Effect of noise stress on count, progressive and non-progressive sperm motility, body and genital organ weights of adult male rats

Effects and possible mechanisms of combined exposure to noise and carbon monoxide on male reproductive system in rats

Environmental hazards are an increasing concern due to the rapid pace of industrialization. Among these hazards, noise and carbon monoxide (CO) are common risk factors and have been shown to cause serious health problems. However, existing studies focused on the individual effects of noise and CO exposure and the combined effects of these two factors remain poorly understood. Our study aimed to examine the combined effects of noise and CO exposure on testicular function by constructing individual and combined exposure models. Our findings indicated that combined exposure to noise and CO was associated with a higher risk of testicular damage and male reproductive damage when compared to exposure alone. This was evidenced by poorer semen quality and more severe pathological damage to the testis. This combined exposure led to higher levels of oxidative stress and apoptosis in the testes, with bioinformatics analyses suggesting the signaling pathways involved in these responses. Specifically, activation of the P53 signaling pathway was found to contribute to the testicular damage caused by the combined exposure. Encouragingly, pterostilbene (PTE), a novel phytochemical, alleviated combined exposure-induced testicular damage by reducing oxidative stress and germ cell apoptosis. Overall, we identified joint reproductive toxicity resulting from the exposure to noise and CO, and found that PTE is a promising potential treatment for injuries caused by these factors. The cover image is based on the Research Article Effects and possible mechanisms of combined exposure to noise and carbon monoxide on male reproductive system in rats by Yingqing Li et al., https://doi.org/10.1002/tox.23927.

Assortment of kaempferol and zinc gluconate improves noise-induced biochemical imbalance and deficits in body weight gain

This study investigated the effects of pretreatment with antioxidants, kaempferol, and zinc gluconate on serum biochemical changes and impairment in body weight gain following noise-exposure in Wistar rats. Thirty-five animals were evenly grouped into five cohorts: Groups II, III, IV, and V were exposed to noise stress, induced by exposing rats to 100 dB (4 hr/day) for 15 days, from days 33 to 48 after starting the drug treatments. Treatment with kaempferol and/or zinc mitigated noise-induced deficits in body weight gain, and levels of serum lipid and protein fractions. The combined treatment significantly (p < .05) decreased malondialdehyde concentration in kaempferol + zinc gluconate treated group, compared to the group administered deionized water + noise. This result demonstrates that biochemical dyshomeostasis and lipid peroxidation may be involved in the molecular mechanism underlying noise stress and the assortment of kaempferol and zinc gluconate produced an improved mitigating outcome in Wistar rats.

Comparison of mice' sperm parameters exposed to some hazardous physical agents

The present study was aimed to compare the effects of exposure to noise, vibration, lighting, and microwave on male mice' sperm parameters. The mice were randomly assigned to five groups of eight, which comprised of the unexposed group and exposure groups including the lighting (1000 lux), noise (100 dB(A)), vibration (acceleration of 1.2 m/s2) and microwave (power density of 5 watts). The exposure groups were subjected to the four agents for 8 hours a day, 5 days a week during a 2-week period. Semen analysis were done according to World Health Organization guidelines. The highest significant mean difference in sperm count (-1.35×106/mL) had being observed between the microwave group and the control one (P=0.001). The highest difference in immotile percent (25.88 %) had being observed between the noise group and the control one (P=0.001). The highest difference in normal morphology (-27.06 %) observed between the lighting exposure group and the control group (P=0.001). The four agents can cause changes in different sperm parameters, however for definite conclusion; more laboratory and field studies are required. In total, exposure to microwave has had the greatest effect on sperm count and exposure to light has had the greatest effect on normal morphology and non-progressive motility. Moreover, exposure to noise has had the greatest effect on progressive motility and immotile percent, respectively.

Antioxidant and antiapoptotic paracrine effects of mesenchymal stem cells on spermatogenic arrest in oligospermia rat model

BACKGROUND

Oligospermia is one of the common causative factors of male infertility. Some medical and hormonal therapy for male infertility is typically with unsatisfactory outcome. Stem cell therapy has become a new therapeutic strategy for restoring function in addition to inducing proliferation and differentiation of malfunctioning germ cells. This work aims at investigating the potential ability of BM-MSCs to repair the spermatogenic arrest in oligospermic rat model.

METHODS

In this work, a rat model of oligospermia was induced using two intraperitoneal injections of busulfan (15 mg/kg) with two weeks interval. Rats were divided into (i) donor group [source of the bone marrow mesenchymal stem cells (BM-MSCs) that were labelled and transfected with green fluorescent protein (GFP)] and (ii) experimental groups that were subdivided into: GpI (control), GpII (spermatogenic arrest model), GpIII (untreated rats), and GpIV (BM-MSCs treated rats). Estimation of the testicular weight, sperm count and motility % were performed. Histological and immunohistochemical staining for inducible nitric oxide synthase (iNOS) and caspase-3 (Cas-3) were conducted. Besides, the level of the testicular malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α) and testicular testosterone were estimated by ELISA.

RESULTS

Oligospermic rats illustrated hypospermatogenesis of the seminiferous tubule with spermatocyte and spermatid arrest, focal thickening of the basement membrane and significant increase in germ cells apoptosis and testicular oxidative stress. Compared with the control, MDA and TNF-α were markedly elevated with marked suppression of the testicular testosterone. Intra-testicular injection of BM-MSCs substantially ameliorated these changes and effectively improved the sperm count and motility %.

CONCLUSIONS

BM-MSCs improved the induced-spermatogenic arrest in the rat model mainly through anti-apoptotic and antioxidant paracrine effects.

Nighttime environmental noise and semen quality: A single fertility center cohort study

With increased population and urban development, there are growing concerns regarding health impacts of environmental noise. We assessed the relationship between nighttime environmental noise and semen quality of men who visited for fertility evaluation. This is a retrospective cohort study of 1,972 male patient who had undertaken semen analysis between 2016-2018 at a single fertility center of Seoul, South Korea. We used environmental noise data of National Noise Information System (NNIS), Korea. Using semiannual nighttime noise measurement closest to the time of semen sampling, individual noise exposures at each patient's geocoded address were estimated with empirical Bayesian kriging method. We explored the association between environmental noise and semen quality indicators (volume, concentration, % of progressive motility, vitality, normal morphology, total motile sperm count, oligozoospermia, asthenozoospermia, and severe teratozoospermia) using multivariable regression and generalized additive models. Estimated exposure to nighttime environmental noise level in the study population was 58.3±2.2 Leq. Prevalence of oligozoospermia, asthenozoospermia, and severe teratozoospermia were 3.3%, 14.0%, and 10.1%. Highest quartile nighttime noise was associated with 3.5 times higher odds of oligozoospermia (95% CI: 1.18, 10.17) compared to lowest quartile. In men whose noise exposure is in 3rd quartile, odds ratio (OR) of severe teratozoospermia was 0.57 (95% CI: 0.33, 0.98). The OR for 4th quartile noise were toward null. In generalized additive model, the risk of oligozoospermia increases when the nighttime noise is 55 Leq dB or higher. Our study adds an evidence of potential impact of environmental noise on semen quality in men living in Seoul. Additional studies with more refined noise measurement will confirm the finding.

Non Concurrent Multimodal Stress Decreases Sperm Quality and Motor Activity in Male Wister Albino Rats

Every human being is exposed to the stress in one or the other form in the day to day life. Most of the existing studies on the impact of stress on the male reproduction were assessed by using single stressor, which may lead habituation to that stressor. The present study intends to estimate the consequence of stress on motor activity, sperm quality and histopathology of the testis in stress-induced male rats using multimodal stress one per day. Four weeks old Wister albino rats were randomly split into 4 groups and induced multimodal stress at different ages of life span. After induction of stress serum corticosterone levels, muscle strength and coordination, quality of sperm and histopathology of testes were estimated. Elevated serum corticosterone levels and body weight, reduced muscle strength, coordination. Sperm concentration and motility was significantly reduced and increased morphologically abnormal sperm in stress induced animals but sperm viability was not altered much. Histopathology of testes in stress received animals showed decreased tubular diameter and increased intertubular space. Multimodal stress caused elevated serum corticosterone and body weight, decreased motor activity, sperm quality and degenerative changes in the testis

Novel Epigenomic Biomarkers of Male Infertility Identified by Methylation Patterns of CpG Sites Within Imprinting Control Regions of H19 and SNRPN Genes

Male infertility is an important global health burden that can benefit from novel biomarkers and diagnostics innovation. Aberrant methylation of the imprinted genes H19 and SNRPN (small nuclear ribonucleoprotein polypeptide N) in sperm DNA has been implicated in abnormal sperm parameters and male infertility. However, whether certain methylation patterns of one or multiple CpG sites within an imprinted gene are pathological for multiple sperm defects remains poorly understood. To examine the diagnostic potential of certain methylation patterns of CpG sites for multiphenotype defects in human sperm, the sperm DNA methylation patterns of individual CpG sites within imprinting control regions (ICRs) of imprinted genes H19 and SNRPN were measured by bisulfite pyrosequencing in a Han Chinese population sample: 39 oligoasthenozoospermia (OA) patients, 36 asthenoteratozoospermia (AT) patients, and 50 normozoospermia (N) controls. A partial least squares discriminant analysis model was built with the CpG sites as independent variables. Among the 16 CpG sites screened, the methylation patterns of eight CpG sites within H19-ICR (CpG sites 1, 6-9, 12 and 15-16), and eight CpG sites within SNRPN-ICR (CpG sites 2, 5-6, 8-10, 13, and 16) correctly classified 74.4% and 72.0% of the samples in terms of male fertile status, respectively. Furthermore, by combination of these 16 selected CpG sites within ICRs of H19 and SNRPN, 88.0% of the samples could be successfully classified. Our study demonstrates that methylation profiles of CpG sites within ICRs of imprinted genes H19 and SNRPN may potentially serve as epigenomic biomarkers for assessment of infertility in men with multiple sperm defects. Further studies in independent population samples are called for diagnostic significance of methylation patterns of CpG sites within imprinted genes.

Genotoxicity evaluation of zinc oxide nanoparticles in Swiss mice after oral administration using chromosomal aberration, micronuclei, semen analysis, and RAPD profile

The expanded uses of zinc oxide nanoparticles (ZnO NPs) have grown rapidly in the field of nanotechnology. Thus, rising production of nanoparticles (NPs) increases the possible risks to the environment and occupationally exposed humans. Hence, it is indispensable to appraise the safety toxicity including genotoxicity for these NPs. In the present study, we have evaluated the genotoxic effect of ZnO NPs after oral administration to Swiss mice at dose levels of 300 and 2000 mg/kg body weight. These doses were administered for 2 days at 24 h apart. Chromosomal aberration (CA) and micronucleus tests were conducted following Organization for Economic Co-operation and Development guidelines. DNA damage was evaluated at 0, 24, 48, and 72 h posttreatment using a randomly amplified polymorphic DNA (RAPD) assay; additionally, semen analyses were also performed at 34.5 days post oral exposure. The reactive oxygen species (ROS), 8-oxo-2'-deoxyguanosine and CAs were increased ( p < 0.05) at the highest dosage (2000 mg/kg) of ZnO NPs compared to controls. Aberrant sperm morphology with reduced sperm count and motility were also present ( p < 0.05) in the high-dose group. Based on the RAPD assay, the genomic template stability within the high-dose group (<90%) was less than the controls (100%). The results suggested that ZnO NPs are mildly genotoxic in a dose-related manner and this toxicity were induced by generation of ROS.

Exposure to environmental noise and risk for male infertility: A population-based cohort study

BACKGROUND

Noise is associated with poor reproductive health. A number of animal studies have suggested the possible effects of exposure to high noise levels on fertility; to date, a little such research has been performed on humans.

OBJECTIVES

We examined an association between daytime and nocturnal noise exposures over four years (2002-2005) and subsequent male infertility.

METHODS

We used the National Health Insurance Service-National Sample Cohort (2002-2013), a population-wide health insurance claims dataset. A total of 206,492 males of reproductive age (20-59 years) with no history of congenital malformations were followed up for an 8-year period (2006-2013). Male infertility was defined as per ICD-10 code N46. Data on noise exposure was obtained from the National Noise Information System. Exposure levels of daytime and night time noise were extrapolated using geographic information systems and collated with the subjects' administrative district code, and individual exposure levels assigned.

RESULTS

During the study period, 3293 (1.6%) had a diagnosis of infertility. Although there was no association of infertility with 1-dB increments in noise exposure, a non-linear dose-response relationship was observed between infertility and quartiles of daytime and night time noise after adjustment for confounding variables (i.e., age, income, residential area, exercise, smoking, alcohol drinking, blood sugar, body mass index, medical histories, and particulate pollution). Based on WHO criteria, adjusted odds for infertility were significantly increased (OR = 1.14; 95% CI, 1.05-1.23) in males exposed to night time noise ≥ 55 dB.

CONCLUSION

We found a significant association between exposure to environmental noise for four years and the subsequent incidence of male infertility, suggesting long-term exposure to noise has a role in pathogenesis of male infertility.

Proximity to major roadways and prospectively-measured time-to-pregnancy and infertility

We aimed to study the potential impact of proximity to major roadways on time-to-pregnancy and infertility in couples attempting pregnancy in the Longitudinal Investigation of Fertility and Environment (LIFE) study (2005-2009), a population-based, prospective cohort study. Couples attempting pregnancy (n=500) were enrolled and followed prospectively until pregnancy or 12months of trying and 393 couples (78%) had complete data and full follow-up. Time-to-pregnancy was based on a standard protocol using fertility monitors, tracking estrone-3-glucuonide and luteinizing hormone, and pregnancy test kits to detect human chorionic gonadotropin (hCG). The fecundability odds ratio (FOR) and 95% confidence interval (CI) were estimated using proportional odds models. Infertility was defined as 12months of trying to conceive without an hCG pregnancy and the relative risk (RR) and 95% CI were estimated with log-binomial regression. Final models were adjusted for age, parity, study site, and salivary alpha-amylase, a stress marker. Infertile couples (53/393; 14%) tended to live closer to major roadways on average than fertile couples (689m vs. 843m, respectively) but the difference was not statistically significant. The likelihood of pregnancy was increased 3% for every 200m further away the couples residence was from a major roadway (FOR=1.03; CI=1.01-1.06). Infertility also appeared elevated at moderate distances compared to 1000m or greater, but estimates lacked precision. Our findings suggest that proximity to major roadways may be related to reductions in fecundity. Prospective data from larger populations is warranted to corroborate these findings.

A framework to assess evolutionary responses to anthropogenic light and sound

Human activities have caused a near-ubiquitous and evolutionarily-unprecedented increase in environmental sound levels and artificial night lighting. These stimuli reorganize communities by interfering with species-specific perception of time-cues, habitat features, and auditory and visual signals. Rapid evolutionary changes could occur in response to light and noise, given their magnitude, geographical extent, and degree to which they represent unprecedented environmental conditions. We present a framework for investigating anthropogenic light and noise as agents of selection, and as drivers of other evolutionary processes, to influence a range of behavioral and physiological traits such as phenological characters and sensory and signaling systems. In this context, opportunities abound for understanding contemporary and rapid evolution in response to human-caused environmental change.

Sexual behavior attenuates the effects of chronic stress in body weight, testes, sexual accessory glands, and plasma testosterone in male rats

The aim of this study was to evaluate whether continuous sexual behavior could attenuate the effects of chronic stress on spermatogenesis, sexual glands, plasma testosterone and corticosterone in sexually experienced male rats. Rats were exposed to stress by immersion in cold water (ICW) daily for 20 or 50 consecutive days. Plasma testosterone and corticosterone, masculine sexual behavior, as well as the number of offspring, the epithelial area of seminiferous, prostatic and seminal glands were assessed. In stressed males, body and testicular weights decreased, male sexual behavior was disrupted, and adrenal weights increased. In males stressed for 50 days, prostate and seminal glands had lower weights compared with controls. Prostate and seminal epithelial areas also decreased in these males. Seminiferous tubules in testes from rats stressed for 20 or 50 days showed several degenerative signs, such as vacuoles in the basal epithelium, with picnotic indicia; moderate to severe exfoliation of degenerative germinal cells in the tubule lumen was also observed. In males stressed for 50 days a significant decrease in seminiferous epithelial area was observed from stages I-VIII, regardless of copulation. The litters from females that copulated with males stressed for 50 days decreased significantly. Chronic stress caused increase in plasma levels of corticosterone, which were higher in males stressed for 20 days than in males stressed for 50 days. Testosterone decreased in stressed males and it was lower in males stressed for 50 days. In stressed males allowed to copulate, body and testicular weights were similar to controls. Adrenal, seminal glands, and prostate weights, as well as epithelial areas of males stressed for 50 days allowed to copulate were also similar to controls. Corticosterone was lower than in males stressed for 50 days, but still higher than in controls. Testosterone in males stressed for 50 days and allowed to copulate was higher than in stressed males not allowed to copulate and control males without copulation, but still lower than in control copulating males. These results show that chronic stress causes germ cell loss in testes and a decrease in prostate and seminal epithelium, possibly as a result of testosterone decrease, affecting fertility. Continuous copulation can attenuate the effects of stress on testosterone levels and on the epithelial area in male sexual glands, but not on the seminiferous epithelium after 50 days of stress.

Study of spermatogenesis fetal testis exposed noise stress during and after natal period in rat

Noise stress is dangerous natural contaminant that produces harmful physiological, psychological and morphological outcomes to the body. So this study was conducted in order to investigate the effects of noise stress on the parenchyma of testis. Healthy mature females rats (n = 20) were mated with the mature male rats and then randomly allocated equally either to experimental or control groups. Experimental group has given daily noise stress up to birth their child. In the second step, the child's pregnant rats of experimental group were distributed to three subgroups as follow: group I (without exposure to noise stress), group II (exposure to noise for 8 weeks) and group III (exposure to noise for 14 weeks) for morphometric analysis of their child's testicles by sacrificing of them at weeks 14. In general, the testes of non-exposed group were grown larger than ones in the noise exposed groups. Moreover, the testes of the experimental group 1 were larger than the other experimental groups. Indeed, the rate of atrophic seminiferous tubules and jumbled appearance of the interstitial space were more observed in the noise stress exposed group than non-exposed ones. In addition, seminiferous tubules analysis revealed that the characteristics of interstitial space cells and epithelial germinative cells of the seminiferous tubules in the control group were better than the noise exposed groups. It seems that the noise stress has negative influences on the fertility of male based on enhancing of the apoptotic process induced by pathogenesis stress and suppressing the kinetics spermatogenesis.

The effects of honey and vitamin E administration on apoptosis in testes of rat exposed to noise stress

AIMS:

A variety of stress factors are known to inhibit male reproductive functions. So this study was conducted in order to investigate the effects of honey and vitamin E on the germinative and somatic cells of testes of rats exposed to noise stress.

MATERIALS AND METHODS:

Mature male wistar rats (n = 24) were randomly grouped as follows: Group 1 (honey + noise stress), 2 (vitamin E + noise stress), 3 (noise stress,) and 4 as the control group. In groups 1, 2, and 3, rats were exposed to noise stress. In groups 1 and 2, rats also were given honey and vitamin E, respectively, orally for 50 days. After that, the germinative and somatic cells of testes parenchyma were isolated by digesting the whole testes by a standard method. Next, viability, apoptosis, and necrosis of the cells were evaluated by TUNEL kit and flow cytometry.

RESULTS:

The rates of apoptosis and necrosis of the testicular cells were increased (P = 0.003 and P = 0.001, respectively), but viability of these cells decreased in testes of rats exposed to noise stress (P = 0.003). However, administration of honey and vitamin E were significantly helpful in keeping the cells of testis parenchyma alive, which suffers from noise pollution (P < 0.05 and P < 0.05, respectively).

CONCLUSIONS:

Noise stress has negative influences on the cells of testicular tissue by increasing apoptotic and necrotic cells. However, the associated enhancement in healthy cells suggests that honey and vitamin E have positive influences on the testis parenchyma.