Docosahexaenoic Acid Increases Vesicular Glutamate Transporter 2 Protein Levels in Differentiated NG108-15 Cells.

Docosahexaenoic acid (DHA; 22:6n-3), which is enriched in the neuronal membrane, plays a variety of roles in the brain. Vesicular glutamate transporters (VGLUTs) are responsible for incorporating glutamine into synaptic vesicles. We investigated the influence of DHA on the fatty acid profile and the levels of VGLUT1 and VGLUT2 proteins in differentiated NG108-15 cells, a neuroblastoma-glioma hybrid cell line. NG108-15 cells were plated and 24 h later the medium was replaced with Dulbecco's modified Eagle's medium supplemented with 1% fetal bovine serum, 0.2 mM dibutyryl cAMP, and 100 nM dexamethasone, which was added to induce differentiation. After 6 d, the amount of DHA in the cells was increased by addition of DHA to the medium. VGLUT2 levels were increased by the addition of DHA. These data indicate that DHA affected the levels of VGLUT2 in NG108-15 cells under differentiation-promoting conditions, suggesting that DHA affects brain functions involving VGLUT2.

Fully hydrogenated canola oil extends lifespan in stroke-prone spontaneously hypertensive rats.

BACKGROUND: Canola oil (Can) and several vegetable oils shorten the lifespan of stroke-prone spontaneously hypertensive rats (SHRSP). Although similar lifespan shortening has been reported for partially hydrogenated Can, the efficacy of fully hydrogenated oils on the lifespan remains unknown. The present study aimed to investigate the lifespan of SHRSP fed diets containing 10 % (w/w) of fully hydrogenated Can (FHCO) or other oils. METHODS: Survival test: Upon weaning, male SHRSP were fed a basal diet for rodents mixed with one of the test oils -i.e., FHCO, Can, lard (Lrd), and palm oil (Plm) throughout the experiment. The animals could freely access the diet and drinking water (water containing 1 % NaCl), and their body weight, food intake, and lifespan were recorded. Biochemical analysis test: Male SHRSP were fed a test diet with either FHCO, Can, or soybean oil (Soy) under the same condition, except to emphasize effects of fat, that no NaCl loading was applied. Soy was used as a fat source in the basal diet and was set the control group. Blood pressures was checked every 2 weeks, and serum fat levels and histological analyses of the brain and kidney were examined after 7 or 12 weeks of feeding. RESULTS: During the survival study period, the food consumption of FHCO-fed rats significantly increased (15-20 % w/w) compared with that of rats fed any other oil. However, the body weight gain in the FHCO group was significantly less (10-12 %) than that in the control group at 9-11 weeks old. The FHCO (> 180 days) intervention had the greatest effect on lifespan, followed by the Lrd (115 ± 6 days), Plm (101 ± 2 days), and Can (94 ± 3 days) diets. FHCO remarkably decreased the serum cholesterol level compared with Can and the systolic blood pressure from 12 to 16 weeks of age. In addition, while some rats in the Can group exhibited brain hemorrhaging and renal dysfunction at 16 weeks old, no symptoms were observed in the FHCO group. CONCLUSION: This current study suggests that complete hydrogenation decreases the toxicity of Can and even prolongs the lifespan in SHRSP.

Dietary soybean oil, canola oil and partially-hydrogenated soybean oil affect testicular tissue and steroid hormone levels differently in the miniature pig.

The present study was conducted to examine the influence of dietary canola oil (CAN) and partially-hydrogenated soybean oil (HSO) compared to soybean oil (SOY, control) on the morphology and function of testes using miniature pigs as the test subject. Male miniature pigs were fed a diet containing 10%SOY, 9%CAN+1%SOY, or 9%HSO+1%SOY for 18 months. The scheduled autopsies revealed no abnormalities in histopathological examination of the major organs, except the testes. Atrophy of the seminiferous tubules and hyperplasia in the Leydig cells were found in the SOY and CAN groups. DNA microarray analysis indicated downregulation in the CAN and the HSO groups of genes encoding for gonadotropins in the pituitary gland and of enzymes and proteins involved in steroid hormone metabolism in the testes, compared to the SOY group. Plasma levels of sex hormones in the CAN and HSO groups tended to be higher and testosterone and dihydrotestosteorne in the HSO group were significantly higher than in the SOY group. These results demonstrate that testes are morphologically and functionally affected by the dietary oils, while the plasma steroid hormone levels do not necessarily reflect the gene expression, probably owing to feedback regulation via the gonadal hormones in the hypothalamus-pituitary-gonadal axis.

Medicines and Vegetable Oils as Hidden Causes of Cardiovascular Disease and Diabetes.

BACKGROUND: Positive associations have been observed between cardiovascular disease (CVD) and type 2 diabetes mellitus (DM), but their causal relationship has not been clarified. Nevertheless, guidelines from relevant medical societies recommend using cholesterol lowering medication (statin) for both types of patients. Medicines with several different action mechanisms have been developed, and the effectiveness of different lifestyle modifications has been studied extensively for the prevention of DM, which was successful in improving clinical marker status in relatively short-term treatments, but none have been shown to be effective in improving long-term outcomes (mortality from CVD and all causes). SUMMARY: Statin-induced suppression of prenyl intermediates in the cholesterol biosynthetic pathway has been linked to stimulated atherosclerosis and heart failure. On the other hand, certain types of vegetable oil and hydrogenated oil shortened the survival of stroke-prone spontaneously hypertensive rats by decreasing platelet number, increasing hemorrhagic tendency and damaging kidney functions, which could not be accounted for by their fatty acid and phytosterol compositions. These vegetable oils and medicines such as statin and warfarin share, in part, a common mechanism to inhibit vitamin K2-dependent processes, which was interpreted to lead to increased onset of CVD, DM, chronic kidney disease, bone fracture and even mental disorder. Impaired vitamin K2-dependent processes by some types of vegetable oils and medicines, but not plasma high low density lipoprotein cholesterol, were proposed as the cause of CVD, DM and other lifestyle-related diseases. High n-6/n-3 fatty acid ratio of ingested foods, but not animal fats, was emphasized to be another risk factor for many of the diseases described above. KEY MESSAGES: To date, no randomized controlled trials (RCTs) have been performed to prove the above interpretation. However, the opposite types of RCT trials have been performed by increasing the intake of high-linoleic vegetable oils and reducing that of animal fats, which resulted in increased CVD and all-cause mortality. The amounts of these vegetable oils to exhibit adverse effects in animal studies are not huge (<6 energy %), which should not be overlooked nor disregarded.

Effects of arachidonic acid intake on inflammatory reactions in dextran sodium sulphate-induced colitis in rats.

The aim of this study was to investigate the effects of the administration of oral arachidonic acid (AA) in rats with or without dextran sulphate sodium (DSS)-induced inflammatory bowel disease. Male Wistar rats were administered AA at 0, 5, 35 or 240 mg/kg daily by gavage for 8 weeks. Inflammatory bowel disease was induced by replacing drinking water with 3 % DSS solution during the last 7 d of the AA dosing period. These animals passed loose stools, diarrhoea and red-stained faeces. Cyclo-oxygenase-2 concentration and myeloperoxidase activity in the colonic tissue were significantly increased in the animals given AA at 240 mg/kg compared with the animals given AA at 0 mg/kg. Thromboxane B2 concentration in the medium of cultured colonic mucosae isolated from these groups was found to be dose-dependently increased by AA, and the increase was significant at 35 and 240 mg/kg. Leukotriene B4 concentration was also significantly increased and saturated at 5 mg/kg. In addition, AA at 240 mg/kg promoted DSS-induced colonic mucosal oedema with macrophage infiltration. In contrast, administration of AA for 8 weeks, even at 240 mg/kg, showed no effects on the normal rats. These results suggest that in rats with bowel disease AA metabolism is affected by oral AA, even at 5 mg/kg per d, and that excessive AA may aggravate inflammation, whereas AA shows no effects in rats without inflammatory bowel disease.

Three dissimilar high fat diets differentially regulate lipid and glucose metabolism in obesity-resistant Slc:Wistar/ST rats.

Epidemiologic and ecologic studies suggest that dietary fat plays an important role in the development of obesity. Certain Wistar rat strains do not become obese when fed high-fat diets unlike others. In a preliminary study, we confirmed that Slc:Wistar/ST rats did not become obese when fed high-fat diets. The mechanisms governing the response of hepatic lipid-metabolizing enzymes to large quantities of dietary lipids consumed by obesity-resistant animals are unknown. The aim of the present study is to examine how obesity-resistant animals metabolize various types of high-fat diets and why they do not become obese. For this purpose, male Slc:Wistar/ST rats were fed a control low-fat diet (LS) or a high-fat diet containing fish oil (HF), soybean oil (HS), or lard (HL) for 4 weeks. We observed their phenotypes and determined lipid profiles in plasma and liver as well as mRNA expression levels in liver of genes related to lipid and glucose metabolism using DNA microarray and quantitative reverse transcriptase polymerase chain analyses. The body weights of all dietary groups were similar due to isocaloric intakes, whereas the weight of white adipose tissues in the LS group was significantly lower. The HF diet lowered plasma lipid levels by accelerated lipolysis in the peroxisomes and suppressed levels of very-low-density lipoprotein (VLDL) secretion. The HS diet promoted hepatic lipid accumulation by suppressed lipolysis in the peroxisomes and normal levels of VLDL secretion. The lipid profiles of rats fed the LS or HL diet were similar. The HL diet accelerated lipid and glucose metabolism.

Arachidonic acid supplementation during gestational, lactational and post-weaning periods prevents retinal degeneration induced in a rodent model.

Fatty acids and their derivatives play a role in the response to retinal injury. The effects of dietary arachidonic acid (AA) supplementation on N-methyl-N-nitrosourea (MNU)-induced retinal degeneration was investigated in young Lewis rats during the gestational, lactational and post-weaning periods. Dams were fed 0·1, 0·5 or 2·0% AA diets or a basal (< 0·01% AA) diet. On postnatal day 21 (at weaning), male pups received a single intraperitoneal injection of 50 mg MNU/kg or vehicle, and were fed the same diet as their mother for 7 d. Retinal apoptosis was analysed by the terminal deoxynucleotidyl transferase-mediated dUTP digoxigenin nick-end labelling (TUNEL) assay 24 h after the MNU treatment, and retinal morphology was examined 7 d post-MNU. Histologically, all rats that received MNU and were fed the basal and 0·1% AA diets developed retinal degeneration characterised by the loss of photoreceptor cells (disappearance of the outer nuclear layer and the photoreceptor layer) in the central retina. The 0·5 and 2·0% AA diets rescued rats from retinal damage. Morphometrically, in parallel with the AA dose (0·5 and 2·0% AA), the photoreceptor ratio significantly increased and the retinal damage ratio decreased in the central retina, compared with the corresponding ratios in basal diet-fed rats. In parallel with the increase in serum and retinal AA levels and the AA:DHA ratio, the apoptotic index in the central retina was dose-dependently decreased in rats fed the 0·5 and 2·0% AA diets. In conclusion, an AA-rich diet during the gestation, lactation and post-weaning periods rescued young Lewis rats from MNU-induced retinal degeneration via the inhibition of photoreceptor apoptosis. Therefore, an AA-enriched diet in the prenatal and postnatal periods may be an important strategy to suppress the degree of photoreceptor injury in humans.

Biochemical responses to dietary α-linolenic acid restriction proceed differently among brain regions in mice.

Previously, we noted that the dietary restriction of α-linolenic acid (ALA, n-3) for 4 weeks after weaning brought about significant decreases in the BDNF content and p38 MAPK activity in the striatum of mice, but not in the other regions of the brain, compared with an ALA- and linoleic acid (LNA, n-6)-adequate diet. In this study, we examined whether a prolonged dietary manipulation induces biochemical changes in other regions of the brain as well. Mice were fed a safflower oil (SAF) diet (ALA-restricted, LNA-adequate) or a perilla oil (PER) diet (containing adequate amounts of ALA and LNA) for 8 weeks from weaning. The docosahexaenoic acid (DHA, 22:6n-3) contents and p38 MAPK activities in the cerebral cortex, striatum and hippocampus were significantly lower in the SAF group. The BDNF contents and protein kinase C (PKC) activities in the cerebral cortex as well as in the striatum, but not in the hippocampus, were significantly lower in the SAF group. These data indicate that the biochemical changes induced by the dietary restriction of ALA have a time lag in the striatum and cortex, suggesting that the signal is transmitted through decreased p38 MAPK activity and BDNF content and ultimately decreased PKC activity.

Testosterone-lowering activity of canola and hydrogenated soybean oil in the stroke-prone spontaneously hypertensive rat.

Canola and some other types of oil unusually shorten the survival of stroke-prone spontaneously hypertensive rats (SHRSP), compared with soybean oil, perilla oil and animal fats. Since differential effects of canola and soybean oil on steroid hormone metabolism were suggested by a preliminary DNA microarray analysis as a reason for this, the steroid hormone levels in the serum and tissues of SHRSP fed different oils were investigated. The testosterone levels in the serum and the testes were found to be significantly lower in the canola oil group than in the soybean oil group, while no significant differences were detected in the corticosterone and estradiol levels in tissues. In a second experiment, it was found that hydrogenated soybean oil, with a survival-shortening activity comparable to that of canola oil, also decreased the testosterone level in testes to a similar degree. The testosterone-lowering activity of canola and hydrogenated soybean oil observed in SHRSP was considered in relation to other factors possibly affecting the physiology of SHRSP.

Similar changes in clinical and pathological parameters in Wistar Kyoto rats after a 13-week dietary intake of canola oil or a fatty acid composition-based interesterified canola oil mimic.

Canola oil (CO) given as a dietary fat deteriorates hypertension-related condition and shortens the life of stroke-prone spontaneously hypertensive rats (SHRSP). Although substances other than fatty acids have been presumed as causatives, CO mimics consisting of oils other than CO also shorten the life. In this study we intended to examine whether or not fatty acid composition unique to CO participates in the adverse effect. CO or an interesterified CO mimic (ICOM) consisting of safflower oil, flaxseed oil and erucic acid was fed as a dietary fat for 13 weeks to Wistar Kyoto (WKY) rats, and clinical and pathological signs were compared. WKY rats were used to avoid the difficulty in evaluating the results in SHRSP due to irregular deterioration in conditions by stroke. Compared to a standard diet, both diets containing CO or ICOM similarly elevated blood pressure, increased plasma lipids, activated hepatic glucose-6-phosphate dehydrogenase, decreased platelets, shortened blood coagulation times and induced abnormalities in the kidney. Thus, CO-specific fatty acid composition appeared to affect the pathophysiology of the rat and produce consequent aggravation of pathological status, especially in SHRSP. However, the existence of causative factors other than fatty acids was suggested by increased neutrophil count exclusively induced by CO.

Dietary intake of rapeseed oil as the sole fat nutrient in Wistar rats--lack of increase in plasma lipids and renal lesions.

Dietary rapeseed (canola) oil (CO) given as the only fat nutrient shortens life in stroke-prone spontaneously hypertensive rats (SHRSP), compared with SHRSP given soybean oil (SO) instead of CO. CO ingestion increases plasma lipids and causes renal lesions in SHRSP and in spontaneously hypertensive rats (SHR), and increases plasma lipids also in Wistar Kyoto (WKY) rats, a normotensive counterpart of SHR. This study examined whether or not such unfavorable effects of CO are restricted to these closely related strains. For this purpose Wistar rats, the strain from which these strains were derived, were fed a diet containing 10% CO or SO as the sole fat nutrient for 10 weeks, and changes in clinical signs, urinalysis, blood biochemistry and pathology were compared. CO ingestion did not induce any abnormalities in Wistar rats, except significant increases in plasma concentrations of aldosterone and Na(+), compared with the SO group. Thus, the unfavorable effects of CO ingestion appear to be restricted to SHRSP and its closely related strains. The role of increased aldosterone and Na(+ )in the unfavorable events caused by CO in SHRSP, SHR and WKY rats, and any factors which could induce such increases in aldosterone and Na(+), remain to be elucidated.

Different effects of 26-week dietary intake of rapeseed oil and soybean oil on plasma lipid levels, glucose-6-phosphate dehydrogenase activity and cyclooxygenase-2 expression in spontaneously hypertensive rats.

We intended to determine whether or not dietary canola oil (CO) elevates plasma lipids and oxidative stress, since both of these are, possibly, related to the CO-induced life shortening through exacerbation of hypertension-associated vascular lesions found in stroke-prone spontaneously hypertensive rats (SHRSP). Spontaneously hypertensive rats (SHR) were used in this study to avoid a potential bias in the results due to the irregular death by stroke seen in SHRSP. SHR were fed for 26 weeks on a chow containing either, 10 wt/wt% of CO or soybean oil (SO), i.e., the control. Elevated plasma lipids and glucose-6-phosphate dehydrogenase (G6PD) activation in the liver and erythrocyte were found in SHR fed CO compared to that fed SO, while anti-oxidative enzymes other than G6PD were not activated. The CO diet brought about significant vascular lesions in the kidney, in which abundant cyclooxygenase-2 (COX-2) positive foci were immunochemically located in the juxtaglomerular apparatus. These results suggest that dietary CO induces a hyperlipidemic condition, in which G6PD may serve as an NADPH provider, and aggravates genetic diseases in SHR (also, probably, in SHRSP). The increased COX-2 expression indicates a role of renin-angiotensin-aldosterone system activation in the increased vascular lesions, whereas the effects of oxidative stress remain unclear.

Dietary lipids impacts on healthy ageing.

Healthy ageing is gaining attention in the lipid nutrition field. As in vivo biomarkers of healthy ageing, we have evaluated the survival, learning/memory performance, and physical potencies in rodents fed a diet supplemented with high-linoleic acid (LNA, omega6) safflower oil or high-alpha-linolenic acid (ALA, omega3) perilla oil for long periods. The results suggested that perilla oil with a low omega6/omega3 ratio is beneficial for healthy ageing. In order to address this issue further, we determined the survival of stroke-prone SHR (SHRSP) rats fed a conventional rodent diet supplemented with 10% fat or oil. Survival was longer with omega3-rich oils compared with omega6-rich oils. However, some kinds of vegetable oils and hydrogenated oils shortened the survival of SHRSP rats to an unusual degree (ca. 40% compared with that of omega6-rich oil) that could not be accounted for by the fatty acid and phytosterol composition of the oils. The observed decrease in platelet counts was associated with pathological changes in the kidney and other organs. Dihydro-vitamin K1 is proposed as a likely candidate as a stroke-stimulating factor in hydrogenated oils. Thus, factors other than fatty acids (omega6/omega3 balance) and phytosterols must be taken into account when fats and oils are evaluated in relation to healthy ageing.

Antiinflammatory effect of topically applied propolis extract in carrageenan-induced rat hind paw edema.

The antiinflammatory effect of an ointment containing propolis extract (3%-7%) was examined using carrageenan-induced hind paw edema in rats. Treatment with the ointment inhibited the edema moderately, and the inhibition was significant at 5% and 7%. Additionally, the effect of the ointment on chemotaxis of human polymorphonuclear leukocytes (PMNs) was investigated using the agarose plate method. Migration of PMNs toward zymosan-treated serum was inhibited in the presence of 5% propolis ointment. These results demonstrate that topical application of propolis extract is effective in inhibiting carrageenan-induced rat hind paw edema, and its inhibitory effect on the chemotaxis of PMNs may also contribute to the antiinflammatory effect.

Exploration for unknown substances in rapeseed oil that shorten survival time of stroke-prone spontaneously hypertensive rats. Effects of super critical gas extraction fractions.

To identify the causative substances for the shortening of survival time by rapeseed (Canola) oil in stroke-prone spontaneously hypertensive rats (SHRSP), SHRSP were fed on a standard chow supplemented with 10 w/w% soybean oil (control), rapeseed oil, one of the fractions of rapeseed oil obtained by super critical gas extraction (SCE) under a pressure of 180-bar or 350-bar, at 40 degrees C, or the residue from the extraction (with 0.5% NaCl in drinking water). In another series of experiment, SHRSP were fed for 8 weeks on the above-mentioned diets without salt loading and autopsied. Fatty acid compositions in these diets were similar, except in the soybean oil diet, and phytosterol contents were: (diet containing) 180-bar fraction>residue>rapeseed oil>350-bar fraction>soybean oil. Survival times in the rapeseed oil, 350-bar fraction and residue groups were shorter than, whereas that in the 180-bar fraction was similar to in the soybean oil group. In the 8-week feeding experiment, chronic nephropathy was found frequently in the groups other than the soybean oil group. The heart weights were higher in the rapeseed oil and residue groups. Cerebral necrosis was found in the residue group. Taken together, the followings are concluded, (1) Neither the fatty acid composition, nor the amount of phytosterols in the diets appeared to be decisive in the shortening of life. (2) SCE appeared to produce a safe (180-bar) fraction, though it failed to separate clearly the causative substances into specific fractions. (3) The factors that facilitate the genetic disease of SHRSP appear to exist in rapeseed oil. However, they might not be identical to those responsible for the life-shortening, since there were no findings common across the rapeseed oil, 350-bar and residue groups, which showed similar life-shortening.

Rapeseed oil ingestion and exacerbation of hypertension-related conditions in stroke prone spontaneously hypertensive rats.

Two groups of 20 stroke prone spontaneously hypertensive rats (SHRSP) at 5 weeks old were fed a diet containing 10 w/w% rapeseed (canola) oil or soybean oil as the only dietary fat, and given drinking water containing 1% NaCl. Life span of the canola oil group (62+/-2 days) was shorter than that of the soybean oil group (68+/-3 days). Stroke-related symptoms were observed in every animal, but the onset of those in the canola oil group, at 47+/-1 days after starting the administration was earlier than that in the soybean oil group, 52+/-2 days. Incidence of cerebral hemorrhage was similar in these groups, and no differences were found between lesions of organs in the groups. In another experiment, two groups of ten SHRSP at 5 weeks of age were fed the defatted diet and given canola oil or soybean oil by gavage at 10 w/w% of consumed food for 4 weeks without NaCl loading. After the 4-week administration, mean systolic blood pressure in the canola oil group and the soybean oil group were 233+/-2 and 223+/-0.3 mmHg, respectively. Phytosterol levels in both plasma and erythrocyte membranes reflected those contained in the oils ingested. Na(+), K(+)-ATPase activities in the brain, heart and kidney were enhanced in the canola oil group. These results indicate that promotion of hypertension-related deterioration in organs is likely to have relevance to the short life span in the canola oil group. Enhanced Na(+), K(+)-ATPase activity by phytosterols in the oil ingested may play a role in these changes.