2.45 GHz microwave radiation induced oxidative and nitrosative stress mediated testicular apoptosis: Involvement of a p53 dependent bax-caspase-3 mediated pathway

Effects of radiofrequency electromagnetic field (RF-EMF) exposure on male fertility: A systematic review of experimental studies on non-human mammals and human sperm in vitro

BACKGROUND

The World Health Organization is coordinating an international project aimed at systematically reviewing the evidence regarding the association between radiofrequency electromagnetic field (RF-EMF) exposure and adverse health effects. Reproductive health outcomes have been identified among the priority topics to be addressed.

OBJECTIVES

To evaluate the effect of RF-EMF exposure on male fertility of experimental mammals and on human sperm exposed in vitro.

METHODS

Three electronic databases (PubMed, Scopus and EMF Portal) were last searched on September 17, 2022. Two independent reviewers screened the studies, which were considered eligible if met the following criteria: 1) Peer-reviewed publications of sham controlled experimental studies, 2) Non-human male mammals exposed at any stage of development or human sperm exposed in vitro, 3) RF-EMF exposure within the frequency range of 100 kHz-300 GHz, including electromagnetic pulses (EMP), 4) one of the following indicators of reproductive system impairment:Two reviewers extracted study characteristics and outcome data. We assessed risk of bias (RoB) using the Office of Health Assessment and Translation (OHAT) guidelines. We categorized studies into 3 levels of overall RoB: low, some or high concern. We pooled study results in a random effects meta-analysis comparing average exposure to no-exposure and in a dose-response meta-analysis using all exposure doses. For experimental animal studies, we conducted subgroup analyses for species, Specific Absorption Rate (SAR) and temperature increase. We grouped studies on human sperm exposed in vitro by the fertility status of sample donors and SAR. We assessed the certainty of the evidence using the GRADE approach after excluding studies that were rated as "high concern" for RoB.

RESULTS

One-hundred and seventeen papers on animal studies and 10 papers on human sperm exposed in vitro were included in this review. Only few studies were rated as "low concern" because most studies were at RoB for exposure and/or outcome assessment. Subgrouping the experimental animal studies by species, SAR, and temperature increase partly accounted for the heterogeneity of individual studies in about one third of the meta-analyses. In no case was it possible to conduct a subgroup analysis of the few human sperm in vitro studies because there were always 1 or more groups including less than 3 studies. Among all the considered endpoints, the meta-analyses of animal studies provided evidence of adverse effects of RF-EMF exposure in all cases but the rate of infertile males and the size of the sired litters. The assessment of certainty according to the GRADE methodology assigned a moderate certainty to the reduction of pregnancy rate and to the evidence of no-effect on litter size, a low certainty to the reduction of sperm count, and a very low certainty to all the other meta-analysis results. Studies on human sperm exposed in vitro indicated a small detrimental effect of RF-EMF exposure on vitality and no-effect on DNA/chromatin alterations. According to GRADE, a very low certainty was attributed to these results. The few studies that used EMP exposure did not show effects on the outcomes. A low to very low certainty was attributed to these results.

DISCUSSION

Many of the studies examined suffered of severe limitations that led to the attribution of uncertainty to the results of the meta-analyses and did not allow to draw firm conclusions on most of the endpoints. Nevertheless, the associations between RF-EMF exposure and decrease of pregnancy rate and sperm count, to which moderate and low certainty were attributed, are not negligible, also in view of the indications that in Western countries human male fertility potential seems to be progressively declining. It was beyond the scope of our systematic review to determine the shape of the dose-response relationship or to identify a minimum effective exposure level. The subgroup and the dose-response fitting analyses did not show a consistent relationship between the exposure levels and the observed effects. Notably, most studies evaluated RF-EMF exposure levels that were higher than the levels to which human populations are typically exposed, and the limits set in international guidelines. For these reasons we cannot provide suggestions to confirm or reconsider current human exposure limits. Considering the outcomes of this systematic review and taking into account the limitations found in several of the studies, we suggest that further investigations with better characterization of exposure and dosimetry including several exposure levels and blinded outcome assessment were conducted.

PROTOCOL REGISTRATION

Protocols for the systematic reviews of animal studies and of human sperm in vitro studies were published in Pacchierotti et al., 2021. The former was also registered in PROSPERO (CRD42021227729 https://www.crd.york.ac.uk/prospero/display_record.php?RecordID = 227729) and the latter in Open Science Framework (OSF Registration DOI https://doi.org/10.17605/OSF.IO/7MUS3).

Effects of 4G mobile phone radiation exposure on reproductive, hepatic, renal, and hematological parameters of male Wistar rat

BACKGROUND AND OBJECTIVE

Mobile phones have become a vital part of human life. Due to drastic increase in the number of mobile phone subscribers, exposure to radiofrequency radiation (RFR) emitted from these phones has increased dramatically. Hence, the effect of RFR on humans is an area of concern. This study was performed to determine the impact of 4G mobile phone radiation on the male reproductive system, liver, kidney, and hematological parameters.

METHODS

Seventy-day-old Wistar rats were exposed to 4G radiation (2350 MHz for 2 h/day for 56 days). Sperm parameters such as sperm count, viability, sperm head morphology, mitochondrial activity, total antioxidant activity, and lipid peroxidation of sperm were evaluated. Histopathology of the testis, prostate, epididymis, seminal vesicle, liver, and kidney was carried out. Complete blood count, liver and kidney function tests, and testosterone hormone analysis were done.

RESULTS

At the end of the experiment, results showed a significant (p < 0.05) decrease in sperm viability with alterations in the histology of the liver, kidney, testis, and other reproductive organs in the exposed group of rats. A reduced level of testosterone, total antioxidant capacity, and decreased sperm mitochondrial function were also observed in the exposed rats. Moreover, the exposed rats showed an increase in sperm lipid peroxidation and sperm abnormality. Hematological parameters like hemoglobin, red blood cells (RBC), and packed cell volume (PCV) showed a significant (p < 0.05) increase in the exposed rats.

CONCLUSION

The results indicate that chronic exposure to 4G radiation may affect the male reproductive system, hematological system, liver, and kidney of rats.

Protective effects of an aqueous extract of Protaetia brevitarsis seulensis larvae against radiation-induced testicular injury in mice

The larvae of Protaetia brevitarsis seulensis have been used as a food ingredient and are known for their nutritional value and anti-inflammatory properties. However, whether P. brevitarsis seulensis larvae demonstrate protective effects against radiation-induced testicular injury has not been investigated. In this study, the protective effects of an aqueous extract of P. brevitarsis seulensis larvae (PBE) against radiation-induced testicular injury were tested. Male C57BL/6 mice were administered PBE (5 or 10 mg/kg) orally for 14 days before exposure to focal pelvic irradiation. Histopathological examinations were conducted at 8 h and 30 d after radiation exposure. PBE pretreatment reduced the radiation-induced apoptosis of germ cells at 8 h after irradiation and significantly increased testis and epididymis weights relative to those of the irradiated control mice at 30 days. PBE protected against histopathological damage and decreased the radiation-induced effects on the epithelium height and seminiferous tubule diameter. Furthermore, the extract ameliorated the radiation-induced morphological abnormalities of sperm cells and improved their motility. It also prevented a decrease in the epididymal sperm count caused by irradiation. Moreover, the extract alleviated the generation of reactive oxygen species, and its antioxidative activity increased in a dose-dependent manner. Among the six major compounds isolated from PBE, benzoic acid and uridine showed the highest antioxidant activities. These results suggest that PBE protects against radiation-induced testicular injury via its antioxidative properties. Thus, it has potential clinical applicability as a neoadjuvant therapy for the prevention of testicular damage caused by cancer radiotherapy.

Effects of 5.8 GHz Microwaves on Testicular Structure and Function in Rats

Objective

To investigate the effects of exposure to 5.8 GHz microwaves on testicular structure and function of male adult rats.

Methods

After 30 days of exposure, we evaluated sperm quality by determining sperm concentration and quantifying the number of abnormal sperm. Testicular morphology was investigated by hematoxylin-eosin (HE) staining. The levels of testosterone (T), follicle-stimulating hormone (FSH), luteinizing hormone (LH), glial cell line-derived neurotrophic factor (GDNF), stem cell factor (SCF), and transferrin (TRF) were determined by enzyme-linked immunosorbent assays (ELISAs). We also used western blotting to determine the levels of GDNF and SCF and apoptosis-related protein (caspase-3) in the testis.

Results

Compared with the sham group, there were no significant differences in terms of sperm count, sperm abnormality, and the levels of T, FSH, LH, GDNF, SCF, and caspase-3 in the microwave group.

Conclusion

Under the experimental conditions, 5.8 GHz microwave exposure has no obvious effect on testicular structure and function of rats.

Acute and Chronic Exposure to 900 MHz Radio Frequency Radiation Activates p38/JNK-mediated MAPK Pathway in Rat Testis

The use of electronic devices such as mobile phones has had a long stretch of rapid growth all over the world. Therefore, exposure to radio frequency radiation (RFR) has increased enormously. Here, we aimed to assess the balance between cell death and proliferation and also investigate the involvement of the JNK/p38 MAPK signaling pathway in the testis of rats exposed to 900 MHz RFR in acute and chronic periods (2 h/day, 5 days/week) for 1 or 10 weeks, respectively. The expression of proliferating cell nuclear antigen (PCNA), Bcl-xL, cleaved caspase-3, phosphorylated-JNK (p-JNK), and phosphorylated-p38 (p-p38) was analyzed in line with histopathology and TUNEL analysis in rat testis. There were no histopathological differences between sham and RFR groups in the acute and chronic groups. PCNA expression was not altered between groups in both periods. However, alterations for cleaved caspase-3 and Bcl-xL were observed depending on the exposure period. TUNEL analysis showed a significant increase in the RFR group in the acute period, whereas no difference in the chronic groups for the apoptotic index was reported. In addition, both p-p38 and p-JNK protein expressions increased significantly in RFR groups in both periods. Our study indicated that 900 MHz RFR might result in alterations during acute period exposure for several parameters, but this can be ameliorated in the chronic period in rat testis. Here, we also report the involvement of the p38/JNK-mediated MAPK pathway after exposure to 900 MHz RFR. Hence, this information might shed light in future studies toward detailed molecular mechanisms in male reproduction and infertility.

The Abscopal Effects of Cranial Irradiation Induce Testicular Damage in Mice

To investigate whether the abscopal effects of cranial irradiation (C-irradiation) cause testicular damage in mice, male C57BL/6 mice (9weeks of age) were randomly divided into a sham irradiation group, a shielded group and a C-irradiation group and administered sham/shielded irradiation or C-irradiation at a dose rate of 2.33Gy/min (5Gy/d for 4 d consecutively). All mice were sacrificed at 4weeks after C-irradiation. We calculated the testis index, observed testicular histology by haematoxylin-eosin (HE) staining and observed testicular ultrastructure by transmission electron microscopy. Western blotting was used to determine the protein levels of Bax, Bcl-2, Cleaved caspase 3, glial cell line-derived neurotrophic factor (GDNF) and stem cell factor (SCF) in the testes of mice. Immunofluorescence staining was performed to detect the expression of Cleaved caspase 3 and 3β hydroxysteroid dehydrogenase (3βHSD), and a TUNEL assay was used to confirm the location of apoptotic cells. The levels of testosterone (T), GDNF and SCF were measured by ELISA. We also evaluated the sperm quality in the cauda epididymides by measuring the sperm count, abnormality, survival rate and apoptosis rate. The results showed that there was no significant difference in testicular histology, ultrastructure or sperm quality between the shielded group and sham group. Compared with the sham/shielded group, the C-irradiation group exhibited a lower testis index and severely damaged testicular histology and ultrastructure at 4weeks after C-irradiation. The levels of apoptosis in the testes increased markedly in the C-irradiation group, especially in spermatogonial stem cells. The levels of serum T and testicular 3βHSD did not obviously differ between the sham group and the C-irradiation group, but the levels of GDNF and SCF in the testes increased in the C-irradiation group, compared with the sham group. In addition, the sperm count and survival rate decreased in the C-irradiation group, while the abnormality and apoptosis rate increased. Under these experimental conditions, the abscopal effects of C-irradiation induced testicular damage with regard to both structure and function and ultimately decreased sperm quality in mice. These findings provide novel insights into prevention and treatment targets for male reproductive damage induced by C-irradiation.

Environmental Factors-Induced Oxidative Stress: Hormonal and Molecular Pathway Disruptions in Hypogonadism and Erectile Dysfunction

Hypogonadism is an endocrine disorder characterized by inadequate serum testosterone production by the Leydig cells of the testis. It is triggered by alterations in the hypothalamic–pituitary–gonadal axis. Erectile dysfunction (ED) is another common disorder in men that involves an alteration in erectile response–organic, relational, or psychological. The incidence of hypogonadism and ED is common in men aged over 40 years. Hypogonadism (including late-onset hypogonadism) and ED may be linked to several environmental factors-induced oxidative stresses. The factors mainly include exposure to pesticides, radiation, air pollution, heavy metals and other endocrine-disrupting chemicals. These environmental risk factors may induce oxidative stress and lead to hormonal dysfunctions. To better understand the subject, the study used many keywords, including “hypogonadism”, “late-onset hypogonadism”, “testosterone”, “erectile dysfunction”, “reactive oxygen species”, “oxidative stress”, and “environmental pollution” in major online databases, such as SCOPUS and PUBMED to extract relevant scientific information. Based on these parameters, this review summarizes a comprehensive insight into the important environmental issues that may have a direct or indirect association with hypogonadism and ED in men. The study concludes that environmental factors-induced oxidative stress may cause infertility in men. The hypothesis and outcomes were reviewed critically, and the mechanistic approaches are applied through oxidant-sensitive pathways. This study also provides reccomendations on future therapeutic interventions and protective measures against such adverse environmental factors-induced hypogonadism and ED.

Effects of 1.5-GHz high-power microwave exposure on the reproductive systems of male mice

High-power microwaves (HPMs) have been reported to have hazardous effects on multiple human and animal organs. However, the biological effects of 1.5-GHz HPMs on the reproductive system are not clear. Here, we studied the effects of 1.5 -GHz HPM whole-body exposure on the pathological structure of the testicles and changes in spermatozoa mobility. C57BL/6 mice of groups L, M, and H were exposed to 1.5-GHz HPM fields for two 15-min intervals at the average specific absorption rates of 3, 6, and 12 W/Kg, respectively. The pathological structure of the testicles and spermatozoa, as well as serum testosterone and sperm motility parameters, were evaluated at 6 h, 1 d, 3 d, and 7 d after exposure. As a result, there were no significant pathological or ultrastructural changes in the testicles or spermatozoa and serum testosterone levels. The number of progressively motile spermatozoa, curvilinear velocity, linear velocity, and average path velocity of the exposure group increased at 6 h, decreased at 1 d, and recovered at 3 d. The opposite results were considered a stress response to the thermal effect of the microwaves. Our results indicated that 1.5-GHz HPM whole-body exposure in mice at SARs of 3, 6, and 12 W/Kg for 30 min did not cause obvious damage to the reproductive system.

Testicular Toxicity of Water Pipe Smoke Exposure in Mice and the Effect of Treatment with Nootkatone Thereon

There is a worldwide increase in the popularity of water pipe (shisha) tobacco smoking including in Europe and North America. However, little is known about the effects of water pipe smoke (WPS) exposure on male reproductivity. We have recently demonstrated that WPS exposure in mice induces testicular toxicity including inflammation and oxidative stress. Nootkatone, a sesquiterpenoid found in grapefruit, has antioxidant and anti-inflammatory effects. However, the possible protective effect of nootkatone on WPS-induced testicular toxicity has not been reported before. Here, we tested the effects of treatment of mice with nootkatone on WPS-induced testicular toxicity. Mice were exposed to normal air or WPS (30 minutes/day, for 30 days). Nootkatone (90 mg/kg) was given orally to mice by gavage, 1 h before WPS or air exposure. Nootkatone treatment significantly ameliorated the WPS-induced increase in plasma levels of inhibin, uric acid, and lactate dehydrogenase activity. Nootkatone also significantly mitigated the decrease in testosterone, androgen-binding protein, and estradiol concentrations in the plasma induced by WPS. In testicular homogenates, WPS exposure caused a decrease in the total nitric oxide level and an increase in the proinflammatory cytokine interleukin-1β level and oxidative stress markers including malondialdehyde, cytochrome C, and 8-Oxo-2'-deoxyguanosine. All the latter effects were significantly alleviated by nootkatone treatment. Moreover, in testicular homogenate, nootkatone inhibited the expression of nuclear factor-kappaB induced by WPS. Likewise, histological examination of mouse testes showed that nootkatone treatment ameliorated the deterioration of spermatogenesis induced by WPS exposure. We conclude that nootkatone ameliorated the WPS-induced testicular inflammation and oxidative stress and hormonal and spermatogenesis alterations.

Effects of 220 MHz Pulsed Modulated Radiofrequency Field on the Sperm Quality in Rats

Under some occupational conditions, workers are inevitably exposed to high-intensity radiofrequency (RF) fields. In this study, we investigated the effects of one-month exposure to a 220 MHz pulsed modulated RF field at the power density of 50 W/m² on the sperm quality in male adult rats. The sperm quality was evaluated by measuring the number, abnormality and survival rate of sperm cells. The morphology of testis was examined by hematoxylin-eosin (HE) staining. The levels of secreting factors by Sertoli cells (SCs) and Leydig cells (LCs) were determined by enzyme linked immunosorbent assay (ELISA). The level of cleaved caspase 3 in the testis was detected by immunofluorescence staining. Finally, the expression levels of the apoptosis-related protein (caspase 3, BAX and BCL2) in the testis were assessed by Western blotting. Compared with the sham group, the sperm quality in the RF group decreased significantly. The levels of secreting factors of SCs and the morphology of the testis showed an obvious change after RF exposure. The level of the secreting factor of LCs decreased significantly after RF exposure. The levels of cleaved caspase 3, caspase 3, and the BAX/BCL2 ratio in the testis increased markedly after RF exposure. These data collectively suggested that under the present experimental conditions, 220 MHz pulsed modulated RF exposure could impair sperm quality in rats, and the disruption of the secreting function of LCs and increased apoptosis of testis cells induced by the RF field might be accounted for by this damaging effect.