Reproduction, nutrition, development最新文献

A total of 226 out of 245 postpartum lactating dairy cows in a commercial dairy farm were allocated to two groups of oestrous synchronisation protocols in order to evaluate reproductive performance. One group was treated with oestradiol benzoate (ODB) and PGF2alpha on day 10 of the oestrous cycle with insemination at the detected oestrus, the second group underwent the Ovsynch (OVS) protocol (GnRH + PGF2alpha + GnRH) with timed AI. Pregnancy was diagnosed by ultrasonography on day 28 after AI and confirmed by rectal palpation on day 45. A higher (P < 0.001) proportion of cows in OVS (100%) were inseminated within (19.2 +/- 3.8 h) following the second GnRH injection than those of cows in EPE (ODB + PGF2alpha + ODB) (70.6%) inseminated at the detected oestrus within (35.6 +/- 5.2 h) following the second ODB injection. Pregnancy rates for the first AI at day 28 (64.0 +/- 4.6, 62.4 +/- 5.5%) and at day 45 post-insemination (40.4 +/- 4.7, 40.0 +/- 5.6%) for OVS and EPE cows respectively, did not differ between the two treatments, whereas, the overall pregnancy rates tended to be higher (P < 0.08) for the OVS (85.1 +/- 3.8%) cows than the EPE cows (74.1 +/- 4.5%). No differences were observed in pregnancy rates for first AI and overall up to fourth AI between primiparous (34.7 +/- 5.8 and 85.3 +/- 4.7%) and multiparous cows (43.5 +/- 4.5 and 77.4 +/- 3.6%). Days open for pregnant cows tended to be lower (P < 0.08) for OVS (76.2 +/- 3) than for EPE cows (84.7 +/- 4), while days open were higher (P < 0.05) in primiparous cows (85.3 +/- 4) than in multiparous cows (75.6 +/- 3). The results indicate that pregnancy rates for first AI were similar, but overall pregnancy rates up to the fourth AI tended to be higher for OVS than EPE cows, while days open was tended to be lower for OVS than EPE cows.

The present study was carried out to elucidate the effect of a single episode of oxidative stress on pyramidal neurons of the rat hippocampus. A significant increase in the number of neurons that were immunolabeled for the toxic lipid peroxidation product, 4-hydroxynonenal (HNE) was observed in field CA3 of the hippocampus, at 1 day, 7 days and 14 days after intracerebroventricular injection of 1 microL of 5 mM ferrous ammonium citrate, compared to ammonium citrate injected controls at these time points. The number of HNE positive cells was fewer at 14 days, compared to 1 day, after ferrous ammonium citrate injection. The changes in HNE immunoreactivity were paralleled by changes in cytoplasmic phospholipase A2 (cPLA2) labeling in the pyramidal neurons in adjacent sections, suggesting that some of the HNE could have arisen as a result of peroxidation of arachidonic acid that was released by cPLA2. Interestingly, despite the HNE and cPLA2 labeling, no loss of neurons was observed in adjacent Nissl and Fluoro-Jade stained sections. Electron microscopy also showed that the HNE or cPLA2 labeled cells had features of injured neurons, rather than necrotic neurons. The reduction of HNE immunoreactivity in neurons at 14 days after oxidative injury, and the absence of cell loss at any of the time intervals, shows that hippocampal pyramidal neurons have remarkable ability to recover from a single episode of oxidative stress, if repeated injury such as seizures / excitotoxicity could be avoided.

Dietary intake of omega-3 fatty acids has been positively correlated with cardiovascular and neuropsychiatric health in several studies. The high seafood intake by the Japanese and Greenland Inuit has resulted in low ratios of the omega-6 fatty acid arachidonic acid (AA, 20:4n-6) to eicosapentaenoic acid (EPA, 20:5n-3), with the Japanese showing AA:EPA ratios of approximately 1.7 and the Greenland Eskimos showing ratios of approximately 0.14. It was the objective of this study to determine the effect of supplementation with high doses (60 g) of flax and fish oils on the blood phospholipid (PL) fatty acid status, and AA/EPA ratio of individuals with Attention Deficit Hyperactivity Disorder (ADHD), commonly associated with decreased blood omega-3 fatty acid levels. Thirty adults with ADHD were randomized to 12 weeks of supplementation with olive oil (< 1% omega-3 fatty acids), flax oil (source of alpha-linolenic acid; 18:3n-3; alpha-LNA) or fish oil (source of EPA and docosahexaenoic acid; 22:6n-3; DHA). Serum PL fatty acid levels were determined at baseline and at 12 weeks. Flax oil supplementation resulted in an increase in alpha-LNA and a slight decrease in the ratio of AA/EPA, while fish oil supplementation resulted in increases in EPA, DHA and total omega-3 fatty acids and a decrease in the AA/EPA ratio to values seen in the Japanese population. These data suggest that in order to increase levels of EPA and DHA in adults with ADHD, and decrease the AA/EPA ratio to levels seen in high fish consuming populations, high dose fish oil may be preferable to high dose flax oil. Future study is warranted to determine whether correction of low levels of long-chain omega-3 fatty acids is of therapeutic benefit in this population.

This study was designed to investigate the effect of myristic acid on the biosynthesis and metabolism of highly unsaturated fatty acids, when it is supplied in a narrow physiological range in the diet of the rat (0.2-1.2% of total dietary energy). Three experimental diets were designed, containing 22% of total dietary energy as lipids and increasing doses of myristic acid (0.71, 3.00 and 5.57% of total fatty acids). Saturated fat did not exceed 31% of total fat and the C18:3 n-3 amount in each diet was strictly equal (1.6% of total fatty acids). After 7 weeks, the diets had no effect on plasma cholesterol level but greatly modified the liver, plasma and adipose tissue saturated, monounsaturated and polyunsaturated fatty acid profiles. Firstly, daily intakes of myristic acid resulted in a dose-dependent tissue accumulation of myristic acid itself. Palmitic acid was significantly increased in the tissues of the rats fed the higher dose of myristic acid. A dose-response accumulation of tissue C16:1 n-7 as a function of dietary C14:0 was also shown. Secondly, a main finding was that, among n-3 and n-6 polyunsaturated fatty acids, a dose-response accumulation of liver and plasma C20:5 n-3 and C20:3 n-6 (two precursors of eicosanoids) as a function of dietary C14:0 was shown. This result suggests that dietary myristic acid may participate in the regulation of highly unsaturated fatty acid biosynthesis and metabolism.

The principal biological role of alpha-linolenic acid (alphaLNA; 18:3n-3) appears to be as a precursor for the synthesis of longer chain n-3 polyunsaturated fatty acids (PUFA). Increasing alphaLNA intake for a period of weeks to months results in an increase in the proportion of eicosapentaenoic acid (EPA; 20:5n-3) in plasma lipids, in erythrocytes, leukocytes, platelets and in breast milk but there is no increase in docosahexaenoic acid (DHA; 22:6n-3), which may even decline in some pools at high alphaLNA intakes. Stable isotope tracer studies indicate that conversion of alphaLNA to EPA occurs but is limited in men and that further transformation to DHA is very low. The fractional conversion of alphaLNA to the longer chain n-3 PUFA is greater in women which may be due to a regulatory effect of oestrogen. A lower proportion of alphaLNA is used for beta-oxidation in women compared with men. Overall, alphaLNA appears to be a limited source of longer chain n-3 PUFA in humans. Thus, adequate intakes of preformed long chain n-3 PUFA, in particular DHA, may be important for maintaining optimal tissue function. Capacity to up-regulate alphaLNA conversion in women may be important for meeting the demands of the fetus and neonate for DHA.

Pathological conditions in the brain, such as ischemia, trauma and seizure are accompanied by increased levels of free n-6 and n-3 polyunsaturated fatty acids (PUFA), mainly arachidonic acid (AA, 20:4n-6) and docosahexaenoic acid (DHA, 22:6n-3). A neuroprotective role has been suggested for PUFA. For investigation of the potential molecular mechanisms involved in neuroprotection by PUFA, we studied the regulation of the concentration of intracellular Ca2+ ([Ca2+]i) in rat brain astrocytes. We evaluated the presence of extracellular PUFA and the release of intracellular PUFA. Interestingly, only the constitutive brain PUFA AA and DHA, but not eicosapentaenoic acid (EPA) had prominent effects on intracellular Ca2+. AA and DHA suppressed [Ca2+]i oscillation, inhibited store-operated Ca2+ entry, and reduced the amplitudes of Ca2+ responses evoked by agonists of G protein-coupled receptors. Moreover, prolonged exposure of astrocytes to AA and DHA brought the cells to a new steady state of a moderately elevated [Ca2+]i level, where the cells became virtually insensitive to external stimuli. This new steady state can be considered as a mechanism of self-protection. It isolates disturbed parts of the brain, because AA and DHA reduce pathological overstimulation in the tissue surrounding the damaged area. In inflammation-related events, frequently AA and DHA exhibit opposite effects. However, in astrocytes AA and DHA exerted comparable effects on [Ca2+]i. Extracellularly added AA and DHA, but not EPA, were also able to induce the release of [3H]AA from prelabeled astrocytes. Therefore, we also suggest the involvement of phospholipase A2 activation and lysophospholipid generation in the regulation of intracellular Ca2+ in astrocytes.

Docosahexaenoic acid (DHA) accumulates in the brain during the 1st and 2nd years of life. The objective of this study was to see if an increased content of DHA in breast-milk via maternal fish oil (FO)-supplementation affects mental development in term infants. one hundred twenty-two Danish mothers with a habitual fish intake below the population median were randomized to 4.5 g.d(-1) of FO or olive oil (OO) for the first four months of lactation. Fifty-three mothers with habitual fish intake in the highest quartile were included as reference group. The effect of the resulting increase in infant DHA-intake and RBC-DHA level was assessed on problem solving ability at nine months and language at one and two years of age. Infants in the three groups performed equally well on the problem test and no association was observed between problem solving and erythrocyte-DHA at four months. Passive vocabulary at one year was lower in the children of the FO- compared with the OO-group (P < 0.05), but no differences were found at two years of age. Word comprehension at one year was inversely associated with erythrocyte-DHA at four months. The trial indicate a small effect of DHA levels in breast-milk on early language development of breast-fed infants.

With 22 carbons and 6 double bonds docosahexaenoic acid (DHA) is the longest and most unsaturated fatty acid commonly found in membranes. It represents the extreme example of a class of important human health promoting agents known as omega-3 fatty acids. DHA is particularly abundant in retinal and brain tissue, often comprising about 50% of the membrane's total acyl chains. Inadequate amounts of DHA have been linked to a wide variety of abnormalities ranging from visual acuity and learning irregularities to depression and suicide. The molecular mode of action of DHA, while not yet understood, has been the focus of our research. Here we briefly summarize how DHA affects membrane physical properties with an emphasis on membrane signaling domains known as rafts. We report the uptake of DHA into brain phosphatidylethanolamines and the subsequent exclusion of cholesterol from the DHA-rich membranes. We also demonstrate that DHA-induced apoptosis in MDA-MB-231 breast cancer cells is associated with externalization of phosphatidylserine and membrane disruption ("blebbing"). We conclude with a proposal of how DHA incorporation into membranes may control cell biochemistry and physiology.

Phospholipids are integral components of the nuclear membranes and intranuclear domains. Alterations in phospholipid metabolism occur during cellular differentiation, proliferation, and apoptosis, but the molecular mechanism involved in the above processes remains unknown. We propose that the coordinated expression of different genes responsible for the expression of transcription factors, neurotrophins, and cytokines, along with lipid mediators generated by the action of phospholipases A2, C, and D (PLA2, PLC, and PLD), play a very important role in differentiation, proliferation, and apoptosis. The purpose of this minireview is to discuss recent developments in PLA2, PLC, and PLD-mediated signaling in the nucleus of LA-N-1 neuroblastoma cell cultures. In brain tissue, arachidonic acid is mainly released by the action of PLA2 and phospholipase C/diacylglycerol lipase (PLC/DAG-lipase) pathways. We have used LA-N-1 cell cultures to study activities of PLA2, C, and D during retinoic acid (RA)-mediated differentiation. The treatment of LA-N-1 cells with RA produces an increase in PLA2 activity in the nuclear fraction. This increase in PLA2 activity can be prevented with BMS493, a pan retinoic acid receptor antagonist, suggesting that RA-induced stimulation of PLA2 activity is a RA receptor-mediated process. The treatment of LA-N-1 cells with 12-O-tetradecanoyl-phorbol-13 acetate (TPA) and RA increases diacylglycerol (DAG) levels indicating the stimulation of PLC activity. This stimulation is blocked by D609, tricyclodecan-9-yl potassium xanthate, a competitive PtdCho-specific PLC inhibitor. LA-N-1 cells also contain DAG-and monoacylglycerol (MAG) lipase activities. Two isoforms of PLD, oleate-dependent and TPA-dependent, are also present in LA-N-1 cell homogenates. RA stimulates the oleate-dependent isoform of PLD, whereas RA does not stimulate the TPA-dependent isoform. Our studies have indicated that lipid mediators generated by the action of PLA2, PLC, and PLD on nuclear phospholipids markedly affect neuritic outgrowth and neurotransmitter release in cells of neuronal and glial origin. We propose that RA receptors coupled with PLA2, PLC, and PLD activities in the nucleus may play an important role in the redistribution of arachidonic acid and its metabolites and DAG in nuclear and non-nuclear neuronal membranes during differentiation and growth suppression.