Role of nuclear and mitochondrial genes in human male infertility: a review

Yoga and Lifestyle Changes: A Path to Improved Fertility - A Narrative Review

Infertility, a widespread medical condition affecting numerous couples globally, persists as a challenge despite advances in assisted reproductive technologies (ARTs), often burdened by financial, physical, and emotional strains. Complementary and alternative approaches, notably yoga, have garnered attention for potentially enhancing fertility outcomes. Studies reveal yoga's influence on factors contributing to infertility, including reduced oxidative stress (OS) and oxidative DNA damage (ODD). OS, linked to mutagenic base formation, higher malondialdehyde levels, abnormal methylation, and altered gene expression, can impair sperm genome integrity. Yoga's efficacy is evident in lowering OS, positively affecting signal transmission, gene expression, and physiological systems. Furthermore, yoga has a positive impact on addressing the dysregulation of apoptosis, resulting in improved processes such as spermatogenesis, sperm maturation, and motility, while also reducing DNA fragmentation. OS correlates with genome-wide hypomethylation, telomere shortening, and mitochondrial dysfunction, contributing to genome instability. Yoga and meditation significantly reduce OS and ODD, ensuring proper reactive oxygen levels and preserving physiological systems. The review explores potential mechanisms underlying yoga's positive impact on infertility, including enhanced blood flow, reduced inflammation, relaxation response, and modulation of the hypothalamic-pituitary-adrenal axis. Furthermore, a comprehensive review of the literature reveals substantial evidence supporting the positive effects of yoga on infertility factors. These include oxidative stress (OS), oxidative DNA damage (ODD), epigenetic changes, hormonal balance, ovarian function, menstrual irregularities, and stress reduction. In summary, yoga emerges as a promising adjunctive therapy for infertility, demonstrating the potential to mitigate key factors influencing reproductive success. Although preliminary evidence indicates the positive effects of yoga on infertility, further clinical research is imperative to define specific benefits, molecular mechanisms associated, optimal protocols, and long-term effects in infertility treatment plans.

Sperm Mitochondria, the Driving Force Behind Human Spermatozoa Activities: Its Functions and Dysfunctions - A Narrative Review

Male infertility is a major issue, and numerous factors contribute to it. One of the important organelles involved in the functioning of human spermatozoa is mitochondria. There are 50-75 mitochondria helically arranged in mid-piece bearing one mitochondrial DNA each. Sperm mitochondria play a crucial role in sperm functions, including the energy production required for sperm motility and the production of reactive oxygen species, which in the physiological range helps in sperm maturation, capacitation, and acrosome reaction. It also plays a role in calcium signaling cascades, intrinsic apoptosis, and sperm hyperactivation. Any structural or functional dysfunction of sperm mitochondria results in increased production of reactive oxygen species and, a state of oxidative stress, decreased energy production, all leading to sperm DNA damage, impaired sperm motility and semen parameters, and reduced male fertility. Furthermore, human sperm mitochondrial DNA mutations can result in impaired sperm motility and parameters leading to male infertility. Numerous types of point mutations, deletions, and missense mutations have been identified in mtDNA that are linked with male infertility. Methods: Recent literature was searched from English language peer-reviewed journals from databases including PubMed, Scopus, EMBASE, Scholar, and Web of Science till September 2021. Search terms used were "Sperm mitochondria and male fertility", "Bioenergetics of sperm", "Sperm mitochondria and reactive oxygen species", "Sperm mitochondrial mutations and infertility". Conclusion: Sperm mitochondria is an important organelle involved in various functions of human spermatozoa and sperm mitochondrial DNA has emerged as one of the potent biomarkers of sperm quality and male fertility.

Fractal methods applied to the seminiferous lumen images can quantify testicular changes induced by heat stress

Male infertility affects many couples around the world and can be related to environmental factors such as exposure to high temperatures. Even so, automated methods evaluating the seminiferous tubules to detect testicular damage are still scarce. In search of new approaches to automation in the microscopic analysis of the testis; the present study used the fractal dimension, lacunarity, multifractality and quantitative morphometry to quantify changes in microphotographs of the seminiferous lumen in testicles reversibly damaged by heat stress (43 °C, 12 min). The parameters fractal dimension, lacunarity, multifractality (Dq and α), perimeter, feret and circularity were able to detect changes in the seminiferous lumen at 7, 15 and 30 days after the testicular damage. These methods also detected the recovery of spermatogenesis at 60 days after heat stress. Area, f(α), centroid X and Y, roundness, rectangle height and width were unable to detect changes caused by heat stress. In conclusion, computer assisted methods applied to the seminiferous lumen images can be a useful new viewpoint to analyze microscopic changes in the testicles, a fast low-cost tool to assist in the automated quantification of testicular damage.

Large-scale mtDNA deletions as genetic biomarkers for susceptibility to male infertility: A systematic review and meta-analysis

Several complex rearrangements such as deletions in mitochondrial DNA (mtDNA) have been identified in sperm deficiencies. This study aimed to investigate the association of common mtDNA deletions with male infertility using a meta-analysis approach. Standard databases were systematically searched to discover relevant studies. Pooled odds ratios (ORs) with corresponding 95% confidence intervals (CI) were estimated to analyze the association of mtDNA deletions with male infertility. Our data revealed a significant association between a common 4977-bp deletion and an increased risk of male infertility. A similar association was observed in an Asian population. Stratified analysis by infertility phenotype showed significant associations between the 4977-bp deletion and increased risk of asthenozoospermia, oligoasthenoteratozoospermia, and asthenoteratozoospermia. In addition, significant associations were found in studies with sample sizes >100, age of participants <45 years, subject selection according to WHO criteria, and studies of moderate to high quality. Regarding the other common mtDNA deletions, significant associations were observed between 7436-bp, 7599-bp, and 4866-bp deletions and the risk of male infertility. Our findings suggest that the 4977-bp deletion might be a risk factor for male infertility, especially in an ethnic and infertility phenotype dependent manner.