Differential involvement of rat sperm choline glycerophospholipids and sphingomyelin in capacitation and the acrosomal reaction

Rat spermatozoa main lipid classes and their fatty acids were studied to assess their possible changes in capacitation and the acrosomal reaction (AR), induced in vitro. Capacitation-associated protein tyrosine phosphorylation, and the efflux of 30% of the total cholesterol from gametes to the medium, took place concomitantly with the release of a similar percentage, i.e., a larger amount, of the total phospholipid, mostly after hydrolysis of the major choline glycerophospholipids (CGP). Main medium lipid metabolites after capacitation were lyso-CGP and polyenoic fatty acids typical of CGP (22:4n-9, 22:5n-6), as free fatty acids (FFA). The AR, induced by a calcium ionophore, resulted in further phospholipid loss, but the produced metabolites remained in the gametes. CGP decrease in AR accounted for some additional FFA and lyso-CGP, but mostly for (22:5n-6-rich) diglycerides. Hydrolysis of sphingomyelins (SM) to ceramides also occurred, mostly affecting species with very long chain polyenoic fatty acids. Quantitatively, CGP and SM were the lipid classes decreasing the most after capacitation and AR, respectively. The massive cholesterol and phospholipid loss from the gametes during capacitation is thus associated with protein phosphorylation, a function that has been located to the sperm tail. The lipid metabolites produced during AR, by accumulating in the gamete heads, could be implicated in sperm–oocyte interactions.     

Effects of dietary n-3 fatty acids on characteristics and lipid composition of ovine sperm

The fatty acid composition of sperm affects the fertilization rate. The objective was to investigate the effects of dietary fish oil (as a source of n-3 fatty acids) on semen quality and sperm fatty acid composition in sheep. Eight Zandi fat-tailed rams were randomly allocated into two groups and fed either a control diet or a diet supplemented with fish oil. Both diets were isocaloric and isonitrogenous and were fed for 13 weeks, starting in the middle of the breeding season. Semen samples were collected weekly and their characteristics evaluated by standard methods, whereas samples collected at the start and end of the study were assessed (gas chromatography) for sperm lipid composition. Mean (±s.e.m.) sperm concentrations (4.3 × 109 ± 1.3 × 108 v. 3.9 × 109 ± 1.3 × 108 sperm/ml and percentages of motile (77.25 ± 3.34 v. 60.8 ± 3.34) and progressively motile sperm (74.13 ± 1.69 v. 62.69 ± 1.69) were significantly higher in the fish oil group than control. Dietary fish oil increased the proportion of docosahexaenoic acid (DHA, C22:6 n-3) in sperm fatty acid composition. We concluded that feeding fish oil as a source of n-3 fatty acids attenuated seasonal declines in semen quality in rams, perhaps through increased DHA in sperm.     

Combined effect of DHA and alpha-tocopherol enrichment on sperm quality and fertility in the turkey

The aim of the present study was to characterize the dietary effects of n-3 LC-PUFA and alpha-tocopheryl acetate (vE) on the quality, phospholipid fatty acid composition, alpha-tocopherol content (alpha-T) and in vitro susceptibility to lipid peroxidation in turkey semen. Fertility of fresh semen was also evaluated. Male turkeys were randomly divided and fed either a control diet or a fish oil and vE rich diet (FO diet) from 40 to 60 weeks of age. The FO diet increased the proportion of n-3 fatty acids in spermatozoa and as a consequence the (n-3)/(n-6) ratio also increased. These changes did not affect the proportion of n-9 PUFAs, particularly of C22:3n-9, in semen. The sperm content of alpha-T was dependent by the dietary supplementation of the vitamin and the sperm content was more than doubled supplying 120 mg kg(-1) of feed to the males compared to the 60 mg kg(-1) of feed in the control diet. In agreement with the major content of alpha-T in spermatozoa collected from the FO group were significantly less susceptible to in vitro induced oxidation. The reproductive capacity of the male breeders was not affected by the diet; however the result is considered of some relevance for field conditions where even very small changes have economic interest being applied to large bird population.     

Dietary n-6 PUFA deprivation for 15 weeks reduces arachidonic acid concentrations while increasing n-3 PUFA concentrations in organs of post-weaning male rats

Few studies have examined effects of feeding animals a diet deficient in n-6 polyunsaturated fatty acids (PUFAs) but with an adequate amount of n-3 PUFAs. To do this, we fed post-weaning male rats a control n-6 and n-3 PUFA adequate diet and an n-6 deficient diet for 15 weeks, and measured stable lipid and fatty acid concentrations in different organs. The deficient diet contained nutritionally essential linoleic acid (LA,18:2n-6) as 2.3% of total fatty acids (10% of the recommended minimum LA requirement for rodents) but no arachidonic acid (AA, 20:4n-6), and an adequate amount (4.8% of total fatty acids) of α-linolenic acid (18:3n-3). The deficient compared with adequate diet did not significantly affect body weight, but decreased testis weight by 10%. AA concentration was decreased significantly in serum (− 86%), brain (− 27%), liver (− 68%), heart (− 39%), testis (− 25%), and epididymal adipose tissue (− 77%). Eicosapentaenoic (20:5n-3) and docosahexaenoic acid (22:6n-3) concentrations were increased in all but adipose tissue, and the total monounsaturated fatty acid concentration was increased in all organs. The concentration of 20:3n-9, a marker of LA deficiency, was increased by the deficient diet, and serum concentrations of triacylglycerol, total cholesterol and total phospholipid were reduced. In summary, 15 weeks of dietary n-6 PUFA deficiency with n-3 PUFA adequacy significantly reduced n-6 PUFA concentrations in different organs of male rats, while increasing n-3 PUFA and monounsaturated fatty acid concentrations. This rat model could be used to study metabolic, functional and behavioral effects of dietary n-6 PUFA deficiency.     

Maternal dietary fat alters amniotic fluid and fetal intestinal membrane essential n-6 and n-3 fatty acids in the rat

We investigated whether maternal fat intake alters amniotic fluid and fetal intestine phospholipid n-6 and n-3 fatty acids. Female rats were fed a 20% by weight diet from fat with 20% linoleic acid (LA; 18:2n-6) and 8% alpha-linolenic acid (ALA; 18:3n-3) (control diet, n = 8) or 72% LA and 0.2% ALA (n-3 deficient diet, n = 7) from 2 wk before and then throughout gestation. Amniotic fluid and fetal intestine phospholipid fatty acids were analyzed at day 19 gestation using HPLC and gas-liquid chromotography. Amniotic fluid had significantly lower docosahexaenoic acid (DHA; 22:6n-3) and higher docosapentaenoic acid (DPA; 22:5n-6) levels in the n-3-deficient group than in the control group (DHA: 1.29 +/- 0.10 and 6.29 +/- 0.33 g/100 g fatty acid; DPA: 4.01 +/- 0.35 and 0.73 +/- 0.15 g/100 g fatty acid, respectively); these differences in DHA and DPA were present in amniotic fluid cholesterol esters and phosphatidylcholine (PC). Fetal intestines in the n-3-deficient group had significantly higher LA, arachidonic acid (20:4n-6), and DPA levels; lower eicosapentaenoic acid (EPA; 20:5n-3) and DHA levels in PC; and significantly higher DPA and lower EPA and DHA levels in phosphatidylethanolamine (PE) than in the control group; the n-6-to-n-3 fatty acid ratio was 4.9 +/- 0.2 and 32.2 +/- 2.1 in PC and 2.4 +/- 0.03 and 17.1 +/- 0.21 in PE in n-3-deficient and control group intestines, respectively. We demonstrate that maternal dietary fat influences amniotic fluid and fetal intestinal membrane structural lipid essential fatty acids. Maternal dietary fat can influence tissue composition by manipulation of amniotic fluid that is swallowed by the fetus or by transport across the placenta.     

Effect of long-term supplementation with arachidonic or docosahexaenoic acids on sperm production in the broiler chicken

The possibility was investigated that dietary supplementation of the male chicken with long-chain polyunsaturated fatty acids of the n-6 and n-3 series may prevent the decrease in sperm output that normally occurs by 60 weeks of age. From 26 weeks of age, birds were raised on wheat-based diets supplemented with either maize oil (rich in linoleic acid, 18:2n-6), arasco oil (rich in arachidonic acid, 20:4n-6) or tuna orbital oil (rich in docosahexaenoic acid, 22:6n-3). The effects of the last two oils were investigated at two levels of vitamin E supplementation (40 and 200 mg kg(-1) feed). By 60 weeks of age, there was a small increase in the proportion of the main polyunsaturate of chicken sperm phospholipid, docosatetraenoic acid 22:4n-6, in chickens fed arasco oil diet compared with chickens given the maize oil diet, an effect that was potentiated at the higher dietary intake of vitamin E. Supplementation with tuna orbital oil significantly reduced the proportions of 20:4n-6 and 22:4n-6 in the sperm phospholipid and increased the proportion of 22:6n-3. The diet supplemented with tuna orbital oil and the lower level of vitamin E markedly depleted vitamin E from the tissues of the birds and decreased the concentration of vitamin E in the semen; these effects were largely prevented by the higher level of vitamin E in the diet. The susceptibility of semen to lipid peroxidation in vitro was increased in chickens fed arasco and tuna orbital oils with 40 mg vitamin E kg(-1) feed, but was reduced when 200 mg vitamin E kg(-1) feed was provided in the diet. The number of spermatozoa per ejaculate decreased by 50% between 26 weeks and 60 weeks of age in the birds fed the maize oil diet. This age-related decrease in the number of spermatozoa was almost completely prevented by feeding the birds with the oils enriched in either 20:4n-6 or 22:6n-3. Testis mass at 60 weeks of age was approximately 1.5 times greater in birds given of the arasco and tuna orbital oil diets compared with those given the maize oil diet.     

Changes in fatty acid composition of Mytilus galloprovincialis (Lmk) fed on microalgal and wheat germ diets

Dietary fatty acid incorporation and changes in various lipid and phospholipid classes in the mussel Mytilus galloprovincialis subjected to three different dietary regimens were analysed and compared. Group A was unfed; group B received a diet consisting of 100% Thalassiosira weissflogii, exhibiting the typical fatty acid composition of diatoms, and group C received a diet consisting of 100% wheat germ conferring a 18:2:n-6 abundance. Biochemical analyses of diets and mussels were carried out at the beginning and at the end of the 30-day experimental period. Starvation and T. weissflogii based diet poorly affected mussel growth and fatty acid composition which remained unchanged. On the contrary, the wheat germ-based diet increased the condition index and deeply affected the fatty acid profile of all lipid and phospholipid classes. The high dietary 18:2n-6 level drastically reduced tissue content of 20:4n-6, 20:5n-3 and 22:6n-3. The biosynthesis of Non Methylene Interrupted (NMI) dienoic fatty acid appeared to be insensitive to the high input of 16:1n-7 and 18:1n-9 respectively from diet B and C, and to the PUFA shortage of diet C. Nevertheless the two NMI trienoic derivatives, 20:3Δ5,11,14 and 22:3Δ7,13 16, were found higher in C with respect to other groups, presumably due to the high 18:2n-6 content of this diet.     

Dietary polyunsaturated n-6 lipids effects on the growth and fatty acid composition of rat mammary tumors

The aim of this study was to analyze the effects of a polyunsaturated n-6 high-fat diet on rat DMBA-induced breast cancer at different stages of the carcinogenesis and to investigate if changes in the tumor fatty acid composition are one of the mechanisms by which dietary lipids could exert their effects. 14 fatty acids were evaluated in 6 lipid fractions. The results firstly showed that this high-fat diet stimulated the malignant mammary tumor growth, mainly all in the promotion group. The tumor lipid analysis indicated: 1) that each lipid fraction presented distinct major fatty acids (>5%) which were not the most abundant in the diet, except in the case of the triacylglicerides, suggesting the different resistance to dietary fatty acid modification of the tumor lipid fractions; 2) a higher arachidonic acid content in the fractions with less linoleic acid, above all in phospholipids, particularly in the phosphatidylethanolamine, indicating a different efficiency of conversion; 3) the three most abundant fatty acids in the dietary lipid (18:2n-6, 18:1n-9 and 16:0) were those which essentially displayed the differences between groups; thus, the high-fat diet changed the tumor lipid profile, increasing the 18:2n-6 relative content and decreasing that of the 18:1n-9; differences were significant in phosphatidylcholine, free fatty acids and triacylglycerides. Any change was obtained in the phosphatidylinositol. The greatest number of differences was found in the promotion group. Taken as a whole, our results suggest the different roles of lipid fractions in breast cancer cells and an association between cancer malignancy and the content of linoleic and oleic acids.     

Incorporation and effects of dietary eicosapentaenoate (20:5(n-3)) on plasma and erythrocyte lipids of the marmoset following dietary supplementation with differing levels of linoleic acid

The effect of dietary eicosapentaenoic acid (EPA, 20:5(n-3), as the ethyl ester) on plasma lipid levels and the incorporation of EPA into erythrocyte and plasma lipids were investigated in the marmoset monkey. Marmosets were fed high mixed-fat diets (14.5% total fat) supplemented with or without 0.8% EPA for 30 weeks. Markedly elevated plasma cholesterol (16.4 mmol/l) was induced by an atherogenic-type diet but with EPA supplementation, plasma cholesterol increased to only 6.6 mmol/l. Plasma triacylglycerol levels were not elevated with an atherogenic type diet. Substantial EPA incorporation was evident for plasma phospholipid, triacylglycerol and cholesterol ester fractions. The proportion of docosapentaenoic acid (22:5(n-3)) but not docosahexaenoic acid (22:6(n-3)) was also elevated in these plasma lipid fractions. Greatest incorporation of EPA occurred when it was administered with an atherogenic type diet having a P:M:S (polyunsaturated:monounsaturated:saturated) fatty acid ratio of about 0.2:0.6:1.0 in comparison to the control diet of 1.0:1.0:1.0. Incorporation of EPA and 22:5(n-3)) into erythrocyte phospholipids was also apparent and this was at the expense of linoleic acid (18:2(n-6)). These results in the marmoset highlight both the cholesterol-lowering properties of EPA and the extent of its incorporation into plasma lipids and erythrocyte membrane phospholipids with far greater incorporation occurring when the level of dietary linoleic acid was reduced.     

Albumin-mediated changes in sperm sterol content during capacitation

The role of albumin in mouse sperm capacitation was studied in relation to its activities as a lipid-solubilizing protein and a sterol acceptor. Two bovine serum albumins (BSA) which supported capacitation, Fraction V and fatty acid-free, both contained cholesterol and phospholipid but were without detectable levels of serum high-density lipoprotein (HDL). The lipid content of BSA could be reduced by trichloroacetic acid (TCA) precipitation; however, removal of all detectable lipids required precipitation with ethanolic acetone and diethyl ether extraction. In medium supplemented with Fraction V, fatty acid-free, or TCA-precipitated BSA, mouse sperm were capacitated as evidenced by their ability to fertilize eggs, concomitant with decreases in total cellular sterol and increases in phospholipid content. Delipidated BSA, fractionated on Sephadex G-100 in guanidine HCl also supported capacitation and mediated a 20% decrease in sperm sterol content, while cellular phospholipid levels remained unchanged. When BSA was modified by cholesterol augmentation, fertilization was inhibited in a cholesterol dose-dependent manner. These findings suggest that modulation of sperm lipid levels comprises an event of capacitation and that albumin mediates this process through its activity as a sterol acceptor.     

Dietary low linolenic acid compared with docosahexaenoic acid alter synaptic plasma membrane phospholipid fatty acid composition and sodium-potassium ATPase kinetics in developing rats

The objective of this study was to investigate if maternal dietary 20:4n-6 arachidonic acid (AA) and 22:6n-3 compared with adequate or low levels of 18:3n-3 linolenic acid (LNA) increases synaptic plasma membrane (SPM) cholesterol and phospholipid content, phospholipid 20:4n-6 and 22:6n-3 content, and Na,K-ATPase kinetics in rat pups at two and five weeks of age. At parturition, Sprague-Dawley rats were fed semi-purified diets containing either AA + docosahexaenoic acid (DHA), adequate LNA (control; 18:2n-6 : 18:3n-3 ratio of 7.1 : 1) or low LNA (18:2n-6 : 18:3n-39 ratio of 835 : 1). During the first two weeks of life, the rat pups received only their dams' milk. After weaning, pups received the same diet as their respective dams to five weeks of age. No significant difference was observed among rat pups fed the diet treatments for SPM cholesterol or total and individual phospholipid content at two and five weeks of age. Fatty acid analysis revealed that maternal dietary AA + DHA, compared with feeding the dams the control diet or the low LNA diet, increased 20:4n-6 in phosphatidylserine and 22:6n-3 content of SPM phospholipids. Rats fed dietary AA + DHA or the control diet exhibited a significantly increased Vmax for SPM Na,K-ATPase. Diet treatment did not alter the Km (affinity) of SPM Na,K-ATPase in rat pups at two and five weeks of age. It is concluded that dietary AA + DHA does not alter SPM cholesterol and phospholipid content but increases the 22:6n-3 content of SPM phospholipids modulating activity of Na,K-ATPase.     

Effect of docosahexaenoic acid and alpha-tocopherol enrichment in chicken sperm on semen quality, sperm lipid composition and susceptibility to peroxidation

The aim of the present experiment was to study the effect of fish oil and Vitamin E rich diets on semen production, sperm functions and composition in broiler breeders. The following parameters were measured: semen volume and concentration, sperm motility and viability, sperm susceptibility to induced peroxidation, sperm lipid and alpha-tocopherol contents. Dietary n-3 PUFA were successfully transferred into spermatozoan phospholipid by fish oil feeding according to the following main features: (a) the C22:6n-3 and C22:5n - 3 contents were increased, but C22:4n-6 remained the peculiar and major polyunsaturate; (b) the content and proportion of total PUFA did not change; (c) the proportional increase of n-3 PUFA was compensated by the decrease of n-6 PUFA, an increase in the proportion of n-9 fatty acids was also found. The sperm content of alpha-tocopherol was doubled increasing the dietary availability of the vitamin to 300 mg/kg of feed. The specific n-3 PUFA and Vitamin E enrichment of chicken sperm affected cell functions. Significant interactions between the two treatments were also found for some parameters. The best sperm quality condition in control sperm (rich mainly in n-6 PUFA) was found supplying 200mg Vitamin E/kg of feed to the male breeders, and in contrast in n-3 rich sperm supplying 300 mg Vitamin E/kg.     

The influence of dietary essential fatty acids on uterine C20 and C22 fatty acid composition.

The effect of dietary fatty acids on uterine fatty acid composition was studied in rats fed control diet or semi-synthetic diet supplemented with 1.5 microliter/g/day evening primrose oil (EPO) or fish oil (FO). Diet-related changes in uterine lipid were detected within 21 days. Changes of 2- to 20-fold were detected in the uterine n-6 and n-3 essential fatty acids (EFA) and in certain saturated and monounsaturated fatty acids. The FO diet was associated with higher uterine C20 and C22 n-3, and the EPO diet, with higher uterine n-6 fatty acid. High uterine C18:2 n-6 was detected in neutral lipid (NL) of rats fed high concentrations of this fatty acid, but there was little evidence of selective incorporation or retention of C18:2 n-6 by uterine NL. The incorporation of EFA into uterine phospholipids (PL) was greater than NL EFA incorporation, and uterine PL n-3/n-6 ratios showed greater diet dependence. Tissue/diet fatty acid ratios in NL and PL also indicated preferential incorporation/synthesis of C16:1 n-9, and C16:0, and there was greater incorporation of C12:0 and C14:0 into uteri of rats fed EPO and FO. Replacement of 50-60% of arachidonate with n-3 EFA in uterine PL may inhibit n-6 EFA metabolism necessary for uterine function at parturition.     

Percoll gradient-centrifuged capacitated mouse sperm have increased fertilizing ability and higher contents of sulfogalactosylglycerolipid and docosahexaenoic acid-containing phosphatidylcholine compared to washed capacitated mouse sperm

Although Percoll gradient centrifugation has been used routinely to prepare motile human sperm, its use in preparing motile mouse sperm has been limited. Here, we showed that Percoll gradient-centrifuged (PGC) capacitated mouse sperm had markedly higher fertilizing ability (sperm-zona pellucida [ZP] binding and in vitro fertilization) than washed capacitated mouse sperm. We also showed that the lipid profiles of PGC capacitated sperm and washed capacitated sperm differed significantly. The PGC sperm had much lower contents of cholesterol and phospholipids. This resulted in relative enrichment of male germ cell-specific sulfogalactosylglycerolipid (SGG), a ZP-binding ligand, in PGC capacitated sperm, and this would explain, in part, their increased ZP-binding ability compared with that of washed capacitated sperm. Analyses of phospholipid fatty acyl chains revealed that PGC capacitated sperm were enriched in phosphatidylcholine (PC) molecular species containing highly unsaturated fatty acids (HUFAs), with docosahexaenoic acid (DHA; C22: 6n-3) being the predominant HUFA (42% of total hydrocarbon chains of PC). In contrast, the level of PC-HUFAs comprising arachidonic acid (20:4n-6), docosapentaenoic acid (C22:5n-6), and DHA in washed capacitated sperm was only 27%. Having the highest unsaturation degree among all HUFAs in PC, DHA would enhance membrane fluidity to the uppermost. Therefore, membranes of PGC capacitated sperm would undergo fertilization-related fusion events at higher rates than washed capacitated sperm. These results suggested that PGC mouse sperm should be used in fertilization experiments and that SGG and DHA should be considered to be important biomarkers for sperm fertilizing ability.     

Liquid storage of turkey semen: changes in quality parameters, lipid composition and susceptibility to induced in vitro peroxidation in control, n-3 fatty acids and alpha-tocopherol rich spermatozoa

The study considered two major aims: (a) to measure the changes in quality parameters, lipid composition and antioxidant activity occurring in turkey spermatozoa during liquid storage; (b) to determine if the enrichment of sperm in n-3 fatty acids and alpha-tocopherol affect sperm survival during storage. Turkey breeders were fed a control diet or an Omega3 diet enriched with fish oil and alpha-tocopheryl-acetate. Ejaculates were pooled (5ejaculates/pool; 4pools/treatment) and stored in vitro for 48h at 4 degrees C. Viability, motility, susceptibility to induced peroxidation and alpha-tocopherol content were measured in spermatozoa; lipid and phospholipid fatty acid composition were measured in spermatozoa and seminal plasma. The proportion of motile and viable spermatozoa significantly decreased, and the proportion of dead spermatozoa significantly increased. The susceptibility of turkey spermatozoa to induced peroxidation also significantly increased during storage. The enrichment of turkey spermatozoa with n-3 long chain PUFA and vitamin E by dietary treatment did not prevent the negative effect of storage on sperm quality and sensitivity to induced in vitro peroxidation; however, it was efficient in partially prevent the increase of sperm death, therefore the proportion of dead spermatozoa was higher in control (37.4%) compared to treated spermatozoa (31.7%) after 48h liquid storage. Major changes were recorded in the lipid composition of turkey spermatozoa during liquid storage in both experimental dietary groups, whereas no significant changes were measured in seminal plasma. In spermatozoa, a great loss in the phospholipid and free cholesterol content was measured. Moreover, the loss in total sperm phospholipid was associated to a peculiar and selective decrease in the bounded fatty acids: saturates and monounsaturates were greatly reduced and polyunsaturates did not change. As a consequence, the polyunsaturated to saturated fatty acid ratio increased during 48h liquid storage. The observed changes in the lipid and phospholipid-bound fatty acid composition of turkey spermatozoa occurring during liquid storage might be related to different events and have been discussed.     

The effects of dietary lipid and strain difference on polyunsaturated fatty acid composition and conversion in anadromous and landlocked salmon (Salmo salar L.) parr

Five experimental diets containing different proportions of olive, sunflower and linseed oils were used in a 55-day feeding trial on both anadromous and landlocked parr of Atlantic salmon (Salmo salar) of the same age, in order to study the effects of diet and strain on growth and fatty acid composition and absolute gains in fish whole body triacylglycerols (TAG) and phospholipids (PL). Growth rate was higher in landlocked than in anadromous parr, but not between the different diets. By contrast, the effect of diet on whole body fatty acid composition was much more pronounced than that of strain difference. The fatty acids deposition results establish significant (P<0.05) positive correlations and linear relationships between the percentage of several fatty acids (18:1n-9, 18:2n-6, 18:3n-3) in dietary lipids and their absolute gains in whole body TAG and PL of both stocks. They also indicate the selective deposition of 18:1n-9 compared with linoleic acid (LLA) and linolenic acid (LNA). Finally, the results suggest the occurrence of the conversion of LLA and LNA to long-chain polyunsaturated fatty acids, its stimulation by increased substrate availability, a significantly higher n-3 and n-6 polyunsaturated fatty acids conversion capacity in landlocked than in anadromous parr and a strong genetic influence on docosahexaenoic acid content in salmon parr PL.     

Quality and lipid composition of spermatozoa in rabbits fed DHA and vitamin E rich diets

The effects of fish oil (FO) and vitamin E (vE) dietary supplementation on semen quality, sperm susceptibility to lipid peroxidation, tocopherols content and fatty acid profiles were studied in rabbits. Fifty-two rabbit bucks randomly divided in four groups received a control diet and enriched diets containing either FO (1.5%, w/w), vE (200 mg/kg) or both. Semen volume, concentration, motility and viability were analysed at various time-points and the lipid composition was assessed on sperm cells. The phospholipid fatty acid profile was determined: n-6 PUFA were the major fatty acids found, with a proportion of 42%, whereas the n-3 PUFA accounted for nearly 1%, mainly represented by C22:6n-3 (docosahexaenoic acid, DHA). FO supplementation produced a seven-fold increase in the content of DHA in sperm phospholipids and a comprehensive rearrangement of the phospholipid fatty acid composition, while an unexpected negative effect of feeding high level of vE on the proportion of total PUFA was found. Despite the remarkable changes observed in sperm lipid composition, semen quality parameters were not affected by the dietary treatments and the interaction between the two dietary supplements had a significant effect only on sperm concentration. An increase in semen production by ageing and a concomitant rise in sperm susceptibility to in vitro peroxidation was found. α- and δ-tocopherol, present in rabbit sperm in similar amount, were not affected by dietary treatment. δ-tocopherol content had a significant linear negative regression with age and showed a significant negative correlation with the susceptibility to peroxidation values.     

Partial and total fish meal replacement by agricultural products in the diets improve sperm quality in African catfish (Clarias gariepinus)

This study investigated the long-term effects of total and partial replacement of dietary fish meal (FM) by a mixture of agricultural products on sperm quality of African catfish Clarias gariepinus. Four isonitrogenous and isoenergetic diets were formulated containing graded levels of either 50% FM and maize meal (diet 1); 25% FM mixed with crude sunflower oil cake (SFOC) and bean meal (BM) (diet 2); 12.5% FM mixed with sunflower oil cake, BM and ground nut oil cake (GOC) (diet 3) and 0% FM mixed with de-hulled sunflower oil cake (SFOCD), BM and ground nut oil cake (diet 4). Gonadosomatic index (GSI), sperm quality, plasma sex steroids (11-keto testosterone [11-KT]; testosterone [T]; estradiol-17beta [E2]) were evaluated on 10 to 24 fish fed on each diet. Sperm quality was assessed using computer-assisted sperm analysis (CASA). Total replacement of fish meal by plant products markedly increased sperm volume, spermatocrit, spermatozoa integrity, and sperm motility. Fish fed diet 3 (12.5% fish meal) provided intermediate results on sperm quality whereas the lowest values were obtained in fish fed diets 1 and 2. In fish fed 0% fish meal (diet 4), androgen levels were higher and estrogen levels were lower than in fish fed fish meal diets. Based on dietary lipid and fatty acid analyses, these results suggest a positive impact of short chain n-6 fatty acids on androgen synthesis and sperm quality. In conclusion, a combination of ground nut oil cake, bean meal and sunflower oil cake (preferably when the sunflower is dehulled) in African catfish diet improves the sperm quality.     

Role of dietary oleic acid from two different sources on fatty acid composition of erythrocyte membrane and blood pressure in healthy subjects

This study has been undertaken to determine the effect of a diet enriched with olive oil (OO) and high-oleic sunflower oil (HOSO) on fatty acid composition of erythrocyte membrane phospholipids and blood pressure in healthy women. OO and HOSO were used as natural sources of monounsaturated fatty acids (MUFAs) in a random-order sequence over two 4-week periods with a 4-week washout period between both MUFA diets. HOSO diet resulted in significant increases in oleic [(18:1n-9) 8.6%, P < 0.001], eicosenoic [(20:1n-9) 33.3%, P < 0.05], arachidonic [(20:4n-6) 6.2%, P < 0.05], and docosapentaenoic [(22:5n-6) 56.0%, P < 0.001] acids, whereas OO diet besides increased the content of stearic acid [(18:0) 13.6%, P < 0.01] and long-chain polyunsaturated fatty acids (PUFAs) of the n-3 family (22:5n-3 and 22:6n-3), when compared with the baseline [a diet high in saturated fatty acids (SFAs) and low in MUFAs]. In contrast, there was a significant decrease in linoleic acid [(18:2n-6) 21.8%, P < 0.001] for both MUFA diets. Consistent with these data, dietary intake of OO significantly raised total PUFAs (7.2%, P < 0.05), the n-3 fatty acids (22.2%, P < 0.01) and the PUFAs/SFAs ratio (9.3%, P < 0.01), as well as decreased the ratio of cholesterol to phospholipids (26,1%, P < 0.001) versus HOSO-based diet. Interestingly, dietary OO, but not HOSO, was able to significantly reduce the systolic (3%, P < 0.05) and diastolic (4%, P < 0.05) blood pressures. Although both vegetable oils provided a similar content of MUFAs (mainly oleic acid), our findings rather indicate that OO has important benefits to modulate the fatty acid composition of membranes and the mechanisms involved in the regulation of blood pressure in human.