Role of platelet-activating factor in reproduction:sperm function

Since its discovery nearly thirty years ago, platelet-activating factor has emerged as one of the more important lipidmediators known. Platelet-activating factor (PAF; 1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphorylcholine) exists en-dogenously as a mixture of molecular species with structural variants of the alkyl moiety. PAF is a novel potent signal-ing phospholipid that has unique pleiotropic biological properties in addition to platelet activation. PAF also plays a sig-nificant role in reproduction. PAF content in squirrel monkey sperm is significantly higher during the breeding seasonthan the non-breeding season. PAF content in human sperm has a positive correlation with seminal parameters and preg-nancy outcomes. High-fertility boars have significantly more PAF in their sperm than low-fertility boars. The enzymes(lyso-PAF-acetyltransferase and PAF-acetylhydrolase) necessary for PAF activation and deactivation are present insperm. PAF-acetylhydrolase may act as a 'decapacitation factor'. Removal of this enzyme during capacitation maypromote PAF synthesis increasing motility and fertilization. PAF also plays a significant role in the fertilization process,enhancing the fertilization rates of oocytes. Enhanced embryo development has also been reported in oocytes fertilizedwith PAF-treated sperm. PAF antagonists inhibit sperm motility, acrosome reaction, and fertilization, thus suggestingthe presence of receptors for PAF. The PAF-receptor is present on sperm, with altered transcript levels and distributionpatterns on abnormal cells. Whereas the exact mechanism of PAF in sperm function and reproduction is uncertain, itsimportance in normal fertility is substantial. The reproductive significance of PAF activity in sperm and fertility plus therole of PAF in the establishment of pregnancy requires further study.

Roles of BN52021 in platelet-activating factor pathway in inflammatory MS1 cells

AIM: To determine the effects of BN52021 on platelet-activating factor receptor (PAFR) signaling molecules under lipopolysaccharide (LPS)-induced inflammatory conditions in MS1 cells. METHODS: MS1 cells (a mouse pancreatic islet endothelial cell line) were grown in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum, 2 mmol/L glutamine and 100 μg/mL penicillin/streptomycin in 5% CO 2 at 37 ℃. After growth to confluency in media, the cells were processed for subsequent studies. The MS1 cells received 0, 0.1, 1 and 10 μg/mL LPS in this experiment. The viability/prolifera-tion of the cells induced by LPS was observed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric assay. Apoptosis and necrosis of the cells under the inflammatory condition described previously were observed using Hoechst 33342-propidium iodide staining. Adenylate cyclase (AC), phospholipase A 2 (PLA 2 ), phospholipase Cβ (PLCβ), protein tyrosine kinase (PTK), G protein-coupled receptor kinases (GRK) and p38-mitogen-activated protein kinase (p38 MAPK) mRNA in the PAFR signaling pathway were measured by real-time polymerase chain reaction. The protein expression level of phosphorylated AC (p-AC), phosphorylated PLA 2 (p-PLA 2 ), phosphorylated PTK (p-PTK), phosphorylated p38 MAPK (p-p38 MAPK), PLCβ and GRK was measured using Western blotting analysis. RESULTS: The activity of MS1 cells incubated with dif- ferent concentrations of LPS for 6 h decreased significantly in the 1 μg/mL LPS group (0.49 ± 0.10 vs 0.67 ± 0.13, P < 0.05) and 10 μg/mL LPS group (0.44 ± 0.10 vs 0.67 ± 0.13, P < 0.001), but not in 0.1 μg/mL group. When the incubation time was extended to 12 h (0.33 ± 0.05, 0.32 ± 0.03 and 0.25 ± 0.03 vs 0.69 ± 0.01) and 24 h (0.31 ± 0.01, 0.29 ± 0.03 and 0.25 ± 0.01 vs 0.63 ± 0.01), MS1 cell activity decreased in all LPS concentration groups compared with the blank control (P < 0.001). BN52021 significantly improved the cell activity when its concentration reached 50 μmol/L compared with the group that received LPS treatment alone, which was consistent with the results obtained from fluorescence staining. The mRNAs levels of AC (4.02 ± 0.14 vs 1.00 ± 0.13), GRK (2.63 ± 0.03 vs 1.00 ± 0.12), p38 MAPK (3.87 ± 0.07 vs 1.00 ± 0.17), PLA 2 (3.31 ± 0.12 vs 1.00 ± 0.12), PLCβ (2.09 ± 0.08 vs 1.00 ± 0.06) and PTK (1.85 ± 0.07 vs 1.00 ± 0.11) were up-regulated after LPS stimulation as compared with the blank control (P < 0.05). The up- regulated mRNAs including AC (2.35 ± 0.13 vs 3.87 ± 0.08), GRK (1.17 ± 0.14 vs 2.65 ± 0.12), p38 MAPK (1.48 ± 0.18 vs 4.30 ± 0.07), PLCβ (1.69 ± 0.10 vs 2.41 ± 0.13) and PLA 2 (1.87 ± 0.11 vs 2.96 ± 0.08)were significantly suppressed by BN52021 except for that of PTK. The level of p-AC (1.11 ± 0.12 vs 0.65 ± 0.08), GRK (0.83 ± 0.07 vs 0.50 ± 0.03), PLCβ (0.83 ± 0.16 vs 0.50 ± 0.10) and p-p38 MAPK (0.74 ± 0.10 vs 0.38 ± 0.05) was up-regulated after LPS stimulation as compared with the blank control (P < 0.05). The up-regulated proteins, including p-AC (0.65 ± 0.15 vs 1.06 ± 0.14), GRK (0.47 ± 0.10 vs 0.80 ± 0.06), PLCβ (0.47 ± 0.04 vs 0.80 ± 0.19) and p-p38 MAPK (0.30 ± 0.10 vs 0.97 ± 0.05), was significantly suppressed by BN52021, but p-PLA 2 and p-PTK protein level were not suppressed. CONCLUSION: BN52021 could effectively inhibit LPS-induced inflammation by down-regulating the mRNA and protein levels of AC, GRK, p38 MAPK, PLA 2 and PLCβ in the PAFR signaling pathway.

Compound Kushen injection induces immediate hypersensitivity reaction through promoting the production of platelet-activating factor via de novo pathway

OBJECTIVE Compound Kushen injection(CKI)is a bis-herbal formulation extracted from Kushen(Radix Sophorae Flavescentis)and Baituling(Rhizoma Heterosmilacis Japonicae).Clinically,it is used as the adjuvant treatment of cancer.However,with the increased application,the cases of immediate hypersensitivity reactions(IHRs)also gradually rise.In this study,we investigated the underlying mechanism(s)and active constituent(s)for CKI-induced IHRs in experimental models.METHODS T helper 2(Th2)immunity-amplified mice were prepared by aluminum adjuvant.Anaphylactic shock was detected by measuring rectal thermometry in propranolol pretreated mice.For evaluating microvascular permeability,Evans blue extravasation assay was used.Platelet-activating factor(PAF),serum total IgE(tIgE)and mouse mast cell protease 1(MMCP1)were measured by ELISA.RESULTS The obtained results showed that CKI did not elevate serum tIgE and MMCP1 after consecutive immunization for five weeks,but could induce Evans blue extravasation(local)and cause obvious hypothermia(systemic)after a single injection.Further study showed that alkaloids in Kushen,especially matrine,were responsible for CKI-induced IHRs.Mechanism study showed that various PAF receptor antagonists could significantly counter CKI-induced IHRs locally or systemically.In cell system,CKI was able to promote PAF production in a non-cell-selective manner.In cell lysate,the effect of CKI on PAF production became stronger and could be abolished by blocking de novo pathway.CONCLUSION In conclusion,our study identifies,for the first time,that CKI is a PAF inducer.It causes non-immunologic IHRs,rather than IgE-dependent IHRs,by promoting PAF production through de novo pathway.Alkaloids in Kushen,especially matrine,are the prime culprits for IHRs.Our findings may provide a potential approach for preventing and treating CKI-induced IHRs.

The actions,detection and synthesis of platelet-activating factor (PAF) in mammalian pregnancy

Platelet-activating factor (PAF) exhibits a variety of biological activities and it be thought to involved in various pathophysiological process. In this paper, some studies were summarized about those roles ofPAF in a variety productive processes of female of mammalian that inctude fertilization, implantation and parturition, and that was involved in the concentration, synthesis, deiradation and some assay methods of PAF. Therelationship between PAF and early pregnancy factor (EPF) was reviewed.

Platelet-activating factor mediates hydrogen peroxide induced endothelial-leukocyte adhesion

The effects of hydrogen peroxide（H2O2）on endothelial-polymorphonuclear leuko-cyte（EC-PMN）adhesion and their mechanisms were studied in cultured bovine pulmonaryartery endothelial monolayers in vitro.H2O2 at various concentrations(10-3,10-2,10-1mol/Lrespectively)stimulated EC-dependent PMN adhesion,of which 10-2mol/L H2O2 was the mostpotent one,increasing adhesion to 2.3 times that of the control.Pretreatment of PMNs with SRI63-441,a platelet-activating factor（PAF）receptor antagonist,had no inhibition effect on H2O2induced EC-PMN adhesion.Pretreatment of ECs with SRI 63-441 before H2O2 exposure signifi-cantly decreased PMN adherence to ECs.Pretreatment of ECs with phospholipase A2 inhibitorp-bromophenacyl-bromide or calmodulin antagonist chlorpromazine and calcium ion chelate EG-TA obviously decreased H2O2 induced increment of EC-PMN adhesion.These results suggestthat H2O2 may activate ECs,causing the inflow of extracellular calcium or the release of calciumfrom intracellular deposits.Increased intracellar Ca2+may bind with calmodulin to activate phos-pholipase A2,thus initiating PAF synthesis and promoting EC-PMN adhesion.

Physiological Roles of Platelet-activating Factor in Mammalian and Human Reproduction

This review described origination, biosynthesis and functions of platelet-activating factor （PAF） in the reproductive system of mammals and human beings. The article mainly focused on biological roles of the phospholipid mediator in sperm fertilization and embryonic implantation. As an autocrine product of sperm and embryos, PAF markedly stimulates sperm motility and fertilization and serves as a capacitation factor in a ligand-receptor manner, After fertilization, embryo-derived PAF improves its own development, especially from fertilized ova to blastocyst stage and is thought to act as an embryo growth factor in the same manner as on sperm. Its mechanism of action was also clarified. At the end, it was presented some advances in its clinical application, followed by discussion of some issues possibly concerning in its current application.

Serum platelet-activating factor level of patients with cerebral infarction from TIA and its correlation with coagulation function and inflammatory response

Objective: To study the serum platelet-activating factor (PAF) level of patients with cerebral infarction from transient ischemic attack (TIA) and its correlation with coagulation function and inflammatory response. Methods: TIA patients who were hospitalized in Neurology Department of Foshan Second People's Hospital between September 2016 and July 2017 were selected and divided into simple TIA group and cerebral infarction group according to the progression into cerebral infarction or not within 1 week;healthy subjects who received physical examination during the same period were selected as the control group. Serum levels of PAF, coagulation function indexes and inflammation indexes were detected. Results: Serum PAF, FVIII, vWF, TNF-α, hs-CRP, MCP-1 and IL-17 contents of cerebral infarction group and simple TIA group were significantly higher than those of control group while PT, APTT and TT levels were significantly shorter than those of control group;serum PAF, FVIII, vWF, TNF-α, hs-CRP, MCP-1 and IL-17 contents of cerebral infarction group were significantly higher than those of simple TIA group while PT, APTT and TT levels were significantly shorter than those of simple TIA group;serum FVIII, vWF, TNF-α, hs-CRP, MCP-1 and IL-17 contents of TIA patients with high PAF content were significantly higher than those of TIA patients with low PAF content while PT, APTT and TT levels were significantly shorter than those of TIA patients with low PAF content. Conclusion: Excessively generated PAF can promote TIA progression to cerebral infarction by activating coagulation pathway and inflammatory response.

Association of Platelet-Activating Factor Receptor Gene rs5938(G/T) and rs313152(T/C) Polymorphisms with Coronary Heart Disease and Blood Stasis Syndrome in A Chinese Han Population

Objective: To explore the association of the platelet-activating factor receptor(PAFR) gene rs5938, rs313152 and rs76744145 polymorphisms with coronary heart disease(CHD) and blood stasis syndrome(BSS) of CHD in Chinese Han population. Methods: A total of 570 CHD patients(299 with BSS and 271 with non-BSS) and 317 controls were enrolled. The PAFR gene rs5938, rs313152 and rs76744145 polymorphisms were genotyped using the multiplex SNaP shot technology. The statistical analysis was conducted using a multiple variable logistic regression model. Results: Significant differences were detected in the genotypes frequency distributions of the rs5938(P<0.01), but not the rs313152(P>0.05), between the controls and CHD patients. Individuals with an rs5938 or rs313152 mutated allele had a low risk for CHD [adjusted odds ratio(aOR)=0.35, 95% confidence interval(CI): 0.23 to 0.56, P<0.01; aOR=0.65, 95% CI: 0.46 to 0.91, P<0.05, respectively]. After the CHD patients were stratified as BSS or non-BSS according to their Chinese medicine patterns, the rs5938 polymorphism mutated alleles had a significant association with a low risk for BSS of CHD(aOR=0.32, 95% CI: 0.18 to 0.57, P<0.01) and non-BSS of CHD(aOR=0.31, 95% CI: 0.17 to 0.55, P<0.01). The rs313152 polymorphism was associated with a low risk for BSS(aOR=0.51, 95% CI: 0.33 to 0.79, P<0.01), but not for non-BSS(aOR=1.22, 95% CI: 0.81 to 1.85, P>0.05). Furthermore, the interaction effect of the rs5938 and rs313152 polymorphisms for BSS of CHD was significantly based on an aOR value associated with the combination of the rs5938 GT genotype with the rs313152 TC genotype of 0.27(95% CI: 0.1 to 0.7, P<0.01). Conclusion: The PAFR gene rs5938 or rs313152 polymorphisms might be a potential biomarker for susceptibility to CHD, especially to BSS of CHD in Chinese Han population.

Platelet-activating factor receptor affects food intake and body weight

“Let’s Move!”is a comprehensive initiative,launched by the First Lady,Michelle Obama,dedicates to solving problems of obesity,which is growing in child.The life behaviors do affect obesity;however,the mechanistic insight in molecular level is still not clear.In this study,by continually monitoring mouse body weight under chow and high fat western diets as well as metabolic,physical activity and food intake behaviors assessed in a CLAMS Comprehensive Lab Animal Monitoring System,we demonstrated that the platelet-activating factor receptor(PTAFR)contributes to modification of life behaviors.PTAFR does not affect metabolism of ingested dietary fat and carbohydrate in young animals;however,Ptafr ablation dramatically increased weight gain without affecting adipose tissue accumulation.Ptafr/mice possess new habits that increased food intake and decreased movement.Our studies suggest that regulation of PTAFR activity may be a novel strategy to control obesity in children or young adults.

Effects of decompression joint Governor Vessel electro-acupuncture on rats with acute upper cervical spinal cord injury

Decompression is the major therapeutic strategy for acute spinal cord injury,but there is some debate about the time window for decompression following spinal cord injury.An important goal and challenge in the treatment of spinal cord injury is inhibiting or reversing secondary injury.Governor Vessel electroacupuncture can improve symptoms of spinal cord injury by inhibiting cell apoptosis and improving the microenvironment of the injured spinal cord.In this study,Governor Vessel electroacupuncture combined with decompression at different time points was used to treat acute spinal cord injury.The rat models were established by inserting a balloon catheter into the atlanto-occipital space.The upper cervical spinal cord was compressed for 12 or 48 hours prior to decompression.Electroacupuncture was conducted at the acupoints Dazhui（GV14） and Baihui（GV 20）（2 Hz,15 minutes） once a day for 14 consecutive days.Compared with decompression alone,hind limb motor function recovery was superior after decompression for 12 and 48 hours combined with electroacupuncture.However,the recovery of motor function was not significantly different at 14 days after treatment in rats receiving decompression for 12 hours.Platelet-activating factor levels and caspase-9 protein expression were significantly reduced in rats receiving electroacupuncture compared with decompression alone.These findings indicate that compared with decompression alone,Governor Vessel electroacupuncture combined with delayed decompression（48 hours） is more effective in the treatment of upper cervical spinal cord injury.Governor Vessel electroacupuncture combined with early decompression（12 hours） can accelerate the recovery of nerve movement in rats with upper cervical spinal cord injury.Nevertheless,further studies are necessary to confirm whether it is possible to obtain additional benefit compared with early decompression alone.

Alkaline sphingomyelinase(NPP7) in hepatobiliary diseases: A field that needs to be closely studied

Alkaline sphingomyelinase cleaves phosphocholine from sphingomyelin, platelet-activating factor, lysophosphatidylcholine, and less effectively phosphatidyl-choline. The enzyme shares no structure similarities with acid or neutral sphingomyelinase but belongs to ectonucleotide pyrophosphatase/phosphodiesterase(NPP) family and therefore is also called NPP7 nowadays. The enzyme is expressed in the intestinal mucosa in many species and additionally in human liver. The enzyme in the intestinal tract has been extensively studied but not that in human liver. Studies on intestinal alkaline sphingomyelinase show that it inhibits colonic tumorigenesis and inflammation, hydrolyses dietary sphingomyelin, and stimulates cholesterol absorption. The review aims to summarize the current knowledge on liver alkaline sphingomyelinase in human and strengthen the necessity for close study on this unique human enzyme in hepatobiliary diseases.

Effects of kadsurenone on the systemic inflammatory response in rat model of acute pancreatitis

Objective： To study the effects of kadsurenone on inflammatory mediators Platelet-activating factor （PAF）, tumor necrosis factor-α（TNF-α） and interleukin-6（IL-6） in rat model of acute pancreatitis（AP）. Methods： SD male rats （104） were randomly divided into sham group （n = 24）, AP group （n = 40） and kadsurenone group （n = 40）. The rats were killed 3, 6, 12 and 24 hours after operation. The serum level of PAF, TNF-α and IL-6 was measured. Results： The serum level of PAF, TNF-α and IL-6 of AP group was significantly increased（P 〈 0.01 ）compared with control group. The serum level of TNF-α got to a peak 6 hours after operation, and the serum IL-6 getting to a peak 12 hours after operation in AP group. After kadsurenone was administered to AP rats, pancreas and lung myeloperoxidase （MPO）, serum amylase activity was reduced. Histology showed a trend toward improvement. The serum level of PAF, TNF-α and IL-6 was significantly decreased （P 〈 0.05）. Conclusion. Kadsurenone can reduce the severity of systemic inflammation in rats with AP and relieve the damage of the pancreas and lung in AP rats. These results suggested that kadsurenone may be useful in the treatment of acute pancreatitis.

The inhibitory effects of β－adrenoceptor activation on vascular permeability increment induced by platelet－activating factor

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The Activity of Plasma Platelet－activating Factor Derived from Pregnant Women before and after Delivery and lts Relation to P

The activity of plasma platelet-activating factor(PAF) from pregnant women before and after delivery was determined. Plasma samples were taken from 74 pregnant women, among whom 24 were normotensive controls, 30 mild and moderate hypertensive and 20 severe hypertensive. Of the two hypertensive groups(pregnancy-induced hypertension, PIH), PAF activity measured by a bioassay was significantly higher than that of normotensive control at 38 weeks in gestation , indicating a possible role of this potent lipid mediator in the pathophysiological mechanism of PIH. After delivery, PAF activity was obviously increased in all three groups , showing the regulation of placenta in PAF metabolism.

Regulatory effects of phospholipase A_2 inhibitors on platelet activating factor in endotoxic shock in rabbits

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The PARF Antagonist AChE Inhibitor PMS777 Attenuates LPS-Induced Acute Neuroinflammation

When injected into the fourth ventricle, the proinflammagen lipopolysaccharide (LPS) induces acute neuroinflammation in the whole brain of rats. The new compound PMS777 is a novel platelet-activating factor receptor (PAFR) antagonist and acetylcholinesterase (AChE) inhibitor. The current study determined whether PMS777 could provide neuroprotection from the cytotoxic effects associated with LPS-induced neuroinflammation. Acute LPS infusions impaired recognition in rats as measured by the Morris water maze. In addition, LPS infusions decreased the number of AChE positive cells, and increased the number of OX-42 immunoreactive microglia and GFAP immunoreactive astrocytes in the hippocampus, the cortex and the basal nuclei. Furthermore, acute infusions of LPS also impaired organelles associated with protein synthesis. Peripheral administration of PMS777 (i.e., intraperitoneal injection) protected against the impairment in recognition, and attenuated the cytotoxic effects of the acute inflammatory processes upon cholinergic cells, microglia, astrocytes and ultrastructure of hippocampal cells. Here, we propose that the cytotoxic effects of acute neuroinflammation may involve the release of PAF and loss of cholinergic neurons, and this mechanism leads to neuronal dysfunction and spatial memory impairment. The PAFR antagonist inhibitor and AChE inhibitor PMS777 could provide neuroprotection from the cytotoxic effects induced by LPS.

The Neuroinflammatory Response Induced by PAF Can Be Attenuated by BN52021 Administration

Objective: The purpose of this study was to determine whether BN52021, a platelet-activation factor receptor (PAFR) antagonist, could provide neuroprotection from the cytotoxic effects of PAF-induced neuroinflammation. Methods: The inflammagen platelet-activation factor (PAF) was first added to cultured PC12 cells. BN52021 was then added 24 hours later, survival rate and rate of apoptosis of the PC12 cells was determined by the MTT method and flow cytometry. In addition, PAF was injected into the fourth ventricle, and the effect of BN52021 administration was determined in rats. Results: PAF induced apoptosis in cultured PC12 cells, and BN52021 administration protected PC12 cells from PAF-induced apoptosis. When PAF is injected into the fourth ventricle, PAF induces acute neuroinflammation in the whole brain of rats. Acute PAF infusions also impaired spatial recognition in rats. The peripheral administration of BN52021 (i.p.) protected the rats from this impairment in spatial recognition. Conclusion: The PAFR antagonist BN52021 provides neuroprotection from the cytotoxic effects induced by the inflamagen PAF.

Inhibitory effects of isoproterenol on PAF-induced endothelial cell permeability and morphological changes

Using a model to study vascular permeability under hydrostatically perfused bovine pulmonary artery endothelial cell (EC) monolayers and a software to automatically analyse cell morphological parameters in a computer image workstation, the effects of isoproterenol (IPN) on platelet-activating factor (PAF)-induced changes in EC monolayer permeability and cell morphological parameters were studied. Albumin has the fortifying effect on endothelial barrier function. After treatment of EC monolayer with 10-8mol/L PAF, trans-monolayer permeability increased, cell surface area decreased, and intercellular space enlarged. As pretreatment with 10-4mol/L IPN, PAF-induced EC permeability increment and morphological changes were blocked. The results suggest that EC contraction and intercellular gap expansion are important mechanisms for PAF-induced high vascular permeability. IPN inhibits the effects of PAF via stabilization of EC morphology and prevention of intercellular gap formation.