Low-dose radiation-induced risk in spermatogenesis

Radiation and male reproductive system: Damage and protection

Male fertility has been declining in recent decades, and a growing body of research points to environmental and lifestyle factors as the cause. The widespread use of radiation technology may result in more people affected by male infertility, as it is well established that radiation can cause reproductive impairment in men. This article provides a review of radiation-induced damage to male reproduction, and the effects of damage mechanisms and pharmacotherapy. It is hoped that this review will contribute to the understanding of the effects of radiation on male reproduction, and provide information for research into drugs that can protect the reproductive health of males.

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.

In utero exposure to ionizing radiation and metabolic regulation: perspectives for future multi- and trans-generation effects studies

PURPOSE

The radiation protection community has been particularly attentive to the risks of delayed effects on offspring from low dose or low dose-rate exposures to ionizing radiation. Despite this, the current epidemiologic studies and scientific data are still insufficient to provide the necessary evidence for improving risk assessment guidelines. This literature review aims to inform future studies on multigenerational and transgenerational effects. It primarily focuses on animal studies involving in utero exposure and discusses crucial elements for interpreting the results. These elements include in utero exposure scenarios relative to the developmental stages of the embryo/fetus, and the primary biological mechanisms responsible for transmitting heritable or hereditary effects to future generations. The review addresses several issues within the contexts of both multigenerational and transgenerational effects, with a focus on hereditary perspectives.

CONCLUSIONS

Knowledge consolidation in the field of Developmental Origins of Health and Disease (DOHaD) has led us to propose a new study strategy. This strategy aims to address the transgenerational effects of in utero exposure to low dose and low dose-rate radiation. Within this concept, there is a possibility that disruption of epigenetic programming in embryonic and fetal cells may occur. This disruption could lead to metabolic dysfunction, which in turn may cause abnormal responses to future environmental challenges, consequently increasing disease risk. Lastly, we discuss methodological limitations in our studies. These limitations are related to cohort size, follow-up time, model radiosensitivity, and analytical techniques. We propose scientific and analytical strategies for future research in this field.

The role of HIF-1α-mediated autophagy in ionizing radiation-induced testicular injury

Testis, as a key organ for maintaining male fertility, are extremely sensitive to ionizing radiation (IR). IR-induced testicular dysfunction and infertility are common adverse effects of radiation therapy in patients with pelvic cancer. To study the phenotype and mechanism of IR-induced testicular injury, the mice were irradiated with different radiation doses (0, 2 and 5 Gy) below the semi-lethal dose for one month. Our present results showed that testicular weight and the serum testosterone levels significantly decreased with the structural injury of the testis in an IR dose-dependent manner, indicating that IR caused not only the structural damage of the testis, but also the functional damage. Further analysis by TUNEL staining and Western blotting found that IR induced the apoptosis in a dose-dependent manner as indicated by increased expressions of cleaved caspase3, p53 and Bax on Day 15 after IR treatment. Combined with significantly increased oxidative stress, these results indicated that IR-induced testicular damage may be a long-term, progressively aggravated process, accompanied by apoptosis. Given the role of autophagy in apoptosis, the present study also detected and analyzed the localization and expressions of autophagy-related proteins LC-3I/II, beclin1, p62 and Atg12 in testicular cells, and found that LC-3II, beclin1 and Atg12 expressions significantly increased in the testicular cells of mice irradiated with 2 Gy and 5 Gy, while p62 expression significantly decreased with 5 Gy, implying autophagy was involved in the apoptosis of testicular cells induced by IR. Furthermore, the expressions of HIF-1α and BNIP3 were significantly enhanced in the testis cells of mice irradiated with 2 Gy and 5 Gy, suggesting the potential role of HIF-1α/BNIP3-mediated autophagy in the apoptosis of testicular cells induced by IR. Taken together, our findings demonstrated that HIF-1α/BNIP3-mediated autophagy not only plays a protective effect on the testicular cells of mice irradiated with 2 Gy, but also induces the apoptosis of the testicular cells of mice irradiated with 5 Gy, indicating the double effects on apoptosis, which will help us further understanding the molecular mechanisms of IR-induced testicular injury, and will facilitate us further studies on testicular radioprotection.

Parental chest computerized tomography examination before IVF/ICSI has no impact on pregnancy and neonatal outcomes: a cohort study of 2680 fresh transfer cycles

BACKGROUND

Some concern has been expressed regarding the negative effects of low-level ionizing radiation exposure in the context of radiological evaluation prior to IVF/ICSI treatment, but the available evidence is limited and conflicting. The aim of this study is to evaluate pregnancy and neonatal outcomes of couples who did chest computed tomography (CT) prior to IVF/ICSI.

METHODS

This was a retrospective cohort study of 2680 IVF/ICSI fresh embryo transfer cycles conducted from January 2019 - August 2020. Fertility outcomes were compared between couples that had or had not undergone CT examination within 3 months prior to the date of oocyte retrieval and sperm collection. Miscarriage was the primary study outcome, while secondary outcomes included the number of oocytes collected, oocyte maturation, normal fertilization, number of good quality cleavage stage embryos, blastocyst formation, implantation, clinical pregnancy, ectopic pregnancy, live birth, multiple birth, Cesarean section rates, gestational weeks, maternal obstetric complications, birth weight, newborn sex ratio, and birth defect incidence. Propensity score matching was used to control for potential confounding variables.

RESULTS

Of the 2680 cycles included in this study, couples underwent CT examination in 731 cycles. After 1:1 propensity score matching, 670 cycles were included in each group. When comparing demographic and fertility-related variables between groups that had and had not undergone CT examination after propensity score matching, we detected no significant differences in miscarriage rates (16.99% vs. 15.77%, OR = 1.10, 95CI% = 0.74 to 1.68). Similarly, both groups exhibited comparable oocyte and embryonic development, implantation rates (41.99% vs. 40.42%, OR = 1.07, 95%CI = 0.87 to 1.31), clinical pregnancy rates (45.67% vs. 44.48%, OR = 1.05, 95%CI = 0.85 to 1.30), ectopic pregnancy rates (2.94% vs. 1.68%, OR = 1.78, 95%CI = 0.59 to 5.36), live birth rates (36.57% vs. 35.67%, OR = 1.04, 95%CI = 0.83 to 1.30), multiple birth rates, Cesarean section rates, gestational weeks, maternal obstetric complication rates, and neonatal outcomes.

CONCLUSIONS

Chest CT examination before IVF/ICSI has no impact on pregnancy and neonatal outcomes associated with fresh embryo transfer.

TRIAL REGISTRATION

Not applicable.

Protective effects of Yiqi jiedu decoction on ionizing radiation-induced spermatogenic cell injury

ETHNOPHARMACOLOGICAL RELEVANCE

Ionizing radiation (IR) has found widespread application in modern medicine. As a result, radiotherapy inevitably causes spermatogenic cell injury. Many Chinese herbal prescriptions or natural extracts have the potential to protect against radiation injury.

AIM OF THE STUDY

We used GC-2spd cells to investigate the effects and potential mechanisms of YQJD decoction on protecting spermatogenic cells from ionizing radiation injury.

MATERIALS AND METHODS

Firstly, the GC-2spd cells were irradiated with 60Co γ-rays (1 Gy, 2 Gy, 4 Gy and 8 Gy) to establish an in vitro model of radiation injury. After that, Cells were divided into six groups: negative control group (NC group), model group (IR group), positive drug group (IRA group), high-dose YQJD decoction (IRH group), medium-dose YQJD decoction (IRM group), and low-dose YQJD decoction group (IRL group). DNA damage, oxidative damage and inflammatory factors were measured. Cell apoptosis and cell cycle were detected by Flow cytometry. Transmission electron microscopy was performed to observe the morphological changes.

RESULTS

After irradiation with 60CO γ-ray, the results indicated that the damage of spermatocyte was significantly induced by radiation exposure over 4 Gy. Furthermore, ionizing radiation could make DNA damage and oxidative stress in in GC-2spd cells. In addition, 60CO γ-ray also caused the increase of IL-1β, IL-6 and TNF-α and the change of cell cycle. However, the application of YQJD decoction inhibited the damage and apoptosis of GC-2spd cells in the aspects of anti-oxidation, promoting DNA damage repair and regulating inflammatory reaction.

CONCLUSIONS

Taken together, the protective effects of YQJD decoction on 60CO γ-ray induced spermatocyte injury were confirmed in this study. This exploration might provide a new strategy for the application of Chinese herbs in radioprotection.

Effects of Low-dose Splenic Irradiation on T lymphocyte Immune Function

ABSTRACT

Relevant studies have confirmed that the stimulation of spleen function caused by low-dose splenic irradiation can have positive effects on tumors and other diseases. This study aimed to determine radiation-induced changes in spleen index, lymphocyte subsets, spleen cell apoptosis, and pathological features of the spleen in mice. The mouse model was established by irradiating the spleen at different doses. The mice were divided into the following groups: blank control, low-dose, low-dose fractionated irradiation, and challenge dose irradiation. The mice were sacrificed under humanitarian conditions, and spleen tissue and peripheral blood were collected. The spleen index was calculated, and flow cytometry was used to analyze spleen T lymphocyte subsets and spleen apoptosis. The pathological changes in the spleen were determined by hematoxylin and eosin (H&E) staining. The spleen index of mice in the low-dose fractionated irradiation group was significantly increased compared with that in the blank control group. The spleen indexes of the low-dose irradiation and low-dose fractionated irradiation groups were much higher than that of the challenge dose irradiation group. Compared with the blank control group, the percentage of CD3+ and CD4+ T lymphocytes in the peripheral blood and spleen tissues in the low-dose irradiation and low-dose fractionated irradiation groups was significantly increased, whereas that from the challenge dose irradiation group was obviously decreased. CD8+ T lymphocytes in the peripheral blood and spleen tissues in the low-dose irradiation, low-dose fractionated irradiation, and challenge dose irradiation groups were significantly lower than those in the blank control group. The apoptosis rate of the spleen in the challenge dose irradiation group was significantly higher than that in the blank control, low-dose irradiation, and low-dose fractionated irradiation groups. H&E staining analysis of the spleen showed pathological changes in the different irradiation groups compared with the blank control group. Low-dose irradiation and low-dose fractionated irradiation can change the T lymphocyte subsets in the peripheral blood and spleen of mice, which can promote immune excitation and improve immune effects.

Associations between environmental exposures in the Middle East Area of Operations and pregnancy outcomes in Australian Defence Force veterans

Military personnel deployed on operations may encounter a variety of hazards with the capacity to adversely affect reproductive health. This paper investigates the association between self-reported exposure to reproductive toxicants and adverse pregnancy outcomes in Australian Defence Force veterans who deployed to Iraq and Afghanistan during the period 2001-2009. Utilising the Middle East Area of Operations (MEAO) Census Study data set, descriptive analyses of participants' self-reported exposure were compared with the occupational environmental monitoring data taken at their reported deployment location. Univariate analyses assessed the significance of unadjusted associations between self-reported exposures and reproductive outcomes. There is no systematic or consistent relationship between deployment to the MEAO and adverse pregnancy outcomes. Overall, self-reported adverse reproductive outcomes were significantly increased in veterans who deployed to both Afghanistan and Iraq (p = 0.04) compared to those who only deployed to only one of those locations; particularly in women (p = 0.009). Miscarriage was the most likely of these (p = 0.008). These figures would benefit from being confirmed against medical records but are worthy of further study. In this historical cohort study, causal inference cannot be made due to absence of control groups to exclude sources of potential bias. Imprecision in the assessment of environmental hazards in the MEAO and other methodological constraints make it impossible to calculate precise estimates of risk. The results warrant continued investigation, especially when combined with previous findings related to pregnancy outcomes in this population, the importance of reproductive outcomes, and the potential emergence of new hazards.

Assessment of the potential impacts of the Chernobyl nuclear disaster on maternal and fetal health in Hungary

Objective: Radiation exposure is known to be mutagenic and teratogenic. The aim of this study was to analyze the effects of the increased ionizing radiation emitted by the Chernobyl nuclear disaster on maternal and fetal outcomes in Hungary.Methods: A retrospective analysis of abortion, stillbirth, and congenital anomaly data for pregnancies in Hungary between 1 January 1981 and 31 December 1991 was conducted.Results: Trend analysis revealed increasing trends in spontaneous and voluntary abortion rates in Hungary during the study time period, while late pregnancy losses showed a decreasing trend. Overall, there were generally decreasing incidence rates for birth defects throughout the 1980s. Increased voluntary abortions over the study period might reflect, at least in part, maternal anxiety in the post-Chernobyl years. Decreased late pregnancy loss over the same period may be attributable to improvements in prenatal diagnostics. A notable weakness of this study is that missing data could not be complemented due to the decades that have passed since the incident.Conclusions: In conclusion, the present data suggest that the nuclear catastrophe in 1986 did not cause a significant increase in pregnancy loss or congenital malformations in Hungary.

A Brief Overview of Radiation-Induced Effects on Spermatogenesis and Oncofertility

Simple Summary

Spermatogenesis is one of the most important processes for the propagation of life; however, the testes’ ability to form sperm via this differentiation process is highly radiosensitive and easily impacted by exposure to environmental, occupational, or therapeutic radiation. Furthermore, the possibility that radiation effects on the gonads can be passed on from generation to generation should not be overlooked. This review focuses on the radiation-induced effects on spermatogenesis and the transgenerational effects. We also explore the potential of novel radiobiological approaches to improve male fertility preservation during radiotherapy.

Abstract

The genotoxicity of radiation on germ cells may be passed on to the next generation, thus its elucidation is not only a scientific issue but also an ethical, legal, and social issue in modern society. In this article, we briefly overview the effects of radiation on spermatogenesis and its associated genotoxicity, including the latest findings in the field of radiobiology. The potential role of transgenerational effects is still poorly understood, and further research in this area is desirable. Furthermore, from the perspective of oncofertility, we discuss the historical background and clinical importance of preserving male fertility during radiation treatment and the potential of microbeam radiotherapy. We hope that this review will contribute to stimulating further discussions and investigations for therapies for pediatric and adolescent/young adult patients.

Chronic Background Radiation Correlates With Sperm Swimming Endurance in Bank Voles From Chernobyl

Sperm quantity and quality are key features explaining intra- and interspecific variation in male reproductive success. Spermatogenesis is sensitive to ionizing radiation and laboratory studies investigating acute effects of ionizing radiation have indeed found negative effects of radiation on sperm quantity and quality. In nature, levels of natural background radiation vary dramatically, and chronic effects of low-level background radiation exposure on spermatogenesis are poorly understood. The Chernobyl region offers a unique research opportunity for investigating effects of chronic low-level ionizing radiation on reproductive properties of wild organisms. We captured male bank voles (Myodes glareolus) from 24 locations in the Chernobyl exclusion zone in 2011 and 2015 and collected information on sperm morphology and kinetics. The dataset is limited in size and there overall was a relatively weak correlation between background radiation and sperm quality. Still, some correlations are worth discussing. First, mid-piece segments of spermatozoa tended to be smaller in bank vole males from areas with elevated background radiation levels. Second, we demonstrated a significant positive relationship between background radiation dose rates and the proportion of static spermatozoa among males within and among study locations after 10 as well as 60 min of incubation. Our results provide novel evidence of damaging effects of low dose ionizing radiation on sperm performance in wild rodent populations, and highlight that this topic requires further study across the natural gradients of background radiation that exist in nature.

A systems biology analysis of reproductive toxicity effects induced by multigenerational exposure to ionizing radiation in C. elegans

Understanding the effects of chronic exposure to pollutants over generations is of primary importance for the protection of humans and the environment; however, to date, knowledge on the molecular mechanisms underlying multigenerational adverse effects is scarce. We employed a systems biology approach to analyze effects of chronic exposure to gamma radiation at molecular, tissue and individual levels in the nematode Caenorhabditis elegans. Our data show a decrease of 23% in the number of offspring on the first generation F0 and more than 40% in subsequent generations F1, F2 and F3. To unveil the impact on the germline, an in-depth analysis of reproductive processes involved in gametes formation was performed for all four generations. We measured a decrease in the number of mitotic germ cells accompanied by increased cell-cycle arrest in the distal part of the gonad. Further impact on the germline was manifested by decreased sperm quantity and quality. In order to obtain insight in the molecular mechanisms leading to decreased fecundity, gene expression was investigated via whole genome RNA sequencing. The transcriptomic analysis revealed modulation of transcription factors, as well as genes involved in stress response, unfolded protein response, lipid metabolism and reproduction. Furthermore, a drastic increase in the number of differentially expressed genes involved in defense response was measured in the last two generations, suggesting a cumulative stress effect of ionizing radiation exposure. Transcription factor binding site enrichment analysis and the use of transgenic strain identified daf-16/FOXO as a master regulator of genes differentially expressed in response to radiation. The presented data provide new knowledge with respect to the molecular mechanisms involved in reproductive toxic effects and accumulated stress resulting from multigenerational exposure to ionizing radiation.

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.

Stem Cell Migration: A Possible Mechanism for the Tissue-Sparing Effect of Spatially Fractionated Radiation

Stem cell responses in tissues after exposure to radiation are of significance for maintaining tissue functions. From the point of view of stem cell characteristics, this article seeks to illustrate some contributions of microbeam research to spatially fractionated radiotherapy (SFRT), such as grid radiotherapy and microbeam radiotherapy. Although the tissue-sparing response after SFRT was first reported more than a century ago, current radiation dose-volume metrics are still unable to accurately predict such tissue-level changes in response to spatially fractionated radiation fields. However, microbeam approaches could contribute to uncovering the mechanisms of tissue response, significantly improving the outcomes of SFRT and reducing its adverse effects. Studies with microbeams have shown that the testicular tissue-sparing effect for maintaining spermatogenesis after exposure to spatially fractionated radiation depends on biological parameters, such as the radiation dose distribution at the microscale level for tissue-specific stem cells and the microenvironment, or niche. This indicates that stem cell survival, migration, and repopulation are involved in the tissue-level changes during or after SFRT. The illustration of microbeam applications in this article focuses on the stem cell migration as a possible mechanism of the tissue-sparing effect for preserving functionality.

Spatially Fractionated Microbeam Analysis of Tissue-sparing Effect for Spermatogenesis

Spatially fractionated radiation therapy (SFRT) has been based on the delivery of a single high-dose fraction to a large treatment area that has been divided into several smaller fields, reducing the overall toxicity and adverse effects. Complementary microbeam studies have also shown an effective tissue-sparing effect (TSE) in various tissue types and species after spatially fractionated irradiation at the microscale level; however, the underlying biological mechanism remains elusive. In the current study, using the combination of an ex vivo mouse spermatogenesis model and high-precision X-ray microbeams, we revealed the significant TSE for maintaining spermatogenesis after spatially fractionated microbeam irradiation. We used the following ratios of the irradiated to nonirradiated areas: 50:50, 150:50 and 350:50 µm-slit, where approximately 50, 75 and 87.5% of the sample was irradiated (using center-to-center distances of 100, 200 and 400 µm, respectively). We found that the 50 and 75% micro-slit irradiated testicular tissues showed an almost unadulterated TSE for spermatogenesis, whereas the 87.5% micro-slit irradiated tissues showed an incomplete TSE. This suggests that the TSE efficiency for spermatogenesis is dependent on the size of the nonirradiated spermatogonial stem cell pool in the irradiated testicular tissues. In addition, there would be a spatiotemporal limitation of stem cell migration/competition, resulting in the insufficient TSE for 87.5% micro-slit irradiated tissues. These stem cell characteristics are essential for the accurate prediction of tissue-level responses during or after SFRT, indicating the clinical potential for achieving better outcomes while preventing adverse effects.

Radioprotective effect of a combination of melatonin and metformin on mice spermatogenesis: A histological study

Background

The spermatogenesis system includes highly radiosensitive cells. Hence, this system is a potential target for toxic effects of ionizing radiation during radiotherapy of abdomen and pelvis cancers, as well as after accidental radiation events. Accordingly, metformin and melatonin are two important radioprotectors that have shown an ability to prevent cell death through neutralization of free radicals and stimulating DNA damage responses.

Objective

To evaluate the radioprotective effects of melatonin and metformin on mice spermatogenesis when administered alone or as a combination.

Materials and Methods

In this histological Study, 40 (6-8 wk, 30 gr) NMRI mice were divided into 8 groups (n = 5/each) as control, metformin, melatonin, melatonin + metformin, radiation, radiation + melatonin, radiation + metformin, and radiation + melatonin + metformin. 37 days after the irradiation, the testicular tissues were collected for histological evaluation.

Results

Single administration of melatonin could ameliorate effectively radiation toxicity in mice testis. Metformin showed radioprotective effects on some parameters such as the numbers of spermatogonia and mature sperms. Interestingly, the melatonin and metformin combination reversed the reduced number of sperms rather than single drug administration.

Conclusion

The combination of melatonin with metformin can protect mice spermatogenesis against ionizing radiation more effectively compared to the single forms of these drugs.

The Effect of Low Temperatures on Environmental Radiation Damage in Living Systems: Does Hypothermia Show Promise for Space Travel?

Low-temperature treatments (i.e., hypothermia) may be one way of regulating environmental radiation damage in living systems. With this in mind, hibernation under hypothermic conditions has been proposed as a useful approach for long-term human space flight. However, the underlying mechanisms of hypothermia-induced radioresistance are as yet undetermined, and the conventional risk assessment of radiation exposure during hibernation remains insufficient for estimating the effects of chronic exposure to galactic cosmic rays (GCRs). To promote scientific discussions on the application of hibernation in space travel, this literature review provides an overview of the progress to date in the interdisciplinary research field of radiation biology and hypothermia and addresses possible issues related to hypothermic treatments as countermeasures against GCRs. At present, there are concerns about the potential effects of chronic radiation exposure on neurological disorders, carcinogenesis, ischemia heat failures, and infertility in astronauts; these require further study. These concerns may be resolved by comparing and integrating data gleaned from experimental and epidemiological studies.

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.

High-precision microbeam radiotherapy reveals testicular tissue-sparing effects for male fertility preservation

Microbeam radiotherapy (MRT) is based on a spatial fractionation of synchrotron X-ray microbeams at the microscale level. Although the tissue-sparing effect (TSE) in response to non-uniform radiation fields was recognized more than one century ago, the TSE of MRT in the testes and its clinical importance for preventing male fertility remain to be determined. In this study, using the combination of MRT techniques and a unique ex vivo testes organ culture, we show, for the first time, the MRT-mediated TSE for the preservation of spermatogenesis. Furthermore, our high-precision microbeam analysis revealed that the survival and potential migration steps of the non-irradiated germ stem cells in the irradiated testes tissue would be needed for the effective TSE for spermatogenesis. Our findings indicated the distribution of dose irradiated in the testes at the microscale level is of clinical importance for delivering high doses of radiation to the tumor, while still preserving male fertility.

TGF-β mediates thoracic radiation-induced abscopal effects of testis injury in rat

To investigate the thoracic irradiation induced abscopal effect on distal testes and the underlying inflammatory factors, the rats were irradiated on right thorax with fractionated doses. It was found the testes structures were damaged including disorder of spermatogenic cell arrangement and decrease of sperm number. Moreover, the expressions of caspase-3 and caspase-8 in testis tissue were enhanced, and the concentrations of TGF-β and TNF-α in the rat serum were increased. When TM4 cells were treated with the conditioned medium (CS) collected from irradiated rat, the cellular ROS and apoptosis was significantly increased. When the CS was neutralized with anti-TGF-β, its toxic effects were reduced. These results suggest that the thoracic irradiation-induced TGF-β was involved in the above abscopal damage of testes, which reinforces the necessity of new prevention strategy development of radiotherapy in avoiding any abnormal genetic consequence.

Non-uniform radiation-induced biological responses at the tissue level involved in the health risk of environmental radiation: a radiobiological hypothesis

BACKGROUND

The conventional concept of radiation protection is based on epidemiological studies of radiation that support a positive correlation between dose and response. However, there is a remarkable difference in biological responses at the tissue level, depending on whether radiation is delivered as a uniform or non-uniform spatiotemporal distribution due to tissue sparing effects (TSE). From the point of view of radiation micro-dosimetry, environmental radiation is delivered as a non-uniform distribution, and radiation-induced biological responses at the tissue level, such as TSE, would be implicated in individual risk following exposure to environmental radiation.

HYPOTHESIS

We hypothesize that the health risks of non-uniform radiation exposure are lower than the same dose at a uniform exposure, due to TSE following irradiation. Testing the hypothesis requires both radiobiological studies using high-precision microbeams and the epidemiological data of environmental radiation-induced effects. The implications of the hypothesis will lead to more personalized approaches in the field of environmental radiation protection.

CONCLUSION

The detection of spatiotemporal dose distribution could be of scientific importance for more accurate individual risk assessment of exposure to environmental radiation. Further radiobiological studies on non-uniform radiation-induced biological responses at the tissue level are expected.

Radiation effects on male fertility

BACKGROUND

Spermatogenesis is a process of dynamic cell differentiation. Ionizing radiation impairs spermatogenesis, and spermatogonia are more radiosensitive than spermatocytes or spermatids. Consistent with this assumption and due to improvement in tumor curability, nowadays, fertility preservation represents a public health need.

OBJECTIVES

To discuss radiotherapy-induced risk to male fertility and raise oncologic awareness of male fertility in daily clinical practice.

MATERIALS AND METHODS

PubMed and Clinicaltrials.gov databases were searched for papers in English.

RESULTS

We provide an overview of clinical landscape. Four main issues were proposed: (i) spermatogenesis and radiobiological general concepts; (ii) impairment of spermatogenesis; (iii) impairment of testosterone-producing Leydig cells; (iv) clinical radiotherapy evidence in oncology.

CONCLUSION

This review can be useful in daily clinical work and offer some directions for future research.