Dietary fish oil and cytochrome P-450 monooxygenase activity in rat liver and kidney

Higher dietary cholesterol and ω-3 fatty acid intakes are associated with a lower success rate of Helicobacter pylori eradication therapy in Japan

Background:Helicobacter pylori infection is a known risk factor for duodenal ulcers, gastritis, and gastric cancer. The eradication of H. pylori is successful in treating these disorders; however, the success rate of eradication therapy is declining. There may be an interaction with nutrient intake to account for this decline.Objective: We investigated the influence of food and nutrient intake on H. pylori eradication therapy.Design: In this study, 4014 subjects underwent endoscopy, were tested for serum antibodies to H. pylori (2046 positive; 51.0%), and had their food intake assessed with the use of a food-frequency questionnaire (FFQ). Of the positive subjects, endoscopies showed that 389 (19.0%) had gastritis and/or duodenal ulcers and were also positive for a ¹³C-urea breath test (UBT). These 389 subjects received 1-wk H. pylori eradication therapy with lansoprazole, amoxicillin, and clarithromycin and a second UBT 8 wk after treatment. Complete demographic characteristics, serum lipid, insulin, glycated hemoglobin, C-reactive protein (CRP), and creatinine concentrations as well as complete FFQs were available for 352 subjects. Multivariate logistic regression analyses were performed to determine factors that were associated with successful H. pylori eradication therapy.Results: The success rate of eradication therapy was 60.4% (235 of 389). Factors associated with the failure of eradication therapy included increased age (P = 0.02), higher CRP concentrations (P < 0.01), higher dietary cholesterol (P < 0.01) or egg intake (P < 0.01), higher ω-3 (n-3) fatty acid (P = 0.02) or fish intake (P = 0.01), and higher vitamin D intake (P = 0.02). Moreover, the higher vitamin D intake was strongly linked to higher fish intake. A limitation of the study is that we did not assess the antibiotic resistance of H. pyloriConclusions: Our results indicate that higher egg and fish intake may be negatively correlated with successful H. pylori eradication therapy in H. pylori-positive subjects with gastritis and/or duodenal ulcers.

Omega-3 fatty acid deficiency does not alter the effects of chronic fluoxetine treatment on central serotonin turnover or behavior in the forced swim test in female rats

While translational evidence suggests that long-chain omega-3 fatty acid status is positively associated with the efficacy of selective serotonin reuptake inhibitor drugs, the neurochemical mechanisms mediating this interaction are not known. Here, we investigated the effects of dietary omega-3 (n-3) fatty acid insufficiency on the neurochemical and behavioral effects of chronic fluoxetine (FLX) treatment. Female rats were fed diets with (CON, n=56) or without (DEF, n=40) the n-3 fatty acids during peri-adolescent development (P21-P90), and one half of each group was administered FLX (10mg/kg/day) for 30days (P60-P90) prior to testing. In adulthood (P90), regional brain serotonin (5-HT) and 5-hydroxyindoleacetic (5-HIAA) concentrations, presynaptic markers of 5-HT neurotransmission, behavioral responses in the forced swim test (FST), and plasma FLX and norfluoxetine (NFLX) concentrations were investigated. Peri-adolescent n-3 insufficiency led to significant reductions in cortical docosahexaenoic acid (DHA, 22:6n-3) composition in DEF (-25%, p≤0.0001) and DEF+FLX (-28%, p≤0.0001) rats. Untreated DEF rats exhibited significantly lower regional 5-HIAA/5-HT ratios compared with untreated CON rats, but exhibited similar behavioral responses in the FST. In both CON and DEF rats, chronic FLX treatment similarly and significantly decreased 5-HIAA concentrations and the 5-HIAA/5-HT ratio in the hypothalamus, hippocampus, and nucleus accumbens, brainstem tryptophan hydroxylase-2 mRNA expression, and immobility in the FST. While the FLX-induced reduction in 5-HIAA concentrations in the prefrontal cortex was significantly blunted in DEF rats, the reduction in the 5-HIAA/5-HT ratio was similar to CON rats. Although plasma FLX and NFLX levels were not significantly different in DEF and CON rats, the NFLX/FLX ratio was significantly lower in DEF+FLX rats. These preclinical data demonstrate that n-3 fatty acid deficiency does not significantly reduce the effects of chronic FLX treatment on central 5-HT turnover or behavior in the FST in female rats.

Hypertriglyceridemia and cardiovascular risk reduction

BACKGROUND

Elevated triglyceride (TG) levels are prevalent among the US population, often occurring in persons who are overweight or obese, or who have type 2 diabetes or the metabolic syndrome. There is evidence that elevated TG levels may be a significant independent risk factor for coronary heart disease (CHD), particularly in women.

OBJECTIVE

This article reviews data on the epidemiology, associated risks, treatment, and prevention of hypertriglyceridemia, including recommended TG goals and available TG-lowering agents.

METHODS

MEDLINE was searched for articles published from 1990 through 2006 using the terms hypertriglyceridemia, dyslipidemia, and coronary heart disease, with subheadings for risk, statins, niacin, fibrates, thiazolidinediones, and omega-3 fatty acids. The reference lists of relevant articles were examined for additional citations. Publications discussing the epidemiology of hypertriglyceridemia, CHD risk, treatment guidelines for lipid management, clinical trials involving TG-lowering drugs, and outcomes for lipid-modifying therapies were selected for review.

RESULTS

Concern over the increasing rate of hypertriglyceridemia and its deleterious health consequences is reflected in the most recent National Cholesterol Education Program guidelines. Several lipid-lowering agents are available, including statins, fibrates, niacin, thiazolidinediones, and prescription omega-3 fatty acids. Clinical trials of these drugs have reported lowering of TG by 7% to 50%. Along with lifestyle changes, the use of combination pharmacotherapy to reduce lipid levels (including TG) may be an effective strategy in patients with dyslipidemia.

CONCLUSION

Use of strategies to manage TG levels, along with low-density lipoprotein cholesterol levels, is warranted to help reduce the risk of CHD.

Study of the pharmacokinetic interaction between simvastatin and prescription omega-3-acid ethyl esters

The coadministration of prescription omega-3-acid ethyl esters (P-OM3) with a statin may present a treatment option for patients with mixed hyperlipidemia. This open-label, randomized, 2-way crossover, drug-drug interaction study evaluated the impact of P-OM3 capsules on plasma simvastatin pharmacokinetics in 24 healthy volunteers. Under fasted conditions, 80 mg simvastatin was administered with or without 4 g P-OM3 for two 14-day periods. After 14 days of dosing to achieve steady state, no significant differences were found in either the extent (AUC(tau)) or rate (Cmax) of exposure to simvastatin or its major beta-hydroxy metabolite after coadministration of P-OM3 with simvastatin compared with administration of simvastatin alone. At steady state, the coadministration of P-OM3 capsules did not appear to affect the pharmacokinetics of simvastatin tablets. The combination of P-OM3 capsules and simvastatin appeared to be well tolerated.

Effects of docosahexaenoic acid supplementation on blood lipids, estrogen metabolism, and in vivo oxidative stress in postmenopausal vegetarian women

BACKGROUND

Vegetarians are generally deficient in long-chain n-3 fatty acids. Long-chain n-3 fatty acids have a beneficial effect on plasma lipid levels, and some studies showed that they had breast cancer suppression effect. One of the biomarkers of breast cancer risk is the ratio of urinary 2-hydroxyestrone (2-OHE(1)) to 16alpha-hydroxyestrone (16alpha-OHE(1)).

OBJECTIVE

To investigate the effect of docosahexaenoic acid (DHA, 22:6n-3) supplementation on blood lipids, estrogen metabolism and oxidative stress in vegetarians.

DESIGN

Single-blind, randomized, placebo-controlled trial.

INTERVENTIONS

Twenty-seven postmenopausal vegetarian women were recruited. After a 2-week run-in period with 6 g placebo corn oil, the subjects were subsequently randomized to receive either 6 g corn oil (n=13) or 6 g DHA-rich algae oil (2.14 g of DHA/day) (n=14) for 6 weeks. Two subjects in corn oil group withdrew before completion.

MAIN OUTCOME MEASURES

Plasma lipids, urinary 2-OHE(1) and 16alpha-OHE(1), urinary F(2)-isoprostanes and plasma alpha-tocopherol.

RESULTS

Plasma LDL-DHA and EPA level increased significantly by DHA supplementation. DHA decreased plasma cholesterol (C) levels (P=0.04), but did not influence the levels of plasma TG, LDL-C and HDL-C, alpha-tocopherol, urinary F(2)-isoprostanes, 2-OHE(1), 16alpha-OHE(1) and ratio of 2-OHE(1) to 16alpha-OHE(1) as compared to corn oil.

CONCLUSION

DHA supplementation at a dose of 2.14 g/day for 42 days decreases plasma cholesterol but neither does it show beneficial effects on estrogen metabolism, nor does it induce deleterious effects on the observed in vivo antioxidant or oxidative stress marker in postmenopausal vegetarian women.

SPONSORSHIP

A grant (# DOH89-TD-1062) from Department of Health, Executive Yuan, Taiwan.

Fish oil (Eicosapen) is less effective than metronidazole, in combination with pantoprazole and clarithromycin, for Helicobacter pylori eradication

BACKGROUND

In vitro omega-3-fatty acids (Eicosapen) are bacteriostatic to Helicobacter pylori and have a variety of immuno-modulating effects.

AIM

To investigate the efficacy and tolerability of eicosapen (E) as an antibiotic-sparing component of a triple H. pylori eradication regimen in non-ulcer dyspepsia patients in a randomized, double-blind trial.

METHODS

Non-ulcer dyspepsia patients (n=199), with a normal upper endoscopy and a positive (13)C-urea breath test (UBT) were randomly assigned to either pantoprazole, clarithromycin and metronidazole (PCM) or pantoprazole, clarithromycin and eicosapen (PCE) for 7 days. Four weeks after treatment, H. pylori eradication was determined by UBT. Symptoms were followed up to 16 months.

RESULTS

In the intention-to-treat population, PCM eradicated infection in 78% but PCE was successful in only 34% (P < 0.001). Symptomatic improvement occurred in both groups, and was not related to H. pylori eradication.

CONCLUSION

Eicosapen is unlikely to be useful in H. pylori eradication regimens.

EET homologs potently dilate coronary microvessels and activate BKCa channels

Epoxyeicosatrienoic acids (EETs) are released from endothelial cells and potently dilate small arteries by hyperpolarizing vascular myocytes. In the present study, we investigated the structural specificity of EETs in dilating canine and porcine coronary microvessels (50–140 μm ID) and activating large-conductance Ca2+-activated K+(BKCa) channels. The potencies and efficacies of EET regioisomers and enantiomers were compared with those of two EET homologs: epoxyeicosaquatraenoic acids (EEQs), which are made from eicosapentaenoic acid by the same cytochrome P-450 epoxygenase that generates EETs from arachidonic acid, and epoxydocosatetraenoic acids (EDTs), which are EETs that are two carbons longer. With EC50 values of 3–120 pM but without regio- or stereoselectivity, EETs potently dilated canine and porcine microvessels. Surprisingly, the EEQs and EDTs had comparable potencies and efficacies in dilating microvessels. Moreover, 50 nM 13,14-EDT activated the BKCa channels with the same efficacy as either 11,12-EET enantiomer at 50 nM. We conclude that coronary microvessels and BKCa channels possess low structural specificity for EETs and suggest that EEQs and EDTs may thereby also be endothelium-derived hyperpolarizing factors.

Effect of dietary oil intake on hepatic cytochrome P450 activity in the rat

The objective of the present study was to investigate whether or not different dietary oils, commonly used as drug vehicles, alter hepatic microsomal drug metabolism in the rat. Male adult Sprague-Dawley rats were administered 1 mL/kg/d of either corn, olive, sesame, or soybean oil via oral gavage for 7 days. An additional rat group was given an equal volume of water each day to serve as a control. We found that the hepatic cytochrome P450 (CYP) 3A2 protein level increased by 16% (p < 0.01) in rats given soybean oil compared with control rats. In contrast, CYP2C11 protein levels decreased by 32% (p < 0.01) in the corn oil group and by 31% (p < 0. 01) in rats given olive oil. The changes in the in vitro production of 6beta- and 2alpha-hydroxytestosterone, markers of CYP3A2 and 2C11 activities, respectively, were consistent with their protein levels, although not statistically different than controls. The results demonstrate that dietary oils may have differential effects on specific hepatic CYP isoforms and may add to the variability in metabolism when xenobiotics are administered using dietary oils as vehicles.

Regulation of gene expression by dietary fat

Dietary fat is an important macronutrient for the growth and development of all organisms. In addition to its role as an energy source and its effects on membrane lipid composition, dietary fat has profound effects on gene expression, leading to changes in metabolism, growth, and cell differentiation. The effects of dietary fat on gene expression reflect an adaptive response to changes in the quantity and type of fat ingested. Specific fatty acid-regulated transcription factors have been identified in bacteria, amphibians, and mammals. In mammals, these factors include peroxisome proliferator-activated receptors (PPAR alpha, -beta, and -gamma), HNF4 alpha, NF kappa B, and SREBP1c. These factors are regulated by (a) direct binding of fatty acids, fatty acyl-coenzyme A, or oxidized fatty acids; (b) oxidized fatty acid (eicosanoid) regulation of G-protein-linked cell surface receptors and activation of signaling cascades targeting the nucleus; or (c) oxidized fatty acid regulation of intracellular calcium levels, which affect cell signaling cascades targeting the nucleus. At the cellular level, the physiological response to fatty acids will depend on (a) the quantity, chemistry, and duration of the fat ingested; (b) cell-specific fatty acid metabolism (oxidative pathways, kinetics, and competing reactions); (c) cellular abundance of specific nuclear and membrane receptors; and (d) involvement of specific transcription factors in gene expression. These mechanisms are involved in the control of carbohydrate and lipid metabolism, cell differentiation and growth, and cytokine, adhesion molecule, and eicosanoid production. The effects of fatty acids on the genome provide new insight into how dietary fat might play a role in health and disease.

Modulation of peroxisomal and microsomal fatty acid oxidation by acetone. A comparative study between liver and kidney

The effect of acetone consumption on some microsomal and peroxisomal activities was studied in rat kidney and these results were compared with data from former investigations in liver. Acetone increased the microsomal lauric acid hydroxylation, the aminopyrine N-demethylation catalyzed by cytochrome P450 and the microsomal UDP-glucuronyltransferase activity. Also, acetone increased the peroxisomal beta-oxidation of palmitoyl CoA and catalase activities in kidney. These studies suggest that acetone is a common inducer of the microsomal and peroxisomal fatty acid oxidation, as previously shown in both starved and ethanol treated rats. Our results support the hypothesis that microsomal fatty acid omega-hydroxylation results in the generation of substrates being supplied for peroxisomal beta-oxidation. We propose that the final purpose of these linked fatty acid oxidations could be the catabolism of fatty acids or the generation of a substrate for the synthesis of glucose from fatty acids. This pathway would be triggered by acetone treatment in a similar way in liver and kidney.

Peroxisomal and microsomal fatty acid oxidation in liver of rats after chronic ethanol consumption

1. Microsomal P450 and peroxisomal fatty acid oxidation activities were studied in liver of rats after long-term ethanol consumption. 2. Ethanol increased the microsomal lauric acid omega-hydroxylation and the aminopyrine N-demethylation catalyzed by cytochrome P450. 3. Ethanol increased peroxisomal beta-oxidation of palmitoyl CoA and catalase activity in liver. 4. Both microsomal and peroxisomal activities behaved in a coordinate way in the liver of rats with long-term ethanol consumption. 5. These results would support a role of microsomal omega-hydroxylation and peroxisomal beta-oxidation of fatty acids in an extramitochondrial pathway of lipid oxidation in the liver.

Effects of chronic ethanol consumption on extramitochondrial fatty acid oxidation and ethanol metabolism by rat kidney

1. We evaluated the effects of chronic ethanol consumption on microsomal and peroxisomal fatty acid oxidation and on ethanol oxidation by the kidney. 2. When mature rats were fed 20% ethanol for 10 weeks, an increase in alcohol dehydrogenase and catalase activities were observed in the kidney. 3. Renal microsomal and peroxisomal oxidation of fatty acids also increased by the treatment, but total cytochrome P450 content did not. 4. We concluded that chronic ethanol consumption results in an increased extramitochondrial disposition of fatty acids and ethanol oxidation by the kidney.

Polyunsaturated fatty acid suppression of hepatic fatty acid synthase and S14 gene expression does not require peroxisome proliferator-activated receptor alpha

Dietary polyunsaturated fatty acids (PUFA) induce hepatic peroxisomal and microsomal fatty acid oxidation and suppress lipogenic gene expression. The peroxisome proliferator-activated receptor alpha (PPARalpha) has been implicated as a mediator of fatty acid effects on gene transcription. This report uses the PPARalpha-deficient mouse to examine the role of PPARalpha in the PUFA regulation of mRNAs encoding hepatic lipogenic (fatty acid synthase (FAS) and the S14 protein (S14)), microsomal (cytochrome P450 4A2 (CYP4A2)), and peroxisomal (acyl-CoA oxidase (AOX)) enzymes. PUFA ingestion induced mRNAAOX (2.3-fold) and mRNACYP4A2 (8-fold) and suppressed mRNAFAS and mRNAS14 by >/=80% in wild type mice. In PPARalpha-deficient mice, PUFA did not induce mRNAAOX or mRNACYP4A2, indicating a requirement for PPARalpha in the PUFA-mediated induction of these enzymes. However, PUFA still suppressed mRNAFAS and mRNAS14 in the PPARalpha-deficient mice. Studies in rats provided additional support for the differential regulation of lipogenic and peroxisomal enzymes by PUFA. These studies provide evidence for two distinct pathways for PUFA control of hepatic lipid metabolism. One requires PPARalpha and is involved in regulating peroxisomal and microsomal enzymes. The other pathway does not require PPARalpha and is involved in the PUFA-mediated suppression of lipogenic gene expression.