Japanese-style Diet Research Articles

P14-030-23 Japanese-Style Diet Is Associated With Low Prevalence of Depressive Symptoms: Japan Epidemiology Collaboration on Occupational Health Study

P14-030-23 Japanese-Style Diet Is Associated With Low Prevalence of Depressive Symptoms: Japan Epidemiology Collaboration on Occupational Health Study

Effects of Both Japanese-Style Dietary Patterns and Nutrition on Falling Incidents among Community-Dwelling Elderly Individuals: A Cross-Sectional Study.

Approximately 20% of the community-dwelling Japanese elderly (≥65 years) experience falling annually, with injury frequency rising with age. Increased nursing home admission/hospitalization risk influences healthy aging and QOL. Nutrition for musculoskeletal health is necessary, though the relationship of falling with nutritional status in the elderly is largely unknown. We investigated falling incidents and nutritional status, including a Japanese-style diet in a community-dwelling cohort. Using a cross-sectional design, 186 subjects (median age 83.0 years, males/females 67/119) were analyzed. Oral and systemic health conditions were assessed. A brief-type self-administered diet history questionnaire (BDHQ) was given for nutritional status. Analysis of covariance (adjusted for gender, age, BMI, articular disease/osteoporosis history, present tooth number, educational level) and the Japanese-Mediterranean diet (jMD) score adapted for Japan were used. The jMD score and falling incidents were significantly associated, with point increases related to a significantly decreased falling risk of 28% (OR: 0.72; 95%CI: 0.57-0.91). Of the 13 jMD food components, fish, eggs, and potatoes had a significant relationship with reduced falling, while significant associations of intake of animal protein, potassium, magnesium, zinc, and cholesterol (p < 0.05) were also observed. The results suggest that the jMD dietary pattern is an important factor for the prevention of falling incidents in elderly individuals.

Relationships between Food Production Experience and the Behavior, Attitude, and Knowledge of Dietary Recommendations among Japanese Adults: A Cross-Sectional Study.

The Japanese Ministry of Agriculture, Forestry, and Fisheries proposed to educate more people in food production as one of the objectives of the Basic Plan for Food and Nutrition Education Promotion. This cross-sectional study aims to elucidate the relationship between food production experience (agricultural, forestry, and fishery experiences) and the behavior, attitude, and knowledge of dietary recommendations among Japanese adults. This study was conducted using data obtained from the “Survey on Dietary Habits and Agriculture, Forestry, and Fishery Experiences (2019)”. This survey was conducted by mailing paper questionnaires to respondents aged 20–69 years living in 17 regions across Japan. The independent variable was food production experience. The dependent variables were each of the 13 goals of the dietary guidelines in Japan, the total score for adherence to the 13 items (low scores indicate good adherence), adherence to a Japanese-style diet, and four items on the attitude and knowledge of dietary recommendations. I also examined the association between the point in life the food production experience occurred and the above outcomes. The data obtained from 3461 participants aged 20 to 69 years were used for multivariate logistic and linear regression analyses. Food production experience was positively associated with an improved behavior, attitude, and knowledge of dietary recommendations among adults in Japan. The study found a strong relationship with food production experiences in adulthood.

Japanese-Style Diet and Cardiovascular Disease Mortality: A Systematic Review and Meta-Analysis of Prospective Cohort Studies.

This systematic review and meta-analysis elucidate the effects of the Japanese-style diet and characteristic Japanese foods on the mortality risk of cardiovascular disease (CVD), cerebrovascular disease (stroke), and heart disease (HD). This review article followed the PRISMA guidelines. A systematic search in PubMed, The Cochrane Library, JDreamIII, and ICHUSHI Web identified prospective cohort studies on Japanese people published till July 2020. The meta-analysis used a random-effects model, and heterogeneity and publication bias were evaluated with I2 statistic and Egger’s test, respectively. Based on inclusion criteria, we extracted 58 articles, including 9 on the Japanese-style diet (n = 469,190) and 49 (n = 2,668,238) on characteristic Japanese foods. With higher adherence to the Japanese-style diet, the pooled risk ratios (RRs) for CVD, stroke, heart disease/ischemic heart disease combined (HD/IHD) mortality were 0.83 (95% CI, 0.77–0.89, I2 = 58%, Egger’s test: p = 0.625, n = 9 studies), 0.80 (95% CI, 0.69–0.93, I2 = 66%, Egger’s test: p = 0.602, n = 6 studies), and 0.81 (95% CI, 0.75–0.88, I2 = 0%, Egger’s test: p = 0.544, n = 6 studies), respectively. Increased consumption of vegetables, fruits, fish, green tea, and milk and dairy products decreased the RR for CVD, stroke, or HD mortality. Increased salt consumption elevated the RR for CVD and stroke mortality. Increased consumption of dietary fiber and plant-derived protein decreased the RR for CVD, stroke, and HD/IHD mortality. The Japanese-style diet and characteristic Japanese foods may reduce CVD mortality. Most studies conducted diet surveys between 1980 and the 1990s. This meta-analysis used articles that evaluated the same cohort study by a different method. A new large-scale cohort study matching the current Japanese dietary habits is needed to confirm these findings.

Relationship between the Japanese-style diet, gut microbiota, and dementia: A cross-sectional study

ObjectivePrevious studies have shown associations between the gut microbiota, microbial metabolites, and cognitive decline. However, the effect of the dietary composition on such associations has not been fully investigated. The aims of this study were to evaluate the relationships between adherence to a Japanese-style diet, the gut microbiota, and cognitive decline. Furthermore, we aimed to evaluate the three forms of the Japanese diet index (JDI; the conventional [JDI9], updated [JDI12], and a newly modified JDI) to determine which would show the closest relationships with cognition and the gut microbiota. MethodsWe performed a cross-sectional subanalysis of data from a prospective hospital-based cohort study. We assessed the patients’ demographic characteristics, dietary composition, risk factors, cognitive function, brain imaging, gut microbiome, and microbial metabolites. On the basis of previous studies, a nine-component traditional JDI (JDI9), a 12-component modern JDI (JDI12), and a 12-component revised JDI (rJDI12), were defined. We evaluated the relationships between the JDI scores, cognitive function, and the gut microbiome and microbial metabolites using multivariable logistic regression analyses. ResultsWe analyzed data from 85 eligible participants (61% women; mean age: 74.6 ± 7.4 y). Compared with participants who had dementia, those without dementia were more likely to consume foods in the JDI12, including fish and shellfish (64.5 versus 39.1%, P = 0.048), mushrooms (61.3 versus 30.4%, P = 0.015), soybeans and soybean-derived foods (62.9 versus 30.4%, P = 0.013), and coffee (71 versus 43.5%, P = 0.024). There were non-significant trends toward lower fecal concentrations of gut microbial metabolites in participants with a more traditional Japanese diet. Participants with dementia had lower JDI scores than those without dementia (dementia versus non-dementia, median JDI9 score: 5 versus 7, P = 0.049; JDI12: 7 versus 8, P = 0.017; and rJDI12: 7 versus 9, P = 0.006, respectively). ConclusionsAdherence to a traditional Japanese diet was found to be inversely associated with cognitive decline and tended to be associated with lower concentrations of gut microbial metabolites.

The Major Source of Antioxidants Intake From Typical Diet Among Rural Farmers in North-eastern Japan in the 1990s.

BackgroundPrevious Japanese studies have led to the erroneous conclusion of antioxidant capacity (AOC) intakes of the overall Japanese diet due to limitations in the number and types of food measured, especially in rice and seafood intake. The aims of the study were to construct an AOC database of foods representative of the typical Japanese diet and to clarify the high contributors to AOC intake from the overall diet of the Japanese population.MethodsCommonly consumed foods were estimated using 3-day dietary records (DRs) over the four seasons among 55 men and 58 women in Japan. To generate an AOC database suitable for the typical Japanese diet, hydrophilic (H-)/lipophilic (L-) oxygen radical absorbance capacity (ORAC) values of foods in each food group were measured via validated methods using the food intake rankings. Subsequently, we estimated the AOC intake and the AOC characteristics of a typical Japanese diet.ResultsOf 989 food items consumed by the participants, 189 food items were measured, which covered 78.8% of the total food intake. The most commonly consumed types of antioxidant-containing food were tea, soybean products, coffee, and rice according to H-ORAC, and soybean products, fish and shellfish, vegetables, and algae according to L-ORAC.ConclusionsThe characteristics of high AOC intake in rice and seafood more appropriately reflected the Japanese-style diet. Further studies are expected to clarify the association between food-derived AOC and its role in preventing or ameliorating lifestyle-related diseases.

Pharmacological restoration of autophagy reduces hypertension-related stroke occurrence

ABSTRACT The identification of the mechanisms predisposing to stroke may improve its preventive and therapeutic strategies in patients with essential hypertension. The role of macroautophagy/autophagy in the development of hypertension-related stroke needs to be clarified. We hypothesized that a defective autophagy may favor hypertension-related spontaneous stroke by promoting mitochondrial dysfunction. We studied autophagy in the stroke-prone spontaneously hypertensive (SHRSP) rat, which represents a clinically relevant model of stroke associated with high blood pressure. We assessed autophagy, mitophagy and NAD+:NADH levels in brains of SHRSP and stroke-resistant SHR fed with high salt diet. Vascular smooth muscle cells silenced for the mitochondrial complex I subunit Ndufc2 gene (NADH:ubiquinone oxidoreductase subunit C2) and cerebral endothelial cells isolated from SHRSP were also used to assess autophagy/mitophagy and mitochondrial function in response to high salt levels. We found a reduction of autophagy in brains of high salt-fed SHRSP. Autophagy impairment was associated with NDUFC2 downregulation, mitochondrial dysfunction and NAD+ depletion. Restoration of NAD+ levels by nicotinamide administration reactivated autophagy and reduced stroke development in SHRSP. A selective reactivation of autophagy/mitophagy by Tat-Beclin 1 also reduced stroke occurrence, restored autophagy/mitophagy and improved mitochondrial function. Endothelial progenitor cells (EPCs) from subjects homozygous for the thymine allele variant at NDUFC2/rs11237379, which is associated with NDUFC2 deficiency and increased stroke risk, displayed an impairment of autophagy and increased senescence in response to high salt levels. EPC senescence was rescued by Tat-Beclin 1. Pharmacological activation of autophagy may represent a novel therapeutic strategy to reduce stroke occurrence in hypertension. Abbreviations 10 VSMCs: aortic vascular smooth muscle cells; COX4I1/COX IV: cytochrome c oxidase subunit 4I1; ECs: endothelial cells; EPCs: endothelial progenitor cells; JD: Japanese-style diet; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; NAD: nicotinamide adenine dinucleotide; NDUFC2: NADH:ubiquinone oxidoreductase subunit C2; NMN: nicotinamide mononucleotide; RD: regular diet; SHRSP: stroke-prone spontaneously hypertensive rat; SHRSR: stroke-resistant spontaneously hypertensive rat.

A Decrease of Brain MicroRNA-122 Level Is an Early Marker of Cerebrovascular Disease in the Stroke-Prone Spontaneously Hypertensive Rat.

Based on preliminary evidence that highlights microRNA-122 as a contributing factor to stroke pathogenesis, we aimed at assessing its expression level, along with the presence of early signs of cerebrovascular disease, in the brain of stroke-prone spontaneously hypertensive rat (SHRSP), a suitable model of human disease that accelerates stroke occurrence under a high sodium/low potassium (Japanese-style) diet (JD). After one month of JD, before stroke occurrence, brain microRNA-122 level was significantly decreased in SHRSP as compared to the stroke-resistant SHR (SHRSR). At this time, levels of markers of oxidative stress and inflammation, as well as of endothelial integrity and function, apoptosis and necrosis were differently modulated in the brains of JD-fed SHRSP as compared to SHRSR, pointing to a significant activation of all deleterious mechanisms underlying subsequent stroke development in SHRSP. We also showed that miR-122 improved survival of rat endothelial cerebral cells upon stress stimuli (excess NaCl, hydrogen peroxide). Our data suggest that a decrease of brain microRNA-122 level is deleterious and can be considered as an early marker of stroke in the SHRSP. Understanding the mechanisms by which microRNA-122 protects vascular cells from stress stimuli may provide a useful approach to improve preventive and treatment strategies against stroke.

Prevention of Alzheimer's Disease and Nutrients

The dietary recommendations for the prevention and management of Alzheimer's disease (AD), are the Mediterranean diet and the Japanese-style diet, both of which contain well-balanced nutrients from fish and vegetables. These diets are rich in vitamin E, carotenes, antioxidant flavonoids, vitamin B12, folate, and n-3PUFA. According to recent review supplementation of folate and vitamin E may protect against elderly people's cognitive decline when the serum folate is <12 nmol/L or the vitamin E intake is <6.1 mg/day. Another nutritional topic with regard to dementia and diet is the association of type-2 diabetes and hyperinsulinemia with AD. Expression array data of the brain tissue of AD patients in the Hisayama study strongly suggests a disturbance in insulin signaling in the AD brain. The dysfunction of insulin signaling could directly lead to disrupted glucose utilization in the AD brain. Instead of improperly utilized glucose, the medium chain triglyceride ketone bodies can be an alternative energy resource for the AD brain. In conclusion, the dietary recommendations for the prevention and management of AD are a high consumption of fish, vegetables, and low glycemic index fruits; a moderate amount of meat and dairy products; and a lower amount of carbohydrates and refined sugar.

Relationship of Consumption of Meals Including Grain, Fish and Meat, and Vegetable Dishes to the Prevention of Nutrient Deficiency: The INTERMAP Toyama Study.

A Japanese-style diet consists of meals that include grain (shushoku), fish and meat (shusai), and vegetable dishes (fukusai). Little is known about the association of such meals (designated well-balanced meals hereafter) with nutrient intake. We therefore examined the frequency of well-balanced meals required to prevent nutrient deficiency. Participants were Japanese people, ages 40 to 59 y, from Toyama, recruited for INTERMAP, in an international population-based study. Each person provided 4 in-depth 24-h dietary recalls (149 men, 150 women). The prevalence of risk ratios of not meeting the Dietary Reference Intakes for Japanese (2015) was calculated. Well-balanced diets were assessed by the Japanese Food Guide Spinning Top. We counted the frequencies of meals in which participants consumed 1.0 or more servings of all 3 dishes categories. We divided the frequency of consumption of well-balanced meals into the following 4 groups: <1.00 time/d, 1.00-1.49 times/d, 1.50-1.74 times/d, and ≥1.75 times/d. Compared with participants in the highest frequency group for well-balanced meals, those who consumed well-balanced meals less than once a day had a higher risk of not meeting the adequate intake for potassium and the recommended dietary allowance for vitamin A. Those who consumed well-balanced meals on average less than 1.50 times per day had a higher risk of not meeting the recommended dietary allowance for calcium and vitamin C. Our results suggest that individuals should on average consume well-balanced meals more than 1.5 times per day to prevent calcium and vitamin C deficiencies.

Adequacy of iodine intake in three different Japanese adult dietary patterns: a nationwide study.

BackgroundIodine intake is considered to be high in Japan due to regular seaweed consumption. Subgroups that do not have a traditional Japanese-style diet may consume insufficient amounts of iodine.MethodThree hundred and ninety apparently healthy adults (195 men and 195 women) aged 20 to 69 years from 20 areas throughout Japan completed four-day diet records and collected a 24-h urine sample. Dietary patterns were extracted from 31 food groups by cluster analysis. The iodine adequacy of each dietary pattern was examined using reference values from the Dietary Reference Intakes for Japanese.ResultsThree dietary patterns, labelled “Cluster I (Rice and vegetables)” (n = 101), “Cluster II (Meat, non-Japanese noodles, and sugar-sweetened beverages)” (n = 34), and “Cluster III (Fish, Japanese noodles, and alcohol)” (n = 60), were identified in male subjects. Another set of three patterns, “Cluster I (Rice and vegetables)” (n = 22), “Cluster II (Fish and Japanese noodles)” (n = 33), and “Cluster III (Bread and non-Japanese noodles)” (n = 140), was found in female subjects. Although the habitual iodine intake of almost all participants was above the estimated average requirement (EAR), iodine intake was statistically significantly lowest in Cluster II in men and Cluster III in women. Moreover, the mean participant age was the youngest in these clusters.ConclusionAlthough Japan is known as a high iodine-consuming country, some Japanese individuals who do not eat a traditional Japanese-style diet consume low amounts of iodine. Since younger people tend to have modern, Westernized dietary patterns, iodine deficiency might be given additional consideration hereafter in Japan.Electronic supplementary materialThe online version of this article (doi:10.1186/s12937-015-0116-y) contains supplementary material, which is available to authorized users.

Abstract P160: Role of Uncoupling Protein 2 in Stroke Susceptibility of Stroke-prone Spontaneously Hypertensive Rat

Mitochondrial dysfunction causes severe cellular derangements potentially underlying tissue injury and consequent diseases. Evidence of a direct involvement of mitochondrial dysfunction in hypertensive target organ damage is still poor. The gene encoding Uncoupling Protein 2 (UCP2), a inner mitochondrial membrane protein, maps inside stroke QTL/STR1 in stroke prone spontaneously hypertensive rat (SHRSP). We explored the role of UCP2 in stroke pathogenesis of SHRSP. Male SHRSP, stroke resistant SHR (SHRSR) and reciprocal STR1/congenic rats were fed with stroke permissive Japanese style diet (JD). A group of SHRSP received JD plus fenofibrate (150 mg/kg/die). Rats were sacrificed at stroke occurrence. Additional SHRSR and SHRSP rats were sacrificed at 1, 3, 6, 12 months of age upon regular diet. SBP, BW, proteinuria, stroke signs were monitored. Brains were used for molecular analysis (UCP2 gene and protein expression, Nf-kB protein expression, oxidative stress quantification) and for histological analyses. As a result, brain UCP2 expression was reduced to 20% by JD only in SHRSP (showing 100% stroke occurrence by 7 weeks of JD). Fenofibrate protected SHRSP from stroke and upregulated brain UCP2 (+ 100%). Congenic rats carrying STR1/QTL showed increased (+100%) brain UCP2 expression, as compared to SHRSP, when resistant to stroke, and, viceversa, decreased (-50%) brain UCP2 levels, as compared to SHRSR, when susceptible to stroke. Brain UCP2 expression progressively decreased with aging only in SHRSP, down to 15% level at one year of age (when SHRSP showed spontaneous stroke). Both brain Nf-kB expression and oxidative stress levels increased when UCP2 expression was downregulated, and viceversa. Histological analysis showed both ischemic and haemorrhagic lesions at stroke occurrence. Our results highlight a role of UCP2 in stroke predisposition associated to hypertension in an animal model of complex human disease.

Protective effects of Brassica oleracea sprouts extract toward renal damage in high-salt-fed SHRSP: role of AMPK/PPARα/UCP2 axis.

Renal damage precedes occurrence of stroke in high-sodium/low-potassium-fed stroke-prone spontaneously hypertensive rat (SHRSP). We previously reported a marked suppression of uncoupling protein-2 (UCP2) upon high-salt Japanese-style diet in SHRSP kidneys. Vegetable compounds are known to exert protective effects in cardiovascular diseases. We aimed at evaluating the impact of Brassica oleracea sprouts juice toward renal damage in Japanese diet-fed SHRSP and exploring the role of 5'-adenosine monophosphate-activated protein kinase (AMPK)/NAD-dependent deacetylase sirtuin-1 (SIRT1)/peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α)/peroxisome proliferator-activated receptor-α (PPARα)/UCP2 axis. SHRSP received Japanese diet for 4 weeks. A group of SHRSP received Japanese diet and B. oleracea. A third group received Japanese diet, B. oleracea, and PPARα inhibitor (GW6471). A group of SHRSP fed with regular diet served as control. Japanese diet induced marked increases of oxidative stress, inflammation, and proteinuria, along with glomerular and tubular damage, as compared with regular diet. A significant suppression of AMPK/UCP2 pathway was observed. Despite Japanese diet feeding, concomitant administration of B. oleracea prevented oxidative stress accumulation, inflammation, renal damage, and proteinuria. All components of the UCP2 regulatory pathway were significantly increased by B. oleracea. Superoxide dismutase 2 and phosphoendothelial nitric oxide synthase were also stimulated. Addition of PPARα inhibitor to B. oleracea and Japanese diet significantly reduced the B. oleracea beneficial effects. SBP levels were comparable among the different groups of rats.In vitro, UCP2 inhibition by genipin offset the antioxidant effect of B. oleracea in renal mesangial and proximal tubular cells. B. oleracea administration prevented renal damage in salt-loaded SHRSP, independently from SBP, with parallel stimulation of AMPK/SIRT1/PGC1α/PPARα/UCP2 axis. Stimulation of the latter mechanism may provide relevant renal protective effect and play a therapeutic role in target organ damage progression in hypertension.

和食中心の園内給食の食育効果について―和食中心の園内給食と業者弁当との比較より―

A survey was conducted targeted at the parents of kindergarten children attending three kindergartens in the city of Fukuoka serving meals prepared at the school consisting primarily of Japanese style meals (Group A) and the parents of kindergarten children attending kindergartens serving commercially prepared lunches (Group B). Both groups were assessed for differences in intake of nutrients and so forth contained in the meals as well as differences in diet, eating habits and so on, the results of which are summarized below.1. With respect to differences observed in the lifestyles of the children, 51% of the children in Group A went to bed after 9:00 PM, while 66% of the children in Group B went to bed after 9:00 PM, and this accounted for the largest percentage of children in that group. Thus, a trend was observed in which children tended to go to bed somewhat later in Group B (p<0.01).2. Those nutrients that did not satisfy daily nutritional target values consisted of energy (93%) lipids (69%), vitamin D (56%) in Group A, and calcium (76%), vitamin D (49%) in Group B.3. Energy ratios were such that the percentage of energy from protein was 18.1% and that from lipids was 20% and that from carbohydrate was 61.9% in Group A, while that from proteins was 15.4% and that from lipids was 35.3% and that from carbohydrate was 49.3% in Group B. This demonstrated that the percentage of energy from lipids is extremely low in Group A, while the percentage of energy from lipids is extremely high in Group B. The percentage of energy from lipids is extremely high in Group B and the percentage of the energy from lipid has exceeded 30% of maximums of the proper ratio of the lipid of infancy. Prepared Lunches needs to be looked again in group B4. In Group B in which meals were provided in the form of commercially prepared lunches, it is evident that considerations are being given to nutritional factors due to the use of 30% milled rice and 70% milled rice and the use of a larger amount of fish than Group A. Conversely, at the homes of the children of Group A in which meals were prepared at the school and consisted primarily of Japanese style meals, there were higher frequencies of use of oils, wheat products and eggs as compared with Group B. Consideration of making a meal at a home which the guardian of A and a B group compensates with each supply of food heard.5. The overall image of the meals services was such that meals were provided in Group A that emphasized a Japanese-style diet consisting mainly of grains, beans, vegetables and kelp, meals were not served that used large amounts of oil such as in deep-fried foods and the like, and were evaluated highly. In addition, the use of frozen foods and processed foods was found to be more common in Group B.6. Changes in diet that occurred after the children had entered kindergarten consisted of improved eating habits and eating behavior in Group A as compared with Group B, and changes with respect to food in Group A were found to be considerable from the standpoint of providing meals. The supply of food based on Japanese Style Meals Prepared at School is considered to have brought the education effect of a meal to the guardian who makes a meal at home.

Histomorphometric, biochemical and ultrastructural changes in the aorta of salt-loaded stroke-prone spontaneously hypertensive rats fed a Japanese-style diet

Background and Aim: It is demonstrated that dietary habits play a role in cardiovascular diseases. In stroke-prone spontaneously hypertensive rats (SHRsp), concomitant salt loading and a Japanese-style diet greatly accelerate hypertension and the appearance of cerebrovascular lesions by directly damaging arterial vessels. A number of studies have characterised medium and small vessel lesions in SHRsp, but little attention has been paid to the changes in the wall structure of large arteries induced by exposure to a salt-enriched diet. The aim of this study was to investigate the effects of a Japanese-style diet and salt loading on the thoracic aorta. Methods and Results: Two-month-old SHRsp were kept on a Japanese-style diet with 1% sodium chloride solution replacing tap water. Two months later, they were sacrificed and compared with age-matched or two-month-old control SHRsp kept on a standard diet and tap water in terms of the histomorphometry, ultrastructure and biochemical composition of the thoracic aorta. The vessel was consistently thicker in the four-month-old SHRsp (+20%, p<0.05 vs two-month-old rats) regardless of diet. The salt-loaded SHRsp showed a significant reduction in elastic fibre density (−20%, p<0.05 vs two-month-old rats) and an increase in the other matrix components (+50%), whereas the four-month-old controls showed preserved elastic fibres and a significant increase in the other matrix components (+65%, p<0.05 vs two-month-old rats). There was a considerable increase in the amounts of 4-OH-proline (+147%), 5-OH-lysine (+174%) and desmosines (+360%) in the four-month-old controls vs their two-month-old counterparts ( p<0.01), but not in the salt-loaded animals. Ultrastructural analysis revealed clear damage and accelerated aging in the thoracic aorta of the salt-loaded SHRsp. Conclusions: Salt loading and a Japanese-style diet destabilise thoracic aorta architecture in SHRsp after two months of treatment.

Altered regulation of endothelin A receptor subtype in the cerebral arterioles in response to a Japanese-style diet, in stroke-prone hypertensive rats.

To investigate the expression of endothelin (ET)-1 and its receptors in the cerebral arterioles of stroke-prone (spSHR) and control spontaneously hypertensive rats (SHRs) and the changes in endothelin receptor subtypes A and B density elicited by a stroke-permissive diet, before the development of stroke. Six-week-old SHRs (n=11) and spSHRs (n=11) were assigned to either a regular or a "Japanese"-style diet, in addition to 1% NaCl in the drinking water, for 4 weeks. Cryosections (10 microm thick) of rat brain were assessed for endothelin receptor distribution and density by autoradiography with [125I]ET-1 (10(-10) mol/l) in the presence of cold ET-1 (10(-6) mol/l) or the peptide antagonists BQ-123 (10(-6) mol/l) or BQ-788 (10(-6) mol/l). Reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry were used to detect specific mRNAs and localize immunoreactive ET-1 and ET(A) and ET(B). In both strains, immunoreactive ET-1 was detected in the endothelium of cerebral arterioles, and RT-PCR and autoradiography demonstrated the coexistence of both receptor subtypes in brain homogenates and the cerebral arteriole walls, respectively. With the regular diet, the ET(A) receptor density was lower in SHRs than in spSHRs (P = 0.007), whereas the ET(B) receptor density was similar (P = NS). The Japanese-style diet increased the density of ET(A) receptors (P = 0.006) in SHRs, but decreased it (P = 0.019) in spSHRs. No effect was seen on ET(B) receptor density. ET(A) and ET(B) receptor subtypes are expressed in the wall of cerebral arterioles of SHRs and spSHRs. The latter strain showed a marked increase in ET(A) receptor density under a regular diet, in addition to an altered regulation in response to a stroke-permissive diet.

Defective suppression of the aldosterone biosynthesis during stroke permissive diet in the stroke-prone phenotype of the spontaneously hypertensive rat.

Previous studies have shown that short-term high salt intake unmasks blunted plasma aldosterone suppression in stroke-prone spontaneously hypertensive rats (SHRsp). The aim of this study was to evaluate the response of aldosterone biosynthesis and production to a sustained exposure to the stroke-permissive Japanese-style diet (JD) in young stroke-prone and stroke-resistant SHRs. For this purpose, 6-week old male rats from both strains were divided into 2 dietary groups and received regular diet (SHR = 37, SHRsp = 32) or the JD and 1% saline to drink (SHR = 34, SHRsp = 30) for 4 weeks. All measurements were carried out at the end of the dietary periods. After JD, plasma aldosterone levels were significantly decreased in SHR (from 357.8 +/- 57 to 163.3 +/- 31.5 pg/ml, p < 0.05) but markedly increased in SHRsp (from 442 +/- 56.5 to 739 +/- 125.7 pg/ml, p < 0.05). Consistently, the adrenal aldosterone synthase expression was reduced by JD in SHR (p < 0.05), whereas it was even slightly raised by JD in SHRsp so that, at the end of JD, aldosterone synthase mRNA was 5-fold higher in SHRsp than in SHR. Urinary sodium excretion (mEq/24h) achieved lower levels in SHRsp, so that fractional excretion of sodium was 80.2 +/- 9% in SHR and 40.3 +/- 8% in SHRsp (p < 0.05) in balance studies performed at the end of JD. These different responses of mineralocorticoid biosynthesis and urinary sodium excretion to JD were not accounted for by different adaptations of the renin-angiotensin and atrial natriuretic peptide systems, of serum potassium levels, or of adrenal 11beta-hydroxylase expression in the two strains. Systolic blood pressure was comparable in both strains throughout the experiment. These results demonstrate enhanced aldosterone biosynthesis, associated with reduced urinary excretion of sodium in response to JD in SHRsp before the onset of stroke. This abnormality may play a role in the higher susceptibility to stroke of this model.

Analysis of the genetic basis of the endothelium-dependent impaired vasorelaxation in the stroke-prone spontaneously hypertensive rat: a candidate gene approach.

To investigate the role of potential candidate genes in the pathogenesis of the endothelium-dependent impaired vasorelaxation that associates and co-segregates with stroke in the stroke-prone spontaneously hypertensive rat (SHRsp) compared with the stroke-resistant SHR (SHRsr). An SHRsp/SHRsr F2-intercross (n = 137; 64 males, 73 females) was obtained and, at the age of 6 weeks, it was placed under a stroke permissive Japanese-style diet for 4 weeks. At the end of the treatment the vascular function of each rat was characterized. The maximal vasorelaxation to acetylcholine after maximal vasoconstriction (delta ratio) was considered as the quantitative phenotype. The following candidate genes were related to the delta ratio: renin, angiotensinogen, angiotensin-converting enzyme, angiotensin II AT1b receptor, atrial natriuretic peptide, brain natriuretic peptide, atrial natriuretic peptide GC-A receptor, kallikrein, endothelial nitric oxide synthase. In addition, polymorphic markers located inside areas of the rat genome where other candidates (i.e. adrenomedullin, endothelin, Ang II AT1a receptor) are known to map were included. The endothelial vascular dysfunction of the SHRsp showed a variable distribution among SHRsp/SHRsr F2 descendants, independently from the blood pressure levels. A genotype/phenotype co-segregation analysis for each of the genes tested did not show any statistically significant co-segregation with the vascular phenotype. A candidate gene approach used to investigate the genetic basis of the endothelial-dependent vascular dysfunction of the SHRsp strain did not reveal any evidence to support the hypothesis that the genes tested play any role in the pathogenesis of the stroke-related vascular abnormality.

Differential brain atrial natriuretic peptide expression co-segregates with occurrence of early stroke in the stroke-prone phenotype of the spontaneously hypertensive rat.

To determine how the downregulation of atrial natriuretic peptide (ANP) gene expression, previously demonstrated to occur only in the brain of the stroke-prone spontaneously hypertensive rat (SHRsp), in contrast to the stroke-resistant SHR (SHRsr), co-segregates with stroke occurrence in SHRsp/SHRsr F2 descendants in order to study the 'protective' role towards stroke previously demonstrated in SHRsp for the quantitative trait locus STR2 that also carries the ANP gene. Eight male SHRsp, eight male SHRsr and 16 male SHRsp/SHRsr F2-intercross animals (progeny of brother/sister mated F1 hybrids from an original cross between F0 SHRsp and SHRsr) were selected for this study. All rats were exposed to a stroke-permissive Japanese-style diet starting at the age of 6 weeks. Half of the F2 animals had early strokes; the remainder had late strokes. Blood pressure was measured before sacrifice. Analysis of brain ANP expression using an RNase protection assay was performed in all animals. Downregulation of brain ANP in the stroke-prone phenotype was found to co-segregate with the occurrence of early strokes in the F2 rats independently of blood pressure levels. The observed lower expression of ANP in the brains of stroke-prone rats appears to be the result of an inhibitory effect by another gene or genes. It seems unlikely that this specific trait represents a primary protective mechanism.

Impaired vasorelaxant responses to natriuretic peptides in the stroke-prone phenotype of spontaneously hypertensive rats.

We have previously shown that a locus on rat chromosome 5, termed STR 2, co-localizes with the genes encoding atrial natriuretic and brain natriuretic peptides, and is closely linked to the development of strokes in rats of a F2 hybrid cohort obtained by crossing stroke-prone spontaneously hypertensive rats and spontaneously hypertensive rats. We also demonstrated that there are significant differences in vascular functioning that are co-segregated with stroke latency of stroke-prone spontaneously hypertensive rats. To investigate the vascular responses to natriuretic peptides in the stroke-prone phenotype of spontaneously hypertensive rats. In view of the important vasoactive properties of natriuretic peptides, we tested the vascular responses to 10(-11)-10(-9) mol/l atrial natriuretic peptide and to 10(-11)-10(-7) mol/l brain natriuretic peptide in isolated rings of aortas and internal carotid arteries obtained from stroke-prone and stroke-resistant spontaneously hypertensive rats. The 6-week-old rats were exposed for 4 weeks either to their regular diet (n = 15 of both strains) or to the stroke-permissive Japanese-style diet (n = 14 of both strains). A group of 14 normotensive, age-matched and sex-matched Wistar-Kyoto rats was also studied. Systolic blood pressures in stroke-prone and stroke-resistant spontaneously hypertensive rats were similar, and were significantly higher than those in Wistar-Kyoto rats. Vascular responses to nitroglycerin, atrial natriuretic peptide, and brain natriuretic peptide in rats of the two hypertensive strains and in Wistar-Kyoto rats fed their regular diet were comparable. In contrast, the vasorelaxant responses to atrial natriuretic peptide in stroke-prone spontaneously hypertensive rats fed Japanese diet were lower both in aortas and in internal carotid arteries than were those in spontaneously hypertensive rats (both P < 0.05 by analysis of variance) and in Wistar-Kyoto rats (both P < 0.05). Similarly, vasorelaxant responses to brain natriuretic peptide were lower both in aortas and in internal carotid arteries of stroke-prone spontaneously hypertensive rats than they were in spontaneously hypertensive rats (both P < 0.05) and in Wistar-Kyoto rats (P < 0.05). The responses to nitroglycerin in the stroke-prone spontaneously hypertensive rats and spontaneously hypertensive rats fed Japanese-style diet were also similar. The vasorelaxant effects of natriuretic peptides are impaired in stroke-prone spontaneously hypertensive rats. This abnormality could play a role in the pathogenesis of stroke incidence in this hypertensive model.