Biomedical subjects

Aziz Hichami

Publications and source records attributed to Aziz Hichami.

18 recordsLinked to original sources

PubMed2006

Peroxisome proliferator-activated receptor alpha deficiency increases the risk of maternal abortion and neonatal mortality in murine pregnancy with or without diabetes mellitus: Modulation of T cell differentiation.

We assessed the implication of peroxisome proliferator-activated receptor (PPAR) alpha deficiency in pregnancy outcome and neonatal survival and in the modulation of T cell differentiation in murine diabetic pregnancy and their offspring. Pregnant wild-type (WT) and PPAR alpha-null mice of C57BL/6J genetic background were rendered diabetic by five low doses of streptozotocin. We observed that, in the absence of diabetes, PPAR alpha deficiency resulted in an increase in abortion rate, i.e. 0% in WT mice vs. 20% in PPAR alpha-null mice [odds ratio (OR) = 14.33; P = 0.013]. Under diabetic conditions, the abortion rate was enhanced, i.e. 8.3% in WT mice vs. 50% in PPAR alpha-null mice (OR = 4.28; P = 0.011). In the pups born to diabetic dams, the offspring mortality, due to the absence of PPAR alpha, was enhanced, i.e. 27.7% in WT mice vs. 78.9% in PPAR alpha-null animals (OR = 11.48; P < 0.001). Moreover, we observed that T helper (Th) 1/Th2 balance was shifted to a pregnancy protecting Th2 phenotype in WT diabetic dams and to a noxious Th1 phenotype in PPAR alpha-null mice with diabetic pregnancy. Furthermore, offspring born to diabetic WT dams were hyperinsulinemic and hyperglycemic, and they exhibited up-regulated profile of Th2 cytokines, whereas those born to diabetic PPAR alpha-null dams were hypoinsulinemic and hyperglycemic, and they showed down-regulated profile of Th2 cytokines. However, IFN-gamma, a Th1 cytokine, was up-regulated in the offspring of both diabetic WT and PPAR alpha-null dams. Altogether, our results suggest that PPAR alpha deficiency in mice may be implicated in the increase in maternal abortion, neonatal mortality, and T cell differentiation.

Abortion, Spontaneous↗

PubMed2006

N-3 fatty acids modulate Th1 and Th2 dichotomy in diabetic pregnancy and macrosomia.

We assessed the implication of Th (helper)-cells and the modulation of the Th1/Th2 dichotomy by n-3 polyunsaturated fatty acids (PUFA) in type I diabetic pregnancy (DP) and macrosomia. Female gestant rats fed a standard diet or n-3 PUFA regimen were rendered diabetic by administration of five low doses of streptozotocin. The macrosomic (MAC) offspring were sacrificed at the age of 90 days. The mRNAs of IL-2 and IFN-gamma (Th1 cytokines) and IL-4 (Th2 cytokine) were downregulated in the pancreas and spleen of diabetic pregnant rats. The levels of IL-10 mRNA, another Th2 cytokine, were unchanged in the spleen or upregulated in the pancreas of these animals. Feeding an n-3 PUFA diet to rats with DP upregulated IL-10 mRNA in the pancreas and IL-4 and IL-10 mRNA in the spleen. In MAC offspring, high expression of IL-2 and IFN-gamma mRNA, but not of Th2 cytokines, was observed. The n-3 PUFA diet diminished Th1 mRNA quantities and increased the levels of IL-4, but not of IL-10, mRNA in MAC offspring. Our study shows that DP is associated with a decreased Th1 phenotype and IL-4 mRNA expression in the pancreas and spleen, and an n-3 PUFA diet upregulates Th2 profile. In MAC offspring, the Th1 phenotype is upregulated and an n-3 PUFA diet downregulates this phenomenon.

Animals↗

PubMed2006

On cell signalling mechanism of Mycobacterium leprae soluble antigen (MLSA) in Jurkat T cells.

We investigated the role of Mycobaterium leprae soluble antigen (MLSA) in the modulation of calcium signalling, phosphorylation of mitogen-activated protein (MAP) kinases and IL-2 mRNA expression in human Jurkat T cells. We observed that MLSA induced an increase in free intracellular calcium concentrations, [Ca2+]i, via opening CRAC (Ca2+-release activated- Ca2+) channels. Furthermore, MLSA failed to potentiate both thapsigargin- and anti-CD3 antibodies-induced capacitative calcium influx in Jurkat T cells. We observed that MLSA failed to affect the degree of phosphorylation of two MAP kinases, i.e., ERK1/ERK2, stimulated by anti-CD3 antibodies alone or phorbol 12-myristate 13-acetate (PMA) alone. In order to mimic co-stimulation of T cells, we stimulated them by both PMA and anti-CD3 antibodies. MLSA significantly curtailed the phosphorylation of ERK1/ERK2, stimulated by both PMA and anti-CD3 antibodies in Jurkat T cells. Also MLSA was found to reduce the transcription of IL-2 gene in PMA plus anti-CD3 antibodies-activated Jurkat T cells. Our finding demonstrates that Ca2+ influx via CRAC channels, inhibition of ERK1/ERK2 phosphorylation and IL-2 gene transcription may be implicated in immunosuppressive effects of MLSA antigen.

Antigens, Bacterial↗

PubMed2006

Cassava-enriched diet is not diabetogenic rather it aggravates diabetes in rats.

Chronic intake of cassava has been thought to play a role in the pathogenesis of diabetes. We investigated the effects of dietary cassava (Manihot esculenta), which naturally contains cyanogenic glycosides, in the progression of diabetes mellitus in rats. Diabetes was induced by five mild doses of streptozotocin, in male Wistar rats which were fed a standard or cyanide-free cassava (CFC) diet containing or not containing exogenous cyanide with or without methionine. Methionine was employed to counterbalance the toxic effects of cyanide. During diabetes progression, we determined glycaemia and antioxidant status, by measuring vitamin C levels and activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione reductase (GSSG-Red). Feeding CFC diet did not induce diabetes in control rats; rather this diet, in diabetic animals, aggravated hyperglycaemia the severity of which was increased in these animals fed CFC diet, supplemented with cyanide. Addition of methionine curtailed the toxic effects of cyanide supplementation in CFC diet-fed diabetic animals. In standard diet-fed animals, the activities of SOD, GSH-Px and GSSG-Red were lower in diabetic rats than control rats. Interestingly, all of the CFC diets with or without cyanide or methionine, increased vitamin C levels and antioxidant enzyme activities in both control and diabetic animals. However, supplementing cyanide to CFC diet (without methionine) curtailed SOD and GSH-Px activities in diabetic rats. Our study shows that cassava diet containing cyanide is 'diabetes-aggravating'.

Animals↗

PubMed2005

Diacylglycerol-containing docosahexaenoic acid in acyl chain modulates airway smooth muscle tone.

We synthesized and assessed the role of a diacylglycerol (DAG)-containing docosahexaenoic acid (DHA), that is, 1-stearoyl-2-docosahexaenoyl-sn-glycerol (SDHG), in the contraction of guinea pig airway smooth muscle (ASM). We compared its action with 1-stearoyl-2-arachidonoyl-sn-glycerol (SAG) and 1,2-dioctanoyl-sn-glycerol (1,2-DiC8), a stable DAG analog. The three DAGs (SAG, SDHG, and 1,2-DiC8) induced reversible concentration-dependent contraction of ASM. SDHG induced higher guinea pig ASM contraction than did SAG and 1,2-DiC8. The effects of SDHG were blocked, to different extents, by nifedipine (L-type Ca2+ channel blocker). By employing GF-109203X (protein kinase C [PKC] inhibitor) and lanthanum (La3+), a nonselective cation channel blocker, we observed that SDHG evoked ASM contractile response via PKC-dependent and PKC-independent (but Ca2+-dependent) pathways. Interestingly, SAG exerted its action only by increasing [Ca2+]i and did not require PKC activation. To probe the implication of calcium mobilization, we employed thapsigargin (TG), which also induced ASM contraction in a calcium-dependent manner. SDHG and 1,2-DiC8, in a PKC-dependent manner, induced the phosphorylation of CPI-17 (myosin light chain phosphatase inhibitor of 17 kD). Furthermore, SAG and TG failed to phosphorylate CPI-17 in ASM cells. Our results suggest that different DAG species, produced during a dietary supplementation with fatty acids, could modulate the reactivity of airway smooth muscles in a PKC-dependent and -independent manner, and hence, may play a critical role in health and disease.

Animals↗

PubMed2005

n-3 PUFAs modulate T-cell activation via protein kinase C-alpha and -epsilon and the NF-kappaB signaling pathway.

We elucidated the mechanisms of action of two n-3 PUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in Jurkat T-cells. Both DHA and EPA were principally incorporated into phospholipids in the following order: phosphatidylcholine < phosphatidylethanolamine < phosphatidylinositol/phosphatidylserine. Furthermore, two isoforms of phospholipase A(2) (i.e., calcium-dependent and calcium-independent) were implicated in the release of DHA and EPA, respectively, during activation of these cells. The two fatty acids inhibited the phorbol 12-myristate 13-acetate (PMA)-induced plasma membrane translocation of protein kinase C (PKC)-alpha and -epsilon. The two n-3 PUFAs also inhibited the nuclear translocation of nuclear factor kappaB (NF-kappaB) and the transcription of the interleukin-2 (IL-2) gene in PMA-activated Jurkat T-cells. Together, these results demonstrate that DHA and EPA, being released by two isoforms of phospholipase A(2), modulate IL-2 gene expression by exerting their action on two PKC isoforms and NF-kappaB in Jurkat T-cells.

Cell Membrane↗

PubMed2005

Modulation of lipid metabolism by n-3 polyunsaturated fatty acids in gestational diabetic rats and their macrosomic offspring.

The time course of changes in lipid metabolism by dietary n-3 PUFAs (polyunsaturated fatty acids) in streptozotocin-induced diabetic rats during pregnancy (days 12 and 21) and their macrosomic offspring at birth (day 0) and through adulthood (days 60 and 90) was studied with respect to adipose tissue, liver and serum lipid concentrations, and fatty acid composition. Glucose and insulin levels were also assessed in order to characterize the diabetic state of macrosomic offspring. Pregnant diabetic and control rats were fed either an Isio-4 or EPAX diet (enriched with n-3 PUFA). The same diets were also consumed by pups at weaning. Compared with control rats, during pregnancy diabetic rats had a significant elevation in liver and serum triacylglycerol (triglyceride) and cholesterol concentrations. At birth, macrosomic pups had higher serum insulin and glucose levels than control pups. The macrosomic rats maintained accelerated postnatal growth combined with high adipose tissue weight and lipid content through the first 12 weeks of age. The macrosomic pups from diabetic rats fed the Isio-4 diet also showed a significant enhancement in liver and serum triacylglycerol and cholesterol levels at birth and during adulthood. Feeding the EPAX diet to diabetic mothers as well as their macrosomic pups increased serum and liver levels of EPA (eicospentaenoic acid) and DHA (docosahexaenoic acid) with a reduction in arachidonic acid. The EPAX diet induced a significant decrease in liver and serum triacylglycerol and cholesterol concentrations in mothers during pregnancy and in their macrosomic pups during adulthood. Since the EPAX diet improves lipid anomalies considerably in diabetic mothers and their macrosomic offspring, it may prevent long-term metabolic abnormalities associated with macrosomia.

Adipose Tissue↗

PubMed2004

Thapsigargin-stimulated MAP kinase phosphorylation via CRAC channels and PLD activation: inhibitory action of docosahexaenoic acid.

This study was conducted on human Jurkat T-cells to investigate the role of depletion of intracellular Ca(2+) stores in the phosphorylation of two mitogen-activated protein kinases (MAPKs), i.e. extracellular signal-regulated kinase (ERK) 1 and ERK2, and their modulation by a polyunsaturated fatty acid, docosahexaenoic acid (DHA). We observed that thapsigargin (TG) stimulated MAPK activation by store-operated calcium (SOC) influx via opening of calcium release-activated calcium (CRAC) channels as tyrphostin-A9, a CRAC channel blocker, and two SOC influx inhibitors, econazole and SKF-96365, diminished the action of the former. TG-stimulated ERK1/ERK2 phosphorylation was also diminished in buffer containing EGTA, a calcium chelator, further suggesting the implication of calcium influx in MAPK activation in these cells. Moreover, TG stimulated the production of diacylglycerol (DAG) by activating phospholipase D (PLD) as propranolol (PROP) (a PLD inhibitor), but not U73122 (a phospholipase C inhibitor), inhibited TG-evoked DAG production in these cells. DAG production and protein kinase C (PKC) activation were involved upstream of MAPK activation as PROP and GF109203X, a PKC inhibitor, abolished the action of TG on ERK1/ERK2 phosphorylation. Furthermore, DHA seems to act by inhibiting PKC activation as this fatty acid diminished TG- and phorbol 12-myristate 13-acetate-induced ERK1/ERK2 phosphorylation in these cells. Together these results suggest that Ca(2+) influx via CRAC channels is implicated in PLD/PKC/MAPK activation which may be a target of physiological agents such as DHA.

Calcium↗

PubMed2004

Modulation of intracellular calcium concentrations and T cell activation by prickly pear polyphenols.

Opuntia ficus indica (prickly pear) polyphenolic compounds (OFPC) triggered an increase in [Ca2+]i in human Jurkat T-cell lines. Furthermore, OFPC-induced rise in [Ca2+]i was significantly curtailed in calcium-free buffer (0% Ca2+) as compared to that in 100% Ca2+ medium. Preincubation of cells with tyrphostin A9, an inhibitor of Ca2+ release-activated Ca2+ (CRAC) channels, significantly diminished the OFPC-induced sustained response on the increases in [Ca2+]i. Lanthanum and nifedipine, the respective inhibitors of voltage-dependent and L-type calcium channels, failed to curtail significantly the OFPC-induced calcium response. As OFPC still stimulated increases in [Ca2+]i in 0% Ca2+ medium, the role of intracellular calcium was investigated. Hence, addition of thapsigargin (TG), an inhibitor of Ca2+-ATPase of the endoplasmic reticulum (ER), during the OFPC-induced peak response exerted an additive effect, indicating that the mechanism of action of these two agents are different. Furthermore, U73122, an inhibitor of IP3 production, completely abolished increases in [Ca2+]i, induced by OFPC, suggesting that these polyphenols induce the production of IP3 that recruits calcium from ER pool. Polyphenolic compounds do act extracellularly as addition of fatty acid-free bovine serum albumin (BSA) significantly diminished the rise in [Ca2+]i evoked by the formers. OFPC also induced plasma membrane hyperpolarisation which was reversed by addition of BSA. OFPC were found to curtail the expression of IL-2 mRNA and T-cell blastogenesis. Together these results suggest that OFPC induce increases in [Ca2+]i via ER pool and opening of CRAC channels, and exert immunosuppressive effects in Jurkat T-cells.

Calcium↗

PubMed2004

n-3 fatty acids modulate T-cell calcium signaling in obese macrosomic rats.

OBJECTIVE: We investigated the effects of a diet containing EPAX-7010, rich in PUFAs such as eicosapentaenoic acid [20:5(n-3)] and docosahexaenoic acid [22:6(n-3)], i.e., a PUFA/EPAX regimen, on T-cell activation in diabetic pregnant rats and their obese pups. RESEARCH METHODS AND PROCEDURES: Mild hyperglycemia in pregnant rats was induced by intraperitoneal injection of streptozotocin on Day 5 of gestation. T-cell blastogenesis was assayed by using (3)H-thymidine, whereas intracellular free calcium concentrations ([Ca(2+)]i) were measured by using Fura-2 in diabetic pregnant rats and their obese offspring. RESULTS: Concavalin-A-stimulated T-cell proliferation was decreased in both pregnant diabetic rats and their obese pups as compared with control animals. Feeding the PUFA/EPAX diet restored T-cell proliferation in both groups of animals. We also employed ionomycin, which at 50 nM opens calcium channels, and thapsigargin (TG), which recruits [Ca(2+)]i from endoplasmic reticulum pool. We observed that ionomycin-induced increases in [Ca(2+)]i in T-cells of diabetic mothers and obese offspring were greater than in those of control rats. Furthermore, feeding PUFA/EPAX diet diminished significantly the ionomycin-evoked rise in [Ca(2+)]i in diabetic and obese animals. TG-induced increases in [Ca(2+)]i in T-cells of diabetic pregnant rats and their obese offspring were greater than in those of control rats. The feeding of the experimental diet significantly curtailed the TG-evoked increases in [Ca(2+)]i in both diabetic and obese rats. DISCUSSION: Together, these observations provide evidence that T-cell activation and T-cell calcium signaling are altered during gestational diabetes and macrosomia. Hence, dietary fish oils, particularly eicosapentaenoic acid and docosahexaenoic acid, may restore these T-cell abnormalities.

Animals↗

PubMed2003

Diacylglycerols containing Omega 3 and Omega 6 fatty acids bind to RasGRP and modulate MAP kinase activation.

We elucidated the effects of different diacylglycerols (DAGs), i.e. 1-stearoyl-2-arachidonoyl-sn-glycerol (SAG), 1-stearoyl-2-docosahexaenoyl-sn-glycerol (SDG), and 1-stearoyl-2-eicosapentaenoyl-sn-glycerol (SEG), on [3H]PDBu binding to RasGRP. The competition studies with these DAGs on [3H]PDBu binding to RasGRP revealed different Ki values for these DAG molecular species. Furthermore, we transfected human Jurkat T cells by a plasmid containing RasGRP and assessed the implication of endogenous DAGs on activation of MAP kinases ERK1/ERK2, induced by phorbol-12-myristate-13-acetate (PMA). In control cells, GF109203X, a protein kinase C inhibitor, inhibited ERK1/ERK2 activation. However, this agent curtailed but failed to completely diminish ERK1/ERK2 phosphorylation in RasGRP-overexpressing cells, though calphostin C, a DAG binding inhibitor, suppressed the phosphorylation of MAP kinases in these cells. In cells incubated with arachidonic acid (AA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), PMA induced the production of endogenous DAGs containing these fatty acids, respectively: DAG-AA, DAG-DHA, and DAG-EPA. The inhibition of production of DAG-AA and DAG-DHA significantly inhibited MAP kinase activation in RasGRP overexpressing, but not in control, cells. Our study demonstrates that three DAG molecular species bind to RasGRP, but only DAG-AA and DAG-DHA participate in the modulation of RasGRP-mediated activation of MAP kinases in Jurkat T cells.

Animals↗

PubMed2003

Docosahexaenoic acid and other fatty acids induce a decrease in pHi in Jurkat T-cells.

1. Docosahexaenoic acid (DHA) induced rapid (t1/2=33 s) and dose-dependent decreases in pHi in BCECF-loaded human (Jurkat) T-cells. Addition of 5-(N,N-dimethyl)-amiloride, an inhibitor of Na+/H+ exchanger, prolonged DHA-induced acidification as a function of time, indicating that the exchanger is implicated in pHi recovery. 2. Other fatty acids like oleic acid, arachidonic acid, eicosapentaenoic acid, but not palmitic acid, also induced a fall in pHi in these cells. 3. To assess the role of calcium in the DHA-induced acidification, we conducted experiments in Ca2+-free (0% Ca2+) and Ca2+-containing (100% Ca2+) buffer. We observed that there was no difference in the degree of DHA-induced transient acidification in both the experimental conditions, though pHi recovery was faster in 0% Ca2+ medium than that in 100% Ca2+ medium. 4. In the presence of BAPTA, a calcium chelator, a rapid recovery of DHA-induced acidosis was observed. Furthermore, addition of CaCl2 into 0% Ca2+ medium curtailed DHA-evoked rapid pHi recovery. In 0% Ca2+ medium, containing BAPTA, DHA did not evoke increases in [Ca2+]i, though this fatty acid still induced a rapid acidification in these cells. These observations suggest that calcium is implicated in the long-lasting DHA-induced acidosis. 5. DHA-induced rapid acidification may be due to its deprotonation in the plasma membrane (flip-flop model), as suggested by the following observations: (1) DHA with a -COOH group induced intracellular acidification, but this fatty acid with a -COOCH3 group failed to do so, and (2) DHA, but not propionic acid, -induced acidification was completely reversed by addition of fatty acid-free bovine serum albumin in these cells. 6. These results suggest that DHA induces acidosis via deprotonation and Ca2+ mobilization in human T-cells.

Docosahexaenoic Acids↗

PubMed2002

Implication of three isoforms of PLA(2) in human T-cell proliferation.

We observed that human (Jurkat) T-cells constitutively expressed the mRNA, encoding for the four isoforms of phospholipase A(2) (PLA(2)), i.e. two secretory (type IB and type V), and two cytosolic (type IV, Ca(2+)-dependent and type VI, Ca(2+)-independent). In order to assess whether these PLA(2) isoforms are active, we labeled Jurkat T-cells with [(3)H]arachidonic acid ([(3)H]AA) and determined its release into the extracellular medium in the presence of phorbol 12-myristate 13-acetate (PMA) and ionomycin. The three PLA(2) isoforms seem functional as aristolochic acid and bromoenol lactone (BEL), the respective inhibitors of type IB/type V and type VI PLA(2)s, significantly inhibited the release of free [(3)H]AA. On the other hand, arachidonyl trifluoromethyl ketone (AACOCF(3)), an inhibitor of type IV PLA(2), failed to curtail significantly the release of free [(3)H]AA into the extracellular medium. We assessed the implication of these PLA(2) isoforms in transcription of the interleukin-2 (IL-2) gene, involved in T-cell proliferation. Hence, aristolochic acid and BEL, but not AACOCF(3), significantly inhibited the PMA and ionomycin-induced induction of mRNA of IL-2. Similarly, aristolochic acid and BEL, but not AACOCF(3), significantly inhibited the PMA and ionomycin-induced secretion of IL-2 in the culture supernatants. Together these results suggest that human Jurkat T-cells possess two secretory and two cytosolic PLA(2) isoforms and only three of them (type IB, type V and type VI) are implicated in T-cell proliferation.

Arachidonic Acid↗

PubMed2002

Impaired lipoprotein metabolism in obese offspring of streptozotocin-induced diabetic rats.

The time course of changes in lipoprotein metabolism of obese offspring of mildly diabetic rats was studied with respect to serum lipoprotein composition as well as LCAT and tissue lipoprotein lipase (LPL) activities. Mild hyperglycemia in pregnant rats was induced by intraperitoneal injection of streptozotocin on day 5 of gestation. Control pregnant rats were injected with citrate buffer. At birth, obese pups had higher serum glucose, insulin, and lipoprotein (VLDL, LDL-HDL1, HDL(2-3)) levels than control pups. After 1 mon of life, all of these parameters in obese rats became similar to those of controls. However, LCAT, adipose tissue LPL, and hepatic triacylglycerol lipase activities were high. At 2 mon of age, VLDL-TAG levels were higher in obese females than in controls. By the age of 3 mon, obese offspring had developed insulin resistance with hyperglycemia, hyperinsulinemia, and higher serum lipoprotein concentrations. Indeed, qualitative abnormalities of lipoproteins were seen and were typical of obese and diabetic human beings. Fetal hyperinsulinemia should be considered as a risk factor for later metabolic diseases, including dyslipoproteinemia.

Adipose Tissue↗

PubMed2002

Eicosapentaenoic acid and docosahexaenoic acid modulate MAP kinase enzyme activity in human T-cells.

In order to investigate the implication of docosahexacnoic acid (DHA) and eicosapentaenoic acid (EPA) in T signalling, we assessed their effects on the activation of two mitogen activated protein (MAP) kinases, i.e. extracellularly-regulated kinases 1 and 2 (ERK1/ERK2) in Jurkat T-cells. The n-3 polyunsaturated fatty acids (PUFAs) alone failed to induce MAP kinase (MAPK) enzyme activity. To elucidate whether DHA and EPA act via protein kinase C (PKC) dependent and independent pathways, we employed their respective activators, i.e. phorbol 12-myristate 13-acetate (PMA) and antiCD3 antibodies. We observed that U0126, an inhibitor of MAPK kinase-ERK kinase 1/2 (MEK1/2), abolished the actions of these two agents on MAPK activation, suggesting that they act upstream of MEK1/2. Further EPA and DHA diminished both the PMA- and antiCD3 antibodies-induced enzyme activity of ERK1/ERK2 in Jurkat T-cells. Interestingly, okadaic acid (OA), a phosphatase inhibitor seems to act downstream of MEK1/2 as U0126 failed to inhibit the OA-induced MAPK activation. It is noteworthy that EPA and DHA not only failed to curtail the OA-induced MAPK activity but also these n-3 PUFAs at 20 microM potentiated the action of OA. Therefore, EPA and DHA seem to modulate MAPK activation upstream and downstream of MEK1/2. On the hand, arachidonic acid, an n-6 PUFA potentiated the MAPK enzyme activity. In conclusion, our study shows that EPA and DHA may regulate T-cells functions by modulating MAPK enzyme activity.

Antibodies↗

PubMed2002

Age-related changes in fatty acids in obese offspring of streptozotocin-induced diabetic rats.

OBJECTIVE: The long-term effects of fetal hyperinsulinemia, time course of changes in liver and very-low-density lipoprotein (VLDL) lipid levels and fatty acid compositions were investigated in obese offspring of streptozotocin-induced mildly diabetic rats. RESEARCH METHODS AND PROCEDURES: Mild hyperglycemia in pregnant rats was induced by intraperitoneal injection of streptozotocin on day 5 of gestation. Control pregnant rats were injected with citrate buffer. Liver and VLDL lipids and fatty acids were analyzed in offspring at different ages. RESULTS: At birth, obese pups had higher VLDL triglyceride levels, saturated fatty acids, and C20:4n-6. They also had lower C18:2n-6 proportions in VLDL triglycerides, phospholipids, and cholesteryl esters than controls pups. In 1-month-old male and female obese rats, VLDL and liver lipid amounts were similar to those in their respective controls; however, high levels of C18:2n-6 and C20:4n-6 were noted in liver and VLDL lipids. At the age of 2 months, liver and VLDL triglyceride levels were higher in obese females than in control females. Fatty acid abnormalities seen in obese rats included low C18:3n-3 and high C22:6n-3 proportions in liver triglycerides and phospholipids. At the age of 3 months, obese rats, both males and females, compared with control animals, had higher VLDL and hepatic lipids with reduced C20:4n-6 levels and polyunsaturated/saturated fatty acids ratios in hepatic and VLDL triglycerides and phospholipids. DISCUSSION: Fetal obesity, associated with alterations in VLDL lipid fatty acid composition, represents an important risk factor for adult obesity and diabetes.

Aging↗

PubMed2002

Role of three isoforms of phospholipase A2 in capacitative calcium influx in human T-cells.

The present study was conducted on human Jurkat T-cell lines in order to elucidate the role of phospholipase A2 in capacitative calcium entry. We have employed thapsigargin (TG) that induces increases in [Ca2+]i by emptying the calcium pool of endoplasmic reticulum, followed by capacitative calcium entry. We designed a Ca2+ free/Ca2+ reintroduction (CFCR) protocol for the experiments, conducted in Ca2+-free medium. By employing CFCR protocol, we observed that addition of exogenous arachidonic acid (AA) stimulated TG-induced capacitative calcium influx. The liberation of endogenous AA and its autocrine action seems to be implicated during TG-induced capacitative calcium influx: TG potentiates the induction of constitutively expressed mRNA of four PLA2 isoforms (type 1B, IV, V, VI), the inhibitors of the three PLA2 isotypes (type 1B, V, VI) inhibit TG-induced release of [3H]AA into the extracellular medium, and finally, these PLA2 inhibitors do curtail TG-stimulated capacitative calcium entry in these cells. These results suggest that stimulation of three isoforms of PLA2 by thapsigargin liberates free AA that, in turn, induces capacitative calcium influx in human T-cells.

Arachidonic Acid↗

PubMed2002

1-O-alkylglycerols improve boar sperm motility and fertility.

1-O-alkylglycerols are naturally occurring ether lipids with potent biological activities. They may interfere with lipidic signaling, and they amplify platelet-activating factor (PAF) biosynthesis in a monocyte cell line. The PAF is produced by mammalian sperm and is an important activator of sperm motility. The aim of this study was to evaluate the effect of in vitro treatment of boar spermatozoa with natural 1-O-alkylglycerols (10 microM) on 1) boar sperm motility; 2) production of PAF and its metabolite, lyso-PAF, by spermatozoa; and 3) fertility in artificial inseminations of breeding sows. Using a computer-assisted spermatozoa analyzer, we found that 1-O-alkylglycerols increased percentage motility as well as velocity parameters after 24 h. These effects were partially or totally reversed by the PAF receptor-antagonist SR 27417. After [3H]-1-O-alkylglycerol incubation with boar spermatozoa, we identified [3H]lyso-PAF by high-performance liquid chromatography. Production of PAF and lyso-PAF was measured with a biological assay using [3H]serotonin release from rabbit platelets. 1-O-alkylglycerols significantly increased lyso-PAF production but had no effect on PAF production. The effect of 1-O-alkylglycerols on fertilization was also evaluated in industrial breedings: 1-O-alkylglycerol-treated or untreated semen dilutions were alternately used for artificial inseminations of sows on 12 farms. 1-O-alkylglycerol treatment increased the number of farrows but had no effect on the mean size of the litters. This study demonstrates that 1-O-alkylglycerol treatment of boar spermatozoa in vitro improves their motility and fertility, and it suggests that this effect is related to PAF metabolism and function in boar spermatozoa.

Animals↗