Oxidative Stress in Male Infertility: Causes, Effects in Assisted Reproductive Techniques, and Protective Support of Antioxidants

Abstract

The spermatozoon is a highly specialized cell, whose main function is the transport of the intact male genetic material into the oocyte. During its formation and transit throughout male and female reproductive tracts, sperm cells are internally and externally surrounded by reactive oxygen species (ROS), which are produced from both endogenous and exogenous sources. While low amounts of ROS are known to be necessary for crucial physiological sperm processes, such as acrosome reaction and sperm–oocyte interaction, high levels of those species underlie misbalanced antioxidant-oxidant molecules, generating oxidative stress (OS), which is one of the most damaging factors that affect sperm function and lower male fertility potential. The present work starts by reviewing the different sources of oxidative stress that affect sperm cells, continues by summarizing the detrimental effects of OS on the male germline, and discusses previous studies addressing the consequences of these detrimental effects on natural pregnancy and assisted reproductive techniques effectiveness. The last section is focused on how antioxidants can counteract the effects of ROS and how sperm fertilizing ability may benefit from these agents.

Piperine Regulates Nrf-2/Keap-1 Signalling and Exhibits Anticancer Effect in Experimental Colon Carcinogenesis in Wistar Rats

“…Piperine treatment repressed the production of MDA levels, which may be due to the alkaloids present in piperine scavenging free radicals due to its potent anti-oxidant activity attenuating the MDA level in treatment groups. Enzymatic and non-enzymatic antioxidants are the primary defenders against cytotoxic oxygen radicals by scavenging intermediates of oxygen reduction [ 42 ]. Some anti-oxidants like SOD and CAT protect against lipid peroxidation in tissues by directly eliminating reactive oxygen metabolites like superoxide (O 2 2• ) and hydroxyl ions (OH • ), providing one of the most efficient defensive mechanisms in the biological system against diseases [ 43 ].…”

Relationship of Seminal Oxidation-Reduction Potential with Sperm DNA Integrity and pH in Idiopathic Infertile Patients

“…The lack of a similar relationship between sORP and SDF suggests that, similarly to what has been commented on the previous paragraph, the incorporation of antioxidants in seminal plasma compensates for testicular ROS levels. High levels of ROS can be offset by high levels of antioxidants that prevent SDF generation, and conversely, basal ROS levels along with a decrease in seminal antioxidants could lead to increased SDF [17][18][19][20]. The SDF generated by ROS occurs mainly in the epididymis and vas deferens but not in the ejaculation stage [57][58][59].…”

“…Over recent decades, a number of studies have shown that redox deregulation, either by an increase in reactive oxygen species (ROS) or a decrease in antioxidant activity, results in alterations in sperm motility, lipid peroxidation or sperm DNA fragmentation (SDF) [13][14][15][16]. Additionally, several works have described that infertile men have higher concentrations of ROS and lower levels of antioxidants [17][18][19][20]. Oxidative stress (OS) assessments are usually based on ROS level measurements in seminal plasma, but antioxidant levels, which can offset or exacerbate this cellular stress, are not usually calculated.…”

Docosahexaenoic acid in the treatment of male infertility caused by high sperm DNA fragmentation

“…Это также одна из причин неразвивающейся беременности, спонтанного аборта и неудачных попыток экстракорпорального оплодотворения [7][8][9][10]. Так как окислительный стресс является ведущим механизмом повреждения генетического материала сперматозоидов, антиоксидантная терапия была предложена в качестве одного из основных методов лечения мужского бесплодия, ассоциированного с высоким уровнем фрагментации ДНК сперматозоидов [11][12][13][14][15][16]. В исследованиях оценена эффективность многих антиоксидантов, однако полученные результаты противоречивы [14,[16][17][18][19][20].…”

“…Применение ПНЖК в клинических исследованиях снижало интенсивность воспалительной симптоматики и улучшало состояние пациентов с болезнью Крона, ревматоидным артритом, кератоконъюнктивитом, периодонтитом и гингивитом [40][41][42][43][44]. Окислительный стресс считается основным механизмом повреждения генетического материала сперматозоидов, а главным источником активных форм кислорода в эякуляте являются лейкоциты [11][12][13][45][46][47]. Воспалительный процесс в добавочных половых железах обусловливает повышение концентрации лейкоцитов в эякуляте и, таким образом, может становиться причиной повышения продукции АФК и развития окислительного стресса [45][46][47].…”