Seminal lipid profiling and antioxidant capacity: A species comparison

Abstract

On their way to the oocyte, sperm cells are subjected to oxidative stress, which may trigger the oxidation of phospholipids (PL). Applying MALDI-TOF MS, HPTLC and ESI-IT MS, we comparatively analyzed the PL compositions of semen and blood of species differing in their reproductive systems and types of nutrition (bull, boar, stallion, lion and man) with regard to the sensitivity to oxidation as well as the accumulation of harmful lyso-PL (LPL), transient products of lipid oxidation. In addition, the protective capacity of seminal fluid (SF) was also examined. The PL composition of erythrocytes and blood plasma is similar across the species, while pronounced differences exist for sperm and SF. Since the blood function is largely conserved across mammalian species, but the reproductive systems may vary in many aspects, the obtained results suggest that the PL composition is not determined by the type of nutrition, but by the relatedness of species and by functional requirements of cell membranes such as fluidity. Sperm motion and fertilization of oocytes require a rather flexible membrane, which is accomplished by significant moieties of unsaturated fatty acyl residues in sperm lipids of most species, but implies a higher risk of oxidation. Due to a high content of plasmalogens (alkenyl ether lipids), bull sperm are most susceptible to oxidation. Our data indicate that bull sperm possess the most effective protective power in SF. Obviously, a co-evolution of PL composition and protective mechanisms has occurred in semen and is related to the reproductive characteristics. Although the protective capacity in human SF seems well developed, we recorded the most pronounced individual contaminations with LPL in human semen. Probably, massive oxidative challenges related to lifestyle factors interfere with natural conditions.

Integrating sperm cell transcriptome and seminal plasma metabolome to analyze the molecular regulatory mechanism of sperm motility in Holstein stud bulls

“…In human studies, men with asthenozoospermia have lower seminal plasma vitamin B6 level compared with men having normal sperm motility. In our study of sperm motility, the trend of two different metabolites involved in vitamin B6 metabolism pathway is the same as that of humans, indicating the similar role of spermatic metabolites in regulating sperm cells in different species ( Jakop et al, 2022 ). Univariate ROC analysis results were consistent with OPLS-DA analysis results (more than 72% of metabolites with AUC value >0.7 were found in differential metabolites).…”

Live cells are not affected by dead sperm in liquid boar semen: New insights based on a thermo‐resistance test

“…Some antioxidant compounds of seminal fluid may provide a degree of protection against these factors (Martinez-Alborcia et al, 2012). In contrast to bull and stallion semen, the seminal fluid of boars has a higher radical reduction capacity per sperm cell (Jakop et al, 2022), which is removed from samples to be frozen but not from samples to be stored at ~17°C. Another influencing factor could be the amount of EDTA present in the extender.…”

Ether lipids and a peroxisomal riddle in sperm

“…Moreover, sperm function is critically influenced by reactive oxygen species (ROS) mainly derived from aerobic metabolism in the mitochondria. Small quantities of ROS are needed for normal sperm function, stimulating both sperm capacitation and fertilization reviewed by O'Flaherty and Scarlata (2022). However, high levels of ROS induce an oxidative stress state that has a detrimental effect on sperm motility, capacitation, acrosome reaction and DNA integrity, leading to male infertility reviewed by Aitken et al, (2022).…”

“…Thus, lipids are of special interest as potential fertility markers and therapeutic targets not only because of their structural functions in sperm, but also because they are sensitive to external and environmental signals, many of which can be recreated in vitro . Ether lipids are a particularly highly abundant subclass of glycerophospholipids found in sperm of different species, such as humans, boars, stallions, bulls, and lions ( Parks and Lynch, 1992 ; Leßig et al, 2004 ; Oresti et al, 2011 ; Jakop et al, 2022 ), suggesting they play a critical role in sperm physiology. In other cell types, ether lipids are key components of cell membranes, providing unique structural attributes with effects on membrane dynamics, including membrane fluidity and membrane fusion, facilitating signaling processes, regulating cell differentiation, and protecting membranes from oxidation by acting as potential endogenous antioxidants reviewed by Dean and Lodhi, (2018) , Jiménez-Rojo and Riezman, (2019) .…”