F4-Neuroprostanes: A Role in Sperm Capacitation

Abstract

F4-neuroprostanes (F4-NeuroPs), derived from the oxidative metabolization of docosahexaenoic acid (DHA), are considered biomarkers of oxidative stress in neurodegenerative diseases. Neurons and spermatozoa display a high DHA content. NeuroPs might possess biological activities. The aim of this in vitro study was to investigate the biological effects of chemically synthetized 4-F4t-NeuroP and 10-F4t-NeuroP in human sperm. Total progressive sperm motility (p < 0.05) and linearity (p = 0.016), evaluated by a computer-assisted sperm analyzer, were significantly increased in samples incubated with 7 ng F4-NeuroPs compared to non-supplemented controls. Sperm capacitation was tested in rabbit and swim-up-selected human sperm by chlortetracycline fluorescence assay. A higher percentage of capacitated sperm (p < 0.01) was observed in samples incubated in F4-NeuroPs than in the controls. However, the percentage of capacitated sperm was not different in F4-NeuroPs and calcium ionophore treatments at 2 h incubation. The phosphorylated form of AMPKα was detected by immunofluorescence analysis; after 2 h F4-NeuroP incubation, a dotted signal appeared in the entire sperm tail, and in controls, sperm were labeled in the mid-piece. A defined level of seminal F4-NeuroPs (7 ng) showed a biological activity in sperm function; its addition in sperm suspensions stimulated capacitation, increasing the number of sperm able to fertilize.

A Study to Validate the Relevance of Semen F2-Isoprostanes on Human Male Infertility

“…Recently, a mild increase in semen F 2 -IsoP levels, lower than the cut-off point found in the present research, has been found to have a positive relationship with sperm DNA integrity and good embryo quality [15]. These observations support that the F 2 -IsoP concentration < 29.96 ng/mL is normal and can represent a marker of metabolic activity in human semen, as was also detected for F 4 -neuroprostanes, molecules derived from the oxidative metabolism of docosahexaenoic acid, which at defined levels are able to stimulate sperm capacitation [17].…”

“…Afterward, sample acidification was obtained by adding HCl 1 N (1:0.5, v:v), and a tetradeuterated derivative of prostaglandin (PGF 2α -d4, 500 pg) was added as an internal standard. Sample purification was carried out by two different solid-phase extractions (octadecylsilane, C18 cartridge, and aminopropyl, NH 2 cartridge) to obtain a final eluate to be derivatized before the GC/NICI-MS/MS was performed [17]. The amounts of 8-iso-PGF 2α , the most represented isomer for F 2 -IsoP detection (also known as 15-F 2t -IsoP), were quantified by measuring m/z 299 product ion, derived from the [M-181] − precursor ions, and compared to the m/z 303 ion produced by PGF 2α -d4 in the applied GC/NICI-MS/MS [17].…”

“…Sample purification was carried out by two different solid-phase extractions (octadecylsilane, C18 cartridge, and aminopropyl, NH 2 cartridge) to obtain a final eluate to be derivatized before the GC/NICI-MS/MS was performed [17]. The amounts of 8-iso-PGF 2α , the most represented isomer for F 2 -IsoP detection (also known as 15-F 2t -IsoP), were quantified by measuring m/z 299 product ion, derived from the [M-181] − precursor ions, and compared to the m/z 303 ion produced by PGF 2α -d4 in the applied GC/NICI-MS/MS [17]. For quantification, a calibration curve was constructed using reference 8-iso-PGF 2α compound (Cayman Chemical, Item No.…”

Polyunsaturated fatty acids and fatty acid-derived lipid mediators: Recent advances in the understanding of their biosynthesis, structures, and functions

“…One particular focus of our group is the biological relevance of 4-(RS)-4-F 4t -NeuroP and its unique ability to protect the ryanodine receptors in vitro and in vivo , where potent antiarrhythmic properties have been shown via this mechanism of action [ 244 ]. Recently, F 4 -NeuroPs showed a biological activity in sperm function and was able to induce capacitation via increasing AMPK phosphorylation, and its role at ryanodine receptors is currently being explored [ 245 ]. Finally, Lee and co-workers showed that 4-(RS)-4-F 4t -NeuroP can cross the blood brain barrier into rat brain tissue and alter brain omega-3 and omega-6 PUFA profiles, where anti-inflammatory and pro-resolvin lipid biomarkers were significantly elevated [ 246 ].…”

A Dynamic Model for Estimating the Interaction of ROS–PUFA–Antioxidants in Rabbit

“…Dietary levels of n-3 PUFA that are too high can increase F 4 -NeuroPs and negatively affect the oxidative status of rabbit sperm [14]. However, at certain levels, F 4 -NeuroPs (7 ng/mL) can also have positive effects on human reproduction, increasing the number of sperm able to fertilise eggs [28].…”