The Impact of High Ambient Temperature on Human Sperm Parameters: A Meta-Analysis

The Spontaneous Abortion of Females is Influenced by Their Male Partner's Heat Wave Exposure During Adolescence: A Nationwide Observational Study in China

OBJECTIVE

Heat wave exposure significantly impacts human health. Nevertheless, studies on the long-term effects of heat wave exposure during adolescence on adverse pregnancy outcomes (APOs) are rare. This study aimed to investigate the relationship between the long-term effects of heat wave exposure during adolescence and APOs.

METHODS

We analyzed data from 3,376 female and 3,013 male participants across 31 provinces in China. All adolescents (10-19 years old), early adolescents (10-14), and late adolescents (15-19) were chosen as exposure windows. Heat waves were defined as periods lasting 2‒4 consecutive days with the daily temperature exceeding the 75th, 90th, and 92.5th percentiles. We employed multivariate logistic regression models to assess the associations between exposure to heat waves during adolescence and APOs.

RESULTS

The results revealed significant associations between male exposure to heat wave events during late adolescence and spontaneous abortion (P < 0.05), which was more pronounced in South China. In contrast, no statistically significant associations were detected between males' exposure to heat wave events during adolescence and their partners' preterm birth (P > 0.05 for all comparisons). The exposure of females to heat waves during adolescence was not significantly associated with subsequent spontaneous abortion or preterm birth (P > 0.05 for all comparisons).

CONCLUSIONS

This study demonstrates that spontaneous abortion in females is associated with heat wave exposure in their male partner during adolescence.

Negative effect of seasonal heat stress on testis morphology and transcriptomes in Angora rabbit

BACKGROUND

The temperature of testes exposed to hyperthermic conditions can affect livestock reproductive performance. This study aimed to explore the difference in semen quality, testicular morphological structure, and gene expression profiles of testes of Angora rabbits in spring (no heat stress), summer (intense heat stress), and autumn (no heat stress) seasons.

RESULTS

Heat stress during summer significantly reduced semen quality and damaged testicular morphology and spermatogenesis, which recovered to normal levels in autumn, although semen quality recovery was notably slow. RNA-Seq analysis showed that the expression levels of 8703 genes changed significantly in summer, but their expression levels in autumn returned to those in spring, which was consistent with the testicular morphology analysis results in different seasons. Enrichment analysis revealed that the DEGs were primarily associated with spermatogenesis, sperm motility, spermatid development, cell death, regulation of apoptotic processes, and responses to external stimuli. The MAPK, Rap1, TNF, Ras, Apoptosis, and Wnt signaling pathways regulated reproduction under heat stress. In addition, minimal variations in testicular morphology and gene expression profiles were observed between autumn and spring. Gene expression pattern analysis showed that genes with high expression in summer mainly participated in the regulation of cell apoptosis, immunity, and response to heat stress, whereas genes with low expression in summer mainly participated in the regulation of spermatogenesis.

CONCLUSIONS

This study investigated the influence of different seasons on the reproductive performance of male Angora rabbits and provided initial insights into the molecular regulatory mechanisms underlying the testicular response to heat stress during summer.

Sauna therapy in rheumatic diseases: mechanisms, potential benefits, and cautions

Rheumatic diseases (RDs) present a major global health challenge, particularly in aging populations, due to chronic inflammation, progressive joint damage, and impaired mobility. While pharmacologic interventions, such as non-steroidal anti-inflammatory drugs (NSAIDs) and disease-modifying antirheumatic drugs (DMARDs), remain central to RDs management, concerns regarding their side effects and incomplete symptom relief have increased interest in complementary therapies. Sauna therapy, particularly its Finnish and infrared modalities, has emerged as a promising non-pharmacologic intervention with potential anti-inflammatory, musculoskeletal, and cardiovascular benefits. Heat exposure modulates inflammatory pathways by reducing pro-inflammatory agents (TNF-α, CRP, PGE2, LTB4) while promoting IL-10-mediated anti-inflammatory effects. Additionally, sauna therapy mitigates oxidative stress and enhances neuroendocrine regulation, contributing to systemic health benefits. Clinical evidence points to benefits of sauna therapy related to alleviating pain, reducing stiffness, and improving mobility in patients with rheumatoid arthritis (RA), ankylosing spondylitis (AS), and osteoarthritis (OA). Some studies have demonstrated reductions in pain scores and inflammatory markers, improved physical function, and disease stability following infrared sauna exposure. Moreover, cardiovascular advantages of regular sauna use are particularly relevant for RD patients with cardiovascular comorbidities. Given the growing body of evidence supporting its therapeutic potential, sauna therapy represents a viable adjunctive strategy for RD management. Further research is warranted to optimize treatment protocols, assess long-term safety, and delineate patient-specific benefits. Integrating sauna therapy into comprehensive RD care may enhance symptom control, improve quality of life, and reduce reliance on pharmacologic interventions.

The involvement of TRPV1 in the apoptosis of spermatogenic cells in the testis of mice with cryptorchidism

Cryptorchidism is associated with an increased risk of male infertility and testicular cancer. Persistent exposure to high temperature in cryptorchidism can lead to the apoptosis of spermatogenic cells. Transient receptor potential vanilloid 1 (TRPV1), a thermosensitive cation channel, has been found to have differential effects on various apoptosis processes. However, whether TRPV1 is involved in spermatogenic cell apoptosis induced by cryptorchidism remains unclear. Herein, we first observed the expression pattern of TRPV1 in the testes of mice with experimental cryptorchidism, and then investigated the role and mechanism of TRPV1 in spermatogenic cell apoptosis by using Trpv1-/- mice. The results showed that TRPV1 was highly expressed on the membrane of spermatocytes in mouse testis, and the expression increased significantly in the testis of mice with experimental cryptorchidism. After the operation, Trpv1-/- mice exhibited less reproductive damage and fewer spermatogenic cell apoptosis compared to the wild-type (WT) mice. Transcriptome sequencing revealed that the expression of apoptosis-related genes (Capn1, Capn2, Bax, Aifm1, Caspase 3, Map3k5, Itpr1 and Fas) was down-regulated in spermatocytes of cryptorchid Trpv1-/- mice. Our results suggest that TRPV1 promotes the apoptosis of spermatocytes in cryptorchid mice by regulating the expression of apoptosis-related genes.

Urology on a changing planet: links between climate change and urological disease

Urological diseases and their varied forms of management warrant special attention in the setting of climate change. Regarding urological cancers, climate change will probably increase the incidence and severity of cancer diagnoses through exposures to certain environmental risk factors, while simultaneously disrupting cancer care delivery and downstream outcomes. Regarding benign urological diseases, a burgeoning body of work exists on climate-related heat waves, dehydration, urolithiasis, renal injury and infectious and vector-borne diseases. Adding to the potential effect on disease pathogenesis, many patients with urological diseases undergo high-tech, resource-intensive interventions, such as robotic surgery, and entail intensive longitudinal assessments over many years. These features incur a considerable carbon footprint, generate substantial waste, and can introduce vulnerabilities to climate-related weather events. Links exist between planetary health (the health of humans and the natural systems that support our health), climate change and urological disease and urological care providers face many challenges in the era of anthropogenic climate change. The next steps and priorities for research, management, and health care delivery include identification and prioritization of health care delivery strategies to minimize waste and carbon emissions, while supporting climate resilience. Examples include supporting telemedicine, limiting low-value care, and building resilience to minimize impacts of climate-related disasters to prepare for the challenges ahead.

Paternal Effects in Mammalian Reproduction: Functional, Environmental, and Clinical Relevance of Sperm Components in Early Embryos and Beyond

In addition to widely recognized contributions of the paternal genome, centriole, and oocyte-activation factors, sperm deliver a wide range of macromolecules to the fertilized embryo. The impacts of these factors on the embryo, progeny, and even subsequent generations have become increasingly apparent, along with an understanding of an extensive potential for male health and environmental exposures to exert both immediate and long-term impacts on mammalian reproduction. Available data reveal that sperm factors interact with and regulate the actions of oocyte factors as well as exerting additional direct effects on the early embryo. This review provides a summary of the nature and mechanisms of paternal effects in early mammalian embryos, long-term effects in progeny, susceptibility of sperm components to diverse environmental factors, and potential approaches to mitigate adverse effects of such exposures.

A Case-Control Study of the Association Between GSTP1 Gene Polymorphisms (rs1695 and rs1138272) and the Susceptibility to Male Infertility in the Moroccan Population

Background: Infertility affects 10-15% of couples worldwide, with male factors accounting for half of cases. Environmental, behavioral, and genetic problems contribute to spermatogenic failure in 30% of idiopathic male infertility cases. Other factors, such as oxidative stress (OS), cause impaired spermatogenesis, abnormal sperm morphology, and reduced motility, eventually triggering male infertility. In the male reproductive tract, glutathione S-transferase (GST) family antioxidants are essential for preventing OS, detoxification, and DNA damage protection. Methods: GSTP1 isoenzyme, one of GST members, has previously been linked to male infertility, and this case-control study is the first to assess the possible association of GSTP1 gene polymorphisms (rs1695 and rs1138272) with nonobstructive azoospermia and severe oligospermia within 300 patients and 300 controls from the Moroccan population using an allele-specific PCR. The statistical analysis was performed with the R programming language. Results: Genotyping of GSTP1 polymorphisms fitted the Hardy-Weinberg equilibrium in both cases and controls (p > 0.05), but no significant association was found in rs1695 (odds ratio [OR] = 1.238, 95% confidence interval [CI] = 0.855 to 1.794, p = 0.258, power = 0.204) and in rs1138272 (OR = 1.192, 95% CI = 0.852 to 0.1668, p = 0.304, power = 0.176). Likewise, results from haplotype analysis (OR = 1.25, 95% CI = 0.61 to 2.57, p = 0.537) and SNP-SNP interactions (OR = 1.522, 95% CI = 0.838 to 2.762, p = 0.166) demonstrated no correlation with the risk of male infertility. Conclusion: The two SNPs (rs1695 and rs1138272) of the GSTP1 gene loci are not associated with male infertility susceptibility in Moroccan subjects. Yet, future investigations with a larger sample size may conclusively help to confirm this association.

The association between ambient temperature and semen quality in a Northern Peninsular Province, China

BACKGROUND

Extreme ambient temperature has been linked to decline in males' semen quality. Although the temperature-semen quality association has been examined in certain cities of South China, how the effect size of the extreme temperature may lag over critical windows in spermatogenesis and whether the strength of association may vary in North China have yet been adequately explored.

OBJECTIVES

To quantify the association between air temperature and semen quality, and identify critical exposure windows in a Northern Peninsular Province, China.

MATERIALS AND METHODS

Data on semen quality in 2014-2019 were collected from the Human Sperm Bank of Institute of Women, Children and Reproductive Health, Shandong University, China. Daily meteorological data (0.01°×0.01°) were assigned to each subject's residential address. The linear mixed-effect model combined with the distributed lag nonlinear model was used to estimate the effect of ambient temperature over critical spermatogenesis windows.

RESULTS

The temperature-semen quality association was inverted V-shaped, with the maximum lag being 0-45 days before ejaculation and the threshold being 9.2°C. Progressively and total motile sperm number, and total sperm number declined more substantially than other semen quality parameters. Semen quality was more sensitive to cold exposure during the epididymal storage period than the sperm motility development period. By contrast, semen quality was insensitive to heat exposure during both critical spermatogenesis windows. Impairment of certain semen quality parameters was more obvious for males with higher educational attainment and those aged over 35 years.

DISCUSSION AND CONCLUSION

Exposure to non-optimal temperature is associated with decreased semen quality in North China, with the epididymal storage and sperm motility development periods more sensitive to cold exposure than heat. Older males and those with higher educations may need particular awareness.

The RNA-seq mapping of Testicular Development after Heat Stress in Sexually Mature Mice

The testis serves as the primary site for spermatogenesis in mammals and is a crucial organ for the secretion of male hormones. Heat stress (HS) can have adverse effects on the seminiferous tubules, sperm quality, and sperm fertilization capability within the testis. Despite numerous previous studies describing various time points after heat stress in mice, a systematic and comprehensive dataset on heat stress and recovery in mice has been lacking. This study aimed to explore the gene expression changes in the recovery of multiple seminiferous epithelial cycles and spermatogenic cycles in mouse testicles after heat stress. We obtained high-throughput bulk RNA-seq data from testicular tissue of 4 NC mice and 32 HS mice (divided into 9 groups: NC, 30 min, 2 h, 6 h, 24 h, 3d, 8d, 24d, 47d, and 95d) and illustrated the dynamic changes in differential genes. This data set provides valuable insights into the detailed dynamic changes of one or more spermatogenic cycles after heat stress in mouse testicles, as well as the molecular mechanisms involved.

Global Warming and Endocrinology: The Hyderabad Declaration of the South Asian Federation of Endocrine Societies

Global warming and endocrine disorders are intertwined issues posing significant challenges. Greenhouse gases emanating from human activities drive global warming, leading to temperature rise and altered weather patterns. South Asia has experienced a noticeable temperature surge over the past century. The sizable population residing in the region heightens the susceptibility to the impact of global warming. In addition to affecting agriculture, water resources, and livelihood, environmental changes interfere with endocrine functioning. Resulting lifestyle changes increase the risk of metabolic and endocrine disorders. Individuals with diabetes face heightened vulnerability to extreme weather due to impaired thermoregulation. A high ambient temperature predisposes to heat-related illnesses, infertility, and nephropathy. Additionally, essential endocrine drugs and medical devices are susceptible to temperature fluctuations. The South Asian Federation of Endocrine Societies (SAFES) calls for collaboration among stakeholders to combat climate change and promote healthy living. Comprehensive approaches, including the establishment of sustainable food systems, promotion of physical activity, and raising awareness about environmental impacts, are imperative. SAFES recommends strategies such as prioritizing plant-based diets, reducing meat consumption, optimizing medical device usage, and enhancing accessibility to endocrine care. Raising awareness and educating caregivers and people living with diabetes on necessary precautions during extreme weather conditions are paramount. The heat sensitivity of insulin, blood glucose monitoring devices, and insulin pumps necessitates proper storage and consideration of environmental conditions for optimal efficacy. The inter-connectedness of global warming and endocrine disorders underscores the necessity of international collaboration guided by national endocrine societies. SAFES urges all stakeholders to actively implement sustainable practices to improve endocrine health in the face of climate change.

The Impact of Oxidative Stress on Male Reproductive Function: Exploring the Role of Antioxidant Supplementation

Male reproductive function is highly susceptible to oxidative stress, which arises from an imbalance between reactive oxygen species (ROS) production and antioxidant defense mechanisms. Oxidative stress can significantly impair sperm quality, including count, motility, morphology, and DNA integrity, leading to male infertility. Antioxidants play a crucial role in maintaining reproductive health by neutralizing ROS and protecting sperm cells from oxidative damage. This review article explores the impact of oxidative stress on male reproductive function and investigates the potential benefits of antioxidant supplementation in mitigating its detrimental effects. A comprehensive literature search was conducted to gather relevant studies examining the effects of oxidative stress on male fertility and the outcomes of antioxidant supplementation. The findings reveal that antioxidant supplementation can improve sperm quality, DNA integrity, and fertility outcomes in some individuals. However, conflicting research findings and limitations in study design highlight the need for further investigation. Factors such as individual variations, underlying causes of infertility, dosage, and duration of supplementation should be carefully considered. Lifestyle modifications, including a healthy diet and exercise, are crucial in reducing oxidative stress and optimizing male reproductive health. This review article provides valuable insights into the complex relationship between oxidative stress and male reproductive function, emphasizing the potential role of antioxidant supplementation as a supportive strategy. Further research is warranted to establish optimal protocols, identify specific subgroups that may benefit the most, and explore advancements in antioxidant therapies to improve male fertility outcomes.

Effects of Heat Stress on Motion Characteristics and Metabolomic Profiles of Boar Spermatozoa

Heat stress (HS) commonly causes boar infertility and economic loss in the swine industry. The heat tolerance of boar semen presents obvious differences among individuals. However, whether heat stress affects motion characteristics and the metabolome profile in boar sperm remains unclear. In this study, the kinetic features of sperm from HS and non-HS (NHS) groups were detected by computer-assisted sperm analysis, and metabolomic profiling was performed by liquid chromatography−mass spectrometry. The results showed that heat stress significantly reduced sperm motility, average path distance (APD), straight-line velocity (VSL), straightness (STR), and linearity (LIN) (p < 0.05). A total of 528 and 194 metabolites in sperm were identified in the positive and negative ion modes, respectively. Lipids and lipid-like molecules, and organic acids and derivatives were major metabolic classes in the two modes. Furthermore, we separately identified 163 and 171 differential metabolites in the two modes between HS and NHS groups. Clustering analysis further revealed significant metabolic changes in sperm after heat stress. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that differential metabolites in the two modes were enriched in glycerophospholipid, choline, and alanine, aspartate, and glutamate and lysine metabolism. Taken together, these results demonstrate that heat stress can alter the motion characteristics and metabolomic profiles of boar sperm.