Naomi Yasui

Establishment of a new animal model of metabolic syndrome: SHRSP fatty (fa/fa) rats.

1. We established a new animal model of metabolic syndrome, SHRSP fatty (fa/fa) rats, by crossing stroke‐prone spontaneously hypertensive rats of the Izumo strain (SHRSP/Izm) to Zucker fatty (ZF) (fa/fa) rats.

Caffeic acid phenethyl ester suppresses oxidative stress in 3T3-L1 adipocytes

The generation of oxidative stress, characterized by enhanced reactive oxygen species (ROS) formation, has been found in obesity. ROS production was increased during the differentiation of 3T3-L1 cells into adipocytes. We previously reported that caffeic acid phenethyl ester (CAPE) suppresses 3T3-L1 differentiation to adipocytes through the inhibition of peroxisome proliferator-activated receptor γ. In this study, the preventive effect of CAPE on oxidative stress in 3T3-L1 cells was observed. The results were as follows: (1) ROS production during 3T3-L1 cell differentiation to adipocytes was significantly (p < 0.05) suppressed by CAPE treatment in a concentration-dependent manner, (2) with CAPE treatment, the extracellular superoxide dismutase mRNA expression level significantly increased, but the NOX4 mRNA expression level did not change, and (3) CAPE treatment significantly increased superoxide dismutase (SOD) activity in 3T3-L1 cells. From these results, we suggest that the increased oxidative stress in 3T3-L1 differentiation to adipocytes is attenuated by CAPE treatment. This attenuation may be partly caused by increased SOD production.

EFFECTS OF PRUNE EXTRACT ON BLOOD PRESSURE ELEVATION IN STROKE-PRONE SPONTANEOUSLY HYPERTENSIVE RATS

1 Prunes are recognized as a health food. They contain large amounts of phenolics and show high anti‐oxidant activity. In this study, both hydroxyl radicals and superoxide anion were scavenged by prune extract in electron spin resonance (ESR) analysis. 2 In angiotensin II challenged vascular smooth muscle cells (VSMCs) from stroke‐prone spontaneously hypertensive rats (SHRSP), the reactive oxygen species (ROS) level was decreased in caffeic acid‐treated cells compared with the control. 3 After 5 weeks of prune extract treatment, the elevation of blood pressure in the prune extract‐treated SHRSP was suppressed in comparison with the control group. 4 Our findings suggest that prune extract may contribute to the primary prevention of cardiovascular diseases.

Isoflavones regulate secretion of leukemia inhibitory factor and transforming growth factor β and expression of glycodelin in human endometrial epithelial cells

Isoflavones have attracted much attention due to their association with health benefits; however, comprehensive understanding of the beneficial impacts of isoflavones on uterine biology at the molecular level remains unexplored. In the present study, our data showed that isoflavones aglycones AglyMax, genistein, and equol, but not daidzein, within the range of plasma concentration, displayed bioavailability in regulating the secretion of leukemia inhibitory factor (LIF) and transforming growth factor beta (TGF-beta) in Ishikawa cells, which was blocked by an estrogen receptor antagonist ICI 182 780, mitogen-activated protein kinase kinase (MEK)1/2 inhibitor PD98059, and p38 mitogen-activated protein kinase inhibitor SB203580. We also found that AglyMax and genistein increased in cyclic AMP release and the expression of glycodelin protein in Ishikawa cells assayed using western blot and immunochemical staining. The MEK1/2 inhibitor PD98059 and the protein kinase A inhibitor H89, but not SB203580, attenuated this glycoprotein expression. Moreover, isoflavone aglycones AglyMax stimulated LIF, and TGF-beta secretion, and glycodelin expression in separate primary endometrial epithelial cells in the follicular phase or luteal phase from healthy subject donors. Overall, our findings suggest that isoflavones may alter the uterine expression of estrogen-responsive genes.

ISOFLAVONE AGLYCONES PROMOTE THE mRNA EXPRESSION OF ENDOTHELIAL NITRIC OXIDE SYNTHASE IN AORTA AND REDUCED BLOOD PRESSURE IN STROKE‐PRONE SPONTANEOUSLY HYPERTENSIVE RATS

1 The aim of the present study was to assess the effects of isoflavone aglycones (IFA; AglyMaxTM; Nichimo Co. Ltd, Tokyo, Japan), containing 32.9% IFA, on the production of nitric oxide (NO) and systolic blood pressure (SBP) in stroke‐prone spontaneously hypertensive rats (SHRSP). 2 Twelve male SHRSP rats, aged 5 weeks, were used. Rats were divided into two groups: (i) the IFA group (n = 6); and (ii) the control group (n = 6). Administration of IFA (20 mg/kg equivalent of isoflavones) resulted in a significant decrease in SBP in the IFA‐treated group compared with the control group. 3 Nitric oxide levels in the urine and serum were also significantly higher in the IFA‐treated group than in the control group. Significantly higher levels of endothelial NO synthase mRNA were also confirmed in the IFA group compared with the control group. 4 Isoflavone aglycones could decrease SBP significantly by increasing the formation of NO.

EFFECTS OF DIETARY FIBRE ON SHR/NDmcr-cp (fak/fak) RAT, A MODEL OF METABOLIC SYNDROME

1 SHR/NDmcr‐cp (fak/fak) (CP) rats have a genetic background from spontaneously hypertensive rats and carry a non‐sense mutation of the leptin receptor derived from obese Koletsky rats. CP rats show several metabolic disorders similar to patients with metabolic syndrome. The aim of the present study was to examine whether the intake of a fibre‐supplemented diet prevented the abnormalities in this metabolic syndrome rat model. 2 Male CP rats aged 6 weeks were divided into three groups and fed ad libitum a normal diet (control), a 10% soluble–insoluble fibre mixture diet (MF) and a 10% soluble fibre diet, indigestible dextrin (SF). At 23 weeks of age, abdominal obesity was attenuated in the MF group. Bodyweight gain was significantly reduced in the MF group from 16 weeks of age compared with the control group. 3 Our study suggests that a soluble–insoluble fibre mixture diet may be more effective in the primary prevention of metabolic syndrome than an insoluble diet only.

PS 18-23 Urinary sodium excretion and heart rate as a novel marker of salt-sensitive blood pressure elevation in young male normotensive Tanzanian

Objective: Many studies have reported that blood pressure (BP) response to dietary salt intake vary among individuals, which is a phenomenon described as salt-sensitivity of BP. Salt intake is an important risk of hypertension. In the present study, we evaluated the effect of 24hour urinary salt excretion and heart rate (HR) on blood pressure in young male normotensive Tanzanian. Design and Method: Total 100 males aged 25 to 35 years, who were residents of seven wards in the Temeke district of Tanzania, were randomly invited to participate. 33 normotensive subjects in 100 participate were selected according to the criteria values, non-obese, systolic BP (SBP) <120 mmHg and diastolic BP (DBP) <80 mmHg. Subjects ingested 140mEq of a NaCl supplement for one week. Blood pressure and heart rate were measured before and after NaCl loading. Twenty four hour urine was collected and before and on the last day of salt loading phase. Results: The subjects of 24hour urinary salt excretions higher than means, 5.05 g/day, were divided into higher and lower HR groups: HR ⩽ the mean, 66.9 beats/min group (L-HR) and HR> the mean group (H-HR). The SBP, DBP and mean BP (MBP) were not significantly differences between groups before salt loading. At the last day of salt loading phase, DBP and MBP in H-HR (65.3 ± 2.3, 81.2 ± 2.3mmHg) tended to be higher than in L-HR (58.1 ± 2.7, 74.7 ± 2.1mmHg). The percent increases of SBP and MBP in H-HR (102.8 ± 2.2, 104.5 ± 2.8%) were significantly higher than in L-HR (95.1 ± 1.4, 94.9 ± 2.0%). Conclusions: These findings of this study suggested the possibility that 24 hour urinary salt excretion and HR may become the simple marker of the salt-sensitive blood pressure elevation in young male normotensive Tanzanian.

ASSOCIATION OF THE PLASMA ARG/ADMA RATIO WITH THE SALT-SENSITIVITY: PP.9.370

Objectives: Asymmetric dimethylarginine (ADMA) is the unique endogenous inhibitor of the NO synthases. As NO plays important roles both in the regulation of the systemic vascular tone and of salt excretion in the kidney, ADMA may be a key player in the regulation of salt-sensitivity. In this communication, we explored the relation of ADMA with the salt-sensitivity in Africans by a salt-loading experiment on volunteers. Design and Method: Thirthy-one Tanzanian male healthy volunteers without hypertension (25–35 years old) were recruited for the experiment. A salt-loading experiment was performed following the protocol designed previously (Hypertens Res 2002;25:809). Briefly, the participants ingested 140mEq/day NaCl additional to their normal diet (containing about 85mEq/day NaCl) in the first week and then took 25 mg/day hydrochlorthiazide (without the salt-loading) in the second week. Blood sampling and blood pressure (BP) measurement was performed at the entry, on the 4th and 7th days of the each week. L-arginine (Arg), ADMA and symmetric dimethylarginine (SDMA) were measured in plasma with HPLC. All the participants gave an informed consent. Results: The change in the mean BP (δMBP) between the salt-loading and the diuretic phase showed a biphasic distribution; the participants with a larger δMBP were defined as a salt-sensitive group (SS, δMBP = -7.3 ± 2.7mmHg, n = 8) while the others were as a salt-resistant group (SR, δMBP = 3.4 ± 4.2mmHg, n = 23). The basal level of ADMA was significantly greater in SS than in SR (SS:0.57 ± 0.09mmol/L, SR: 0.49 ± 0.06mmol/L, p = 0.006) although it was quite stable either in the salt-loading or in the diuretic phase. The increase in the Arg/ADMA ratio from the salt-loading to the diuretic phase (δArg/ADMA_diuret-salt) was significantly greater in SS than in SR (p = 0.04). δArg/ADMA_diuret-salt showed an clear inverse correlation with δMBP (r = -0.53, p = 0.002). The multiple regression analysis confirmed the independent effect of δArg/ADMA_diuret-salt with other factors of the basal ADMA level and the change in the serum Chloride level. Conclusions: The plasma Arg/ADMA ratio was found to be related to the salt-sensitivity in healthy African males.