Activation of sperm EGFR by light irradiation is mediated by reactive oxygen species.

To acquire fertilization competence, spermatozoa must undergo several biochemical and motility changes in the female reproductive tract, collectively called capacitation. Actin polymerization and the development of hyperactivated motility (HAM) are part of the capacitation process. In a recent study, we showed that irradiation of human sperm with visible light stimulates HAM through a mechanism involving reactive-oxygen-species (ROS), Ca(2+) influx, protein kinases A (PKA), and sarcoma protein kinase (Src). Here, we showed that this effect of light on HAM is mediated by ROS-dependent activation of the epidermal growth factor receptor (EGFR). Interestingly, ROS-mediated HAM even when the EGFR was activated by EGF, the physiological ligand of EGFR. Light irradiation stimulated ROS-dependent actin polymerization, and this effect was abrogated by PBP10, a peptide which activates the actin-severing protein, gelsolin, and causes actin-depolymerization in human sperm. Light-stimulated tyrosine phosphorylation of Src-dependent gelsolin, resulting in enhanced HAM. Thus, light irradiation stimulates HAM through a mechanism involving Src-mediated actin polymerization. Light-stimulated HAM and in vitro-fertilization (IVF) rate in mouse sperm, and these effects were mediated by ROS and EGFR. In conclusion, we show here that irradiation of sperm with visible light, enhances their fertilization capacity via a mechanism requiring ROS, EGFR and HAM.

Light-mediated activation reveals a key role for protein kinase A and sarcoma protein kinase in the development of sperm hyper-activated motility.

BACKGROUND: Hyper-activated motility (HAM) is part of the sperm capacitation process, which is necessary for fertilization. In this study, we investigated the effect of visible light on sperm motility and hyperactivation and evaluated pathways mediating these effects. METHODS: Human sperm (1 × 107 cells/ml) in capacitation media were irradiated for 3 min with 40 mW/cm² visible light (400-800 nm with maximum energy at 600 nm). Sperm motility was assessed and analyzed by computer-assisted sperm analysis. The involvement of sperm capacitation factors was investigated as follows. The generation of reactive oxygen species (ROS) was measured using 20,70-dichlorofluorescein diacetate. Protein kinase A (PKA) and sarcoma protein kinase (Src) activity were measured using western blot analysis and inhibited using 50 µM H89 and 10 µM PP2, respectively. Soluble adenlyl cyclase was inhibited using 20 µM 2-OH-Estradiol. The intracellular concentration of free Ca(2+) was assessed using the fluorescent calcium indicator, Fluo-4/AM. Sperm DNA fragmentation was determined using the sperm chromatin dispersion test. RESULTS: Light irradiation of human sperm caused a significant increase in hyper-HAM but not total motility. The production of ROS and activation of soluble adenylyl cyclase and PKA mediated the effect of light on HAM. Light irradiation also activated Src, and inhibition of Src significantly reduced the effect of light on HAM. Light irradiation caused a rapid increase in intracellular Ca²âº concentration and the increase in HAM was significantly reduced when voltage-dependent-Ca²âº-channel activity was blocked or when Ca²âº-deficient medium was used. CONCLUSIONS: Light irradiation of human sperm for a short time causes a significant increase in HAM in a mechanism mediated by ROS production, activation of PKA, Src and Ca²âº influx.

Extremely low frequency electromagnetic field exposure affects fertilization outcome in swine animal model.

Modern society continuously exposes the population to electromagnetic radiation, the effects of which on human health, in particular reproduction, are still unknown. The aim of this research was to assess the effect of acute (1h) exposure of boar spermatozoa to a 50 Hz extremely low frequency electromagnetic field (ELF-EMF) on early fertility outcome. The effect of intensities ranging from 0 to 2 mT on morpho-functional integrity of capacitated spermatozoa was examined in vitro. The oviducts containing or without spermatozoa were then exposed to the minimum in vivo, TD(50,) and maximum intensities determined in vitro, 4h before ovulation. The effects of ELF-EMF on spermatozoa in terms of early embryo development were evaluated after 12h and 6 days. It was found that in vitro ELF-EMF > 0.5 mT induced a progressive acrosome damage, thus compromising the ability of spermatozoa to undergo acrosomal reaction after zona pellucida stimulation and reducing the in vitro fertilization outcome. These effects became evident at 0.75 mT and reached the plateau at 1 mT. Under in vivo conditions, the ELF-EMF intensity of 1 mT was able to compromise sperm function, significantly reducing the fertilization rate. In addition, the exposure of oviducts to fields > or = 0.75 mT in the absence of spermatozoa was able to negatively affect early embryo development. In fact, it was found to cause a slowdown in the embryo cleavage. In conclusion, it was demonstrated how and at which intensities ELF-EMF negatively affect early fertility outcome in a highly predictive animal model.

[The influence of ultrasound and constant magnetic field on gametes, zygotes, and embryos of the sea urchin].

The influence of constant magnetic field, power 7 T, and ultrasound, frequency 2, 4 and 8 MHz, on gametes, fertization, embryos and larvae of the sea urchin was studied. It was shown that magnetic field breaks the process of the gamete fusion but does not influence gametes, embryos, and larvae. Ultrasound impairs the motility of spermatozoa and larvae, prevents the fertilization, and breaks the embryonic development. It is assumed that the effect of the magnetic field is connected with the response of the cortical cytoskeleton, which consists of bundles of actin microfilaments. The rearrangement of the cortical cytoskeleton occurs during the first 20 minutes after the contact of sperm with the egg. Also there is effect of magnetic fields on calcium ions, which are liberated during the first seconds after gamete contact. The effect of the ultrasound is explained by a small increase in water temperature and cavitation process, which break celluar structures.

[Occupational medical research of male reproductive capacity]. / Arbejdsmedicinsk forskning i maends forplantningsevne.

During the past 15 years, approximately 50 occupational medical sperm quality investigations have been carried out in the world as a whole. The discovery of reduced testicular function among workers exposed to the chemical agent dibromochloropropane (DBCP) was an important incitment for the conduct of these investigations. These have not demonstrated new occupational medical influences with as dramatic an effect as DBCP but moderately reduced sperm quality has, however, been proved or suspected after occupational exposure to a series of other agents: certain cell poisons (ethylene dibromide, carbaryl, chlordecone), certain glycoethers (in paint, glue, printing inks, antifreeze solutions), certain organic solvents e.g. styrene (plastic casting), choroprene (plastic production), low exposure to lead, metal welding, thermal influences and high frequent electromagnetic fields (300 kHz-300 mHz). Only a few investigations illustrate the significance of the male factors for infertility and delay before deliberate pregnancy and there are still no well-proved examples of human paternal teratogenic agents or carcinogens. Our present knowledge only serves to prevent a limited proportion of reproductory failure in men. Reports of decreased sperm quality in the population and the influence of the environment on reproduction in domestic animals indicate that further investigations are necessary. Longitudinal investigations of sperm quality together with investigations of fertility or delay till deliberate pregnancy are proposed subjects for future strategy.