Melatonin Effects on Sperm Quality and Reproductive Health
Summary
Melatonin, a neurohormone produced predominantly by the pineal gland during the dark phase, serves as both a master circadian regulator and a powerful antioxidant in reproductive tissues. In males, melatonin acts through specific membrane-bound receptors in the testis, epididymis and germ cells to influence spermatogenesis, sperm maturation and capacitation. Its capacity to scavenge reactive oxygen species preserves mitochondrial function, membrane integrity and DNA stability, thereby enhancing sperm motility, viability and morphology. Exogenous melatonin supplementation has emerged as a valuable strategy to counteract oxidative damage during cryopreservation, improving post-thaw sperm quality across species. Seasonal fluctuations in endogenous melatonin align with changes in testosterone levels and antioxidant enzyme activity, underpinning reproductive seasonality in livestock. Collectively, these findings underscore melatonin’s dual endocrine and local actions, with broad implications for natural fertility, assisted reproductive technologies and livestock management worldwide.
Research from Nature Portfolio
A study of slow-release melatonin implants in rams demonstrated sustained elevation of seminal and plasma melatonin, leading to larger testicular volume, higher testosterone concentrations and an increased number of sperm per ejaculate without altering motility or morphology. Notably, treated rams exhibited reduced sperm DNA fragmentation during the non-breeding season and an improved likelihood of ejaculate collection, confirming both systemic endocrine modulation and direct testicular effects of melatonin on male reproductive efficiency.
Melatonin Effects on Sperm Quality and Reproductive Health publication trend
The graph below shows the total number of articles in melatonin effects on sperm quality and reproductive health across all publications each year (not limited to Nature Index journals).
Technical terms
Melatonin: A hormone secreted by the pineal gland that regulates circadian rhythms and acts as an antioxidant in reproductive tissues.
Reactive oxygen species (ROS): Chemically reactive molecules derived from oxygen that can damage lipids, proteins and DNA within sperm cells.
Oxidative stress: An imbalance between ROS production and antioxidant defences leading to cellular injury and impaired sperm function.
Cryopreservation: A process of freezing biological samples at very low temperatures to preserve cell viability, often used for sperm storage.
MT1 and MT2 receptors: Membrane-bound proteins on reproductive cells that mediate the cellular effects of melatonin.
References
- The Role of Melatonin on Caprine (Capra hircus) Sperm Freezability: A Review. Antioxidants (2024).
- The Role of Melatonin to Ameliorate Oxidative Stress in Sperm Cells. International Journal of Molecular Sciences (2023).
- Role of Melatonin in Bovine Reproductive Biotechnology. Molecules (2023).
- Utility of antioxidants during assisted reproductive techniques: an evidence based review. Reproductive Biology and Endocrinology (2014).
- Exogenous melatonin advances the ram breeding season and increases testicular function. Scientific Reports (2020).
- Melatonin MT1 and MT2 Receptors in the Ram Reproductive Tract. International Journal of Molecular Sciences (2017).
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