Infused juice concentrate of Japanese plum Prunus mume attenuates inflammatory vascular remodeling in a mouse model of hypertension induced by angiotensin II.

Fruit from the Prunus mume tree is a traditional food in Japan. Recently, bainiku-ekisu, an infused juice concentrate of Japanese Prunus mume, is attracting attention as a health promoting supplement. Angiotensin II (Ang II) plays a central role in development of hypertension. It has been reported that bainiku-ekisu treatment attenuates the growth-promoting signaling induced by Ang II in vascular smooth muscle cells. However, whether bainiku-ekisu has any effect on an animal model of hypertension remains unknown. Therefore, this study was designed to explore the potential anti-hypertensive benefit of bainiku-ekisu utilizing a mouse model of hypertension with Ang II infusion. Male C57BL/6 mice were infused with Ang II for 2 weeks and given 0.1% bainiku-ekisu containing water or normal water for 2 weeks with blood pressure evaluation. After 2 weeks, mice were euthanized, and the aortas were collected for evaluation of remodeling. Aortic medial hypertrophy was observed in control mice after Ang II infusion, which was attenuated in bainiku-ekisu group with Ang II infusion. Bainiku-ekisu further attenuated aortic induction of collagen producing cells and immune cell infiltration. Development of hypertension induced by Ang II was also prevented by bainiku-ekisu. Echocardiograph indicated protection of Ang II-induced cardiac hypertrophy by bainiku-ekisu. In vascular fibroblasts, bainiku-ekisu attenuated vascular cell adhesion molecule-1 induction, an endoplasmic reticulum stress marker, inositol requiring enzyme-1α phosphorylation, and enhancement in glucose consumption in response to Ang II. In conclusion, Bainiku-ekisu prevented Ang II-induced hypertension and inflammatory vascular remodeling. Potential cardiovascular health benefit to taking bainiku-ekisu should be further studied.

Roles of Phytoestrogen in the Pathophysiology of Intracranial Aneurysm.

Background and Purpose: The incidences of intracranial aneurysm and aneurysmal subarachnoid hemorrhage are high in postmenopausal women. Although population-based studies suggest that hormone replacement therapy is beneficial for postmenopausal women with intracranial aneurysms, estrogen replacement may no longer be recommended for the prevention of chronic diseases given its association with adverse outcomes, such as cancer and ischemic stroke. The isoflavone daidzein and its intestinal metabolite equol are bioactive phytoestrogens and potent agonists of estrogen receptors. Given their estrogenic properties, we investigated whether the isoflavones daidzein and equol are protective against the formation and rupture of intracranial aneurysms in a mouse model of the postmenopausal state. Methods: We induced intracranial aneurysms in ovariectomized adult female mice using a combination of induced systemic hypertension and a single injection of elastase into the cerebrospinal fluid. We fed the mice with an isoflavone-free diet with/without daidzein supplementation, or in a combination of intraperitoneal equol, or oral vancomycin treatment. We also used estrogen receptor beta knockout mice. Results: Both dietary daidzein and supplementation with its metabolite, equol, were protective against aneurysm formation in ovariectomized mice. The protective effects of daidzein and equol required estrogen receptor-ß. The disruption of the intestinal microbial conversion of daidzein to equol abolished daidzein's protective effect against aneurysm formation. Mice treated with equol had lower inflammatory cytokines in the cerebral arteries, suggesting that phytoestrogens modulate inflammatory processes important to intracranial aneurysm pathogenesis. Conclusions: Our study establishes that both dietary daidzein and its metabolite, equol, protect against aneurysm formation in ovariectomized female mice through the activation of estrogen receptor-ß and subsequent suppression of inflammation. Dietary daidzein's protective effect required the intestinal conversion to equol. Our results indicate the potential therapeutic value of dietary daidzein and its metabolite, equol, for the prevention of the formation of intracranial aneurysms and related subarachnoid hemorrhage.

Direct evidence of intracrine angiotensin II signaling in neurons.

The existence of a local renin-angiotensin system (RAS) in neurons was first postulated 40 years ago. Further studies indicated intraneuronal generation of ANG II. However, the function and signaling mechanisms of intraneuronal ANG II remained elusive. Since ANG II type 1 receptor (AT1R) is the major type of receptor mediating the effects of ANG II, we used intracellular microinjection and concurrent Ca(2+) and voltage imaging to examine the functionality of intracellular AT1R in neurons. We show that intracellular administration of ANG II produces a dose-dependent elevation of cytosolic Ca(2+) concentration ([Ca(2+)]i) in hypothalamic neurons that is sensitive to AT1R antagonism. Endolysosomal, but not Golgi apparatus, disruption prevents the effect of microinjected ANG II on [Ca(2+)]i. Additionally, the ANG II-induced Ca(2+) response is dependent on microautophagy and sensitive to inhibition of PLC or antagonism of inositol 1,4,5-trisphosphate receptors. Furthermore, intracellular application of ANG II produces AT1R-mediated depolarization of hypothalamic neurons, which is dependent on [Ca(2+)]i increase and on cation influx via transient receptor potential canonical channels. In summary, we provide evidence that intracellular ANG II activates endolysosomal AT1Rs in hypothalamic neurons. Our results point to the functionality of a novel intraneuronal angiotensinergic pathway, extending the current understanding of intracrine ANG II signaling.

An extract from brown rice inhibits signal transduction of angiotensin II in vascular smooth muscle cells.

BACKGROUND: Health benefits of brown rice over white rice have been described previously. However, whether the outer bran of rice contains an ingredient useful to prevent cardiovascular diseases remains unknown. The subaleurone layer of rice, which is usually lost by milling brown rice for whitening, is rich in varied nutrients, suggesting that some ingredient contained within this layer may be beneficial for the cardiovascular system. METHODS: To assess potential benefits of the subaleurone layer toward pathological vascular remodeling, we examined the effects of the layer extracts from Japanese rice (Oryza sativa var. japonica) on angiotensin II (Ang II)-induced signal transduction and hypertrophy in cultured rat vascular smooth muscle cells (VSMCs). RESULTS: Pretreatment of the ethyl acetate extract (100 µg/ml), but not other extracts, inhibited Ang II (100 nmol/l)-induced immediate signal transduction events. Also, the extract diminished c-Fos expression and hypertrophic protein accumulation induced by Ang II in the cells. CONCLUSION: These data suggest that an ingredient in the ethyl acetate extract from the subaleurone layer of rice has a protective effect toward cardiovascular diseases by interfering with signal transduction induced by Ang II.

Fruit-juice concentrate of Asian plum inhibits growth signals of vascular smooth muscle cells induced by angiotensin II.

Bainiku-ekisu, the fruit-juice concentrate of the Oriental plum (Prunus mume) has recently been shown to improve human blood fluidity. We have shown that angiotensin II (AngII) stimulates growth of vascular smooth muscle cells (VSMCs) through epidermal growth factor (EGF) receptor transactivation that involves reactive oxygen species (ROS) production. To better understanding the possible cardiovascular protective effect of Bainiku-ekisu, we have studied whether Bainiku-ekisu inhibits AngII-induced growth promoting signals in VSMCs. Bainiku-ekisu markedly inhibited AngII-induced EGF receptor transactivation. H(2)O(2)-induced EGF receptor transactivation was also inhibited by Bainiku-ekisu. Thus, Bainiku-ekisu markedly inhibited AngII-induced extracellular signal-regulated kinase (ERK) activation. However, EGF-induced ERK activation was not affected by Bainiku-ekisu. AngII stimulated leucine uptake in VSMCs that was significantly inhibited by Bainiku-ekisu. Also, Bainiku-ekisu possesses a potent antioxidant activity. Since the activation of EGF receptor, ERK and the production of ROS play central roles in mediating AngII-induced vascular remodeling, these data suggest that Bainiku-ekisu could exert a powerful cardiovascular protective effect with regard to cardiovascular diseases.