Spatial arrangement of testicular cells disrupted by transient scrotal hyperthermia and subsequent impairment of spermatogenesis

Fertility loss and recovery dynamics after repeated heat stress across life stages in male Drosophila melanogaster: patterns and processes

Frequent and extreme temperatures associated with climate change pose a major threat to biodiversity, particularly for organisms whose metabolism is strictly linked to ambient temperatures. Many studies have explored thermal effects on survival, but heat-induced fertility loss is emerging as a greater threat to population persistence. However, while evidence is accumulating that both juvenile and adult stages heat exposure can impair fertility in their own ways, much less is known about the immediate and longer-term fitness consequences of repeated heat stress across life stages. To address this knowledge gap, we used male Drosophila melanogaster to investigate (i) the cumulative fitness effects of repeated heat stress across life stages, (ii) the potential of recovery from these heat exposures, and (iii) the underlying mechanisms. We found individual and combined effects of chronic juvenile and acute adult heat stress on male fitness traits. These effects tended to exacerbate over several days after brief heat exposure, indicating a substantial fertility loss for these short-lived organisms. Our findings highlight the cumulative and persistent effects of heat stress on fitness. Such combined effects could accelerate population declines, particularly in more vulnerable species, emphasizing the importance of considering reproduction and its recovery for more accurate models of species persistence.

The Impact of Photobiomodulation Therapy on Enhancing Spermatogenesis and Blood-Testis Barrier Integrity in Adult Male Mice Subjected to Scrotal Hyperthermia

Introduction: Unhealthy lifestyle choices such as alcohol, chemicals, and heat stress can worsen male infertility. Heat stress can cause damage to the essential structure known as the blood-testis barrier (BTB). Photobiomodulation therapy (PBMT) has been employed in various studies to enhance sperm quality in individuals with genital inflammatory conditions in recent times. The current research sought to study how laser therapy affects spermatogenesis and the structure of the BTB in a mouse model of scrotal heat exposure. Methods: Thirty adult male NMRI mice, 8 weeks old, were divided into three groups: Control, Hyperthermia, and Hyperthermia+Laser 0.03 J/cm2. The animals in the hyperthermia group had their testicles exposed to water at 43 °C for 20 minutes five times every other day. Then, the testicles were exposed to laser radiation every other day for 35 days, lasting 3 minutes each time, with an energy density of 0.03 J/cm2. Animals were sacrificed, and sperm parameters, reactive oxygen species (ROS) and glutathione (GSH) levels, stereological parameters, and gene expression were assessed in the end. Results: The study showed that PBMT can significantly enhance sperm quality, quantity of spermatogenic cells, testicular volume, levels of ROS and GSH, and gene expression related to the blood-testis barrier. Conclusion: Currently, PBMT is a novel approach for addressing male infertility by preserving the integrity of the BTB in Sertoli cells, which in turn supports the growth and specialization of germ cells.

Effects of environmental temperature extremes exposure on sperm quality - evidence from a prospective cohort study in Anhui Province, China

Extreme weather is becoming more frequent due to drastic changes in the climate. Despite this, the body of research focused on the association between temperature extreme events and sperm quality remains sparse. In this study, we elucidate the impact of exposure to environmental temperature extremes on sperm quality. Data for this investigation were derived from the Anhui Prospective Assisted Reproduction Cohort, encompassing the period from 2015 to 2020. Parameters such as sperm concentration, total sperm count, total motility, progressive motility, total motile sperm count, and progressive motile sperm count were quantified from semen samples. We assessed the exposure of participants to temperature extremes during the 0-90 days prior to sampling. This investigation encompassed 15,112 participants, yielding 28,267 semen samples. Our research findings indicate that exposure to low temperature extreme for three consecutive days (at the first percentile threshold) has a detrimental correlation with sperm count parameters and concentration. Similar trends were observed with the second percentile threshold, where significant adverse effects typically manifested after a four-day exposure sequence. Analysis of high temperature extreme showed that exposure at the 98th percentile had adverse effects on all six sperm quality parameters, and the sperm count parameter was particularly sensitive to high temperature, showing significant results immediately after three days of exposure. When considering even more temperature extreme (99th percentile), the negative consequences were more pronounced on the sperm count parameter. Additionally, progressive motility showed a stronger negative response. In summary, parameters associated with sperm count are particularly vulnerable to temperature extremes exposure. Exposure to high temperature extremes environments may also be associated with a decrease in sperm concentration and vitality. The findings of this study suggest that male population should pay attention to avoid exposure to temperature extreme environment, which has important significance for improving the quality of human fertility.

Therapeutic Effects of Exosome Therapy and Photobiomodulation Therapy on the Spermatogenesis Arrest in Male Mice After Scrotum Hyperthermia

Introduction: In men, several factors cause infertility, among which we can mention damage to sperm due to high temperature. So far, various treatments have been proposed for it, but they have not been highly effective. The current study aimed to evaluate the effect of exosome therapy (EXO) and photobiomodulation therapy (PBMT) on spermatogenesis arrest in male mice after scrotum hyperthermia. Methods: In this experimental study, the animals were divided into four groups: control, scrotal hyperthermia, scrotal hyperthermia+EXO (100 μL/d) (mice were treated for 30 days), scrotal hyperthermia+PBMT (laser of 0.03 J/cm2 for 30 seconds/for 30 days). Hyperthermia was induced by exposure to the temperature of 43 °C for 20 minute every day for 5 times. After 6 weeks, the animals were sacrificed. Results: The treated groups showed a significant increase in sperm parameters, as compared to the hyperthermic groups. Moreover, these favorable effects were observed in relation to the volume of testicular tissue, the number of germ cells, Leydig cells and Sertoli cells, and the level of testosterone. Research on antioxidants showed a significant reduction in oxidized glutathione (GSSG) and reactive oxygen species (ROS) in the treatment groups in comparison to the hyperthermia group (P<0.001). Also, there has been a significant increase in the amount of hydrogen peroxide enzyme observed in the hyperthermia group as opposed to the treatment group (P<0.001). Conclusion: These findings show that EXO and PBMT can improve spermatogenesis caused by hyperthermia, reduce ROS and GSSG, and increase glutathione (GSH) and sperm quality.

Association between diurnal temperature range and sperm quality: Evidence from a prospective cohort in Central China

Inter-day temperature variability has been reported to be associated with sperm quality in a city-level exposure assessment study. However, studies exploring the impact of temperature variability within a single day on sperm quality at individual level are still lacking. The present study aims to bridge this research gap by analyzing the linear and non-linear associations between diurnal temperature range (DTR) exposure and sperm quality, utilizing data from the Anhui Prospective Assisted Reproduction Cohort. The study included 15,112 males (totaling 28,267 tests) and assessed individual exposure to various environmental factors (residential greenness, ambient particulate matter, sulfur dioxide, relative humidity, ambient temperature, and DTR) during the 0-90 day period before semen analysis. A combination of a linear mixed model, natural cubic splines, and subgroup analysis was employed. Significant "U"-shaped non-linear associations were observed between DTR exposure and total motility, sperm concentration, sperm count, total motile sperm count, and progressive motile sperm count. Lower DTR levels negatively impacted these parameters, whereas higher DTR levels showed a positive effect. Notably, these associations were more pronounced at ambient temperatures below 16.5 °C, while absent in warmer conditions. Sperm quality demonstrates increased sensitivity to DTR exposure in cooler environments. Therefore, implementing effective individual temperature management strategies is crucial for mitigating decreased sperm quality associated with DTR exposure, highlighting the potential benefits of government policies aimed at achieving carbon neutrality to enhance overall sperm quality in the general population.

Exploring Intercellular Dynamics: Ultra-Weak Biophoton Emission as a Novel Indicator of Altered Cell Functions and Disease in Oligospermia Mice

Introduction: Biophoton emission, the spontaneous release of photons from living cells, has emerged as an attractive field of research in the study of biological systems. Scientists have recently discovered that changes in biophoton emission could serve as potential indicators of pathological conditions. This intriguing phenomenon suggests that cells might communicate and interact with each other through the exchange of these faint but significant light signals. Therefore, the present study introduces intercellular relationships with biophoton release to detect normal and abnormal cell functions to further achieve cellular interactions by focusing on cell and cell arrangement in disease conditions. Methods: Twenty male mice were assigned to control and busulfan groups. Five weeks after the injection of busulfan, the testis was removed, and then the stereological techniques and TUNEL assay were applied to estimate the histopathology of the testis tissue sections. Results: The findings revealed that the ultra-weak biophoton emission in the control group was significantly lower than in the busulfan group. The oligospermia mice model showed that it significantly changed the spatial arrangement of testicular cells and notably decreased the testis volume, length of seminiferous tubules, and the number of testicular cells. The results of the TUNEL assay showed that the percentage of apoptotic cells significantly increased in the busulfan group. Conclusion: The ultra-weak biophoton emission from testis tissue was reduced in oligospermia mice. As a result, the decline of ultra-weak biophoton can indicate a change in cell arrangement, a decrease in intercellular interaction, and eventually disease.

Retinoic acid loaded with chitosan nanoparticles improves spermatogenesis in scrotal hyperthermia in mice

OBJECTIVE

High temperatures can trigger cellular oxidative stress and disrupt spermatogenesis, potentially leading to male infertility. We investigated the effects of retinoic acid (RA), chitosan nanoparticles (CHNPs), and retinoic acid loaded with chitosan nanoparticles (RACHNPs) on spermatogenesis in mice induced by scrotal hyperthermia (Hyp).

METHODS

Thirty mice (weighing 25 to 30 g) were divided into five experimental groups of six mice each. The groups were as follows: control, Hyp induced by a water bath (43 °C for 30 minutes/day for 5 weeks), Hyp+RA (2 mg/kg/day), Hyp+CHNPs (2 mg/kg/72 hours), and Hyp+RACHNPs (4 mg/kg/72 hours). The mice were treated for 35 days. After the experimental treatments, the animals were euthanized. Sperm samples were collected for analysis of sperm parameters, and blood serum was isolated for testosterone measurement. Testis samples were also collected for histopathology assessment, reactive oxygen species (ROS) evaluation, and RNA extraction, which was done to compare the expression levels of the bax, bcl2, p53, Fas, and FasL genes among groups. Additionally, immunohistochemical staining was performed.

RESULTS

Treatment with RACHNPs significantly increased stereological parameters such as testicular volume, seminiferous tubule length, and testicular cell count. Additionally, it increased testosterone concentration and improved sperm parameters. We observed significant decreases in ROS production and caspase-3 immunostaining in the RACHNP group. Moreover, the expression levels of bax, p53, Fas, and FasL significantly decreased in the groups treated with RACHNPs and RA.

CONCLUSION

RACHNPs can be considered a potent antioxidative and antiapoptotic agent for therapeutic strategies in reproductive and regenerative medicine.

A Review on the Impact of Oxidative Stress and Medicinal Plants on Leydig Cells

Leydig cells are essential for steroidogenesis and spermatogenesis. An imbalance in the production of reactive oxygen species (ROS) and the cellular antioxidant level brings about oxidative stress. Oxidative stress (OS) results in the dysfunction of Leydig cells, thereby impairing steroidogenesis, spermatogenesis, and ultimately, male infertility. To prevent Leydig cells from oxidative insults, there needs to be a balance between the ROS production and the cellular protective capacity of antioxidants. Evidence indicates that medicinal plants could improve Leydig cell function at specific concentrations under basal or OS conditions. The increased usage of medicinal plants has been considered a possible alternative treatment for male infertility. This review aims to provide an overview of the impact of oxidative stress on Leydig cells as well as the effects of various medicinal plant extracts on TM3 Leydig cells. The medicinal plants of interest include Aspalathus linearis, Camellia sinensis, Moringa oleifera, Morinda officinale, Taraxacum officinale, Trichilia emetica, Terminalia sambesiaca, Peltophorum africanum, Ximenia caffra, Serenoa repens, Zingiber officinale, Eugenia jambolana, and a combination of dandelion and fermented rooibos (CRS-10). According to the findings obtained from studies conducted on the evaluated medicinal plants, it can, therefore, be concluded that the medicinal plants maintain the antioxidant profile of Leydig cells under basal conditions and have protective or restorative effects following exposure to oxidative stress. The available data suggest that the protective role exhibited by the evaluated plants may be attributed to their antioxidant content. Additionally, the use of the optimal dosage or concentration of the extracts in the management of oxidative stress is of the utmost importance, and the measurement of their oxidation reduction potential is recommended.

SARS-CoV-2 and male infertility: from short- to long-term impacts

PURPOSE

The coronavirus 2019 (COVID-19) pandemic-caused by a new type of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-has posed severe impacts on public health worldwide and has resulted in a total of > 6 million deaths. Notably, male patients developed more complications and had mortality rates ~ 77% higher than those of female patients. The extensive expression of the SARS-CoV-2 receptor and related proteins in the male reproductive tract and the association of serum testosterone levels with viral entry and infection have brought attention to COVID-19's effects on male fertility.

METHODS

The peer-reviewed articles and reviews were obtained by searching for the keywords SARS-CoV-2, COVID-19, endocrine, spermatogenesis, epididymis, prostate, and vaccine in the databases of PubMed, Web of Science and Google Scholar from 2020-2022.

RESULTS

This review summarizes the effects of COVID-19 on the male reproductive system and investigates the impact of various types of SARS-CoV-2 vaccines on male reproductive health. We also present the underlying mechanisms by which SARS-CoV-2 affects male reproduction and discuss the potentially harmful effects of asymptomatic infections, as well as the long-term impact of COVID-19 on male reproductive health.

CONCLUSION

COVID-19 disrupted the HPG axis, which had negative impacts on spermatogenesis and the epididymis, albeit further investigations need to be performed. The development of vaccines against various SARS-CoV-2 variations is important to lower infection rates and long-term COVID risks.

Photobiomodulation therapy reverses spermatogenesis arrest in hyperthermia-induced azoospermia mouse model

Testicular heat stress leads to impairment of spermatogenesis in mammals. Involved mechanism in this vulnerability to heat-induced injury remains unclear, and research is being conducted to find an approach to reverse spermatogenesis arrest caused by hyperthermia. Recently, different studies have utilized photobiomodulation therapy (PBMT) therapy for the improvement of sperm criteria and fertility. This study aimed at evaluating the effect of PBMT on the improvement of spermatogenesis in mouse models of hyperthermia-induced azoospermia. A total of 32 male NMRI mice were equally divided into four groups consisting of control, hyperthermia, hyperthermia + Laser 0.03 J/cm2, and hyperthermia + Laser 0.2 J/cm2. To induce scrotal hyperthermia, mice were anesthetized and placed in a hot water bath at 43 °C for 20 min for 5 weeks. Then, PBMT was operated for 21 days using 0.03 J/cm2 and 0.2 J/cm2 laser energy densities in the Laser 0.03 and Laser 0.2 groups, respectively. Results revealed that PBMT with lower intensity (0.03 J/cm2) increased succinate dehydrogenase (SDH) activity and glutathione (GSH)/oxidized glutathione (GSSG) ratio in hyperthermia-induced azoospermia mice. At the same time, low-level PBMT reduced reactive oxygen species (ROS), mitochondrial membrane potential, and lipid peroxidation levels in the azoospermia model. These alterations accompanied the restoration of spermatogenesis manifested by the elevated number of testicular cells, increased volume and length of seminiferous tubules, and production of mature spermatozoa. After conducting experiments and analyzing the results, it has been revealed that the use of PBMT at a dosage of 0.03 J/cm2 has shown remarkable healing effects in the heat-induced azoospermia mouse model.

Protective Effect of Curculigo orchioides Gaertn. Extract on Heat Stress-Induced Spermatogenesis Complications in Murine Model

Curculigo orchioides Gaertn. is a precious herb used in traditional medicine systems in Asian countries for various health benefits. This study investigated the potential protective effects of C. orchioides extract on reproductive health under heat stress conditions in male mice. Forty-eight mice were divided into eight groups, control condition (C group), C. orchioides extract at the dosages of 100, 200, and 400 mg/kg/day (C100, C200, C400 group), 40 °C heat exposure (H group), and combined 40 °C heat exposure and C. orchioides extract at the dosages of 100, 200, and 400 mg/kg/day (HC100, HC200, HC400 group). The result shows that the mice that received only C. orchioides extract without heat stress do not have a significant change in histological structure and testosterone level. The histological analysis of testicular tissue showed that heat stress conditions reduced reproductive function and inhibited the spermatogenesis of male mice. The C. orchioides rhizome extract treatment attenuated the heat stress-induced spermatogenesis complications in the murine model. Mice in the heat-stress group treated with C. orchioides extract had increased spermatogenic cells and spermatozoa compared with mice exposed to heat without C. orchioides treatment. Moreover, the aqueous extract of C. orchioides rhizome enhanced the serum total testosterone levels in heat-exposed mice. In conclusion, the study findings validate that C. orchioides is effective against heat stress-induced spermatogenesis complications in the murine model.

Testicular heat stress, a historical perspective and two postulates for why male germ cells are heat sensitive

Herein, we compare the different experimental regimes used to induce testicular heat stress and summarise their impact on sperm production and male fertility. Irrespective of the protocol used, scrotal heat stress causes loss of sperm production. This is first seen 1-2 weeks post heat stress, peaking 4-5 weeks thereafter. The higher the temperature, or the longer the duration of heat, the more pronounced germ cell loss becomes, within extreme cases this leads to azoospermia. The second, and often underappreciated impact of testicular hyperthermia is the production of poor-quality spermatozoa. Typically, those cells that survive hyperthermia develop into morphologically abnormal and poorly motile spermatozoa. While both apoptotic and non-apoptotic pathways are known to contribute to hyperthermic germ cell loss, the mechanisms leading to formation of poor-quality sperm remain unclear. Mechanistically, it is unlikely that testicular hyperthermia affects messenger RNA (mRNA) abundance, as a comparison of four different mammalian studies shows no consistent single gene changes. Using available evidence, we propose two novel models to explain how testicular hyperthermia impairs sperm formation. Our first model suggests aberrant alternative splicing, while the second model proposes a loss of RNA repression. Importantly, neither model requires consistent changes in RNA species.

Effect of ambient temperature variability on sperm quality: A retrospective population-based cohort study

BACKGROUNDS

Abnormal sperm quality in men is one of the common causes of infertility. Both ambient temperature and extreme heat exposure have been shown to be associated with sperm quality, but there is no epidemiological evidence for the effect of ambient temperature variability. Our aim was to investigate the association between ambient temperature variability exposure and a decline in sperm quality at different stages of sperm development.

METHODS

A total of 4912 semen samples collected from the Guangdong Human Sperm Bank between 1 January 2019 and 31 December 2019 were analyzed. We selected three exposure periods: the full-stage (0-90 lag days), early-stage (34-77 lag days) and late-stage (0-37 lag days) of sperm development, and then calculated the standard deviation of daily temperature (TVSD), the maximum day-to-day temperature difference (TVD_max) and the mean day-to-day temperature difference (TVD_mean) for the three exposure periods. A linear mixed model was used to explore the exposure response relationship between temperature variability exposure and sperm quality indicators (including sperm concentration, sperm count and sperm motility).

RESULTS

There was a significant negative association of decreased sperm count with the exposure to temperature variability during 0-90 days prior to sperm collection. (TVD_max: -0.041; -0.063, -0.019; TVD_mean: -0.237; -0.386, -0.088; TVSD: -0.103; -0.196, -0.011). We observed a significant association between the decline in sperm concentration, sperm count and per 1 °C increase in TVD_mean during early spermatogenesis. No significant association of temperature variability with sperm motility was found.

CONCLUSIONS

The results indicate that exposure to temperature variability during the entire period of sperm development is significantly associated with a decline in sperm counts. We found that mean day-to-day temperature differences had a detrimental effect on sperm counts in the early-stage. Our findings provide a scientific basis for public health policy and further mechanistic studies.

Probing the Potential Mechanism of Quercetin and Kaempferol against Heat Stress-Induced Sertoli Cell Injury: Through Integrating Network Pharmacology and Experimental Validation

Quercetin and kaempferol are flavonoids widely present in fruits, vegetables, and medicinal plants. They have attracted much attention due to their antioxidant, anti-inflammatory, anticancer, antibacterial, and neuroprotective properties. As the guarantee cells in direct contact with germ cells, Sertoli cells exert the role of support, nutrition, and protection in spermatogenesis. In the current study, network pharmacology was used to explore the targets and signaling pathways of quercetin and kaempferol in treating spermatogenic disorders. In vitro experiments were integrated to verify the results of quercetin and kaempferol against heat stress-induced Sertoli cell injury. The online platform was used to analyze the GO biological pathway and KEGG pathway. The results of the network pharmacology showed that quercetin and kaempferol intervention in spermatogenesis disorders were mostly targeting the oxidative response to oxidative stress, the ROS metabolic process and the NFκB pathway. The results of the cell experiment showed that Quercetin and kaempferol can prevent the decline of cell viability induced by heat stress, reduce the expression levels of HSP70 and ROS in Sertoli cells, reduce p-NF-κB-p65 and p-IκB levels, up-regulate the expression of occludin, vimentin and F-actin in Sertoli cells, and protect cell structure. Our research is the first to demonstrate that quercetin and kaempferol may exert effects in resisting the injury of cell viability and structure under heat stress.

Zinc Protects against Heat Stress-Induced Apoptosis via the Inhibition of Endoplasmic Reticulum Stress in TM3 Leydig Cells

Heat stress (HS)-induced apoptosis in Leydig cells is mediated by various molecular mechanisms, including endoplasmic reticulum (ER) stress. Zinc, an inorganic mineral element, exhibits several cytoprotective properties, but its potential protective action against Leydig cell apoptosis and the related molecular mechanisms has not been fully elucidated. In this study, we evaluated the effects of zinc sulfate, a predominant chemical form of zinc, exerted on cell viability, apoptosis, and testosterone production in HS-treated TM3 Leydig cells and investigated the underlying signaling pathways. HS treatment inhibited cell viability and induced apoptosis, which was accompanied by the induction of the activity of caspase 3, an executioner of apoptosis, involved in the expression of pro-apoptotic protein B cell lymphoma 2-associated X protein (Bax), and in the reduction of the expression of anti-apoptotic protein B cell lymphoma 2 (Bcl-2), thereby activating ER stress marker protein expression (glucose-regulated protein 78 (GRP78) and CCAAT/enhancer-binding protein homologous protein (CHOP)). However, zinc sulfate led to the attenuation of deleterious effects, including increases in apoptosis, caspase-3 activity, Bax, GRP78, and CHOP expression, and decreases in cell viability and Bcl-2 protein expression in cells treated with HS or thapsigargin (an ER stress activator). Furthermore, 4-phenylbutyric acid (an ER stress inhibitor) treatment markedly alleviated the HS-induced adverse effects in cells exposed to HS, which was similar to zinc sulfate. Additionally, zinc sulfate supplementation in the culture medium effectively restored the HS-induced decrease in testosterone levels in HS-treated cells. In summary, these findings indicate that HS triggers apoptosis in TM3 Leydig cells via the ER stress pathway and that zinc confers protection against these detrimental effects. This study provides new insights into the benefits of using zinc against HS-induced apoptosis and cell injury.

Non-apoptotic cell death such as pyroptosis, autophagy, necroptosis and ferroptosis acts as partners to induce testicular cell death after scrotal hyperthermia in mice

Cell death is a biologically uncontrollable and regulated process associated with human diseases which usually occur in response to oxidative stress that activates signalling pathways in multiple forms and can therefore contribute to human diseases. Thus, the current study aims to evaluate the signalling pathway involved in cell death after testicular hyperthermia. For this purpose, 32 mice were equally divided into four groups; I: Control; II, III and IV, Scrotal hyperthermia in which the testes are exposed to water at 43°C for 20 min every other day, respectively, 15, 10 and 5 times. Then, animals were euthanized and testicular tissue samples were isolated to evaluate protein expression as well as germ cell gene marker expression by Western blot and real-time PCR tests. Our data showed that the protein expression of Caspase-1, Beclin1, Atg7, Mlkl and Acsl4 together with the expression of Caspase-1, Beclin1, Atg7, Mlkl and Acsl4 genes was significantly up-regulated in scrotal hyperthermia-induced mice. In conclusion, the present study showed that heat stress disrupts spermatogenesis by activating several non-apoptotic signalling pathways in testicular tissue.

Protective Effects of Fisetin in the Mice Induced by Long-Term Scrotal Hyperthermia

Exposure to heat in the male reproductive system can lead to transient periods of partial or complete infertility. The current study aimed to examine the beneficial effects of  Fisetin against spermatogenic disorders in mice affected by long-term scrotal hyperthermia. For this purpose, hyperthermia was induced daily by exposure to the temperature of 43 °C for 20 min for 5 weeks. Except for the Healthy group, six other groups were exposed to heat stress: two treated groups including Preventive and Curative which received oral administration of fisetin (10 mg/kg/day) starting immediately before heat exposure and 15 consecutive days after the end of the heat exposure, respectively. And for each treated group, two groups including Positive Control (Pre/Cur+PC group) and vehicle (Pre/Cur+DMSO group) were considered. Our results showed that the testicular volume; the density of spermatogonia, primary spermatocyte, round spermatid, and Sertoli and Leydig cells; and sperm parameters, as well biochemical properties of the testis tissue, were remarkably higher in both Preventive and Curative groups compared to the other hyperthermia-induced groups and were highest in Preventive ones. Unlike the c-kit gene transcript which was significantly increased in the  Fisetin treatment groups (specially the Preventive group), the expression of HSP72 and NF-kβ genes, Caspase3 protein, and DFI in sperm cells were significantly more decreased in Preventive and Curative groups compared to other hyperthermia-induced groups and were lowest in Preventive ones. Overall,  Fisetin exerts preventive and curative effects against spermatogenic disorders induced by long-term scrotal hyperthermia.

An effective method for establishing animal models of azoospermia and oligospermia

The current study aims to develop a validated animal model to predict successful spermatogenesis retrieval in azoospermia and oligospermia men. Thirty-two mice were equally divided into 4 groups: control, scrotal hyperthermia (15 times), scrotal hyperthermia group (10 times), scrotal hyperthermia group (5 times). In the scrotal hyperthermia groups, their scrotum exposed to water at a temperature of 43°C for 20 min every other day. Then, the mice were euthanised and sperm samples were collected for sperm parameters analysis, and blood samples were obtained for hormonal assay. The testis samples were taken for histopathology experiments, immunofluorescence staining and Western blot in order to examine the protein expression together with RNA extraction in order to examine the gene expression of germ cell markers. The results of sperm analysis and histopathology of testicular tissue as well as the results of gene expression and Western blot showed that hyperthermia can significantly impair spermatogenesis. In conclusion, we have developed a novel model of azoospermia and oligospermia in mouse, which uses a high temperature to suppress spermatogenesis process through demolition of germ cells subsequent cell cycle arrest and apoptosis. The model will contribute to understanding azoospermia in human, oligospermia pathophysiology and the development of treatment.