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.

An experimental approach to comprehend the influence of platelet rich growth factors on spermatogenesis.

MATERIALS AND METHODS: Experimental animals (n = 135) were divided into 5 groups: I - control (n = 10); II - 2IR (n = 35; 2 Gy); III - 2IR + LP-PRP + IGF-1 (n = 30); IV - 2IR + LP-PRP (n = 30); V - LP-PRP (n = 30). RESULTS: Electron irradiation reduces the number of germ cells in comparison with the control group. After injection of LP-PRP + rhIGF-1 significantly increased the number of germ cells, Sertoli and Leydig cells, the height of germinal epithelium, area and diameter of seminiferous tubules. CONCLUSION: LP-PRP + rhIGF-1 has a normalizing effect on structural and functional disorders of the testis caused by electron irradiation.

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.

Scrotal thermographic profile and seminal characteristics of Mangalarga Marchador stallions bred in the Atlantic Rainforest biome / [Perfil termográfico escrotal e características seminais de garanhões Mangalarga Marchador criados no bioma Mata Atlântica]

The objective of this study was to determine the scrotal thermographic profile and to verify the influence of temperature and humidity of the humid tropical climate on testicular temperature and seminal quality of Mangalarga Marchador stallions. The thermal profiles of the proximal, middle, and distal zones of the testicles and total surface temperature (TSTT) were recorded using an FLIR E60bx thermal imager. The average air temperature (°C) and relative humidity (%) were obtained 1, 5, 9, 33, and 66 days before semen collection and showed a mean value of 26.5±2.4 and 80.4±6.0 respectively. The scrotal surface temperature was close to 34°C and there was no variation with the age of the stallion, reproductive activity, and characteristics of the ejaculate (P>0.05). The only significant correlations obtained were between TSTT and minor defects (R = 0.41; P<0.05), between TSTT and total defects (R = 0.46; P<0.01), and between TSTT and percentage of morphologically normal sperm (R = -0.46; P<0.05). It was concluded that the Mangalarga Marchador stallions maintained the testicular temperature within favorable conditions for spermatogenesis, demonstrating the efficiency of testicular thermoregulation mechanisms in the Atlantic Forest biome.

O objetivo deste estudo foi determinar o perfil termográfico escrotal e verificar a influência da temperatura e da umidade do clima tropical úmido na temperatura testicular e na qualidade seminal de garanhões Mangalarga Marchador. Os perfis térmicos das zonas proximal, média e distal dos testículos e a temperatura da superfície total (TSTT) foram registrados usando-se um termovisor FLIR E60bx. A temperatura média do ar (° C) e a umidade relativa (%) foram obtidas um, cinco, nove, 33 e 66 dias antes da coleta de sêmen e apresentaram valor médio de 26,5 ± 2,4 e 80,4 ± 6,0, respectivamente. A temperatura da superfície escrotal foi próxima a 34°C, e não houve variação com a idade do garanhão, a atividade reprodutiva e as características do ejaculado (P>0,05). As únicas correlações significativas obtidas foram entre TSTT e defeitos menores (R=0,41; P<0,05), entre TSTT e defeitos totais (R=0,46; P<0,01), e entre TSTT e porcentagem de espermatozoides morfologicamente normais (R=-0,46; P<0,05). Concluiu-se que os garanhões Mangalarga Marchador mantiveram a temperatura testicular dentro de condições favoráveis para a espermatogênese, demonstrando a eficiência dos mecanismos de termorregulação testicular no bioma Mata Atlântica.

Postpubertal spermatogonial stem cell transplantation restores functional sperm production in rhesus monkeys irradiated before and after puberty.

BACKGROUND: Cancer treatment of prepubertal patients impacts future fertility due to the abolition of spermatogonial stem cells (SSCs). In macaques, spermatogenesis could be regenerated by intratesticular transplantation of SSCs, but no studies have involved cytotoxic treatment before puberty and transplantation after puberty, which would be the most likely clinical scenario. OBJECTIVES: To evaluate donor-derived functional sperm production after SSC transplantation to adult monkeys that had received testicular irradiation during the prepubertal period. MATERIALS AND METHODS: We obtained prepubertal testis tissue by unilaterally castrating six prepubertal monkeys and 2 weeks later irradiated the remaining testes with 6.9 Gy. However, because spermatogenic recovery was observed, we irradiated them again 14 months later with 7 Gy. Three of the monkeys were treated with GnRH-antagonist (GnRH-ant) for 8 weeks. The cryopreserved testis cells from the castrated testes were then allogeneically transplanted into the intact testes of all monkeys. Tissues were harvested 10 months later for analyses. RESULTS: In three of the six monkeys, 61%, 38%, and 11% of the epididymal sperm DNA were of the donor genotype. The ability to recover donor-derived sperm production was not enhanced by the GnRH-ant pretreatment. However, the extent of filling seminiferous tubules during the transplantation procedure was correlated with the eventual production of donor spermatozoa. The donor epididymal spermatozoa from the recipient with 61% donor contribution were capable of fertilizing rhesus eggs and forming embryos. Although the transplantation was done into the rete testis, two GnRH-ant-treated monkeys, which did not produce donor-derived epididymal spermatozoa, displayed irregular tubular cords in the interstitium containing testicular spermatozoa derived from the transplanted donor cells. DISCUSSION AND CONCLUSION: The results further support that sperm production can be restored in non-human primates from tissues cryopreserved prior to prepubertal and post-pubertal gonadotoxic treatment by transplantation of these testicular cells after puberty into seminiferous tubules.

Radiofrequency radiation: A possible threat to male fertility.

Radiofrequency exposure from man-made sources has increased drastically with the era of advanced technology. People could not escape from such RF radiations as they have become the essential part of our routine life such as Wi-Fi, microwave ovens, TV, mobile phones, etc. Although non-ionizing radiations are less damaging than ionizing radiations but its long term exposure effect cannot be avoided. For fertility to be affected, either there is an alteration in germ cell, or its nourishing environment, and RF affects both the parameters subsequently, leading to infertility. This review with the help of in vitro and in vivo studies shows that RF could change the morphology and physiology of germ cells with affected spermatogenesis, motility and reduced concentration of male gametes. RF also results in genetic and hormonal changes. In addition, the contribution of oxidative stress and protein kinase complex after RFR exposure is also summarized which could also be the possible mechanism for reduction in sperm parameters. Further, some preventative measures are described which could help in reverting the radiofrequency effects on germ cells.

Impact of paternal transmission of gamma radiation on reproduction, oogenesis, and spermatogenesis of the housefly, Musca domestica L. (Diptera: Muscidae).

PURPOSE: This study aimed to investigate the impact of gamma radiation of Musca domestica males (resulted from irradiated pupae) crossed with unirradiated females on fecundity, egg hatchability, adult emergence, sex ratio, sterility, in addition to reproductive development at the level of oogenesis and spermatogenesis compared to unirradiated group. MATERIAL AND METHODS: The housefly, M. domestica pupae were exposed to three sublethal doses of 5, 10, and 15 Gy. RESULTS: Fecundity was severely reduced particularly in F2 (11.33 ± 1.528; 7.33 ± 1.115 eggs/♀) and F3 (9.0 ± 1.00; 4.67 ± 1.115 eggs/♀) for doses of 10 and 15 Gy, respectively, compared with (52.0 ± 1.4 eggs/♀) for the control. Data revealed latent dose- and generation-dependent reduction in egg hatchability. Hatchability percentages reduced from 93.59 for the control to 10.07 (F1), 8.09 (F2), and 8.34 (F3) when the highest radiation dose 15 Gy was applied. Irradiation induced paternal deleterious substerility effects. Irradiation with 15 Gy induced substerility that reached about 97.0% in F2 and F3 generations. A significant (P < 0.05) reduction of the mean numbers of adult emergence was remarkably detected in the F1, F2, and F3 generations. Applied gamma doses did not affect the male to female ratio in the Parental or F1 generations. However, the F2 and F3 generations did show changes to the sex ratio with males occurring more frequently than females. This trend became more pronounced as dose increased. Ultrastructural examinations exhibited unusual damage and malformation either for males or female reproductive organs. CONCLUSION: The obtained results clearly show that gamma radiation of M. domestica irradiated as pupae induced considerably visible impact on tested biological aspects and reproductive potential.

Morphological reproductive characteristics of testes and fertilization capacity of cryopreserved sperm after the Fukushima accident in raccoon (Procyon lotor).

Since the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, we have established an archive system of livestock and wild animals from the surrounding ex-evacuation zone. Wildlife within the alert zone have been exposed to low-dose-rate (LDR) radiation for a long continuous time. In this study, we analysed the morphological characteristics of the testes and in vitro fertilization (IVF) capacity of cryopreserved sperm of racoons from the ex-evacuation zone of the FDNPP accident. The radioactivity of caesium-137 (137 Cs) was measured by gamma-ray spectrometry, and the measured radioactivity concentration was 300-6,630 Bq/kg in the Fukushima raccoons. Notably, normal spermatogenesis was observed in the seminiferous tubules of the testes, with the germinal epithelium composed of a spermatogenic cell lineage with no evident ultrastructural alterations; freeze-thawing sperm penetration ability was confirmed using the interspecific zona pellucida-free mouse oocytes IVF assays. This study revealed that the chronic and LDR radiation exposure associated with the FDNPP accident had no adverse effect on the reproductive characteristics and functions of male raccoons.

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.

Meiotic susceptibility for induction of sperm with chromosomal aberrations in patients receiving combination chemotherapy for Hodgkin lymphoma.

Improvements in survival rates with gonad-sparing protocols for childhood and adolescence cancer have increased the optimism of survivors to become parents after treatment. Findings in rodents indicate that chromosomal aberrations can be induced in male germ cells by genotoxic exposures and transmitted to offspring and future generations with effects on development, fertility and health. Thus, there is a need for effective technologies to identify human sperm carrying chromosomal aberrations to assess the germ-line risks, especially for cancer survivors who have received genotoxic therapies. The time-dependent changes in the burden of sperm carrying structural chromosomal aberrations were assessed for the first time in a cancer setting, using the AM8 sperm FISH protocol which simultaneously detects abnormalities in chromosomal structure and number in sperm. Nine Hodgkin lymphoma (HL) patients provided 20 semen samples before, during, and after NOVP therapy (Novantrone, Oncovin, Velban and Prednisone) and radiation therapy that produced scattered gonadal doses from <0.05 to 0.6 Gy. Late meiosis was found to be the most sensitive to NOVP treatment for the production of sperm with chromosomal abnormalities, both in structure and number. Earlier stages of spermatogenesis were less sensitive and there was no evidence that therapy-exposed stem cells resulted in increased frequencies of sperm with abnormalities in chromosomal structure or number. This indicates that NOVP therapy may increase the risks for paternal transmission of chromosomal structural aberrations for sperm produced 32 to 45 days after a treatment with these drugs and implies that there are no excess risks for pregnancies conceived more than 6 months after this therapy. This clinical evaluation of the AM8 sperm FISH protocol indicates that it is a promising tool for assessing an individual's burden of sperm carrying chromosomal structural aberrations as well as aneuploidies after cancer therapy, with broad applications in other clinical and environmental situations that may pose aneugenic or clastogenic risks to human spermatogenesis.

Spermatogonial Stem Cell Culture in Oncofertility.

Infertility caused by chemotherapy or radiation treatments negatively impacts patient-survivor quality of life. The only fertility preservation option available to prepubertal boys who are not making sperm is cryopreservation of testicular tissues that contain spermatogonial stem cells (SSCs) with potential to produce sperm and/or restore fertility. SSC transplantation to regenerate spermatogenesis in infertile adult survivors of childhood cancers is a mature technology. However, the number of SSCs obtained in a biopsy of a prepubertal testis may be small. Therefore, methods to expand SSC numbers in culture before transplantation are needed. Here we review progress with human SSC culture.

Association of hMSH5 C85T polymorphism with radiation sensitivity of testicular cell lines GC-1, GC-2, TM3, and TM4.

BACKGROUND: The hMSH5 C85T polymorphism, which encodes hMSH5 P29S, is associated with individual differences in spermatogenic abnormalities caused by ionizing radiation (IR), but the molecular mechanisms remain unclear. OBJECTIVES: This manuscript aims to explore the role of hMSH5 C85T polymorphism in IR-induced individual differences in spermatogenic abnormalities. MATERIAL AND METHODS: We transfected pcDNA-hMSH5P29S vector into mouse spermatogonia GC-1, mouse spermatocytes GC-2, mouse testicular mesenchymal cells TM3, and mouse testicular support cells TM4. After radiation, we evaluated cell survival with colony formation assay, apoptosis with TUNEL assay and caspase-3 activity assay, DNA damage with comet assay and an in vivo NHEJ activity assay. RESULTS: Results showed that only spermatocytes GC-2 transfected with pcDNA-hMSH5P29S vector had significant differences in IR-induced cell survival and apoptosis when compared to that transfected with pcDNA empty vector and pcDNA-wild-hMSH5 vector, while there was no statistical difference in GC-1, TM3, and TM4. In addition, comet assay showed that the DNA damage of GC-2 transfected with pcDNA-hMSH5P29S vector increased significantly compared to that transfected with pcDNA empty vector and pcDNA-wild-hMSH5 vector after IR. And in vivo NHEJ activity assay showed that the NHEJ activity of GC-2 transfected with pcDNA-hMSH5P29S vector was statistically higher than that transfected with pcDNA empty vector and pcDNA-wild-hMSH5 vector. CONCLUSION: Our study indicates that the hMSH5 C85T polymorphism leads to an abnormal increase in apoptosis and lessen the control on error-prone NHEJ of spermatocyte GC-2, thereby altering the difference of radiation sensitivity of spermatogenesis.

Exposure to Chemotherapy During Childhood or Adulthood and Consequences on Spermatogenesis and Male Fertility.

Over the last decade, the number of cancer survivors has increased thanks to progress in diagnosis and treatment. Cancer treatments are often accompanied by adverse side effects depending on the age of the patient, the type of cancer, the treatment regimen, and the doses. The testicular tissue is very sensitive to chemotherapy and radiotherapy. This review will summarize the epidemiological and experimental data concerning the consequences of exposure to chemotherapy during the prepubertal period or adulthood on spermatogenic progression, sperm production, sperm nuclear quality, and the health of the offspring. Studies concerning the gonadotoxicity of anticancer drugs in adult survivors of childhood cancer are still limited compared with those concerning the effects of chemotherapy exposure during adulthood. In humans, it is difficult to evaluate exactly the toxicity of chemotherapeutic agents because cancer treatments often combine chemotherapy and radiotherapy. Thus, it is important to undertake experimental studies in animal models in order to define the mechanism involved in the drug gonadotoxicity and to assess the effects of their administration alone or in combination on immature and mature testis. These data will help to better inform cancer patients after recovery about the risks of chemotherapy for their future fertility and to propose fertility preservation options.

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 7th 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 7th 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.

The effectiveness of traditional Japanese medicine Goshajinkigan in irradiation-induced aspermatogenesis in mice.

BACKGROUND: Infertility and gonadal dysfunction are well known side-effects by cancer treatment in males. In particularly, chemotherapy and radiotherapy induced testicular damage, resulting in prolonged azoospermia. However, information regarding therapeutics to treat spermatogenesis disturbance after cancer treatment is scarce. Recently, we demonstrated that Goshajinkigan, a traditional Japanese medicine, can completely rescue severe busulfan-induced aspermatogenesis in mice. In this study, we aimed to detect the effects of Goshajinkigan on aspermatogenesis after irradiation. METHODS: This is animal research about the effects of traditional Japanese medicine on infertility after cancer treatment. C57BL/6 J male mice received total body irradiation (TBI: a single dose of 6Gy) at 4 weeks of age and after 60 days were reared a Goshajinkigan (TJ107)-containing or TJ107-free control diet from day 60 to day 120. Then, two untreated females were mated with a single male from each experimental group. On day 60, 120 and 150, respectively, the sets of testes and epididymis of the mice in each group after deep anesthetization were removed for histological and cytological examinations. RESULTS: Histological and histopathological data showed that 6Gy TBI treatment decreased the fertility rate (4/10) in the control diet group; in contrast, in the TJ107-diet group, the fertility rate was 10/10 (p < 0.05 vs. 6Gy group). Supplementation with TJ107 was found to rescue the disrupted inter-Sertoli tight junctions via the normalization of claudin11, occludin, and ZO-1 expression and reduce serum anti-germ cell autoantibodies. CONCLUSIONS: These findings show the therapeutic effect on TBI-induced aspermatogenesis and the recovering disrupted gonadal functions by supplementation with TJ107.

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.

Gamma radiation induces life stage-dependent reprotoxicity in Caenorhabditis elegans via impairment of spermatogenesis.

The current study investigated life stage, tissue and cell dependent sensitivity to ionizing radiation of the nematode Caenorhabditis elegans. Results showed that irradiation of post mitotic L4 stage larvae induced no significant effects with respect to mortality, morbidity or reproduction at either acute dose ≤6 Gy (1500 mGy·h-1) or chronic exposure ≤15 Gy (≤100 mGy·h-1). In contrast, chronic exposure from the embryo to the L4-young adult stage caused a dose and dose-rate dependent reprotoxicity with 43% reduction in total brood size at 6.7 Gy (108 mGy·h-1). Systematic irradiation of the different developmental stages showed that the most sensitive life stage was L1 to young L4. Exposure during these stages was associated with dose-rate dependent genotoxic effects, resulting in a 1.8 to 2 fold increase in germ cell apoptosis in larvae subjected to 40 or 100 mGy·h-1, respectively. This was accompanied by a dose-rate dependent reduction in the number of spermatids, which was positively correlated to the reprotoxic effect (0.99, PCC). RNAseq analysis of nematodes irradiated from L1 to L4 stage revealed a significant enrichment of differentially expressed genes related to both male and hermaphrodite reproductive processes. Gene network analysis revealed effects related to down-regulation of genes required for spindle formation and sperm meiosis/maturation, including smz-1, smz-2 and htas-1. Furthermore, the expression of a subset of 28 set-17 regulated Major Sperm Proteins (MSP) required for spermatid production was correlated (R2 0.80) to the reduction in reproduction and the number of spermatids. Collectively these observations corroborate the impairment of spermatogenesis as the major cause of gamma radiation induced life-stage dependent reprotoxic effect. Furthermore, the progeny of irradiated nematodes showed significant embryonal DNA damage that was associated with persistent effect on somatic growth. Unexpectedly, these nematodes maintained much of their reproductive capacity in spite of the reduced growth.

MitoQ ameliorates testicular damage induced by gamma irradiation in rats: Modulation of mitochondrial apoptosis and steroidogenesis.

AIMS: The deleterious effect of gamma radiation on testicular tissue is a challenging problem in nuclear medicine. This study investigated the potential radioprotective effect of mitoquinol (MitoQ), a mitochondria-targeted antioxidant, against testicular damage induced by gamma irradiation in rats. MAIN METHODS: Rats were allocated into four groups. The first group served as the control, the second group received MitoQ (2 mg / kg / day; i.p.) for seven days, the third group was exposed to gamma radiation (5 Gy as a single dose) and the last group received MitoQ prior to irradiation. Rats were sacrificed. Then, sperm analyses and the serum testosterone were determined. Moreover, evaluation of mitochondrial oxidative stress parameters (SOD, GSH and GPx) as well as apoptosis indicators (cytochrome-c, Bax, Bcl-2 and caspase-3) was performed. Additionally, analysis of steroidogensis biomarkers (StAR, 3ß-HSD and 17ß-HSD) and histopathological investigations were carried out. KEY FINDINGS: MitoQ replenished mitochondrial SOD, GPx and GSH indicating its strong antioxidant effect in addition to its energy preservation manifested by the elevated ATP. MitoQ inhibited the intrinsic apoptosis via diminution of Bax, cytochrome-c and caspase-3 and alleviation of Bcl-2. This antioxidant conferred protection to steroidogenesis as verified by the increase in testosterone and the up-regulation of StAR, 3ß-HSD and 17ß-HSD expression; these effects might be correlated with its antioxidant/anti-apoptotic potential. Histopathological and sperm analyses corroborated the biochemical findings. SIGNIFICANCE: This study identifies MitoQ as a novel agent for the management of testicular toxicity induced by gamma irradiation.