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

Possible association of G6PC2 and MUC6 induced by low‑dose‑rate irradiation in mouse intestine with inflammatory bowel disease

Although there are several types of radiation exposure, it is debated whether low‑dose‑rate (LDR) irradiation (IR) affects the body. Since the small intestine is a radiation‑sensitive organ, the present study aimed to evaluate how it changes when exposed to LDR IR and identify the genes sensitive to these doses. After undergoing LDR (6.0 mGy/h) γ radiation exposure, intestinal RNA from BALB/c mice was extracted 1 and 24 h later. Mouse whole genome microarrays were used to explore radiation‑induced transcriptional alterations. Reverse transcription‑quantitative (RT‑q) PCR was used to examine time‑ and dose‑dependent radiation responses. The histopathological status of the jejunum in the radiated mouse was not changed by 10 mGy of LDR IR; however, 23 genes were upregulated in response to LDR IR of the jejunum in mice after 1 and 24 h of exposure. Upregulated genes were selected to validate the results of the RNA sequencing analysis for RT‑qPCR detection and results showed that only Na+/K+ transporting subunit α4, glucose‑6‑phosphatase catalytic subunit 2 (G6PC2), mucin 6 (MUC6) and transient receptor potential cation channel subfamily V member 6 levels significantly increased after 24 h of LDR IR. Furthermore, G6PC2 and MUC6 were notable genes induced by LDR IR exposure according to protein expression via western blot analysis. The mRNA levels of G6PC2 and MUC6 were significantly elevated within 24 h under three conditions: i) Exposure to LDR IR, ii) repeated exposure to LDR IR and iii) exposure to LDR IR in the presence of inflammatory bowel disease. These results could contribute to an improved understanding of immediate radiation reactions and biomarker development to identify radiation‑susceptible individuals before histopathological changes become noticeable. However, further investigation into the specific mechanisms involving G6PC2 and MUC6 is required to accomplish this.

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.

Impacts of radiation exposure, hindlimb unloading, and recovery on murine skeletal muscle cell telomere length

Astronauts are exposed to harsh conditions, including cosmic radiation and microgravity. Spaceflight elongates human telomeres in peripheral blood, which shorten upon return to Earth and approach baseline levels during postflight recovery. Astronauts also encounter muscle atrophy, losing up to 20% loss of muscle mass on spaceflights. Telomere length changes in muscle cells of astronauts remain unexplored. This study investigates telomere alterations in grounded mice experiencing radiation exposure and muscle atrophy, via a hindlimb unloading spaceflight mimicking model. We find telomere lengthening is present in muscle stem cells and in myofiber nuclei, but not in muscle-resident endothelial cells. We further assessed telomere length in the model following hindlimb unloading recovery. We find that telomere length failed to return to baseline values. Our results suggest a role for telomeres in muscle acclimatization, which is relevant for the well-being of astronauts in space, and upon their return to Earth.

The role of taurine in male reproduction: Physiology, pathology and toxicology

Taurine, a sulfur-containing amino acid, has a wide range of biological effects, such as bile salt formation, osmotic regulation, oxidative stress inhibition, immunomodulation and neuromodulation. Taurine has been proved to be synthesized and abundant in male reproductive organs. Recently, accumulating data showed that taurine has a potential protective effect on reproductive function of male animals. In physiology, taurine can promote the endocrine function of the hypothalamus-pituitary-testis (HPT) axis, testicular tissue development, spermatogenesis and maturation, delay the aging of testicular structure and function, maintain the homeostasis of the testicular environment, and enhance sexual ability. In pathology, taurine supplement may be beneficial to alleviate pathological damage of male reproductive system, including oxidative damage of sperm preservation in vitro, testicular reperfusion injury and diabetes -induced reproductive complications. In addition, taurine acts as a protective agent against toxic damage to the male reproductive system by exogenous substances (e.g., therapeutic drugs, environmental pollutants, radiation). Related mechanisms include reduced oxidative stress, increased antioxidant capacity, inhibited inflammation and apoptosis, restored the secretory activity of the HPT axis, reduced chromosomal variation, enhanced sperm mitochondrial energy metabolism, cell membrane stabilization effect, etc. Therefore, this article reviewed the protective effect of taurine on male reproductive function and its detailed mechanism, in order to provide reference for further research and clinical application.

Low Dose Rate Radiation Regulates M2-like Macrophages in an Allergic Airway Inflammation Mouse Model

We investigated the effects of low dose rate radiation (LDR) on M1 and M2 macrophages in an ovalbumin-induced mouse model of allergic airway inflammation and asthma. After exposure to LDR (1 Gy, 1.818 mGy/h) for 24 days, mice were euthanized and the changes in the number of M1 and M2 macrophages in the bronchoalveolar lavage fluid and lung, and M2-associated cytokine levels, were assessed. LDR treatment not only restored the M2-rich microenvironment but also ameliorated asthma-related progression in a macrophage-dependent manner. In an ovalbumin-induced mouse model, LDR treatment significantly inhibited M2, but not M1, macrophage infiltration. M2-specific changes in macrophage polarization during chronic lung disease reversed the positive effects of LDR. Moreover, the levels of cytokines, including chemokine (C-C motif) ligand (CCL) 24, CCL17, transforming growth factor beta 1, and matrix metalloproteinase-9, decreased in ovalbumin-sensitized/challenged mice upon exposure to LDR. Collectively, our results indicate that LDR exposure suppressed asthmatic progression, including mucin accumulation, inflammation, and Type 2 T helper (Th2) cytokine (interleukin (IL)-4 and IL-13) production. In conclusion, LDR exposure decreased Th2 cytokine secretion in M2 macrophages, resulting in a reduction in eosinophilic inflammation in ovalbumin-sensitized/challenged mice.

Evaluation of Global DNA Methylation and Gene Expression of Izumo1 and Izumo1r in Gonads after High- and Low-Dose Radiation in Neonatal Mice

The intergenerational effects from chronic low-dose exposure are matters of concern. It is thus important to elucidate the radiation-induced effects of germ cell maturation, fertilization and embryonic development. It is well known that DNA methylation levels in CpG sites in gametes are reprogrammed in stages during their maturity. Furthermore, the binding of Izumo on the surface of sperm and Juno on the surface of oocytes is essential for fertilization. Thus, there is a possibility that these genes are useful indicators to evaluate fertility in mice after irradiation exposure. Therefore, in this study, we analyzed global DNA methylation patterns in the testes and gene expression of Izumo1 and Izumo1r (Juno) in the gonads of mice after neonatal acute high-dose ionizing radiation (HDR) and chronic low-dose ionizing radiation (LDR). One-week-old male and female mice were irradiated with a total dose of 4 Gy, with acute HDR at 7 days at a dose rate of 30 Gy/h and LDR continuously at a dose rate of 6 mGy/h from 7 to 35 days. Their gonads were subsequently analyzed. The results of global DNA methylation patterns in the testes showed that methylation level increased with age in the control group, the LDR group maintained its DNA methylation level, and the HDR group showed decreased DNA methylation levels with age. In the control group, the gene expression level of Izumo1 in the testis did not show age-related changes, although there was high expression at 100 days of age. However, in the LDR group, the expression level recovered after the end of irradiation, while it remained low regardless of age in the HDR group. Conversely, gene expression of Izumo1r (Izumo1 receptor) in the ovary decreased with age in the control group. Although the gene expression of Izumo1r decreased with age in the LDR group, it remained low in the HDR group. Our results indicate that LDR can induce different DNA methylation patterns, and both high- and low-dose radiation before sexual maturity might affect gametogenesis and fertility.

Differential Effects of Low and High Radiation Dose Rates on Mouse Spermatogenesis

The adverse effects of radiation are proportional to the total dose and dose rate. We aimed to investigate the effects of radiation dose rate on different organs in mice. The mice were subjected to low dose rate (LDR, ~3.4 mGy/h) and high dose rate (HDR, ~51 Gy/h) radiation. LDR radiation caused severe tissue toxicity, as observed in the histological analysis of testis. It adversely influenced sperm production, including sperm count and motility, and induced greater sperm abnormalities. The expression of markers of early stage spermatogonial stem cells, such as Plzf, c-Kit, and Oct4, decreased significantly after LDR irradiation, compared to that following exposure of HDR radiation, in qPCR analysis. The compositional ratios of all stages of spermatogonia and meiotic cells, except round spermatid, were considerably reduced by LDR in FACS analysis. Therefore, LDR radiation caused more adverse testicular damage than that by HDR radiation, contrary to the response observed in other organs. Therefore, the dose rate of radiation may have differential effects, depending on the organ; it is necessary to evaluate the effect of radiation in terms of radiation dose, dose rate, organ type, and other conditions.

The role of small GTPase Rac1 in ionizing radiation-induced testicular damage

PURPOSE

The main acute and late effects of ionizing radiation on living organisms are the formation of reactive oxygen species (ROS), apoptosis and DNA damage. Since the Rac1 molecule is a subunit of the NADPH oxidase enzyme, it is known to participate in the generation of ROS. The aim of this study was to investigate the role of Rac1 molecule in testicular damage induced by low (0.02 Gy), medium (0.1 Gy) and high (5 Gy) dose irradiation.

MATERIAL AND METHOD

In this study, Wistar rats (except the control group) were received whole body X-ray irradiation. Testicular tissues were removed 2 hours, 24 hours and 7 days after radiation exposure. Testicular damage was examined by hematoxylin-eosin staining and Johnsen's score. Immunohistochemical staining and G-LISA method were used to determine Rac1 expression and activation. To evaluate the generation of ROS in the testicular tissues, intracellular ROS, superoxide dismutase (SOD) and malondialdehyde (MDA) levels were measured.

RESULTS

Increases in testicular damage were detected in all radiation exposed groups in a dose- and time-dependent manner. Compared to the control group, Rac1 expression decreased in all irradiated groups, while Rac1 activation increased. In addition, intracellular ROS and MDA levels were increased and SOD activity levels decreased in the irradiated groups compared to the control group.

CONCLUSION

Our findings suggest that Rac1 has a role in the increase of intracellular ROS and lipid peroxidation which led to an increase in radiation- induced testicular damage.

Effects of chronic exposure to low levels of IR on Medaka (Oryzias latipes): a proteomic and bioinformatic approach

PURPOSE

Chronic exposure to ionizing radiation (IR) at low doses (<100 mGy) has been insufficiently studied to understand fully the risk to health. Relatively little knowledge exists regarding how species and healthy tissues respond at the protein level to chronic exposure to low doses of IR, and mass spectrometric-based profiling of protein expression is a powerful tool for studying changes in protein abundance.

MATERIALS AND METHODS

SDS gel electrophoresis, LC-MS/MS mass spectrometry-based approaches and bioinformatic data analytics were used to detect proteomic changes following chronic exposure to moderate/low doses of radiation in adults and normally developed Medaka fish (Oryzias latipes).

RESULTS

Significant variations in the abundance of proteins involved in thyroid hormone signaling and lipid metabolism were detected, which could be related to the gonadal regression phenotype observed after 21.04 mGy and 204.3 mGy/day exposure. The global proteomic change was towards overexpression of proteins in muscle and skin, while the opposite effect was observed in internal organs.

CONCLUSION

The present study provides information on the impacts of biologically relevant low doses of IR, which will be useful in future research for the identification of potential biomarkers of IR exposure and allow for a better assessment of radiation biosafety regulations.

Melatonin-Caffeine Combination Modulates Gamma Radiation-induced Sperm Malformations in C57BL/6 Male Mice at Sublethal Dose of Gamma Radiation

Aims:

The aim of this study was to assess the protective effect of the melatonin–caffeine combination against γ radiation-induced alterations in the morphological characteristics of sperms.

Settings and Design:

C57BL/6 male mice (n = 30) were randomly divided into five groups: control, radiation (2 Gy), melatonin (100 mg/kg body wt.) + radiation (2 Gy), caffeine (30 mg/kg body wt.) + radiation (2 Gy), melatonin–caffeine (100–30 mg/kg body wt.) + radiation (2 Gy).

Materials and Methods:

All the mice were sacrificed 24 h postirradiation, and cauda epididymis was collected. In this study, sperm concentration along with any abnormality in their morphology (amorphous heads, pinheads, hookless, coiled tails, midpiece defect, and tail-less) was observed in the control and treatment group of animals.

Results:

Radiation exposure (2 Gy) considerably decreases the sperm count when compared with the control group. However, pretreatment with melatonin and melatonin–caffeine combination before gamma irradiation increased the sperm count (P < 0.05), but with caffeine alone could not produce a significant difference. The higher rate of abnormal sperms was observed in the γ-irradiated mice when compared with the control group (P < 0.05). Besides, the numbers of sperm that are hookless and coiled tails were significantly increased after irradiation. Melatonin significantly reduced the number of sperm with amorphous heads and coiled tails. Melatonin–caffeine combination further reduced sperm malformations when compared with the melatonin + 2 Gy radiation and caffeine + 2 Gy radiation group.

Conclusions:

This study suggests that caffeine exerts a protective effect when given in combination with melatonin against gamma irradiation in sperms of C57BL/6 mice and could be a potent combination for the development of radioprotector.

Heavy ion radiation-induced DNA damage mediates apoptosis via the Rpl27a-Rpl5-MDM2-p53/E2F1 signaling pathway in mouse spermatogonia

The risk of exposure to ionizing radiation (IR) environments has increased with the development of nuclear technology. IR exposure induces excessive apoptosis of the spermatogonia, which leads to male infertility. Spermatogonia apoptosis may be involved in ribosomal stress triggered by DNA damage following exposure to IR because ribosomal proteins (RPs) directly interact with mouse double minute 2 homolog (MDM2) to induce apoptosis. This study aimed to use comparative proteomics and transcriptomics approach to screen the differential RPs and ribosomal mRNAs in mouse testes following high linear energy transfer (LET) carbon ion radiation (CIR). The expression of ribosomal large subunit protein 27a (Rpl27a) decreased at both protein and mRNA levels in the spermatogonia in vivo. After 6 h of CIR, the immunofluorescence signal of 8-oxo-dG and phosphorylated ataxia-telangiectasia-mutated protein (ATM)/histone H2Ax increased, but that of Rpl27a decreased in the spermatogonia of p53 wild-type and knockout mouse testes. Moreover, the nucleolin was scattered throughout the nucleoplasm after CIR. These results suggested that CIR-induced DNA damage might trigger ribosomal stress, and the reduction in the expression of Rpl27a was associated with DNA damage in the spermatogonia. Similarly, in vitro, the immunofluorescence signal of 8-oxo-dG increased in the GC-1 cells after CIR. Moreover, the expression of Rpl27a was regulated by DNA damage because the co-transfection of ATM and Rpl27a or inhibition of ATM-treated CIR could restore the expression of Rpl27a. Furthermore, the reduction in the expression of Rpl27a led to weakened binding of E2F transcription factor 1 (E2F1) and p53 to MDM2, causing p53 activation and E2F1 degradation in p53 wild-type and knockdown GC-1 cells. This study proposed that heavy ion radiation-induced DNA damage mediated spermatogonia apoptosis via the Rpl27a-Rpl5-MDM2-p53/E2F1 signaling pathway. The results provided the underlying molecular mechanisms of spermatogonia apoptosis following exposure to high LET radiation.

Effects of Chlorophytum borivilianum Sant. F against gamma radiation-induced testicular injuries in Swiss albino mice

Background:

Radiation therapy is considered as an important tool in cancer treatment. Despite its impressive role in treating cancer, severe side effects in organs have been reported. To address these therapeutic side effects, several combination methods have been identified to minimize adverse effects caused by radiation therapy.

Aims and Objectives:

Based on higher radioactive sensitivity of testicular tissues, administration of Chlorophytumborivilianum (CB) Sant. F extracts was evaluated for its protective effects against radiation in testis.

Materials and methods:

Two forms of CB extracts (CB alone and CB-silver nanoparticles [AgNPs]) were administered at a dose of 50 mg/kg body weight in Swiss albino male mice for 7 consecutive days. Following 6 Gy gamma radiation, animals were observed for 30 days in four phases. Sperm counts, body weight, testicular weight and stereological and histological evaluation of testis were evaluated.

Results:

Following irradiation, a significant decline in body weight (P = 0.008) and testicular weight (P = 0.001) was noted when compared with control. Ununiformed type A and B spermatogonia, partially filled tubules, inter-tubular vacuoles, and disrupted epithelium were the main types of damages caused by irradiation. Reorganization and resumption of histological features emerged from the 15^th day postirradiation in CB extract (CBE)-treated animals.

Conclusion:

Testicular response was observed against radiation in animals treated with CB extracts, while CB-AgNPs indicated better toleration when compared to CB extract alone.

Correlation between expression of CatSper1,2 and sperm parameters in the gamma irradiated adult mouse testis

Propose: CatSper protein channels are responsible for the entry of Ca2+ into sperm cells. These proteins play an important role in motility and male fertility. So it is important to find out whether or not environmental factors, such as gamma radiation, have an effect on the expression of Catsper genes. In this study, we investigated the effects of gamma radiation on the expression of CatSper1 and CatSper2 genes. Materials and methods: Twenty-one male NMRI mice were divided into three groups: a control group without gamma radiation, and two experimental groups; Group 1 treated with 1 Gy of gamma radiation, and Group 2 treated with a higher dose of 2 Gy gamma radiation. Testes were removed from all groups of animals 35 days following irradiation and the testicular tissue, processed and embedded in paraffin blocks for sectioning and histological examination. Sperm samples were also taken from the epididymis for microscopic. Sperm parameters such as sperm count, morphology, motility, and viability rates were analyzed. Expression of CatSper genes was evaluated using Real-time PCR. Data were analyzed using the SPSS software and ANOVA test. Results: Our results showed that after treatment with gamma radiation, testes morphology was changed. Epididymal sperm count, motility, and morphology rates were significantly affected in both experimental groups compared to the control group. The relative expressions of CatSper 1 and 2 genes were significantly reduced in the irradiated mice (1 Gy and 2 Gy) than non-irradiated ones. Conclusions: Gamma radiations not only change testes histology and sperm parameters, but also decrease the expression of CatSper 1 and 2 genes in male mice.

Wuzi Yanzong pill, a Chinese polyherbal formula, alleviates testicular damage in mice induced by ionizing radiation

BACKGROUND

Chinese medicine Wuzi Yanzong pill (WZYZP) was firstly documented in ancient Chinese medical works "She Sheng Zhong Miao Fang" by Shi-Che Zhang in 1550 AD. The traditional herbal formula is widely used in treating nephrasthenia lumbago, prospermia, erectile dysfunction and male sterility. The present study was to explore the effects of WZYZP on ionizing irradiation-induced testicular damage in mice.

METHODS

The pelvic region of male mice was exposed to X-rays for inducing testicular damage. The effects of WZYZP on testicular damage were evaluated in terms of testes weight, sperm quantity and motility, testes oxidative status and serum hormone levels. The alterations in testicular structure were examined by hematoxylin-eosin staining. Additionally, changes in proliferating cell nuclear antigen (PCNA) expression of testes were explored by western blot.

RESULTS

Pelvic exposure to x-ray induced reduction in testes weight and sperm quality, along with oxidative stress and abnormal testicular architecture in testes. Oral administration of WZYZP for 3 weeks markedly increased testes weight, sperm quantity and motility, and attenuated testicular architecture damage. Meanwhile, WZYZP treatment significantly reversed the reduction of serum testosterone, and decreased testes malondialdehyde (MDA) and Oxidative stress index (OSI) relative to the radiated mice. Additionally, WZYZP effectively prevented the downregulation of PCNA expression in testes induced by x-ray irradiation.

CONCLUSION

These findings suggest WZYZP exhibits ameliorating effects against ionizing irradiation-induced testicular damage in mice, which may be related to its antioxidation.

Impact of 2.45 GHz microwave radiation on the testicular inflammatory pathway biomarkers in young rats: The role of gallic acid

The aim of this study was to investigate electromagnetic radiation (EMR) transmitted by wireless devices (2.45 GHz), which may cause physiopathological or ultrastructural changes, in the testes of rats. We addressed if the supplemental gallic acid (GA) may reduce these adverse effects. Six-week-old male Sprague Dawley rats were used in this study. Forty eight rats were equally divided into four groups, which were named: Sham, EMR only (EMR, 3 h day^-1 for 30 days), EMR + GA (30 mg/kg/daily), and GA (30 mg/kg/daily) groups. Malondialdehyde (MDA) and total oxidant status (TOS) levels increased (p = 0.001 for both) in EMR only group. TOS and oxidative stress index (OSI) levels decreased in GA treated group significantly (p = 0.001 and p = 0.045, respectively). Total antioxidant status (TAS) activities decreased in EMR only group and increased in GA treatment group (p = 0.001 and p = 0.029, respectively). Testosterone and vascular endothelial growth factor (VEGF) levels decreased in EMR only group, but this was not statistically significant. Testosterone and VEGF levels increased in EMR+GA group, compared with EMR only group (p = 0.002), and also increased in GA group compared with the control and EMR only group (p = 0.044 and p = 0.032, respectively). Prostaglandin E₂ (PGE₂ ) and calcitonin gene releated peptide (CGRP) staining increased in tubules of the testes in EMR only group (p < 0.001 for both) and decreased in tubules of the testes in EMR+GA group (p < 0.001 for all parameters). In EMR only group, most of the tubules contained less spermatozoa, and the spermatozoon counts decreased in tubules of the testes. All these findings and the regenerative reaction, characterized by mitotic activity, increased in seminiferous tubules cells of the testes in EMR+GA group (p < 0.001). Long term EMR exposure resulted in testicular physiopathology via oxidative damage and inflammation. GA may have ameliorative effects on the prepubertal rat testes physiopathology. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1771-1784, 2016.

The Modification of Tet1 in Male Germline Stem Cells and Interact with PCNA, HDAC1 to promote their Self-renewal and Proliferation

Epigenetic modification plays key roles in spermatogenesis, especially DNA methylation dynamic is important in sustaining normal spermatogenesis. Ten-eleven translocation 1 (Tet1) is not only a key demethylase, which works in specific gene regions, but also crosstalks with partners to regulate epigenetic progress as protein complexes. Dairy goat is an important livestock in China, while the unstable culture system in vitro inhibits optimization of new dairy goat species. The study of epigenetic modification in male germline stem cells (mGSCs) is beneficial to the optimization of adult stem cell culture system in vitro, and the improvement of sperm quality and breeding of selected livestock. In our study, we not only analyzed the morphology, gene expression, DNA methylation and histone methylation dynamic in mouse Tet1 (mTet1) modified mGSCs, we also analyzed the stemness ability by in vivo transplantation and explored the functional mechanism of Tet1 in dairy goat mGSCs. The results showed mTet1 modified mGSCs had better self-renewal and proliferation ability than wild-type mGSCs, mTet1 could also up-regulate JMJD3 to decrease H3K27me3, which also showed to suppress the MEK-ERK pathway. Furthermore, Co-IP analysis demonstrated that TET1 interact with PCNA and HDAC1 by forming protein complexes to comprehensively regulate dairy goat mGSCs and spermatogenesis.

Protective role of Aloe vera against X-ray induced testicular dysfunction

The present investigation was carried out to evaluate the possible radioprotective potential of an Aloe vera extract against whole-body X-ray irradiation-induced testicular alterations in mice. Male balb/c mice were divided into four groups: control, A. vera, X-ray and A. vera pre-treated + X-ray irradiated. Histopathological examination revealed significant structural alterations in testes after X-ray exposure, which was also associated with the presence of apoptotic cells as assessed by TUNEL assay. X-ray irradiation resulted in elevation in the levels of reactive oxygen species, lipid peroxidation, a reduction in glutathione concentration and enhanced activities of antioxidant enzymes such as glutathione reductase, glutathione peroxidase, catalase, superoxide dismutase and glutathione-S-transferase. Sperm count/motility and testosterone levels were significantly decreased in the irradiated group. Irradiated animals pre-treated with A. vera extract revealed an improvement in antioxidant status, inhibition of lipid peroxides, apoptotic cell formation and enhanced testicular parameters when compared to the X-ray-exposed group. These findings suggest that A. vera extract could ameliorate X-ray-induced damage due to its free radical scavenging properties and its potential to boost cellular antioxidant defence machinery.

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.

Electron probe X-ray microanalysis of boar and inobuta testes after the Fukushima accident

We aimed to investigate the effect of chronic radiation exposure associated with the Fukushima Daiichi Nuclear Power Plant (FNPP) accident on the testes of boar and inobuta (a hybrid of Sus scrofa and Sus scrofa domestica). This study examined the contamination levels of radioactive caesium (Cs), especially (134)Cs and (137)Cs, in the testis of both boar and inobuta during 2012, after the Fukushima accident. Morphological analysis and electron-probe X-ray microanalysis (EPMA) were also undertaken on the testes. The (134)Cs and (137)Cs levels were 6430 ± 23 and 6820 ± 32 Bq/kg in the boar testes, and 755 ± 13 and 747 ± 17 Bq/kg in the inobuta testes, respectively. The internal and external exposure of total (134)Cs and (137)Cs in the boar testes were 47.1 mGy and 176.2 mGy, respectively, whereas in the inobuta testes, these levels were 6.09 mGy and 59.8 mGy, respectively. Defective spermatogenesis was not detected by the histochemical analysis of radiation-exposed testes for either animal. In neither animal were Cs molecules detected, using EPMA. In conclusion, we showed that adverse radiation-induced effects were not detected in the examined boar and inobuta testes following the chronic radiation exposure associated with the FNPP accident.

Continuous Exposure to Low-Dose-Rate Gamma Irradiation Reduces Airway Inflammation in Ovalbumin-Induced Asthma

Although safe doses of radiation have been determined, concerns about the harmful effects of low-dose radiation persist. In particular, to date, few studies have investigated the correlation between low-dose radiation and disease development. Asthma is a common chronic inflammatory airway disease that is recognized as a major public health problem. In this study, we evaluated the effects of low-dose-rate chronic irradiation on allergic asthma in a murine model. Mice were sensitized and airway-challenged with ovalbumin (OVA) and were exposed to continuous low-dose-rate irradiation (0.554 or 1.818 mGy/h) for 24 days after initial sensitization. The effects of chronic radiation on proinflammatory cytokines and the activity of matrix metalloproteinase-9 (MMP-9) were investigated. Exposure to low-dose-rate chronic irradiation significantly decreased the number of inflammatory cells, methylcholine responsiveness (PenH value), and the levels of OVA-specific immunoglobulin E, interleukin (IL)-4, and IL-5. Furthermore, airway inflammation and the mucus production in lung tissue were attenuated and elevated MMP-9 expression and activity induced by OVA challenge were significantly suppressed. These results indicate that low-dose-rate chronic irradiation suppresses allergic asthma induced by OVA challenge and does not exert any adverse effects on asthma development. Our findings can potentially provide toxicological guidance for the safe use of radiation and relieve the general anxiety about exposure to low-dose radiation.

Injury to the blood-testis barrier after low-dose-rate chronic radiation exposure in mice

Exposure to ionising radiation induces male infertility, accompanied by increasing permeability of the blood-testis barrier. However, the effect on male fertility by low-dose-rate chronic radiation has not been investigated. In this study, the effects of low-dose-rate chronic radiation on male mice were investigated by measuring the levels of tight-junction-associated proteins (ZO-1 and occludin-1), Niemann-Pick disease type 2 protein (NPC-2) and antisperm antibody (AsAb) in serum. BALB/c mice were exposed to low-dose-rate radiation (3.49 mGy h(-1)) for total exposures of 0.02 (6 h), 0.17 (2 d) and 1.7 Gy (21 d). Based on histological examination, the diameter and epithelial depth of seminiferous tubules were significantly decreased in 1.7-Gy-irradiated mice. Compared with those of the non-irradiated group, 1.7-Gy-irradiated mice showed significantly decreased ZO-1, occludin-1 and NPC-2 protein levels, accompanied with increased serum AsAb levels. These results suggest potential blood-testis barrier injury and immune infertility in male mice exposed to low-dose-rate chronic radiation.

Comparative proteomic profiling and possible toxicological mechanism of acute injury induced by carbon ion radiation in pubertal mice testes

We investigated potential mechanisms of acute injury in pubertal mice testes after exposure to carbon ion radiation (CIR). Serum testosterone was measured following whole-body irradiation with a 2Gy carbon ion beam. Comparative proteomic profiling and Western blotting were applied to identify potential biomarkers and measure protein expression, and terminal dUTP nick end-labeling (TUNEL) was performed to detect apoptotic cells. Immunohistochemistry and immunofluorescence were used to investigate protein localization. Serum testosterone was lowest at 24h after CIR, and 10 differentially expressed proteins were identified at this time point that included eIF4E, an important regulator of initiation that combines with mTOR and 4EBP1 to control protein synthesis via the mTOR signaling pathway during proliferation and apoptosis. Protein expression and localization studies confirmed their association with acute injury following exposure to CIR. These three proteins may be useful molecular markers for detecting abnormal spermatogenesis following exposure to environmental and therapeutic radiation.

Acute histopathological responses of testicular tissues after different fractionated abdominal irradiation in rats

PURPOSE

To compare the effects of different fractionated doses of abdominal radiation therapy on acute histopathological responses of testicular tissues in rats.

METHODS

Thirty-three 3-week-old Wistar albino rats were randomized into 6 groups: group 1 (n = 5), control; group 2 (n = 4), hypofractionated total abdominal irradiation (TAI) of 6 Gy/1 fraction/day for 2 days; group 3 (n = 6), hypofractionated TAI of 4 Gy/1 fraction/day for 3 days; group 4 (n = 6), hypofractionated TAI of 3 Gy/1 fraction/day for 4 days; group 5 (n = 6), conventionally fractionated TAI of 2 Gy/1 fraction/day for 6 days; group 6 (n = 6), conventionally fractionated TAI of 1.7 Gy/1 fraction/day for 7 days. Mean epithelial length and diameter of seminiferous tubules of testicular tissues were determined after euthanasia.

RESULTS

Initially, a highly significant decrease in both the mean tubular diameter and epithelial height of the seminiferous tubules was demonstrated in all irradiated rats compared with the control group. No significant differences regarding both damage parameters were found between different hypofractionated radiation therapies. Both conventional radiation therapies reduced the epithelial height and mean diameter of the seminiferous tubules to a lesser extent when compared with 6 Gy/1 fraction/day hypofractionated therapy. It was further shown that parameter values were comparable between rats that received 3 Gy/day hypofractionated therapy and rats that received either of the two conventional therapies. Furthermore, although 4 Gy/day hypofractionation decreased tubular diameter and epithelial length to a greater degree compared with the conventional therapy of 1.7 Gy/1 fraction/day, no statistically significant difference was found when compared with conventional therapy of 2 Gy/1 fraction/day. Additionally, no statistically significant difference was demonstrated between the two types of conventional radiotherapy application.

CONCLUSION

The present study demonstrated that hypofractionated abdominal irradiation leads to more prominent tissue damage in the testes than conventional irradiation.