosis, we studied five HN analogues including: HNG (HN-S14G, a potent agonist), HNG-F6A (no binding to IGFBP-3), HN-S7A (no self-dimerization), HN-C8P (no binding to BAX), and HN-L12A (a HN antagonist) on CP-induced male germ cell apoptosis in mice. CP-induced germ cell apoptosis was inhibited by HN, HNG, HNG-F6A, HN-S7A, and HN-C8P (less effective); but not by HN-L12A. HN-L12A, but not HN-S7A or HN-C8P, blocked the protective effect of HN against CP-induced male germ cell apoptosis. HN, HN-S7A, and HN-C8P restored CP-suppressed STAT3 phosphorylation. These results suggest that HN: (1) decreases DOX (ex vivo) and CP (in vivo) induced male germ cell apoptosis; (2) action is mediated by the membrane receptor/STAT3 with minor contribution by BAX-binding pathway; (3) self-dimerization or binding to IGFBP-3 may not be involved in HN's effect in testis. HN is an important molecule in the regulation of germ cell homeostasis after injury and agonistic analogues may be developed for treating male infertility or protection against chemotherapy side effects.

Gestational form of Selenium in Free-Choice Mineral Mixes Affects Transcriptome Profiles of the Neonatal Calf Testis, Including those of Steroidogenic and Spermatogenic Pathways

In areas where soils are deficient in Selenium (Se), dietary supplementation of this trace mineral directly to cattle is recommended. Because Se status affects testosterone synthesis and frequency of sperm abnormalities, and the form of Se supplemented to cows affects tissue-specific gene expression, the objective of this study was to determine whether the form of Se consumed by cows during gestation would affect the expression of mRNAs that regulate steroidogenesis and/or spermatogenesis in the neonatal calf testis. Twenty-four predominantly Angus cows were assigned randomly to have individual, ad libitum, access of a mineral mix containing 35 ppm of Se in free-choice vitamin-mineral mixes as either inorganic (ISe), organic (OSe), or a 50/50 mix of ISe and OSe (MIX), starting 4 months prior to breeding and continuing throughout gestation. Thirteen male calves were born over a 3-month period (ISe, n = 5; OSe, n = 4; MIX, n = 4), castrated within 2 days of birth, and extracted testis RNA subjected to transcriptomal analysis by microarray (Affymetrix Bovine 1.0 ST arrays) and targeted gene expression analysis by real-time reverse-transcription PCR (RT-PCR) of mRNAs encoding proteins known to affect steroidogenesis and/or spermatogenesis. The form of dam Se affected (P < 0.05) the expression of 853 annotated genes, including 17 mRNAs putatively regulating steroidogenesis and/or spermatogenesis. Targeted RT-PCR analysis indicated that the expression of mRNA encoding proteins CYP2S1 (cytochrome P450, family 2, subfamily S, polypeptide 1), HSD17B7 (hydroxysteroid (17β) dehydrogenase 7), SULT1E1 (sulfotransferase family 1E, estrogen preferring, member 1), LDHA (lactate dehydrogenase A), CDK5R1 (cyclin-dependent kinase 5, regulatory subunit 1), and LEP (leptin) was affected (P < 0.05) by form of Se consumed by dams of developing bull calves, while AKR1C4 (aldo-keto reductase family 1, member C4) and CCND2 (cyclin D2) tended (P < 0.09) to be affected. Our results indicate that form of Se fed to dams during gestation affected the transcriptome of the neonatal calf testis. If these profiles are maintained throughout maturation, then the form of Se fed to dams may impact bull fertility and the development of Se form-dependent mineral mixes that target gestational development of the testis are warranted.

Testosterone replacement ameliorates nonalcoholic fatty liver disease in castrated male rats

Nonalcoholic fatty liver disease is common in developed countries and is associated with obesity, metabolic syndrome, and type 2 diabetes. T deficiency is a risk factor for developing these metabolic deficiencies, but its role in hepatic steatosis has not been well studied. We investigated the effects of T on the pathogenesis of hepatic steatosis in rats fed a high-fat diet (HFD). Adult male rats were randomly placed into four groups and treated for 15 weeks: intact rats on regular chow diet (RCD), intact rats on liquid HFD (I+HFD), castrated rats on HFD (C+HFD), and castrated rats with T replacement on HFD (C+HFD+T). Fat contributed 71% energy to the HFD but only 16% of energy to the RCD. Serum T level was undetectable in castrated rats, and T replacement led to 2-fold higher mean serum T levels than in intact rats. C+HFD rats gained less weight but had higher percentage body fat than C+HFD+T. Severe micro- and macrovesicular fat accumulated in hepatocytes with multiple inflammatory foci in the livers of C+HFD. I+HFD and C+HFD+T hepatocytes demonstrated only mild to moderate microvesicular steatosis. T replacement attenuated HFD-induced hepatocyte apoptosis in castrated rats. Serum glucose and insulin levels were not increased with HFD in any group. Immunoblots showed that insulin-regulated proteins were not changed in any group. This study demonstrates that T deficiency may contribute to the severity of hepatic steatosis and T may play a protective role in hepatic steatosis and nonalcoholic fatty liver disease development without insulin resistance.

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.

The cytoprotective peptide humanin is induced and neutralizes Bax after pro-apoptotic stress in the rat testis

We have previously demonstrated that the mitochondria-derived cytoprotective peptide humanin (HN), when administered intratesticularly to rats, rescues germ cells from apoptosis secondary to testicular stress of hormonal deprivation induced by gonadotropin-releasing hormone antagonist (GnRH-A). To decipher the cellular mechanisms of HN action in the amelioration of GnRH-A-induced germ cell apoptosis, adult male rats received the following treatments for 5 days: (i) daily intratesticular (IT) injections with saline (control); (ii) a single subcutaneous injection of GnRH-A on Day 1 and daily IT injection of saline; (iii) daily IT injection of synthetic HN; and (iv) GnRH-A injection on Day 1 and daily IT injection of HN (GnRH-A+HN). HN alone had no effect on germ cell apoptosis. GnRH-A increased germ cell apoptosis and BAX in the testicular mitochondrial fractions. Synthetic HN decreased germ cell apoptosis induced by GnRH-A and BAX in the mitochondria. We deduced that the cytoprotective action of synthetic HN on GnRH-A-induced germ cell apoptosis was mediated by attenuating p38 mitogen-activated protein kinase activity and increasing STAT3 phosphorylation. The effect of synthetic HN on the expression of endogenous rat HN in the testis was studied using rat HN specific antibody. GnRH-A treatment increased, but concomitant treatment with synthetic HN reduced endogenous rat HN expression in both cytosolic and mitochondrial fractions in testis. Co-immunoprecipitation experiments demonstrated that the increased rat HN was physically associated with BAX in the cytosolic testicular fractions after GnRH-A treatment. Double-immunofluorescence staining confirmed the co-localization of BAX and rat HN in the cytoplasm of Leydig cells and spermatocytes after GnRH-A treatment. We conclude that the cytoprotective effect of exogenously administered synthetic HN is mediated by interactions of endogenous rat HN with BAX in the cytoplasm preventing the entry of BAX to the mitochondria to govern the fate of germ cell survival or death during pro-apoptotic stress to the testis in rats.

Integrity of the blood-testis barrier in healthy men after suppression of spermatogenesis with testosterone and levonorgestrel

STUDY QUESTION

Do exogenous male hormonal contraceptives that suppress intratesticular testosterone and spermatogenesis interfere with the blood-testis barrier integrity in men?

SUMMARY ANSWER

When spermatogenesis was suppressed by testosterone alone or combined with levonorgestrel (LNG) treatment in men, the structural appearance of Sertoli cell tight junctions remained intact in the human testis.

WHAT IS ALREADY KNOWN

Testosterone promotes the integrity of the blood-testis barrier. Intratesticular androgen deprivation induced by exogenous testosterone plus a progestin to suppress spermatogenesis in a contraceptive regimen may disturb the structural and functional integrity of the blood-testis barrier.

STUDY DESIGN, SIZE AND DURATION

Testicular biopsies were obtained from a sub-study of a randomized clinical trial of 36 healthy Chinese men who were treated for 18 weeks and followed for at least a 12-week recovery period.

PARTICIPANTS/MATERIAL, SETTING, METHODS

Healthy Chinese male volunteers (27-48 years) were randomized to two treatment groups (n = 18/group) for 18 weeks: (1) testosterone undecanoate (TU) 1000 mg i.m. injection followed by a 500 mg injection every 6 weeks and (2) TU + LNG 250 μg orally daily. Blood samples were obtained from all participants before and during treatment and at the end of the recovery phase. Open testicular biopsies for this study were obtained from four men before treatment and from four men in each of the TU and TU + LNG groups at 2 and 9 weeks of treatment. The presence of antisperm antibodies was checked in the archived serum samples of the subjects at baseline, during treatment and at the end of the recovery period. Stored testicular biopsy samples from cynomolgus monkeys treated with either sub-cutaneous testosterone or placebo for 12 weeks were used for additional protein expression studies.

MAIN RESULTS AND ROLE OF THE CHANCE

Expression of blood-testis barrier associated proteins quantified by immunohistochemistry (claudin 3, claudin 11, junctional adhesion molecule-A, zonula occludens-1) remained unchanged despite a significant decrease in the numbers of pachytene spermatocytes and round spermatids in the seminiferous tubules at 9 weeks in the TU + LNG group. This was confirmed by immunoblots showing a lack of quantitative change in these tight junction proteins in monkeys after testosterone treatment. There were no increases in serum antisperm antibodies in the volunteers during the study.

LIMITATIONS/REASONS FOR CAUTION

The duration of the study was short and the long-term effects of male hormonal contraceptive treatments on the integrity of the blood-testis barrier remain to be determined.

WIDER IMPLICATIONS OF THE FINDINGS

This study supports the safety of male hormonal contraceptive treatment and does not corroborate the previous findings of disturbed immunological integrity of the blood-testis barrier from animal studies such as androgen receptor knockout mice and exogenous hormonal treatment in rats.

STUDY FUNDING/COMPETING INTEREST

The study was supported by grants from the Contraceptive Research and Development Program and the Mellon Foundation (MFG-02-64, MFG-03-67), Endocrine, Metabolism and Nutrition Training Grant (T32 DK007571), the Clinical and Translational Science Institute at Los Angeles Biomedical and Harbor-UCLA Medical Center (UL1RR033176 and UL1TR000124) and the Los Angeles Biomedical Research Institute Summer High School Student Program.

Expression levels of 25 genes in liver and testis located in a QTL region for androstenone on SSC7q1.2

A quantitative trait locus (QTL) for boar fat androstenone levels has been identified near the SSC7 centromere in a Large White × Meishan cross. Backcrosses were produced to isolate the Chinese haplotype in a European genetic background. The expression of 25 genes from the QTL region was studied in the testes and livers of 5-month-old backcross boars, with the aim of identifying the causal gene. Using Fluidigm, a new high-throughput technology, the expression of 25 genes was measured in a single real-time PCR experiment. This study found six significantly down-regulated genes (C6ORF106, C6ORF81, CLPS, SLC26A8, SRPK1 and MAPK14) in the testes of MS-LW backcross boars. However, according to current knowledge, none of the genes appear to be related to androstenone metabolism. In the livers, none of the genes were significantly up- or down-regulated, including TEAD3, which was previously designated as a possible candidate to explain this QTL.

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.

Interaction of insulin-like growth factor-binding protein-3 and BAX in mitochondria promotes male germ cell apoptosis

Germ cell apoptosis is crucial for spermatogenesis and can be triggered by various stimuli, including intratesticular hormone deprivation. This study proposes a role for insulin-like growth factor binding protein-3 (IGFBP-3) in male germ cell apoptosis. Groups of adult Sprague-Dawley male rats received one of the following treatments for 5 days: (i) daily intratesticular (IT) injections with saline (control); (ii) a single subcutaneous injection of the gonadotropin-releasing hormone antagonist (GnRH-A), acyline, on day 1 and a daily IT injection of saline; (iii) daily IT injection of IGFBP-3; and (iv) a GnRH-A injection on day 1 and a daily IT injection of IGFBP-3. Germ cell apoptosis increased significantly after IGFBP-3 or GnRH-A treatment which was further enhanced by the combined treatment. After co-immunoprecipitation with BAX antibody, IGFBP-3 association with BAX was demonstrated in total and mitochondrial fractions but not in the cytosol of testis extracts. BAX-associated IGFBP-3 expression was increased in mitochondria after treatment compared with control, which was confirmed by an IGFBP-3 enzyme-linked immunosorbent assay. Dot blot studies further validated the BAX-IGFBP-3 binding in vitro. IGFBP-3 as well as BAX induced release of cytochrome c and DIABLO from isolated testicular mitochondria in vitro. IGFBP-3, when combined with an ineffective dose of BAX, triggered release of these proteins from isolated mitochondria at a 4-fold lower dose than IGFBP-3 alone. Our data demonstrate that the IGFBP-3 and BAX interaction activates germ cell apoptosis via the mitochondria-dependent pathway. This represents a novel pathway regulating germ call homeostasis that may have significance for male fertility and testicular disease.

BH4 peptide derived from Bcl-xL and Bax-inhibitor peptide suppresses apoptotic mitochondrial changes in heat stressed bovine oocytes

Mitochondria play an important role in the integration and transmission of cell death signals mediated by the Bcl-2 family proteins. Experiments were conducted to determine whether the anti-apoptotic peptides BH4 domain of Bcl-xL (TAT-BH4) and Bax inhibitor peptide (BIP) suppresses heat stress (HS) injury in oocytes by reduction of apoptotic-like events. Cumulus-oocyte complexes (COCs) were matured at 39 degrees C (control) or 41 degrees C (HS) for 21 hr then placed in maturation medium containing 0 or 100 microM BIP in water and 0 or 1 microM TAT-BH4 in dimethyl sulfoxide (DMSO), or a combination of both peptides (BIP + BH4). Peptide effects on embryo development, DNA fragmentation, mitochondrial membrane potential (Delta(Psi)m), and mitochondrial DNA (mtDNA) copy number were measured. All groups were fertilized and cultured in vitro at 39 degrees C for 8 days. Compared to control, HS-treated oocytes induced a decrease in embryo development (P < 0.05), increase in proportion of TUNEL-positive chromatin in oocytes and blastocysts (P < 0.05), and loss of oocyte Delta(Psi)m (P < 0.001). In the presence of BIP or BIP + BH4, development of HS-treated oocytes into blastocysts was increased (P < 0.05). Conversely, COCs matured with TAT-BH4 at 41 degrees C showed reduced embryonic development (P < 0.05). Exposure of HS-treated to each or both peptides resulted in a reduction of TUNEL frequency in oocytes and blastocysts cells derived from these oocytes (P < 0.05). The loss of Delta(Psi)m in HS-treated oocytes was not restored by exposure to BIP + BH4 and there was no effect in mtDNA copy number. In conclusion, the present results show that HS-induced apoptosis in bovine oocytes involves Bax and BH4 domain-dependent pathways.

PKC-mediated secretion of death factors in LNCaP prostate cancer cells is regulated by androgens

Activation of PKCdelta in androgen-dependent LNCaP prostate cancer cells leads to apoptosis via the activation of p38 MAPK and JNK cascades. We have recently shown that treatment of LNCaP cells with phorbol 12-myristate 13-acetate (PMA) leads to a PKCdelta-mediated autocrine release of death factors, including the cytokines TNFalpha and TRAIL, and that conditioned medium (CM) collected from PMA-treated LNCaP cells promotes the activation of the extrinsic apoptotic cascade. Interfering with this autocrine loop either at the level of factor release or death receptor activation/signaling markedly impaired the PMA apoptotic response. In the present study we show that this PKCdelta-dependent autocrine mechanism is greatly influenced by androgens. Indeed, upon androgen depletion, which down-regulates PKCdelta expression, TNFalpha and TRAIL mRNA induction and release by PMA are significantly diminished, resulting in a reduced apoptogenic activity of the CM and an impaired ability of the CM to activate p38 MAPK and JNK. These effects can be rescued by addition of the synthetic androgen R1881. Furthermore, RNAi depletion of the androgen-receptor (AR) from LNCaP cells equally impaired PMA responses, suggesting that PKC-mediated induction of death factor secretion and apoptosis in LNCaP prostate cancer cells are highly sensitive to hormonal control.

Mitogen-activated protein kinase signaling in male germ cell apoptosis in the rat

Programmed germ cell death is critical for functional spermatogenesis. Increased germ cell apoptosis can be triggered by various regulatory stimuli, including testicular hyperthermia or deprivation of gonadotropins and intratesticular testosterone. We have previously shown the involvement of the mitogen-activated protein kinase (MAPK) 14 in apoptotic signaling of male germ cells across species after hormone deprivation. This study investigates the role of MAPK14 in germ cell apoptosis in rats triggered by testicular hyperthermia. The contributions of the MAPK1/3 and the MAPK8 to male germ cell death were also examined after this intervention. We show that 1) testicular hyperthermia results in induction of both MAPK1/3 and MAPK14 but not MAPK8; 2) inhibition of MAPK1/3 has no effect on the incidence of heat-induced germ cell apoptosis, suggesting that MAPK1/3 signaling may be dispensable for heat-induced male germ cell apoptosis; and 3) activation of MAPK14 and BCL2 phosphorylation are critical for heat-induced male germ cell apoptosis in rats. Thus, unlike the hormone deprivation model, heat stress through activation of the MAPK14 signaling promotes germ cell apoptosis by provoking BCL2 phosphorylation, leading to its inactivation and the subsequent activation of the mitochondria-dependent death pathway. These novel findings point to a critical role of MAPK14 in stage- and cell-specific activation of male germ cell apoptosis triggered by hormone deprivation or heat stress.

Proteomic analysis of testis biopsies in men treated with injectable testosterone undecanoate alone or in combination with oral levonorgestrel as potential male contraceptive

Treatment with injectable testosterone undecanoate (TU) alone or in combination with oral levonorgestrel (LNG) resulted in marked decreases in sperm concentrations. In this study, we used proteomic analyses to examine the cellular/molecular events occurring in the human testis after TU or TU + LNG treatment. We conducted a global proteomic analysis of the human testicular biopsies before and at 2 weeks after TU alone or TU + LNG treatment. Proteins showing significant changes in expression were identified and analyzed. As a result, 17 and 46 protein spots were found with significant differential expression after the treatment with TU alone and TU + LNG, respectively. TU treatment changed the expression of heterogeneous nuclear ribonucleoprotein K (hnRNP K), proteasome inhibitor PI31 subunit (PSMF1), and superoxide dismutase [Mn] mitochondrial precursor (SOD2). These proteins inhibit "assembly", induce cell death, and promote compensatory "cell survival" in the testis. After TU + LNG treatment, "proliferation/cell survival" and "apoptosis/death" were the predominant responses in the testis. TU + LNG treatment inhibited the expression of Prolyl 4-hydroxylase beta subunit (P4HB) and Annexin A2 (Annexin II). These proteins are involved in apoptosis and cell proliferation, respectively. TU + LNG treatment also enhanced the expression of SOD2 and Parvalbumin alpha (Pvalb). These two proteins may protect testicular cells against apoptosis/death and promote cell survival. In conclusion, TU and TU + LNG treatments suppress spermatogenesis through different pathways by changing the expression of different proteins. hnRNP K, PSMF1, SOD2, P4HB, Annexin II, and Pvalb, are key proteins that may be early molecular targets responsible for spermatogenesis suppression induced by hormone treatment.

Role of caspase 2 in apoptotic signaling in primate and murine germ cells

This study investigates the role of caspase 2 in apoptotic signaling of nonhuman primate male germ cells triggered by mild testicular hyperthermia, testosterone (T(e)) implants, or by combined interventions. Mean incidence of germ cell apoptosis increased significantly by Day 3 in the heat (H(e)) alone group and by Day 8 in the Te alone group but peaked at Day 3 in H(e) + T(e) group. We found activation of caspase 2 in both germ cells and Sertoli cells after induction of apoptosis. Most notably, active caspase 2 immunoreactivity was detected only in those germ cells susceptible to apoptosis compared with controls, where little or no such staining is detected. To further explore the role of caspase 2 in regulating male germ cell death, we next evaluated the efficacy of caspase 2 inhibition in preventing or attenuating heat-induced germ cell apoptosis in rats. Caspase 2 inhibition significantly (P < 0.05) prevented such heat-induced germ cell apoptosis. The protection offered by the caspase 2 inhibitor occurred upstream of mitochondria, involving suppression of mitogen-activated protein kinase (MAPK) 14 activation and inducible nitric oxide synthase (NOS2) induction and, in turn, suppression of cytochrome c-mediated death pathway. Together, our results show that caspase 2 is activated in male germ cells undergoing apoptosis in nonhuman primates after heat stress, hormonal deprivation, or after combined interventions. Blockade of caspase 2 activation prevents heat-induced germ cell apoptosis in rats by suppressing the MAPK14- and NO-mediated intrinsic pathway signaling.

Complete spermatogenesis in orthotopic but not in ectopic transplants of autologously grafted marmoset testicular tissue

Testicular grafting has the potential to become a method to preserve fertility in prepubertal boys undergoing cancer treatment. The possibility of successful germ cell maturation after autologous grafting should be proven preclinically in a nonhuman primate model. Therefore, in two experiments, we analyzed the potential of autologous testicular grafting in the marmoset model. A first experiment in immature and adult hemi-castrated monkeys addressed the question of whether full spermatogenesis in an ectopic graft could be achieved under a relatively normal endocrine milieu and whether the donor's age is of influence. A second experiment in castrated immature animals examined whether the transplantation site [ectopic (back skin) or orthotopic (scrotum)] influences spermatogenic progress and whether cryopreserved tissue can be successfully transplanted. Grafts were analyzed by histology, immunohistochemistry, and morphometry. Bioactive chorionic gonadotropin and serum testosterone were measured. In the adults, ectopic grafts degenerated, whereas in the immature animals, grafts survived at the spermatogonial level. In the castrates, none of the cryopreserved grafts survived, ectopic grafts were meiotically arrested, but orthotopic transplants completed spermatogenesis. Androgen and bioactive chorionic gonadotropin levels were not decisive for graft development. When ectopic and orthotopic transplantation sites were compared, the scrotum has a substantially lower temperature. Thus, the higher temperature at the ectopic transplantation site may contribute to spermatogenic arrest. Autologous grafting of nonhuman primate testicular tissues can result in complete spermatogenesis. Our findings indicate that transplantation site and developmental age of the tissue play a role more important than the endocrine milieu.