Phosphatidylcholine and phosphatidylethanolamine derivatives, membrane fluidity and changes in the lipolytic activity of ram spermatozoa plasma membranes during cryoconservation

Effects of adding mixed chicken and quail egg yolks to the cryodiluent on the quality of ram semen before and after cryopreservation

The effects of adding mixed chicken and Japanese quail egg yolks (EYs) to the cryodiluent on the quality of ram semen before freezing and post-thawing were evaluated. Additionally, the composition of chicken and quail egg EYs and their mixture were analyzed for results explanation. The semen was collected from rams (n = 5) and extended with cryodiluent containing the EY of chicken, quail or their mixture (1:1). The extended semen was chilled slowly to 5 °C within 2 h and equilibrated for 2 h, before frozen on the liquid nitrogen vapor and cryopreserved at -196 °C. The straws were evaluated before freezing and post-thawing for sperm motility, vitality and abnormality besides plasma-membrane and DNA integrities. The moisture, ash, protein, and fatty acid (FA) contents of chicken EY, quail EY and their mixture were analyzed. Sperm vitality, plasma membrane integrity and DNA integrity before freezing were significantly (P < 0.05) higher in quail EY than chicken EY and mixed EYs cryodiluent. The chicken EY extender significantly improved the vitality, plasma membrane and DNA integrities of post-thawed ram semen in comparison with quail EY or mixed EYs extenders. While, the post-thawing sperm abnormalities was lower (P ≤ 0.05) in quail EY than chicken EY and mixed EYs cryodiluent. The post-thawing sperm motion kinetics parameters were higher in quail EY than chicken EY and mixed EYs cryodiluent. The highest percentages of moisture, ash, saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) were detected in quail EY had. While, the highest percentages of fat, protein and polyunsaturated fatty acids (PUFAs) were detected in chicken EY. In conclusion, using of chicken EY can improve total motility, vitality, plasma membrane integrity and DNA integrity of cryopreserved ram semen. While, using of quail EY can improve sperm abnormalities and kinetic motion parameters of cryopreserved ram semen. Mixing chicken and quail EYs added no value for post-thawing ram semen parameters.

PUFA-rich phospholipid classes and subclasses of ram spermatozoa are unevenly affected by cryopreservation with a soybean lecithin-based extender

Cryopreservation is known to affect spermatozoa structure and function. Ram sperm are among the most highly sensitive mammalian gametes to freezing, due to their lipid composition, which limit their efficiency in artificial insemination programs. The aim of this study was to investigate the effects of cryopreservation with a chemically defined soybean lecithin-based extender on ram spermatozoa functionality on the one hand, and quantifiable changes in lipid and fatty acid profile on the other. Freeze-thawing decreased sperm quality, as indicated by post-thaw parameters related to membrane integrity, mitochondrial viability and sperm motility. The most relevant lipid change after cryopreservation was a remarkable loss of all glycerophospholipids containing 22:6n-3. Species of sphingomyelin with very long chain polyunsaturated fatty acids (VLC-PUFA), that are exclusively located in the sperm head, where responsible of its reduction after cryostorage. Freezing caused a reduction in mitochondrial function, which was confirmed by significantly decreased of mitochondrial membrane potential and by the generation of 4-HNE. Mitochondria damage was accompanied by a loss in cardiolipin with 18:2n-6 and phosphatidylethanolamine with 20:4n-6, two well-known lipids that are critical components for mitochondrial membrane functionality. Loss of sterols after cryopreservation occurred along with a decrease in the order of sperm membrane lipids. Our research provides new insights on deleterious effects of cryopreservation on PUFA-rich phospholipids of ram sperm and highlight their importance as biomarkers of ultrastructural, biochemical and functional damage that ram spermatozoa undergo after freezing-thawing.

Oxidative stress contributes to cerebral metabolomic profile changes in animal model of blast-induced traumatic brain injury

INTRODUCTION

Blast-induced neurotrauma (BINT) has been recognized as the common mode of traumatic brain injury amongst military and civilian personnel due to an increased insurgent activity domestically and abroad. Previous studies from this laboratory have identified three major pathological events following BINT which include blood brain barrier disruption the earliest event, followed by oxidative stress and neuroinflammation as secondary events occurring a few hours following blast.

OBJECTIVES

Our recent studies have also identified an increase in oxidative stress mediated by the activation of superoxide producing enzyme NADPH oxidase (NOX) in different brain regions at varying levels with neurons displaying higher oxidative stress (NOX activation) compared to any other neural cell. Since neurons have higher energy demands in brain and are more prone to oxidative damage, this study evaluated the effect of oxidative stress on blast-blast induced changes in metabolomics profiles in different brain regions.

METHODS

Animals were exposed to mild/moderate blast injury (180 kPa) and examined the metabolites of energy metabolism, amino acid metabolism as well as the profiles of plasma membrane metabolites in different brain regions at different time points (24 h, 3 day and 7 day) after blast using ¹H NMR spectroscopy. Effect of apocynin, an inhibitor of superoxide producing enzyme NADPH oxidase on cerebral metabalomics profiles was also examined.

RESULTS

Several metabolomic profile changes were observed in frontal cortex and hippocampus with concomitant decrease in energy metabolism. In addition, glutamate/glutamine and other amino acid metabolism as well as metabolites involved in plasma membrane integrity were also altered. Hippocampus appears metabolically more vulnerable than the frontal cortex. A post-treatment of animals with apocynin, an inhibitor of NOX activation significantly prevented the changes in metabolite profiles.

CONCLUSION

Together these studies indicate that blast injury reduces both cerebral energy and neurotransmitter amino acid metabolism and that oxidative stress contributes to these processes. Thus, strategies aimed at reducing oxidative stress can have a therapeutic benefit in mitigating metabolic changes following BINT.

In vitro supplementation with unsaturated fatty acids improves boar sperm viability after storage at 6 °C

Liquid preservation of the cold-sensitive boar sperm at a lesser temperature than the standard 17 °C would reduce bacterial growth and minimize the use of antibiotics. There was assessment, therefore, of the capacity of individual fatty acids bound to fatty acid free BSA to improve sperm survival at 6 °C because oxidative stress and lipid degradation are prominent detrimental factors. Different effects of the fatty acids were observed. Supplementation with naturally occurring fatty acids (linolenic, linoleic, oleic, palmitoleic acid), which may become metabolically incorporated into sperm lipids, increased the number of motile and progressively motile sperm after 2 days of storage during a thermo-resistance test (5 h at 38 °C) to that of control samples preserved at 17 °C in pure Beltsville Thawing Solution. With the exception of linolenic acid, all naturally occurring fatty acids enhanced the number of sperm with active mitochondria after 3 days of storage. Palmitoleic acid was the most effective supplement with effects already present when sperm were re-warmed for 30 min after 2 and 7 days of storage. The non-endogenous, non-integrated timnodonic acid (20:5) had no effect on sperm variables. Because the application of individual fatty acids attached to BSA had differing effects in preserving boar sperm at 6 °C, the use of combinations of fatty acids could be more efficacious than with use of natural lipid supplements for low temperature preservation of sperm.

Phospholipid Complex Technique for Superior Bioavailability of Phytoconstituents

Phytoconstituents have been utilized as medicines for thousands of years, yet their application is limited owing to major hurdles like deficit lipid solubility, large molecular size and degradation in the gastric environment of gut. Recently, phospholipid-complex technique has unveiled in addressing these stumbling blocks either by enhancing the solubilizing capacity or its potentiating ability to pass through the biological membranes and it also protects the active herbal components from degradation. Hence, this phospholipid-complex-technique can enable researchers to deliver the phytoconstituents into systemic circulation by using certain conventional dosage forms like tablets and capsules. This review highlights the unique property of phospholipids in drug delivery, their role as adjuvant in health benefits, and their application in the herbal medicine systems to improve the bioavailability of active herbal components. Also we summarize the prerequisites for phytosomes preparation like the selection of type of phytoconstituents, solvents used, various methods employed in phytosomal preparation and its characterization. Further we discuss the key findings of recent research work conducted on phospholipid-based delivery systems which can enable new directions and advancements to the development of herbal dosage forms.

Stability of transbilayer phospholipid asymmetry in viable ram sperm cells after cryotreatment

The transbilayer dynamics of lipids in the plasma membrane of mammalian sperm cells is crucial for the fertilization process. Here, the transbilayer movement and distribution of phospholipids in the plasma membrane of fresh, ejaculated and cryopreserved ram spermatozoa was studied by labeling cells with fluorescent analogues of phosphatidylserine and phosphatidylcholine. By co-labeling cells with the DNA-binding dye propidiumiodide as well as by employing fluorescence microscopy and flow cytometry we were able to determine the transbilayer redistribution of fluorescent phospholipid analogues in intact (propidiumiodide-negative) and in impaired (propidiumiodide-positive) spermatozoa. The transbilayer distribution of the fluorescent phosphatidylserine and phosphatidylcholine analogues was not perturbed in intact sperm cells after cryopreservation. In those cells, the phosphatidylserine analogue became rapidly enriched on the cytoplasmic leaflet by the activity of a putative aminophospholipid translocase similar to intact cells of fresh, ejaculated samples. However, upon cryopreservation the activity of the putative aminophospholipid translocase was significantly reduced in intact cells. Employing annexin V-FITC, we found that even after cryopreservation the sequestering of endogenous phosphatidylserine to the cytoplasmic leaflet is maintained in intact cells, but not in impaired cells. The phosphatidylcholine analogue redistributed very slowly remaining essentially confined to the exoplasmic leaflet of the plasma membrane of intact cells from both fresh, ejaculated and cryopreserved samples. The physiological consequences of a perturbed transbilayer asymmetry in sperm plasma membranes is discussed.

Phospholipids of rabbit and bull sperm membranes: structural order parameter and steady-state fluorescence anisotropy of membranes and membrane leaflets

The plasma (PM), outer acrosomal (OAM), and inner acrosomal membranes (IAM) were isolated from rabbit and bull spermatozoa and the major phospholipids characterized. Choline-containing phospholipids, phosphatidylcholine (PC) and sphingomyelin (SM), constituted more than 60% of the total phospholipids (TPL) in all membranes of both species. Approximately more than 50% of PC in membrane preparations contained some form of ether linkage. Compared to OAM and IAM, cholesterol to phospholipid molar ratio was highest in PM of both species. Contrarily, protein to phospholipid ratio for PM was lowest compared to other membranes. The sphingomyelin to phosphatidylcholine ratio increased in the direction from PM to OAM to IAM. The hydrophobic fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH) was used to examine both the steady-state fluorescence anisotropy parameters and structural order parameter SDPH. The data showed higher rigidity in rabbit spermatozoa compared to bull spermatozoa (SDPH = 0.7582 and SDPH = 0.7326). In both species OAM had higher rigidity compared to the other two membranes (SDPH(OAM) = 0.7809, SDPH(PM) = 0.7308, and SDPH(IAM) = 0.7481 for bull; SDPH(OAM) = 0.8091, SDPH(PM) = 0.7857, and SDPH(IAM) = 0.7663 for rabbit). The inner leaflets of bull and rabbit spermatozoal membranes had significantly higher rigidity than the outer leaflets (for inner leaflet: rabbit-SDPH(PM) = 0.8391, SDPH(OAM) = 0.8149, and SDPH(IAM) = 0.7675; bull-SDPH(PM) = 0.8000, SDPH(OAM) = 0.7990, and SDPH(IAM) = 0.7990, and for outer leaflet: rabbit-SDPH(PM) = 0.7021, SDPH(OAM) = 0.7145, and SDPH(IAM) = 0.6867; bull-SDPH(PM) = 0.6986, SDPH(OAM) = 0.5980, and SDPH(IAM) = 0.7388).

Changes in the phospholipid composition and phospholipid asymmetry of ram sperm plasma membranes after cryopreservation

The changes in the phospholipid composition of spermatozoa plasma membranes after freezing were determined by thin-layer chromatography. The results showed an augmentation of the diphosphatidylglycerol and a diminution of phosphatidylglycerol, phosphatidylserine, and phosphatidylethanolamine in sperm plasma membranes after freezing. In intact sperm cells we observed an elevation of the sphingomyelin and phosphatidylinositol levels and a diminution of the phosphatidylethanolamine and diphosphatidylglycerol levels. The effect of freezing on the phospholipid distribution between the inner and outer monolayers of the plasma membrane was also studied using exogenous phospholipases and trinitrobenzene sulfonate. The most important change we observed after freezing, was the translocation of diphosphatidylglycerol from the inner to the outer monolayer of the plasma membrane.

Sphingomyelin and ceramide: phosphoethanolamine synthesis in ram spermatozoa plasma membrane

1. The possibility for sphingomyelin and ceramide: phosphoethanolamine synthesis in ram spermatozoa plasma membranes has been established. 2. Ceramide: phosphoethanolamine formation appears to be higher than the synthesis of sphingomyelin. 3. The pH optimum of the phosphatidylethanolamine: ceramide-phosphoethanolamine transferase is about 7.0. An inhibition of its activity was observed in the presence of Ca2+ and Zn2+ ions.