Autophagy is activated in human spermatozoa subjected to oxidative stress and its inhibition impairs sperm quality and promotes cell death.

Study Question: Does oxidative stress (OS) activate autophagy in human sperm?

Summary Answer: Human spermatozoa subjected to OS activate an autophagic response.

What Is Known Already: Autophagy is a regulated pathway of lysosomal degradation which helps eukaryotic cells to maintain or restore homeostasis, being a cellular stress response mechanism. OS is a main cause of impaired sperm function and is linked to male infertility; however, whether OS activates autophagy in human spermatozoa is unknown.

Endocrine disruptor chemicals. A review of their effects on male reproduction and antioxidants as a strategy to counter it.

Endocrine disruptor chemicals are exogenous molecules that generate adverse effects on human health by destabilizing the homeostasis of endocrine system and affecting directly human reproductive system by inhibiting or activating oestrogenic or androgenic receptors. Endocrine disruptor chemicals generate transgenerational epigenetic problems, besides being associated with male infertility. Epidemiological data indicate that the increase in reproductive problems in males in the last 50 years is correlated with the increase of endocrine disrupting chemicals in the environment, being associated with a decrease in semen quality and direct effects on spermatozoa, such as alterations in motility, viability and acrosomal reaction, due to the generation of oxidative stress, and have also been postulated as a possible cause of testicular dysgenesis syndrome.

Overtime expression of plasma membrane and mitochondrial function markers associated with cell death in human spermatozoa exposed to nonphysiological levels of reactive oxygen species.

In many cell types, the potential of reactive oxygen species to induce death processes has been largely demonstrated. Studies in spermatozoa have associated the imbalance of reactive oxygen species and phosphatidylserine externalisation as an apoptosis marker. However, the lack of consensus about time effect in the joint expression of these and other death markers has made it difficult to understand the set of mechanisms influenced beyond the concentration effect of reactive oxygen species to stimulate cell death.

Multiparameter Flow Cytometry Assay for Analysis of Nitrosative Stress Status in Human Spermatozoa.

Male infertility is an increasing health problem, and oxidative/nitrosative stress plays an important role in the etiology of this condition. Nitrosative stress due to excessive levels of reactive nitrogen species (RNS) is associated with impaired male fertility. Flow cytometry may be a useful tool for semen evaluation, but the availability of multiparameter assays for analysis of sperm quality is limited.

Antioxidant effects of penicillamine against in vitro-induced oxidative stress in human spermatozoa.

Oxidative stress contributes importantly to the aetiology of male infertility, impairing sperm function. The protective effect of antioxidants on seminal parameters has been established, and the antioxidant penicillamine has shown beneficial effects; however, its protective effect on human spermatozoa exposed to oxidative stress has not been reported. The objective of this work was to evaluate the effect of penicillamine on human spermatozoa exposed in vitro to oxidative stress.

Nitrosative stress in human spermatozoa causes cell death characterized by induction of mitochondrial permeability transition-driven necrosis.

Peroxynitrite is a highly reactive nitrogen species and a potent inducer of apoptosis and necrosis in somatic cells. Peroxynitrite-induced nitrosative stress has emerged as a major cause of impaired sperm function; however, its ability to trigger cell death has not been described in human spermatozoa. The objective here was to characterize biochemical and morphological features of cell death induced by peroxynitrite-mediated nitrosative stress in human spermatozoa.

Effect of incubation temperature after devitrification on quality parameters in human sperm cells.

Sperm cryopreservation is common in assisted reproduction laboratories, providing a therapeutic option for several clinical conditions. This process has been optimized; however, the effect of post-thaw incubation temperature has been poorly studied. This work analyzed the effect of incubation temperature after devitrification on human sperm quality.

Thiol oxidation by nitrosative stress: Cellular localization in human spermatozoa.

Unlabelled: Peroxynitrite is a highly reactive nitrogen species and when it is generated at high levels it causes nitrosative stress, an important cause of impaired sperm function. High levels of peroxynitrite have been shown to correlate with decreased semen quality in infertile men. Thiol groups in sperm are mainly found in enzymes, antioxidant molecules, and structural proteins in the axoneme.

Ability of Escherichia coli to produce hemolysis leads to a greater pathogenic effect on human sperm.

Objective: To determine the effect on human sperm of Escherichia coli strains separated on the basis of their ability to produce hemolysis.

Design: Experimental study.

Setting: University-based laboratory.

Mitochondrial permeability transition increases reactive oxygen species production and induces DNA fragmentation in human spermatozoa.

Study Question: Does mitochondrial permeability transition (MPT) induced by calcium overload cause reactive oxygen species (ROS) production and DNA fragmentation in human spermatozoa?

Summary Answer: Studies conducted in vitro suggest that in human spermatozoa, MPT occurs in response to intracellular calcium increase and is associated with mitochondrial membrane potential (ΔΨm) dissipation, increased ROS production and DNA fragmentation.

What Is Known Already: Oxidative stress is a major cause of defective sperm function in male infertility. By opening calcium-dependent pores in the inner mitochondrial membrane (IMM), MPT causes, among other things, increased ROS production and ΔΨm dissipation in somatic cells.

Immunohistochemical evidences showing the presence of thymulin containing cells located in involuted thymus and in peripheral lymphoid organs.

Thymulin is a well-characterized thymic hormone that exists as a nonapeptide coupled to equimolar amounts of Zn2+. Thymulin is known to have multiple biological roles, including T cell differentiation, immune regulation, and analgesic functions. It has been shown that thymulin is produced by the reticulo-epithelial cells of the thymus, and it circulates in the blood from the moment of birth, maintain its serum level until puberty diminishing thereafter in life.

Mitochondrial membrane potential disruption pattern in human sperm.

Background: Loss of mitochondrial membrane potential (DeltaPsi(m)) in spermatozoa is correlated with high levels of reactive oxygen species in semen, abnormal spermiogram parameters, and low success rates of IVF. In somatic cells, the loss of DeltaPsi(m) is primarily associated with several mechanisms of cell death, mainly the activation of caspases. The impact of mitochondrial dysfunction on sperm function is still not fully elucidated, although disruption of DeltaPsi(m) and activation of caspases are processes thoroughly studied in human ejaculates.