Enhancement of learning capacity and cholinergic synaptic function by carnitine in aging rats.

The effects of a carnitine derivative, acetyl-L-carnitine (ALCAR), on the cognitive and cholinergic activities of aging rats were examined. Rats were given ALCAR (100 mg/kg) per os for 3 months and were subjected to the Hebb-Williams tasks and a new maze task, AKON-1, to assess their learning capacity. The learning capacity of the ALCAR-treated group was superior to that of the control. Cholinergic activities were determined with synaptosomes isolated from the cortices. The high-affinity choline uptake by synaptosomes, acetylcholine synthesis in synaptosomes, and acetylcholine release from synaptosomes on membrane depolarization were all enhanced in the ALCAR group. This study indicates that chronic administration of ALCAR increases cholinergic synaptic transmission and consequently enhances learning capacity as a cognitive function in aging rats.

Differentiation of rat oval cells after activation of peroxisome proliferator-activated receptor alpha43.

Peroxisome proliferators (PPs) act as nongenotoxic tumor promoters in rodents. Their hepatocarcinogenicity requires the presence of the PP-activated receptor alpha (PPARalpha); however, the exact role played by this transcription factor in the liver, more precisely in liver cell growth and differentiation, is not known. The aim of this study was to investigate the role of PPARalpha in oval cells, which are considered to be closely related to liver stem cells, act as bipotential progenitors for the two main hepatic lineages, and have been implicated as playing a role in several models of liver carcinogenesis. We studied the PPARalpha-mediated response of primary oval cells isolated from rats fed a choline-deficient ethionine-supplemented diet (CDE diet, a regimen commonly used for the induction of oval cell proliferation in rodents) with or without cotreatment with WY14,643, a prototype PPARalpha-activator. PPARalpha was expressed at relatively low levels in primary oval cells from rats fed the CDE diet alone. In vivo treatment with WY14,643 for 2-6 weeks induced, in the oval cells, the expression of PPARalpha as well as that of the PPARalpha-responsive genes encoding fatty acyl-CoA oxidase and cytochrome P450 4A1. Moreover, the oval cell response to WY14,643 was accompanied by an overall phenotypic modulation toward the hepatocyte lineage. In addition, the PPARalpha activator induced, among the oval cells, a subpopulation of transitional cells showing features of maturing hepatocytes expressing the oncofetal marker, alpha-fetoprotein. These results show that oval cells are responsive to PPs and strongly argue for a role of PPARalpha in the differentiation/maturation of rat oval cells. In the absence of the CDE diet regimen, 9-week treatment with WY14,643 lead to the appearance of a population of large-sized cells somewhat similar to the transitional cells. However, these cells showed little expression of markers of mature hepatocytes, consistent with a block during their maturation process, i.e., they are resistant to PPARalpha-mediated differentiation. Interestingly, the phenotype of these cells resembled that of the cells usually found in neoplastic foci induced by PPs. Our results, together with previous reports, suggest the involvement of oval cells in the hepatocarcinogenicity of PPs.

Increased uncoupling protein2 mRNA in white adipose tissue, and decrease in leptin, visceral fat, blood glucose, and cholesterol in KK-Ay mice fed with eicosapentaenoic and docosahexaenoic acids in addition to linolenic acid.

The effects of n-3 polyunsaturated fatty acids (n-3PUFA) on obesity and diabetes were examined using KK-Ay mice fed with perilla oil (P), soybean oil (S), or lard (L), and those containing 30% fish oil (PF, SF, or LF), containing eicosapentaenoic acid (EPA = 9.9%) and docosahexaenoic acid (DHA = 18.0%). Perilla oil contained the largest proportion of linolenic acid (LNA = 61.9%). Computerized tomography (CT) scans showed narrower areas of visceral fat in the abdominal cross sections of groups given fish oil (PF, SF, and LF) and lower leptin levels (p < 0.05-p < 0.001) compared with controls (P, S, and L), without significant changes in energy intake and body weight. The highest plasma n-3PUFA content (21.31 +/- 0.35%) was attained with PF. This group contained 2.6-fold more plasma DHA (p < 0.001), and expressed 2.7-fold more UCP2 mRNA in white adipose tissue (p < 0.01) than in the P group. The epididymal fat pad (p < 0.05) weighed less, and levels of blood glucose (p < 0.05) and total cholesterol (p < 0.01) were reduced in PF compared with P.

Effect of n-3 fatty acid supplementation on lipid peroxidation and protein aggregation in rat erythrocyte membranes.

Human erythrocytes in the circulation undergo dynamic oxidative damage involving membrane lipid peroxidation and protein aggregation during aging. The present study was undertaken to determine the effect of n-3 fatty acid supplementation on lipid peroxidation and protein aggregation in the circulation and also the in vitro susceptibility of rat erythrocyte membranes to oxidative damage. Wistar male rats were fed a diet containing n-6 fatty acid-rich safflower oil or n-3 fatty acid-rich fish oil with an equal amount of vitamin E for 6 wk. n-3 Fatty acid content in erythrocyte membranes of rats fed fish oil was significantly higher than that of rats fed safflower oil. The degree of membrane lipid peroxidation and protein aggregation of rats fed fish oil was not significantly higher than that of rats fed safflower oil when the amounts of phospholipid hydroperoxides, thiobarbituric acid-reactive substances, and detergent-insoluble protein aggregates were measured. When isolated erythrocytes were oxidized under aerobic conditions in the presence of Fe(III), the degree of membrane lipid peroxidation of erythrocytes from rats fed fish oil was increased to a greater extent than that of rats fed safflower oil, whereas the degree of membrane protein aggregation of both groups was increased in a similar extent. Hence, n-3 fatty acid supplementation did not affect lipid peroxidation and protein aggregation in membranes of circulating rat erythrocytes, and the supplementation increased the susceptibility of isolated erythrocytes to lipid peroxidation, but not to protein aggregation, under the aerobic conditions. If a sufficient amount of vitamin E is supplied, n-3 fatty acid supplementation may give no undesirable oxidative effects on rat erythrocytes in the circulation.

Inhibitory effects of Chinese ant extract (CAE) on nephrotoxicity induced by ferric-nitrilotriacetate (Fe-NTA) in Wistar rats.

We observed the inhibitory effects of Chinese ant extract (CAE), a Chinese traditional medicine, on nephrotoxicity induced by Fe-NTA in Wistar rat. Strong positive staining with Schiff's reagent was found in the proximal tubules of the untreated control rats. In contrast, the positivity was very weak in CAE treated rats. The level of TBARS was also higher in the untreated control rats than in CAE treated rats. Meanwhile, the scavenging effect of CAE on hydroxyl radicals was analyzed by electron spin resonance (ESR) in vitro. The results indicate that CAE can efficiently prevent Fe-NTA induced nephrotoxicity through quenching free radicals mechanism.

Ginseng extract scavenges hydroxyl radical and protects unsaturated fatty acids from decomposition caused by iron-mediated lipid peroxidation.

This study was conducted to investigate whether or not the antioxidation effect of ginseng extract directly inhibits decomposition of unsaturated fatty acid caused by iron and hydrogen peroxide-induced lipid peroxidation, and whether this effect involves a hydroxyl radical-scavenging mechanism. Thiobarbituric acid-reactive substances (TBARS), gas chromatography, and electron spin resonance (ESR) spectrometer were used to measure lipid peroxidation, unsaturated fatty acid, and hydroxyl radical. The results showed TBARS formed and the loss of arachidonic acid during lipid peroxidation, and that hydroxyl radical formed by the Fenton reaction were completely inhibited by ginseng extract. This antioxidant effect of ginseng may be responsible for its wide pharmacological actions in clinical practice by a free radical reaction-inhibition mechanism.

English plantain and psyllium: lack of cross-allergenicity by crossed immunoelectrophoresis.

BACKGROUND: English plantain (Plantago lanceolata) weed pollen and psyllium (Plantago ovata) husk dust are inhalant allergens. Because of the phylogenetic relationship between these plant species, cross-allergenicity has been a concern. OBJECTIVE: The purpose of this study was to investigate the possible cross-allergenicity of plantain and psyllium. METHODS: Homologous and heterologous crossed immunoelectrophoresis (CIE) were performed using a commercial English plantain pollen extract and an extract of psyllium seed embryo. Crossed radioimmunoelectrophoresis (CRIE) was performed using sera from subjects who were RAST positive only to plantain (group A), RAST positive only to psyllium (group B), RAST positive to both plantain and psyllium (group C), or RAST negative to both (group D). RESULTS: All of the group A plantain subjects showed IgE binding to at least one of the six plantain allergens in homologous plantain CRIEs while only one of the sera from the group B subjects reacted very weakly to these plantain allergens. In homologous psyllium CRIE, all group B subjects showed pronounced IgE binding to 2 to 7 of the seven psyllium allergens. Several of the plantain subjects demonstrated only very weak binding to psyllium allergens. Heterologous CRIEs demonstrated little relevant IgE binding. CONCLUSIONS: These results indicate that there is little cross-allergenicity between psyllium husk and English plantain pollen.

Role of ascorbate in protection by nitecapone against cardiac ischemia-reperfusion injury.

The antioxidant properties of nitecapone, a catechol derivative and an inhibitor of catechol-O-methyltransferase, were reported recently. In the present study, the influence of nitecapone on isolated rat heart ischemia-reperfusion injury was investigated to elucidate its cardioprotective role. Nitecapone, administered in the perfusion buffer from the beginning of the pre-ischemic phase, significantly improved recovery of cardiac mechanical function, suppressed enzyme leakage in the coronary effluent, and minimized loss of ascorbate, compared with the control group. In rats fed a diet containing 4% ascorbate, myocardial ascorbate content in ascorbate-fed rats after ischemia-reperfusion was higher than that in control rats fed a normal diet without ischemia. However, supplemented rats did not show any beneficial effects on cardiac mechanical recovery or enzyme leakage, suggesting that maintenance of tissue ascorbate level is not the cause, but the result of the protective effects of nitecapone against cardiac ischemia-reperfusion injury. The iron-chelating effect of nitecapone was also tested. It was confirmed, using electron spin resonance, that 50 microM nitecapone chelates the same concentration of iron released from the heart into the coronary effluent. Hence, the iron-chelating ability of nitecapone may be responsible, at least in part, for its cardioprotective effects in ischemia-reperfusion injury.

Bone mineral density changes in distracted callus stimulated by pulsed direct electrical current.

To evaluate the effect of application of pulsed direct current electrical stimulation to callus tissue, a 1-cm bone-lengthening model using an external lengthener was applied to rabbit tibia. Twenty-microampere pulsed direct current was applied 12 hours daily from the day of osteotomy until 40 days after the completion of lengthening. The area, bone mineral content, and bone mineral density of the distracted callus and of the proximal and distal segments of the tibia were evaluated using dual-energy xray absorptiometry. The absolute and relative values of bone mineral density of the electrically stimulated callus were significantly increased as compared with those in the control group. Pulsed direct current electrical stimulation may be indicated in bone lengthening to stimulate the poorly mineralized callus, and may shorten the overall time course of leg lengthening.

Effects of natural antioxidant ginkgo biloba extract (EGB 761) on myocardial ischemia-reperfusion injury.

Recently, it was reported that Ginkgo biloba extract (EGb 761), which is known to have antioxidant properties, also has antiarrhythmic effects on cardiac reperfusion-induced arrhythmias. In the present study, effects of EGb 761 on cardiac ischemia-reperfusion injury were investigated from the point of view of recovery of mechanical function as well as the endogenous antioxidant status of ascorbate. Isolated rat hearts were perfused using the Langendorff technique, and 40 min of global ischemia were followed by 20 min of reperfusion. EGb 761 improved cardiac mechanical recovery and suppressed the leakage of lactate dehydrogenase (LDH) during reperfusion. Furthermore, EGb 761 diminished the decrease of myocardial ascorbate content after 40 min of ischemia and 20 min of reperfusion. Interestingly, EGb 761 also suppressed the increase of dehydroascorbate. These results indicate that EGb 761 protects against cardiac ischemia-reperfusion injury and suggest that the protective effects of EGb 761 depend on its antioxidant properties.

[Knowledges of foodstuffs in relation to adult diseases in Japanese students--results from Japan Know Your Body Study].

As part of developing the Know Your Body (KYB) program for Japan, a questionnaire survey was administered assessing knowledge, attitudes, and behavior regarding cigarette smoking, alcohol drinking, dietary lifestyle and exercise. The subjects, about 13,000 in total, were students in elementary, junior and senior high schools in 9 prefectures. The main results concerning knowledge of foods that cause or prevent adult diseases are as follows: 1) Correct responses on the relationship of excessive salt intake and hypertension were made by 39% of males and 41% of female in the fifth grade of elementary school. In the third grade of junior high school, the percentage of correct answer for the same question increased to 80% of males and females, and in the third grade of senior high school, it rose to 90% of males and 91% of females. No clear sex difference was seen in all the grades of school. 2) Less than 23% of the students from the first to fourth grade of elementary school knew the word "cholesterol" and could distinguish high cholesterol foods. In the sixth grade of elementary school, more than 50% of students knew the word "cholesterol". In the third grade of junior high school, more than 50% of students could distinguish high cholesterol foods correctly and recognized the relationship of excessive cholesterol intake to heart disease. These results provide a basis for determination of the age for introducing nutrition education. 3) The percentage of correct answers for distinguishing green-yellow vegetables, showed a clear sex differential. The percentage of correct answers concerning dietary fiber was 75% for males and 81% for females in senior high school.

Protective effects of glutathione against lipid peroxidation in chronically iron-loaded mice.

To elucidate the protective effects of glutathione against iron-induced peroxidative injury, changes in the hepatic glutathione metabolism were studied in chronically iron-loaded mice. When the diets of the mice were supplemented with carbonyl iron, iron deposition occurred primarily in the parenchymal cells of the liver. In addition, expiratory ethane production was elevated, suggesting an enhancement in lipid peroxidation. In iron-loaded mice, the total hepatic glutathione contents were higher (6.21 +/- 0.53 mumol/g wet wt.) than in control mice (4.61 +/- 0.31 mumol/g wet wt.), primarily due to an increase in the reduced glutathione contents. The value of oxidized glutathione was also higher (98.5 +/- 8.1 nmol/g wet wt.) than in the controls (60.8 +/- 9.5 nmol/g wet wt.), and the ratio of oxidized glutathione to total glutathione increased. The excretion rate of glutathione from the hepatocytes in iron-loaded mice also increased. These observations suggest that chronic iron-loading of mice stimulates lipid peroxidation and oxidation of glutathione and that peroxidized molecules may be catabolized using reduced glutathione.

The effects of intraperitoneal injection of 6-hydroxydopamine on the turnover and the levels of the brain catecholamines and the levels of plasma corticosterone in rats.

1. The effects of intraperitoneal injection of 6-hydroxydopamine (6-OHDA) on the levels and the turnover of brain catecholamines and the levels of plasma corticosterone were studied in rats. 2. Two weeks after intraperitoneal injection of 6-OHDA (150 mg/kg) a virtually complete disappearance of cardiac noradrenaline was observed. 3. An increment and an accelerated turnover of noradrenaline in the hypothalamus was observed 2 weeks after peripheral administration of 6-OHDA (150 mg/kg). 4. There was no change in the levels and the turnover of noradrenaline in the cortex of the rats so treated. 5. There was not change in the levels and the turnover of dopamine in either the hypothalamus or the cortex of the 6-OHDA-treated rats. 6. An increment and an accelerated turnover of hypothalamic noradrenaline were not associated with any change in plasma corticosterone.