Impact of Melatonin Supplementation in Women with Unexplained Infertility Undergoing Fertility Treatment.

Unexplained infertility occurs when common causes for a couple's inability to conceive have been excluded. Although origins of idiopathic infertility are still unclear, factors, such as an altered oxidative balance, are believed to be involved. Melatonin is an outstanding antioxidant reportedly present in the follicular fluid (FF), which has been suggested as a useful tool in the management of human fertility.

Melatonin diminishes oxidative damage in sperm cells, improving assisted reproductive techniques.

Sperm preparation procedures are a potential generator of oxidative stress-induced DNA damage, which leads to a dramatic drop in fertility. An increasing number of studies suggest that melatonin reduces the oxidative stress induced by manipulation. However, very little is known about the preservative role of melatonin in sperm preparation medium during assisted reproduction procedures.

Exogenous melatonin supplementation prevents oxidative stress-evoked DNA damage in human spermatozoa.

Reactive oxygen species (ROS) are essential for sperm physiological functions such as capacitation, hyperactivation, and acrosome reaction, on the one hand, and for stimulating the apoptotic processes involved in the regulation of spermatogenesis, on the other hand. However, the imbalance between production and removal of ROS leads to oxidative stress, which is referred to as one of the main factors involved in male infertility. The pineal hormone melatonin, given its low toxicity and well-known antioxidant capacity, could be an excellent candidate to improve sperm quality.

A multicenter prospective study to assess the effect of early cleavage on embryo quality, implantation, and live-birth rate.

Objective: To investigate the impact of early cleavage (EC) on embryo quality, implantation, and live-birth rates.

Design: Prospective cross-sectional study.

Setting: Multicenter study.

Melatonin protects human spermatozoa from apoptosis via melatonin receptor- and extracellular signal-regulated kinase-mediated pathways.

Objective: To evaluate whether the protective effect of melatonin on H2O2-induced caspase activation and DNA fragmentation depends on the interaction between melatonin and its surface receptors.

Design: Laboratory study.

Setting: Center for assisted human reproduction at a Spanish hospital.

The correlation between urinary 5-hydroxyindoleacetic acid and sperm quality in infertile men and rotating shift workers.

Background: Serotonin is a neurotransmitter that modulates a wide range of neuroendocrine functions. However, excessive circulating serotonin levels may induce harmful effects in the male reproductive system. The objective of this study was to evaluate whether the levels of urinary 5-hydroxyindoleacetic acid (5-HIIA), a major serotonin metabolite, correlate with different classical seminal parameters.

Melatonin as a potential tool against oxidative damage and apoptosis in ejaculated human spermatozoa.

It is assumed somatic cells can die in the apoptotic, the autophagic, or the necrotic way; however, the mechanisms of sperm death are not clear. Here, ejaculated human spermatozoa were evaluated for apoptosis and reactive oxygen species production in the absence or presence of melatonin, and we concluded that melatonin reverses sperm apoptosis due to its free radical scavenging actions.

Relationship between caspase activity and apoptotic markers in human sperm in response to hydrogen peroxide and progesterone.

Apoptosis plays an essential role in normal spermatogenesis, but deregulations of this biological process, which is closely associated with male infertility, have been found. Whereas calcium homeostasis is a key regulator of cell survival, sustained elevation of intracellular calcium plays a role in apoptosis. The aim of this research was to determine the role of two different calcium mobilizing agents, hydrogen peroxide (H(2)O(2)) and the physiological agonist progesterone, on the apoptosis process of human ejaculated spermatozoa.

Reduced levels of intracellular calcium releasing in spermatozoa from asthenozoospermic patients.

Background: Asthenozoospermia is one of the most common findings present in infertile males characterized by reduced or absent sperm motility, but its aetiology remains unknown in most cases. In addition, calcium is one of the most important ions regulating sperm motility. In this study we have investigated the progesterone-evoked intracellular calcium signal in ejaculated spermatozoa from men with normospermia or asthenozoospermia.

Caspase 3 activation in human spermatozoa in response to hydrogen peroxide and progesterone.

Objective: To determine the role of calcium signaling on apoptosis evoked by the reactive oxygen species H2O2 and by the physiological agonist P in human ejaculated spermatozoa.

Design: Laboratory study.

Setting: Center for assisted human reproduction in a hospital in Spain.

Expression of transcription factors in endometrium during natural cycles.

Purpose: The sex steroid control of the endometrial cycle is mediated by transcription factors, four of which are the estrogen and progesterone receptors, c-jun and c-fos, all expressed by the endometrium. The aim of this study was to analyze the distribution of the transcription factors in the different endometrial compartments during natural cycles.

Methods: We studied 53 reproductively-normal women, of whom 26 were in the proliferative phase and 27 in the secretory phase.