Effect of low-level radiation on the death of male germ cells

Effects of low-dose radiation produced during radiofrequency ablation guided by 3D mapping on mitochondrial apoptosis in diabetic cardiomyocytes

BACKGROUND

Three-dimensional (3D) mapping has been widely used in the clinical radiofrequency ablation of arrhythmia; however, the dose of intraoperative radiation exposure has not been determined. Moreover, whether a single instance of intraoperative radiation exposure has an effect on myocardial tissue or exacerbates diabetic heart injury remains uncertain.

METHODS AND RESULTS

In this study, we evaluated the dose of intraoperative radiation generated during radiofrequency ablation via 3D mapping. ELISA, Western blot, flow cytometry, and oxygen consumption rate detection were used to identify the effects of the intraoperative radiation dose on cardiomyocyte apoptosis via the mitochondrial pathway and its specific mechanism. These results indicated that the exposure radiation used in radiofrequency ablation guided by 3D mapping for all types of arrhythmia was low-dose radiation (LDR; the doses were all less than 200 mGy). Although LDR (50, 100 and 200 mGy) had no significant effect on the mitochondrial apoptosis of normal cardiomyocytes, the 200 mGy radiation dose reduced the mitochondrial apoptosis of cardiomyocytes subjected to high glucose and high lipid (HG/HL) treatment. Mechanistically, an LDR of 200 mGy improved the expression of IL-10, reversed the accumulation of IL-6, ROS, disruption of Δψm, and the impairment of mitochondrial function caused by HG/HL. Additionally, 200 mGy radiation promoted the expression of Bcl-xl while reducing the expression of Bax in cardiomyocytes treated with HG/HL.

CONCLUSION

In summary, this study demonstrated that the exposure radiation dose used in radiofrequency ablation guided by 3D mapping was low-dose radiation (LDR), which had no effect on the mitochondrial apoptosis pathway in normal cardiomyocytes and even had a protective effect on cardiomyocytes treated with HG/HL via increased IL-10 levels and the suppression of IL-6, ROS, and mitochondrial damage induced by HG/HL.

Low-Dose Ionizing Radiation and Male Reproductive Immunity: Elucidating Subtle Modulations and Long-Term Health Implications

Low-dose ionizing radiation (LDIR) is a prevalent environmental factor with profound impacts on male reproductive health, particularly on the testicular immune microenvironment. This review examines the multifaceted effects of LDIR, emphasizing its ability to induce genotoxic stress, oxidative damage, and epigenetic modifications in reproductive cells. These alterations compromise DNA repair, disrupt chromatin structure, and induce immune dysregulation. Immune cells such as macrophages, T cells, natural killer cells, and dendritic cells exhibit significant functional changes under LDIR exposure, destabilizing the immune privilege critical for normal spermatogenesis. The long-term health implications of LDIR include impaired sperm quality, reduced fertility, and transgenerational risks through heritable genomic instability. This review underscores the importance of exploring the mechanisms underlying immune dysregulation and developing effective protective strategies. While LDIR's full impact on male reproductive health remains to be elucidated, addressing the gaps in our understanding of immune microenvironmental changes is crucial for mitigating its adverse effects and improving reproductive health outcomes.

Transgenerational Effects on Lifespan and Pathology of Paternal Pre-conceptional Exposure to Continuous Low-dose-rate Gamma Rays in C57BL/6J Mice

The present work investigates the multigenerational effects of paternal pre-conceptional exposure to continuous low-dose-rate gamma rays in C56BL/6J mice. Male C57BL/6J (F0 sires) mice were exposed to low dose rates of 20, 1, and 0.05 mGy/day for 400 days, to total accumulated doses of 8,000, 400, and 20 mGy, respectively. Upon completion of the radiation exposure, the F0 male mice were immediately bred to non-irradiated 8-week-old C57BL/6J females (F0 dams) to produce the first-generation (F1) mice. Randomly selected F1 males and females were then bred to produce the second-generation (F2) mice. All the mice, except the F0 dams, were subjected to pathological examination upon natural death. Reproductive parameters, lifespan, causes of death, neoplasm incidences and non-neoplastic disease incidences were used as parameters to evaluate the biological effects of continuous pre-conceptional exposure of the sires (F0) to continuous low-dose-rate radiation. There were no significant differences in the pregnancy and weaning rates among the parent (F0) generation. Average litter size and average number of weaned pups (F1) from dams bred to males (F0) exposed to 20 mGy/day were significantly decreased compared to the non-irradiated controls. Significant lifespan shortening in the sires (F0) was observed only in the 20 mGy/day group due to early death from malignant lymphomas. Life shortening was also observed in the F1 progeny of sires (F0) exposed to 20 and 1 mGy/day, but could not be attributed to a specific cause. No significant differences in the causes of death were found between dose groups in any generation. The number of primary tumors per mouse was significantly increased only in the F0 males exposed to 20 mGy/day. Except for the increased incidence rate for Harderian gland neoplasms in sires (F0) exposed to 20 mGy/day, there was no significant difference in neoplasm incidences and tumor spectra in all 3 generations in each sex regardless of radiation exposure. No multi- or transgenerational effects in the parameters examined were observed in the F1 and F2 progeny of sires exposed to 0.05 mGy/day for 400 days.

Ultrastructural Analysis of Large Japanese Field Mouse (Apodemus speciosus) Testes Exposed to Low-Dose-Rate (LDR) Radiation after the Fukushima Nuclear Power Plant Accident

Since the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, great attention has been paid to the impact of chronic low-dose-rate (LDR) radiation exposure on biological systems. The reproductive system is sensitive to radiation, with implications connected to infertility. We investigated the testis ultrastructure of the wild large Japanese field mouse (Apodemus speciosus) from three areas contaminated after the FDNPP accident, with different levels of LDR radiation (0.29 µSv/h, 5.11 µSv/h, and 11.80 µSv/h). Results showed good preservation of the seminiferous tubules, comparable to the unexposed animals (controls), except for some ultrastructural modifications. Increases in the numerical density of lipid droplet clusters in spermatogenic cells were found at high levels of LDR radiation, indicating an antioxidant activity rising due to radiation recovery. In all groups, wide intercellular spaces were found between spermatogenic cells, and cytoplasmic vacuolization increased at intermediate and high levels and vacuolated mitochondria at the high-level. However, these findings were also related to the physiological dynamics of spermatogenesis. In conclusion, the testes of A. speciosus exposed to LDR radiation associated with the FDNPP accident showed a normal spermatogenesis, with some ultrastructural changes. These outcomes may add information on the reproductive potential of mammals chronically exposed to LDR radiation.

Inhibition of p38MAPK signalling pathway alleviates radiation-induced testicular damage through improving spermatogenesis

BACKGROUND AND PURPOSE

Damage to the testis following exposure to ionizing radiation has become an urgent problem to be solved. Here we have investigated if inhibition of p38 mitogen-activated protein kinase (p38MAPK) signalling could alleviate radiation-induced testicular damage.

EXPERIMENTAL APPROACH

In mice exposed to whole body radiation (2-6 Gy), morphological changes of the epididymis and testis was measured by histochemical staining. immunohistochemical and immunofluorescence procedures and western blotting were used to monitor expression and cellular location of proteins. Expression of genes was assessed by qPCR and RNA-Seq was used to profile gene expression.

KEY RESULTS

Exposure to ionizing radiation induced dose-dependent damage to mouse testis. The sperm quality decreased at 6 and 8 weeks after 6 Gy X-ray radiation. Radiation decreased PLZF+ cells and increased SOX9+ cells, and affected the expression of 969 genes, compared with data from non-irradiated mice. Expression of genes related to p38MAPK were enriched by GO analysis and were increased in the irradiated testis, and confirmed by qPCR. Levels of phospho-p38MAPK protein increased at 28 days after irradiation. In irradiated mice, SB203580 treatment increased spermatozoa, SOX9+ cells, the area and diameter of seminiferous tubules, sperm movement rate and density. Furthermore, SB203580 treatment increased SCP3+ cells, accelerating the process of spermatogenesis.

CONCLUSION AND IMPLICATIONS

Exposure to ionizing radiation clearly changed gene expression in mouse testis, involving activation of p38MAPK signalling pathways. Inhibition of p38MAPK by SB203580 partly alleviated the testicular damage caused by radiation and accelerated the recovery of sperms through promoting spermatogenesis.

Exposure to ionizing radiations and changes in blood cells and interleukin-6 in radiation workers

Long-term exposure to ionizing radiation (IR) can cause dire health consequences even less than the dose limits. Previous biomonitoring studies have focused more on complete blood counts (CBCs), with non-coherent results. In this study, we aimed to investigate the association between exposure to IR and cytokine interleukin-6 (IL-6) along with hematological parameters in Tabriz megacity's radiation workers. In this hospital-based study, blood samples were taken from 33 radiation workers (exposed group) and 34 non-radiation workers (control group) in 4 hospitals. Absorbed radiation dose was measured by a personal film badge dosimeter in radiation workers. The studied biomarkers and all of the selected covariates were measured and analyzed using adjusted multiple linear regression models. The exposed doses for all radiation workers were under the dose limits (overall mean = 1.18 mSv/year). However, there was a significant association between exposure to ionizing radiation and IL-6 (49.78 vs 36.17; t = 2.4; p = 0.02) and eosinophils (0.17 vs 0.14; t = 2.02; p = 0.049). The difference between the mean of the other biomarkers in radiation workers was not statistically significant compared to the control group. This study demonstrated that long-term exposure to ionizing radiation, even under the dose limits, is related to a significantly increased level of some blood biomarkers (Il-6 and eosinophil) that, in turn, can cause subsequent health effects such as cancer.

Protective effects of chlorogenic acid against ionizing radiation-induced testicular toxicity

Background

Testicular tissues could damage by ionizing radiation (IR) during the treatment of pelvic cancers. The aim of this study was to investigate both the protective and therapeutic effects of chlorogenic acid (CGA) on IR-induced mouse testis tissue damage.

Methods

In this experimental study, 70 mice were divided into 3 groups, including group 1 (normal saline), group 2 (IR + normal saline), and group 3 (IR + 5, 10, 20, 40, and 80 mg/kg) CGA via I.P injection. Animals in groups 2 and 3 received a dose of 2.0 Gy total-body irradiation in a single fraction. At two determined time points (16 h and 35 days after exposure), the testis and caudal part of both epididymis were isolated and underwent subsequent analyses.

Results

The results showed that irradiation of mice caused massive damage to spermatogenesis, seminiferous tubules, basal lamina, Leydig cells, and sperm parameters. Further biochemical assessment of the data demonstrated that 40 mg/kg CGA almost restored MDA to a normal level. In addition, the level of SOD, TAC, and GSH were significantly increased in the 40 mg/kg CGA treated group. Molecular evidence confirmed the protective effects of CGA and also revealed that the ratio of Bax/Bcl-2 in the presence of 40 mg/kg CGA was significantly decreased compared to IR and some treated groups.

Conclusion

The protective and therapeutic effects of CGA on testis were found to be positively correlated with the dose level.

Ameliorative effect of fractionated low-dose gamma radiation in combination with ellagic acid on nicotine-induced hormonal changes and testicular toxicity in rats

Nicotine is an active pharmacological ingredient in cigarette smoke, which may negatively influence the male reproductive system and fertility. This study aims to investigate the effect of fractionated low-dose radiation (fractionated-LDR) and/or ellagic acid (EA) on nicotine-induced hormonal changes and testicular toxicity in rats. Nicotine was administrated orally (1 mg/kg) for 30 days, afterward, rats were treated with LDR (2 × 0.25 Gy/1-week interval), EA (10 mg/kg, 14 consecutive days p.o.), or a combination of both fractionated-LDR and EA. Rats were sacrificed 24 h after the last dose of treatment, then testes were dissected for histopathology examination, along with some biochemical parameters in serum and testicular tissue were evaluated. Nicotine-induced oxidative stress was evidenced by an increase in testicular thiobarbituric acid reactive substances (TBARS) and a decrease in reduced glutathione (GSH) content. Additionally, the activities of testicular androgenic enzymes were decreased, and the activity of serum lactate dehydrogenase (LDH) was significantly increased. The hormonal changes were verified by a noticeable reduction in follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone serum levels. Histological evaluation revealed that the testicular seminiferous tubules structure was distorted. On the contrary, fractionated-LDR plus EA attenuated the negative changes caused by nicotine observed through biochemical and histological findings. Accordingly, the exposure to fractionated-LDR combined with EA may be a promising candidate for treating hormonal changes and testicular toxicity caused by nicotine.

Effects of Continuous In Utero Low- and Medium-Dose-Rate Gamma-Ray Exposure on Fetal Germ Cells

The effects of radiation exposure on germ cells and the gonads have been well studied at acute high-dose exposures, but the effects of chronic low-dose-rate (LDR) irradiation, particularly relevant for radiation protection, on germ cells and the gonads are largely unknown. Our previous study revealed that chronic exposure of mice to medium-dose-rate (MDR, 200 or 400 mGy/day) gamma-rays in utero for the entire gestation period (18 days) induced only a mild degree of general growth retardation, but with very drastic effects on the gonads and germ cells. In the current study, we further investigated the histomorphological changes in the gonads and the number of germ cells from gestation day (GD) 18 fetuses irradiated with MDR throughout the entire gestation period. The germ cells in the testes and ovaries of the MDR-irradiated fetuses were almost obliterated. Gestation day 18 fetuses exposed to LDR (20 mGy/day) radiation for the entire gestation period showed decreases in the number of the germ cells, which were not statistically significant or only marginally significant at most. Further investigations on the effects of LDR irradiation in utero using more sensitive methods are necessary.

Apoptosis of germ cells in the normal testis of the Japanese quail (Coturnix coturnix japonica)

It has been established that excess germ cells in normal and in pathological conditions are removed from testicular tissue by the mechanism of apoptosis. Studies on germ cell apoptosis in avian species are grossly lacking, and there are only a few reports on induced germ cell degenerations in the testis tissue of birds. This study was designed to investigate the process of apoptosis of germ cells in the Japanese quail (Coturnix coturnix japonica). Germ cell degenerations were investigated in birds of all age groups, namely pre-pubertal, pubertal, adult, and aged. Apoptosis of germ cells in the quails, as shown by hematoxylin & eosin (H&E), TdT dUTP Nick End Labeling (TUNEL) assay and electron microscopy, was similar to that observed in previous studies of germ cells and somatic cells of mammalian species. The observed morphological features of these apoptotic cells ranged from irregular plasma and nuclear membranes in the early stage of apoptosis to rupture of the nuclear membrane, condensation of nuclear material, as well as fragments of apoptotic bodies, in later stages of apoptosis. In the TUNEL-positive cell counts, there was a significant difference between the mean cell counts for the four age groups (P < 0.05). Post hoc analysis revealed a highly significant difference in the aged group relative to the pubertal and adult age groups, while the cell counts of the pre-pubertal group were significantly higher than those of the pubertal group. However, there was no significant difference between cell counts of the pre-pubertal and the adult, and between the pre-pubertal and the aged groups.

Amelioration of sperm count and sperm quality by lycopene supplementation in irradiated mice

Male mice were exposed to lycopene (LYC; 0.15 and 0.30mg kg-1) and irradiation (0.5, 1 Gy) alone or in combination (0.5 Gy+0.15mg kg-1 LYC; 0.5 Gy+0.30mg kg-1 LYC; 1 Gy+0.15mg kg-1 LYC; 1 Gy+0.30mg kg-1 LYC) for 2 weeks. LYC administration in the drinking water was started 24h or on Day 8 after the first irradiation dose or equivalent time point for groups treated with LYC alone. Sperm count, motility, morphology and DNA damage were determined at the end of the 2-week treatment period. Irradiation deteriorated sperm count and quality. Supplementation with LYC from 24h significantly increased the sperm count compared with irradiation alone. In almost all combined treatment groups, the percentage of abnormal spermatozoa was significantly decreased compared with that after irradiation alone. In some cases, combined treatment reduced levels of DNA damage in gametes. Both doses of LYC administered from Day 8 significantly reduced the percentage of morphologically abnormal spermatozoa compared with that seen after 1 Gy irradiation and reduced DNA damage in all combined treatment groups. In conclusion, LYC supplementation after irradiation can ameliorate the harmful effects of irradiation on gametes. Mitigation of radiation-induced damage in germ cells following LYC administration may be useful for radiological accidents and to protect non-treated tissues in patients with cancer undergoing radiotherapy.

Evaluating the effect of low dose rate of gamma rays in germ cells of Drosophila melanogaster

Purpose: Evaluation of genetic risk in germ cells is still matter of research, mainly due to their role in the transmission of genetic information from one generation to another. Although numerous experiments have been carried out in Drosophila in order to study the effect of radiation on germ cells, the role of dose rate (DR) has not been fully explored. The purpose of this study was to evaluate the action of DR on the radioprotection induction on male germ cell of D. melanogaster.Material and method: The productivity and the sex-linked recessive lethal (SLRL) tests were used to evaluate the radio-sensitivity of different states of the germ line of males. Two-day-old males of Canton-S wild type strain were pretreated with 0.2 Gy at 5.4 or 34.3 Gy/h of gamma rays from a ⁶⁰Co source, three hours later, they were irradiated with 20 Gy at 907.7 Gy/h. Thereafter, each single male was crossed with 3 five-day old Basc virgin females, that were replaced every other day by new females. This procedure was conducted three times, to test the whole germ cell stages.Results: Females crossed with males irradiated with 0.2 Gy at both DR tested, laid a higher number of eggs than control, but egg-viability was reduced. On the other hand, in the group of 0.2 Gy + 20 Gy -combined treatments- the total number of eggs laid decreased only when 0.2 Gy were delivered at 34.3 Gy/h however, the egg-viability increased. The dose of 0.2 Gy at both DR did not modify the baseline frequency of SLRL. A tendency to decrease in the frequency of lethals in brood III was found in combined treatments at both DR.Conclusion: The fact that 0.2 Gy at 5.4 or 34.3 Gy/h induced an increase in the egg-viability and a tendency to decrease the genetic damage in pre-meiotic cells provoked by 20 Gy, might indicate the induction of any mechanism that could be interpreted as radioprotection in male germ cells of D. melanogaster. Results emphasize the need to carry out more studies on the effect of the DR on the induction of genetic damage in germ cells.

Impacts of ionising radiation on sperm quality, DNA integrity and post-fertilisation development in marine and freshwater crustaceans

Crustaceans have been designated as internationally important model organisms in the development of environmental radioprotection measures. Despite the known sensitivity of sperm to ionizing radiation, the impacts of chronic radiation exposure on male fertility in crustaceans have not been studied. For the first time, the present study aimed to assess the impacts of chronic radiation exposure on male fertility, sperm DNA damage and concomitant impacts on breeding in two amphipod crustaceans. Echinogammarus marinus and Gammarus pulex (male fertility only) were exposed to phosphorus-32 at dose rates of 0, 0.1, 1 and 10 mGy/d and sperm parameters, DNA damage and knock-on impacts on breeding were assessed. Sperm quality parameters and DNA damage were assessed using a fluorescent staining method and single cell gel electrophoresis respectively. Concomitant effects of male exposure to radiation on fecundity were determined by pairing phosphorus-32 exposed males to unexposed sexually mature females. In E. marinus, a statistically significant reduction of 9 and 11% in the quality of sperm was recorded at dose rates of 1 and 10 mGy/d respectively, with no significant effects recorded on sperm counts. Conversely in the freshwater G. pulex, no significant impact of radiation on sperm quantity or quality was recorded. For E. marinus, a statistically significant increase in DNA damage was recorded at doses of 10 mGy/d. Reduced fecundity and an increase in the frequency of abnormal embryos was recorded in female E. marinus breeding with males exposed to radiation. These findings suggest sperm quality may be a sensitive indicator of radiation exposure in invertebrates with potential impacts on the unexposed embryo, though unclear dose-response and differences between two closely related species necessitate further study before robust conclusions can be drawn.

A Chinese herbal prescription Yiqi Jiedu decoction attenuates irradiation induced testis injury in mice

OBJECTIVE

Yiqi Jiedu (YQJD) decoction is a Chinese herbal prescription, based on an experienced expert of traditional Chinese medicine. It is used for the injuries caused by radiotherapy. The current study was designed to investigate the protective effects of YQJD decoction on radiation damage of testis in mice, and to explore its potential mechanisms.

METHODS

Mice were randomly divided into blank control group (Ctrl), model group (IR), positive drug group (IRA), and YQJD decoction group (IRY). After 10-day period intervention, they were whole-body irradiated with 2 Gy ⁶⁰Co γ-rays and sacrificed on 7^th day after irradiation. The indicators including the index and histopathology examination of testis, spermatogenic cell types and apoptosis, and the expression of TLR5, MyD88, NF-κB, TNF-α, IL-6 and Bcl-2 in testis.

RESULTS

The testis atrophied significantly on 7^th day of exposure to radiation, while YQJD decoction promoted the recovery of testis index and structure. Moreover, spermatogenic cell types and apoptosis had significant changes after irradiation. YQJD decoction protected the testicular function of spermatogenesis, as while as reduced the apoptosis rate of spermatogenic cells. In addition, RT-PCR and immunohistochemical analysis showed that YQJD decoction up-regulated the expression of TLR5 in testis. The levels of TLR5's downstream factors were also up-regulated in YQJD decoction group, which indicated that TLR5 signaling pathway might play an important role in the protective effects of YQJD decoction.

CONCLUSIONS

The results showed that YQJD decoction attenuated irradiation induced testis injury in mice. Its potential mechanism was related to TLR5 signaling pathway.

Low-dose ionizing irradiation triggers apoptosis of undifferentiated spermatogonia in vivo and in vitro

Background

The present study aimed to investigate the mechanism of low-dose ionizing radiation (IR) induced apoptosis of undifferentiated spermatogonia in vivo and in vitro.

Methods

Following 50 mGy IR, testicular tissues were collected from the adult DBA/2 mice at 1, 2 and 24 h; mice in the control group received pseudo-irradiation. Immunofluorescence (IF) staining and TUNEL were performed to assess DNA damage and apoptosis, respectively, in the irradiated testicular tissues. Furthermore, the spermatogonia were also irradiated in vitro, and the expression of apoptosis-related proteins was detected by Western blotting. TUNEL and flow cytometry were applied to assess cell apoptosis.

Results

γH2AX (a marker of DNA damage) was up-regulated in the seminiferous tubules at 1 and 2 h after IR, but it was reduced following the DNA repair. This was consistent with the finding that apoptosis of germline cells was present in the seminiferous tubules after IR, especially at 1 h (IF and TUNEL). Apoptosis was also present in the PLZF(+) spermatogonia, particularly at 1 h after IR. Apoptotic cells decreased with the increase in DNA repair time after IR. Moreover, the caspase-3 protein was expressed in the undifferentiated spermatogonia following IR. The expression of caspase-3, P53, Ku70 and DNA-PKcs in the cultured spermatogonia was also up-regulated following IR in vitro, but their expression decreased gradually over time after IR, which was supported by the findings from flow cytometry, and the apoptosis of spermatogonia peaked at 24 h post IR.

Conclusions

IR may induce the apoptosis of spermatogonia at early stage in vivo, but the apoptosis of spermatogonia secondary to IR occurs at a relatively later time point (24 h) in vitro mainly. The apoptosis of spermatogonia is improved over time after IR.

Coenzyme Q10 mitigates ionizing radiation-induced testicular damage in rats through inhibition of oxidative stress and mitochondria-mediated apoptotic cell death

Radiotherapy is a common treatment modality for cancer patients; however, its use is limited by decreasing the probability of fertility in male cancer survivors. Therefore, this study aimed to define the capability of coenzyme Q10 (CoQ10), a potent stimulator of mitochondrial function, in attenuating ionizing radiation (IR)-induced spermatogenesis impairments. Male Sprague Dawley rats were exposed to a single dose of ϒ-rays (10 Gy) and/or treated with CoQ10 (10 mg/kg, orally, for 2 consecutive weeks). IR mediated irregular seminiferous tubules, which were emerged with typical morphological characteristics of apoptosis, and nuclear condensation, while CoQ10 significantly preserved the testicular structure and maintained spermatogenesis, which was displayed by higher levels of serum estradiol and testosterone. CoQ10 remarkably augmented sperm count, motility, and viability while diminished the rate of sperm-defects relatively to their counterparts after IR exposure. CoQ10 modulations in reproductive parameters were underpinned by attenuating IR-induced oxidative stress as evidenced by decreasing lipid peroxidation and increasing the antioxidant enzymes glutathione peroxidase and glutathione-s-transferase activities, and glutathione level. Supporting the involvement of CoQ10 in the anti-apoptotic response, the reduced mRNA expression levels of p53, Puma, and Bax accompanied by the increased Bcl-2 mRNA expression were observed. Subsequently, CoQ10 ameliorated the mitochondria dependent apoptotic pathway through diminishing Bax/Bcl-2 ratio, caspase-3 protein expression, and DNA fragmentation in testes of irradiated rats. Taken together, our findings showed that CoQ10 conserved against IR-induced steroidogenesis disruption through subsiding mitochondria-mediated oxidative stress injury in germinal cells.

Pelvic Radiation-Induced Testicular Damage: An Experimental Study at 1 Gray

Therapeutic radiation of the pelvic region has been shown to cause damage to testicular germ cells. In this study we aimed to evaluate the effects of a low therapeutic dose of 1 Gy on the induction of cellular and histological damage in early-stage testicular germ cells and the impact of this radiation on offspring sex ratio. Unirradiated and irradiated male rats were mated with unirradiated female rats. Female rats were followed and the sex of the offspring was determined. The male rats were sacrificed at the end of the second week, and the testicular germ cells were subjected to genetic analysis along with cytological and histopathological examination. Sperm DNA was amplified with primers specific to testis-specific Y-linked protein, rat actin beta and testis-specific X-linked genes. The resulting products were separated by capillary electrophoresis. Histopathological changes were investigated by light microscopy along with the TUNEL assay and immunohistochemical staining for caspase-3. There was no significant difference between the two groups for sex ratio and size of offspring. The number of sperm cells bearing X or Y chromosomes' did not differ significantly between these two groups. However, a 1 Gy dose of radiation caused significant cytopathological and histopathological changes in the testicular tissue. In the irradiated group, edematous regions were evident. The number of caspase-3 positive cells in the germinal epithelium of the seminiferous tubules was also significantly higher in the irradiated group. Our results showed that low-dose radiation induced apoptosis and caused significant cyto- and histopathological changes in the testicular tissue. Further research is required to fully elucidate their contribution to apoptosis and if low-dose radiation may potentially lead to long-term effects in the offspring. These results may also lead us to develop a new technique using the caspase-3 staining to monitor the susceptibility to low dose radiation.

Research Progress on the Biological Effects of Low-Dose Radiation in China

Human are exposed to ionizing radiation from natural and artificial sources, which consequently poses a possible risk to human health. However, accumulating evidence indicates that the biological effects of low-dose radiation (LDR) are different from those of high-dose radiation (HDR). Low-dose radiation–induced hormesis has been extensively observed in different biological systems, including immunological and hematopoietic systems. Adaptive responses in response to LDR that can induce cellular resistance to genotoxic effects from subsequent exposure to HDR have also been described and researched. Bystander effects, another type of biological effect induced by LDR, have been shown to widely occur in many cell types. Furthermore, the influence of LDR-induced biological effects on certain diseases, such as cancer and diabetes, has also attracted the interest of researchers. Many studies have suggested that LDR has the potential antitumor and antidiabetic complications effects. In addition, the researches on whether LDR could induce stochastic effects were also debated. Studies on the biological effects of LDR in China started in 1970s and considerable progress has been made since. In the present article, we provide an overview of the research progress on the biological effects of LDR in China.

High fidelity CRISPR/Cas9 increases precise monoallelic and biallelic editing events in primordial germ cells

Primordial germ cells (PGCs), the embryonic precursors of the sperm and egg, are used for the introduction of genetic modifications into avian genome. Introduction of small defined sequences using genome editing has not been demonstrated in bird species. Here, we compared oligonucleotide-mediated HDR using wild type SpCas9 (SpCas9-WT) and high fidelity SpCas9-HF1 in PGCs and show that many loci in chicken PGCs can be precise edited using donors containing CRISPR/Cas9-blocking mutations positioned in the protospacer adjacent motif (PAM). However, targeting was more efficient using SpCas9-HF1 when mutations were introduced only into the gRNA target sequence. We subsequently employed an eGFP-to-BFP conversion assay, to directly compare HDR mediated by SpCas9-WT and SpCas9-HF1 and discovered that SpCas9-HF1 increases HDR while reducing INDEL formation. Furthermore, SpCas9-HF1 increases the frequency of single allele editing in comparison to SpCas9-WT. We used SpCas9-HF1 to demonstrate the introduction of monoallelic and biallelic point mutations into the FGF20 gene and generate clonal populations of edited PGCs with defined homozygous and heterozygous genotypes. Our results demonstrate the use of oligonucleotide donors and high fidelity CRISPR/Cas9 variants to perform precise genome editing with high efficiency in PGCs.

Late Effects of Low-Dose Radiation on the Bone Marrow, Lung, and Testis Collected From the Same Exposed BALB/cJ Mice

We used 3 biological metrics highly relevant to health risks, that is, cell death, inflammation, and global DNA methylation, to determine the late effects of low doses (0.05 or 0.1 Gy) of 137Cs γ rays on the bone marrow, lung, and testis collected at 6 months post-irradiation from the same exposed BALB/cJ mouse. This integrative approach has not been used for such a purpose. Mice exposed to 0 or 1 Gy of radiation served as a sham or positive control group, respectively. The results could deliver information for better health risk assessment across tissues, including better scientific basis for radiation protection and clinical application. We found no changes in the levels of all studied biological metrics (except a significant increase in the levels of an anti-inflammatory cytokine, ie, interleukin 10) in tissues of 0.05-Gy exposed mice, when compared to those in sham controls. In contrast, significantly increased levels of cell death and inflammation, including a significant loss of global 5-hydroxymethylcytosine, were found in all tissues of the same mice exposed to 0.1 or 1.0 Gy. Our data demonstrated not only no harm but also hormesis in the 0.05-Gy exposed mice. However, the hormetic effect appears to be dependent on biological metrics and tissue.

Analysis of the Effect of Chronic and Low-Dose Radiation Exposure on Spermatogenic Cells of Male Large Japanese Field Mice ( Apodemus speciosus ) after the Fukushima Daiichi Nuclear Power Plant Accident

In this study we analyzed the effect of chronic and low-dose-rate (LDR) radiation on spermatogenic cells of large Japanese field mice ( Apodemus speciosus ) after the Fukushima Daiichi Nuclear Power Plant (FNPP) accident. In March 2014, large Japanese field mice were collected from two sites located in, and one site adjacent to, the FNPP ex-evacuation zone: Tanashio, Murohara and Akogi, respectively. Testes from these animals were analyzed histologically. External dose rate from radiocesium (combined ¹³⁴Cs and ¹³⁷Cs) in these animals at the sampling sites exhibited 21 μGy/day in Tanashio, 304-365 μGy/day in Murohara and 407-447 μGy/day in Akogi. In the Akogi group, the numbers of spermatogenic cells and proliferating cell nuclear antigen (PCNA)-positive cells per seminiferous tubule were significantly higher compared to the Tanashio and Murohara groups, respectively. TUNEL-positive apoptotic cells tended to be detected at a lower level in the Murohara and Akogi groups compared to the Tanashio group. These results suggest that enhanced spermatogenesis occurred in large Japanese field mice living in and around the FNPP ex-evacuation zone. It remains to be elucidated whether this phenomenon, attributed to chronic exposure to LDR radiation, will benefit or adversely affect large Japanese field mice.

Temporal Responses to X-Radiation Exposure in Spleen in the pKZ1 Mouse Recombination Assay

The in vivo mouse transgenic pKZ1 chromosomal inversion assay is a sensitive assay that responds to very low doses of DNA-damaging agents. pKZ1 inversions are measured as the frequency of cells expressing E. coli β-galactosidase protein, which can only be produced from an inverted pKZ1 transgene. In previous studies we reported that a single whole-body low dose of 0.01 mGy X rays alone caused an increase in pKZ1 chromosomal inversions in spleen when analyzed 3 days postirradiation, and yet this same dose could protect from high-dose-induced inversions when delivered as a conditioning dose 4 h before or after a 1 Gy challenge dose. In an attempt to explain these results, we performed temporal studies over a wide radiation dose range to determine if the inversion response was temporally different at different doses. pKZ1 mice were irradiated with a single whole-body X-ray dose of 0.01 mGy, 1 mGy or 1 Gy, and spleen sections were then analyzed for pKZ1 inversions at 7 h, 1 day or 7 days after exposure. No change in inversion frequency was observed at the 7 h time point at any dose. At day 1, an increase in inversions was observed in response to the 0.01 mGy dose, whereas a decrease in inversions below sham-treated frequency was observed for the 1 mGy dose. Inversion frequency for both doses returned to sham-treated inversion frequency by day 7. To our knowledge, this is the first reported study to examine the temporal nature of a radiation response spanning a wide dose range, including doses relevant to occupational exposure, and the results are dynamic and dose specific. The results suggest that inversions induced after low-dose irradiation are removed by homeostatic mechanisms within a short time frame, and underscore the importance of studying responses over a period of time when interpreting radiation effects.

Effects of environmental radiation on testes and spermatogenesis in wild large Japanese field mice (Apodemus speciosus) from Fukushima

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident that occurred after the Great East Japan Earthquake in March 2011 released large quantities of radionuclides to the environment. The long-term effects of radioactive cesium (Cs) on biota are of particular concern. We investigated the accumulation of radioactive Cs derived from the FDNPP accident, and chronic effects of environmental radionuclides on male reproduction, in the large Japanese field mouse (Apodemus speciosus). In 2013 and 2014, wild mice were captured at 2 sites in Fukushima Prefecture and at 2 control sites that were distant from Fukushima. Although the median concentrations of (134)Cs and (137)Cs in the mice from Fukushima exceeded 4,000 Bq/kg, there were no significant differences in the apoptotic cell frequencies or the frequencies of morphologically abnormal sperm among the capture sites. Thus, we conclude that radiation did not cause substantial male subfertility in Fukushima during 2013 and 2014, and radionuclide pollution levels in the study sites would not be detrimental to spermatogenesis of the wild mice in Fukushima.

Repetitive exposure to low-dose X-irradiation attenuates testicular apoptosis in type 2 diabetic rats, likely via Akt-mediated Nrf2 activation

To determine whether repetitive exposure to low-dose radiation (LDR) attenuates type 2 diabetes (T2DM)-induced testicular apoptotic cell death in a T2DM rat model, we examined the effects of LDR exposure on diabetic and age-matched control rats. We found that testicular apoptosis and oxidative stress levels were significantly higher in T2DM rats than in control rats. In addition, glucose metabolism-related Akt and GSK-3β function was downregulated and Akt negative regulators PTP1B and TRB3 were upregulated in the T2DM group. Superoxide dismutase (SOD) activity and catalase content were also found to be decreased in T2DM rats. These effects were partially prevented or reversed by repetitive LDR exposure. Nrf2 and its downstream genes NQO1, SOD, and catalase were significantly upregulated by repetitive exposure to LDR, suggesting that the reduction of T2DM-induced testicular apoptosis due to repetitive LDR exposure likely involves enhancement of testicular Akt-mediated glucose metabolism and anti-oxidative defense mechanisms.

Protective Effect of Administered Rolipram against Radiation-Induced Testicular Injury in Mice

Purpose

Pelvic irradiation for the treatment of cancer can affect normal cells, such as the rapidly proliferating spermatogenic cells of the testis, leading to infertility, a common post-irradiation problem. The present study investigated the radioprotective effect of rolipram, a specific phosphodiesterase type-IV inhibitor known to increase the expression and phosphorylation of the cyclic adenosine monophosphate response element-binding protein (CREB), a key factor for spermatogenesis, with the testicular system against pelvic irradiation.

Materials and Methods

Male C57BL/6 mice were treated with pelvic irradiation (2 Gy) and rolipram, alone or in combination, and were sacrificed at 12 hours and 35 days after irradiation.

Results

Rolipram protected germ cells from radiation-induced apoptosis at 12 hours after irradiation and significantly increased testis weight compared with irradiation controls at 35 days. Rolipram also ameliorated radiation-induced testicular morphological changes, such as changes in seminiferous tubular diameter and epithelial height. Additionally, seminiferous tubule repopulation and stem cell survival indices were higher in the rolipram-treated group than in the radiation group. Moreover, rolipram treatment counteracted the radiation-mediated decrease in the sperm count and mobility in the epididymis.

Conclusions

These protective effects of rolipram treatment prior to irradiation may be mediated by the increase in pCREB levels at 12 hours post-irradiation and the attenuated decrease in pCREB levels in the testis at 35 days post-irradiation in the rolipram-treated group. These findings suggest that activation of CREB signaling by rolipram treatment ameliorates the detrimental effects of acute irradiation on testicular dysfunction and the related male reproductive functions in mice.

Classification of the spermatogenic cycle, seasonal changes of seminiferous tubule morphology and estimation of the breeding season of the large Japanese field mouse (Apodemus speciosus) in Toyama and Aomori prefectures, Japan

The large Japanese field mouse, Apodemus speciosus, is a potential indicator of environmental stress, but this function has not been confirmed by histological studies. Since environmental stress affects the reproductive function of mice, we determined the reproductive characteristics of this species at two locations: Toyama (36°35'N, 137°24'E) and Aomori (40°35'N, 140°57'E). Mice were captured during May-November (n=119) and July-November (n=146) at these locations, respectively. We classified the breeding season from the numbers of pregnant females and young, in addition to the spermatogenic cycle and seasonal changes in seminiferous tubule morphology of males. Testicular weight was measured, and seminiferous tubule morphology was examined histologically. Fourteen stages were found in the seminiferous epithelium cycle based on acrosome formation and spermatid head morphology. At both locations, the breeding season peaked from late summer to early autumn and possibly in spring. Spermatogenic activity was classified into 4 periods from June to November: resting around June and October-November; resumptive around July; active around August; and degenerative around September. During the resting period, the seminiferous tubules consisted of Sertoli cells, spermatogonia and spermatocytes. Spermatogenesis began during the resumptive period, and spermatids were observed. During the active period, active spermatogenesis and a broad lumen were observed. During the degenerative period, spermatogenesis ended, and Sertoli cells, spermatogonia, spermatocytes and degenerating exfoliated round spermatids were observed. This study provides scientific information about the testicular histopathological evaluations of the large Japanese field mouse for its use as an index species of environmental pollution.

Protection of murine spermatogenesis against ionizing radiation-induced testicular injury by a green tea polyphenol

Epigallocatechin-3-gallate (EGCG), a bioactive polyphenol in green tea, exerts antiapoptotic activity and prevents tissue damage against different stimuli. Herein, we investigated the effects of EGCG treatment to simultaneously improve spermatogenesis following ionizing radiation (IR) (at a dose of 2 Gy). Mice were intraperitoneally injected with 50 mg/kg EGCG or vehicle control 3 days prior to the irradiation, and the treatment lasted intermittently for 24 days. Supplement with exogenous EGCG protected against short-term germ cell loss and attenuated IR-elicited testicular oxidative stress. Mechanistically, prosurvival effects of EGCG treatment upon IR stress were regulated, at least in part, via the mitogen-activated protein kinase/BCL2 family/caspase 3 pathway. Consistently, at post-IR Day 21, histological analyses revealed tubule damage, desquamation of germ cells, and impairment of caudal parameters in irradiated testis, which could be significantly improved by intermittent EGCG treatment. In addition, long-term EGCG application ameliorated the IR-induced blood-testicular barrier permeability and suppressed testicular steroidogenesis, thus exerting a stimulatory effect on the spermatogenic recovery. Collectively, EGCG appeared to efficiently prevent germ cells from radiation-induced cell death via multiple mechanisms. Employment of this bioactive polyphenol should be an attractive strategy to preserve fertility in males exposed to conventional radiation therapy and warrants further investigation.

Comparison of the effects of bisphenol A alone and in a combination with X-irradiation on sperm count and quality in male adult and pubescent mice

Bisphenol A (BPA) is employed in the manufacturing of epoxy, polyester-styrene, and polycarbonate resins, which are used for the production of baby and water bottles and reusable containers, food and beverage packing, dental fillings and sealants. The study was designed to examine the effects of 8-week exposure (a full cycle of spermatogenesis) to BPA alone and in a combination with X-irradiation on the reproductive organs and germ cells of adult and pubescent male mice. Pzh:Sfis male mice were exposed to BPA (5, 10, and 20 mg/kg) or X-rays (0.05 Gy) or to a combination of both (0.05 Gy + 5 mg/kg bw BPA). The following parameters were examined: sperm count, sperm motility, sperm morphology, and DNA damage in male gametes. Both BPA and X-rays alone diminished sperm quality. BPA exposure significantly reduced sperm count in pubescent males compared to adult mice, with degenerative changes detected in seminiferous epithelium. This may suggest a higher susceptibility of germ cells of younger males to BPA action. Combined BPA with X-ray treatment enhanced the harmful effect induced by BPA alone in male germ cells of adult males, whereas low-dose irradiation showed sometimes protective or additive effects in pubescent mice.

Direct versus indirect radiation action in irradiated vegetal embryos

Maize is one of model plants useful for genetic investigations and also very important for its agrotechnical utilizations. Here the genotoxic effects of low dose X-rays and accelerated electrons in maize caryopses was carried out with focus on the influence of water content at the moment of seed irradiation. X-ray photon beam as well as accelerated electrons were provided with 2.40 Gy min−1 dose rate. Pre-soaked and dry maize caryopses were irradiated with 0.5–3.0–6.0 Gy. Cytogenetic investigations were carried out based on microscope observations of chromosomes stained by Feulgen method. The mitotic index was found diminished in hydrated samples indicating the negative influence of indirect effects of water radicals. As known the water radiolysis release free radicals that attack biomolecules in addition to the directly absorbed radiation impact. Slight positive influence of 0.5 Gy radiation dose on cell division was evidenced. Chromosomal aberrations were identified like: vagrand chromosomes, C-metaphases, picnotic chromosomes, chromatide bridges. General tendency of aberrant mitoses enhancing was recorded in watered samples — with up to the twice increase for 6.0 Gy radiation dose. The results evidenced the hydration role in monitoring cytogenetic effects of low dose radiations in plant systems -with possible biotechnological applications.

Dual‑sensitive HRE/Egr1 promoter regulates Smac overexpression and enhances radiation‑induced A549 human lung adenocarcinoma cell death under hypoxia

The aim of this study was to construct an expression vector carrying the hypoxia/radiation dual‑sensitive chimeric hypoxia response element (HRE)/early growth response 1 (Egr‑1) promoter in order to overexpress the therapeutic second mitochondria‑derived activator of caspases (Smac). Using this expression vector, the present study aimed to explore the molecular mechanism underlying radiotherapy‑induced A549 human lung adenocarcinoma cell death and apoptosis under hypoxia. The plasmids, pcDNA3.1‑Egr1‑Smac (pE‑Smac) and pcDNA3.1‑HRE/Egr-1‑Smac (pH/E‑Smac), were constructed and transfected into A549 human lung adenocarcinoma cells using the liposome method. CoCl2 was used to chemically simulate hypoxia, followed by the administration of 2 Gy X‑ray irradiation. An MTT assay was performed to detect cell proliferation and an Annexin V‑fluorescein isothiocyanate apoptosis detection kit was used to detect apoptosis. Quantitative polymerase chain reaction and western blot analyses were used for the detection of mRNA and protein expression, respectively. Infection with the pE‑Smac and pH/E‑Smac plasmids in combination with radiation and/or hypoxia was observed to enhance the expression of Smac. Furthermore, Smac overexpression was found to enhance the radiation‑induced inhibition of cell proliferation and promotion of cycle arrest and apoptosis. The cytochrome c/caspase‑9/caspase‑3 pathway was identified to be involved in this regulation of apoptosis. Plasmid infection in combination with X‑ray irradiation was found to markedly induce cell death under hypoxia. In conclusion, the hypoxia/radiation dual‑sensitive chimeric HRE/Egr‑1 promoter was observed to enhance the expression of the therapeutic Smac, as well as enhance the radiation‑induced inhibition of cell proliferation and promotion of cycle arrest and apoptosis under hypoxia. This apoptosis was found to involve the mitochondrial pathway.

The effect of Lycium barbarum polysaccharides on the male rats׳ reproductive system and spermatogenic cell apoptosis exposed to low-dose ionizing irradiation

ETHNOPHARMACOLOGICAL RELEVANCE

Lycium barbarum, a Solanaceous defoliated shrubbery, has been used as a kind of traditional Chinese herbal medicines for thousands of years. Lycium barbarum polysaccharide (LBP) is the main bioactive component of Lycium barbarum. The aim of this study was to investigate the radioresistant effect of LBP on the damage of male rats' reproductive system and spermatogenic cells caused by low-dose (60)Co-γ irradiation.

MATERIALS AND METHODS

Male rats were randomly divided into 7 groups and treated with irradiation and/or LBP: normal control group, irradiation control group 1, irradiation control group 2, irradiation control group 3, LBP + irradiation group 1, LBP + irradiation group 2, and LBP + irradiation group 3.

RESULTS

It is found that mating function and testis organ coefficient in LBP + irradiation groups were significantly better than that of the corresponding irradiation control groups. LBP significantly up-regulates the expression of Bcl-2 while down-regulating the expression of Bax. And LBP also plays an important role in prevention mitochondrial membrane potential decrease. In addition, LBP can significantly reduce spermatogenic cells apoptosis.

CONCLUSION

LBP has obvious protective effect on the male rats' reproductive function and spermatogenic dysfunction induced by irradiation.

Low-dose-rate radiation exposure leads to testicular damage with decreases in DNMT1 and HDAC1 in the murine testis

This study examined the effects of continuous low-dose-rate radiation exposure (3.49 mGy/h) of gamma rays on mice testicles. C57BL/6 mice were divided into sham and radiation groups (n = 8 each), and were exposed to either sham irradiation or 2 Gy for 21 days, 0.2 Gy for 2 days, or 0.02 Gy for 6 h of low-dose-rate irradiation. Testicular weight, seminiferous tubular diameter, and seminiferous epithelial depth were significantly decreased in the mice irradiated with 2 Gy at 1 and 9 days after exposure. Moreover, the low-dose-rate radiation exposure induced an increase in malondialdehyde levels, and a decrease in superoxide dismutase activity in the testis of mice irradiated with 2 Gy at 1 and 9 days after exposure. The sperm count and motility in the epididymis also decreased in mice irradiated with 2 Gy at 1 and 9 days after exposure, whereas there was no significant effect on the proportion of abnormal sperm. The expressions of DNA methlytransferases-1 and histone deacetylases 1 in testes irradiated with 2 Gy were significantly decreased compared with the sham group. In conclusion, the damage exerted on the testes and epididymis largely depended on the total dose of low-dose-rate radiation.

Hypoxia- and radiation-induced overexpression of Smac by an adenoviral vector and its effects on cell cycle and apoptosis in MDA-MB-231 human breast cancer cells

A conditionally replicative adenoviral (CRAd) vector, designated as CRAd.pEgr-1-Smac, that promotes the overexpression of second mitochondria-derived activator of caspase (Smac) when stimulated by hypoxia and radiation was constructed. MDA-MB-231 cells were transfected with CRAd.pEgr-1-Smac and treated with 4-Gy X-rays. The hypoxic status in cancer cells was mimicked with the chemical reagent CoCl₂. Smac protein expression was measured by a western blotting assay and cell proliferation was detected with the MTT assay. The cell cycle progression and apoptotic percentage were measured by flow cytometry with PI and Annexin V-FITC staining kits, respectively, following the irradiation of the transfected cells with 4-Gy X-rays. The results showed that CRAd.pEgr-1-Smac was able to increase the Smac protein expression induced by hypoxia and radiation, inhibit cell proliferation and promote apoptosis. Therefore, this method of gene-radiotherapy is indicated to be an ideal strategy for the treatment of breast cancer.

Effects of radioactive caesium on bull testes after the Fukushima nuclear plant accident

We aimed to investigate the effect of chronic radiation exposure associated with the Fukushima Daiichi Nuclear Plant accident on the testis from 2 bulls. Estimated dose of internal exposure in one bull was 0.7-1.2 mGy (¹³⁴Cs) and 0.4-0.6 mGy (¹³⁷Cs) and external exposure was 2.0 mGy (¹³⁴Cs) and 0.8 mGy (¹³⁷Cs) (196 days). Internal dose in the other was 3.2-6.1 mGy (¹³⁴Cs) and 1.8-3.4 mGy (¹³⁷Cs) and external dose was 1.3 mGy (¹³⁴Cs) and 0.6 mGy (¹³⁷Cs) (315 days). Sperm morphology and spermatogenesis were within normal ranges. ¹³⁴,¹³⁷Cs radioactivity was detected but Cs was not detectable in the testis by electron probe microanalysis. Thus, adverse radiation-induced effects were not observed in bull testes following chronic exposure to the above levels of radiation for up to 10 months. Since we could analyse a limited number of testes, further investigation on the effects of ionizing radiation on spermatogenesis should be extended to more animals.

Involvement of endoplasmic reticulum stress in apoptosis of testicular cells induced by low-dose radiation

The study examined the role of endoplasmic reticulum stress (ERS) and signaling pathways of inositol-requiring enzyme-1 (IRE1), RNA-activated protein kinase-like ER kinase (PERK) and activating transcription factor-6 (ATF6) in apoptosis of mouse testicular cells treated with low-dose radiation (LDR). In the dose-dependent experiment, the mice were treated with whole-body X-ray irradiation at different doses (25, 50, 75, 100 or 200 mGy) and sacrificed 12 h later. In the time-dependent experiment, the mice were exposed to 75 mGy X-ray irradiation and killed at different time points (3, 6, 12, 18 or 24 h). Testicular cells were harvested for experiments. H(2)O(2) and NO concentrations, and Ca(2+)-ATPase activity were detected by biochemical assays, the calcium ion concentration ([Ca(2+)]i) by flow cytometry using fluo-3 probe, and GRP78 mRNA and protein expressions by quantitative real-time RT-PCR (qRT-PCR) and Western blotting, respectively. The mRNA expressions of S-XBP1, JNK, caspase-12 and CHOP were measured by qRT-PCR, and the protein expressions of IRE1α, S-XBP1, p-PERK, p-eIF2α, ATF6 p50, p-JNK, pro-caspase-12, cleaved caspase-12 and CHOP by Western blotting. The results showed that the concentrations of H2O2 and NO, the mRNA expressions of GRP78, S-XBP1, JNK, caspase-12 and CHOP, and the protein expressions of GRP78, S-XBP1, IRE1α, p-PERK, p-eIF2α, ATF6 p50, p-JNK, pro-caspase-12, cleaved caspase-12 and CHOP were significantly increased in a time- and dose-dependent manner after LDR. But the [Ca(2+)]i and Ca(2+)-ATPase activities were significantly decreased in a time- and dose-dependent manner. It was concluded that the ERS, regulated by IRE1, PERK and ATF6 pathways, is involved in the apoptosis of testicular cells in LDR mice, which is associated with ERS-apoptotic signaling molecules of JNK, caspase-12 and CHOP.

Effects of Zn deficiency, antioxidants, and low-dose radiation on diabetic oxidative damage and cell death in the testis

Infertility is one of the common complications in diabetic men and mainly due to the loss of germ cells by apoptotic cell death. Although several mechanisms have been proposed to explain the induction of testicular cell death by diabetes, diabetic induction of testicular oxidative stress and damage may be the predominant mechanism responsible for the testicular cell death in diabetes. To explore whether factors that either increase or decrease the testicular oxidative stress and damage will enhance or prevent diabetes-induced testicular cell death, the effect of zinc (Zn) deficiency on diabetes-induced cell death has been examined since Zn was found to play an important role in the protection of testis from oxidative stress and damage. Zn deficiency, induced by its chelator N,N,N,N-Tetrakis(2-pyridylmethyl)-1,2-ethylenediamine, was found to exacerbate diabetes-induced testicular oxidative damage and cell death. In contrast, treatment of diabetic rats with antioxidant N-acetylcysteine or low-dose radiation that can up-regulate endogenous antioxidants significantly attenuated diabetes-induced testicular cell death. These results suggest that diabetes-induced testicular cell death that may eventually cause men's infertility is predominantly mediated by the oxidative stress and damage. To prevent or delay diabetes-caused infertility, diabetic patients should avoid Zn deficiency, and might consider antioxidant supplementation.

Protection by hydrogen against gamma ray-induced testicular damage in rats

The aim of this study was to investigate the possible protective role of hydrogen-rich saline solution (HRSS) and WR-2721 on the testicular damage induced by irradiation. Sprague-Dawley rats were randomly divided into four groups. Group I served as control group. Rats in group II were exposed to the irradiation. The animals in group III and IV were injected intraperitoneally with HRSS (5 ml/kg) and WR-2721 (200 mg/kg), respectively, 15 min. before the start of gamma irradiation. Testis weight, testis dimensions, sperm count, sperm motility, apoptosis index and biochemical assays were assessed after a 4-day initiation of irradiation. Testis weight, testis dimensions, sperm count, sperm motility in group II were significantly lower compared with those in the control group, whereas they were higher in the HRSS and WR-2721 group. Apoptosis index was significantly increased in group II. Treatment of rats with HRSS and WR-2721 significantly reduced the apoptosis index. On the other hand, irradiation markedly decreased activities of SOD. Activities of SOD were significantly improved when treated with HRSS and WR-2721. Significant increase in the MDA level was observed in group II. MDA levels of group III and IV were significantly lowered when compared with group II. HRSS also played a significant role in the recovery of serum testosterone levels. The results from this experimental study suggest that hydrogen has a possible protective effect against radiation-induced testicular damage.

Effects of different gamma exposure regimes on reproduction in the earthworm Eisenia fetida (Oligochaeta)

Ecological risk assessment of ionising radiation requires knowledge about the responses of individuals and populations to chronic exposures, including situations when exposure levels change over time. The present study investigated processes such as recovery and the adaptive response with respect to reproduction endpoints in the earthworm Eisenia fetida exposed to (60)Co γ-radiation. Furthermore, a crossed experiment was performed to investigate the influence of F0 parental and F1 embryonic irradiation history on the response of irradiated or non-irradiated F1 offspring. Recovery: The sterility induced by sub-chronic exposure at 17 m Gy/h (accumulated dose: 25 Gy) was temporary, and 8 weeks after irradiation the worms had regained their reproductive capacity (number of viable offspring produced per adult per week). Adaptive response: Adult worms were continuously exposed at a low priming dose rate of 0.14 mGy/h for 12 weeks (accumulated dose: 0.24 Gy), followed by 14 weeks exposure at a challenge dose rate of 11 mGy/h. The results suggest a lack of adaptive response, since there were no significant differences in the effects on reproduction capacity between the primed and the unprimed groups after challenge doses ranging from 7.6 to 27 Gy. Crossed experiment: The effects of exposure at 11 mGy/h for 21 weeks on growth, sexual maturation and reproduction of offspring, derived either from parent worms and cocoons both exposed at 11 mGy/h, or from non-irradiated parents and cocoons (total accumulated dose 44 and 38 Gy, respectively) were compared. There were no significant differences between the two exposed offspring groups for any of the endpoints. The reproduction capacity was very low for both groups compared to the controls, but the reproduction seemed to be maintained at the reduced level, which could indicate acclimatisation or stabilisation. Finally, parental and embryonic exposures at 11 mGy/h did not affect reproduction in the F1 offspring as adults.

A small-scale anatomic model for testicular radiation dosimetry for radionuclides localized in the human testes

The testis is a radiosensitive tissue. It contains a large number of lobules, which in turn are composed of convoluted seminiferous tubules. The epithelium inside each tubule consists of a complex mosaic of supporting cells and germ cells of different sizes and degrees of maturation. These cells are known to have diverse sensitivity to radiation, those with the highest sensitivity being the spermatogonia, which form part of the basal cell layer, and those with the lowest sensitivity being the mature sperm cells closest to the lumen of the tubule. For many years, the internal dosimetry community has discussed the need for improvements to bring about more detailed, cell-level testicular dosimetry. This paper presents a small-scale dosimetry model for calculation of S factors for several different source-target configurations within the testicular tissue.

METHODS

A model of the testis was designed in which the lobules were approximated by a cross-section of seminiferous tubules arranged in a hexagonal pattern, with interstitial tissue between them. The seminiferous tubules were divided into concentric layers representing spermatogenic development in the seminiferous epithelium. S factors were calculated for electrons, photons, α-particles, and for (18)F, (90)Y, (99m)Tc, (111)In, (125)I, (131)I, (177)Lu, and (211)At using Monte Carlo simulations.

RESULTS

For electrons with low energies the range was small, compared with the diameter of the seminiferous tubules, resulting in high energy deposition close to the source, whereas for higher electron energies more uniform energy deposition was seen, as expected. The same trend was seen for low-energy photons, whose mean free paths are small, compared with the diameter of the seminiferous tubules, resulting in high energy deposition close to the source, whereas for higher photon energies the location of the activity in the testis is less important.

CONCLUSION

The model presented in this paper is a simplification of the organized chaos that constitutes the structure of the actual testis. However, it provides a relevant, small-scale anatomic model to help us understand the significance of the heterogeneity of radioactivity in this important radiosensitive tissue.

Combined action of X-rays and nonylphenol on mouse sperm

The aim of this study was to assess the effects of 2-weeks’ X-ray and/or nonylphenol (NP) exposure on male mice’s sperm count and quality. Pzh:SFIS mice were exposed to X-rays (0.05 Gy, 0.10 Gy, 0.20 Gy) or to nonylphenol (25 mg/kg bw, 50 mg/kg bw, 100 mg/kg bw) or to both agents (0.05 Gy + 25 mg/kg bw NP, 0.10 Gy + 50 mg/kg bw NP). At 24 h and 5 weeks after the end of exposure the sperm count, morphology and frequency of DNA damage in the male germ cells were estimated. Each agent alone diminished sperm count and morphology. The dose of 0.05 Gy of X-rays decreased the frequency of DNA damage. Combined exposure to lower doses of both agents significantly improved sperm morphology and decreased the level of DNA damage compared to one agent alone. Combined exposure to higher doses reduced the frequency of DNA damage compared to the effect of the appropriate dose of NP. Results of combined exposure to low doses of both agents suggest that 0.05 Gy of X-rays stimulate the DNA damagecontrol system and in consequence repair of DNA caused by X-rays and NP. It may be correlated with increased antioxidant capacity.

Protection of spermatogenesis against gamma ray-induced damage by granulocyte colony-stimulating factor in mice

The radioprotective effects of granulocyte colony-stimulating factor (GCSF) were further investigated with respect to the testicular system. Recombinant human GCSF (100 μg kg(-1) body weight/day) was administrated to male C3H/HeN mice by subcutaneous injection for three consecutive days before pelvic irradiation (5 Gy) and histopathological parameters were assessed at 12 h and 21 days post-irradiation (pi). The GCSF protected the germ cells from radiation induced- apoptosis (P < 0.01 vs. irradiated group at 12 h pi). GCSF remarkably attenuated radiation-induced reduction in testis weight, seminiferous tubular diameter, seminiferous epithelial depth and sperm head count in the testes (P < 0.05 versus irradiated group at 21 days pi). Repopulation index and stem cell survival index of the seminiferous tubules were increased in the GCSF-treated group when compared with the radiation group (P < 0.01). The frequency of abnormal sperm in the GCSF group was lower than that in the irradiated group at 21 days pi (P < 0.01). The decrease in the sperm count and in sperm liability in the epididymis caused by irradiation was counteracted by GCSF. The present study suggests that GCSF protects from radiation-induced testicular dysfunction via an anti-apoptotic effect and recovery of spermatogenesis.

Antagonistic effects of Lycium barbarum polysaccharides on the impaired reproductive system of male rats induced by local subchronic exposure to 60Co-γ irradiation

Lycium barbarum, a famous Chinese medicinal herb, has a long history of use in traditional medicine as an antioxidant and to promote sexual fertility. Polysaccharides are the most important functional constituents in L. barbarum fruits. In this study, male rats were exposed to subchronic (60)Co-γ irradiation to investigate the effects of LBP on sperm quantity and motility, sexual ability, serum hormone levels, oxidative status and testicular tissue DNA damage on days 1, 7 and 14 of treatment. It was found that LBP significantly increased the sperm quantity and motility, shortened the erection, capture and ejaculation latencies, increased the number of captures and ejaculations, and improved the sexual ability of male rats. LBP also played a significant role in the recovery of serum testosterone levels, increased superoxide dismutase activity, decreased malondialdehyde levels, promoted oxidative balance and rescued testicular DNA damage. In conclusion, LBP has significant protective effects against damage induced by local subchronic exposure to (60)Co-γ irradiation, allowing rats to achieve near-complete recovery with LBP treatment.

Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 4: intercellular bridges, mitochondria, nuclear envelope, apoptosis, ubiquitination, membrane/voltage-gated channels, methylation/acetylation, and transcription factors

As germ cells divide and differentiate from spermatogonia to spermatozoa, they share a number of structural and functional features that are common to all generations of germ cells and these features are discussed herein. Germ cells are linked to one another by large intercellular bridges which serve to move molecules and even large organelles from the cytoplasm of one cell to another. Mitochondria take on different shapes and features and topographical arrangements to accommodate their specific needs during spermatogenesis. The nuclear envelope and pore complex also undergo extensive modifications concomitant with the development of germ cell generations. Apoptosis is an event that is normally triggered by germ cells and involves many proteins. It occurs to limit the germ cell pool and acts as a quality control mechanism. The ubiquitin pathway comprises enzymes that ubiquitinate as well as deubiquitinate target proteins and this pathway is present and functional in germ cells. Germ cells express many proteins involved in water balance and pH control as well as voltage-gated ion channel movement. In the nucleus, proteins undergo epigenetic modifications which include methylation, acetylation, and phosphorylation, with each of these modifications signaling changes in chromatin structure. Germ cells contain specialized transcription complexes that coordinate the differentiation program of spermatogenesis, and there are many male germ cell-specific differences in the components of this machinery. All of the above features of germ cells will be discussed along with the specific proteins/genes and abnormalities to fertility related to each topic.