Protective Effects of Nobiletin on Hypertension and Cerebral Thrombosis in Stroke-Prone Spontaneously Hypertensive Rats (SHRSP)

Some citrus flavonoids have been reported to possess antioxidant activities that moderate endothelial dysfunction and show protective effects on cardiovascular disease. We have investigated the protective effects of nobiletin (5,6,7,8,3’,4’-hexamethoxy flavone) derived from the peel of Citrus depressa Hayata (Shiikuwasha), a citrus fruit produced in Okinawa prefecture in Japan on hypertension and thrombogenicity in cerebral vessels of stroke-prone spontaneously hypertensive rats (SHRSP). Nobiletin was added to the diet of male SHRSP (7 weeks old) for 4 weeks. The age-related increase in systolic blood pressure usually observed in SHRSP was significantly suppressed in the treated animals. Thrombogenesis in pial blood vessels, determined using a He-Ne laser technique, and antioxidant activity, assessed by measuring urinary 8-hydroxy-2’-deoxyguanosine (8-OHdG), were significantly reduced after treatment. Urinary nitric oxide (NO) metabolites and acetylcholine-induced endothelial relaxation were increased after dietary intervention. These results strongly suggested that antihypertensive and antithrombotic effects of nobiletin may be related to an increase in bioavailable NO, possibly mediated by the scavenging of reactive oxygen species (ROS).

Effect of 2-Selenium Bridged β-Cyclodextrin,Glutathione Peroxidase Mimic on Stroke of Stroke-prone Spontaneously Hypertensive Rats

To investigate the treatment effect of 2-selenium bridged β -cyclodextrin(2-SeCD),a GPX mimic,on the stroke of stroke-prone spontaneously hypertensive rats(SHRSP),fifty-two SHRSP of 8-week old were randomly divided into four groups A,B,C and control group D. The rats of groups A,B,C and D were given 1.0%-1.5% NaCl mass fraction as drinking fluid. After onset of stroke,groups A,B and C were given \{orally\} 16.05,160.5 and 1605 mg·kg -1 ·day -1 of 2-SeCD,respectively,and group D was given water for \{2 weeks.\} The clinical score of stroke,systolic blood pressure(SBP),survival time of rats were recorded and the histopathologic examinations of their brain and carotid artery were made after decapitation. The clinical scores of stroke after treatment with 160.5 mg·kg -1 ·day -1 (Group B) and 1605 mg·kg -1 ·day -1 (Group C) of 2-SeCD are 2.55±0.98 and 1.98±0.79,respectively,those are obviously lower than that of group D(3.41±0.83,p<0.01). The survival days in group B(10.0±8.6) and group C(14.4±7.9) are longer than that for group D(4.7±2.9,p<0.01). The electron microscope study showed that the endothelium of carotid artery was near to normal in group B and group C,while it was seriously injured in control group D and mildly injured in group A. 2-SeCD may effectively be used to treat the stroke for SHRSP.

POTENT HYPOTENSIVE EFFECTS OF ORPHANIN FQ IN CONSCIOUS STROKE-PRONE SPONTANEOUSLY HYPERTENSIVE RATS

Orphanin FQ（OFQ） or nociceptin is a novel neuropeptide consisting of 17 amino acids. This peptide has a primary structure reminiscent of that of opioid peptide but exhibits an opposite effect to make animals hyperreactive. The effect of this new peptide on cardiovascular function are not completely known. The present study was conducted to investigate the effect of intravenous bolus injection of orphanin FQ on mean arterial blood presure （MABP） in conscious stroke-prone spontaneously hypertensive rats (SHRsp). Adult male SHRsp and Wistar normotensive rats （250～300 g body weight, 2. 5～3 months old） were used in this study. The MABP was measured in the conscious state by a tail-cuff method. In SHRsp model, intravenous bolus injection of orphanin FQ or Tyr1-orphanin FQ （0. 5 mg/kg） induced a prolonged and marked reduc- tion in MABP. The maximum changes in MABP were -30. 2±4. 2 mmHg by orphanin FQ and -28. 2± 4. 7 mmHg by Tyr1-orphanin FQ at 10 min after administration,and this effect lasted over 30 min. The Phe1→Tyr substitution in orphanin FQ was found to retain almost fully hypotensive activity. Pretreatment of SHRsp with naloxone-HCI（60 μg/kg）, 5 min before the injection of orphanin FQ, did not block the hy- potensive effect of orphanin FQ. Therefore, opioid receptors could not account for the hypotensive effect of orphanin FQ in SHRsp. In Wistar rats, intravenous bolus injection of the same dose of orphanin FQ did not cause a change in MABP. These observations suggest that orphanin FQ is a novel hypotensive peptide and may have some role in the regulation of blood pressure in SHRsp, rather than in normotensive rats. The ex-act underlying mechanisms are waiting to be clarified.

Dietary <i>γ</i>-Aminobutyric Acid Shortens the Life Span of Stroke-Prone Spontaneously Hypertensive Rats

Dietary γ-amino butyric acid (GABA) has been suggested to decrease systolic blood pressure. This study aimed to ex-amine the effects of dietary GABA on the life span of stroke-prone spontaneously hypertensive rats (SHRSPs). In this study, life span was determined for SHRSPs provided 1% NaCl solution or 0.01% GABA in 1% NaCl solution as drinking water. The life span of the GABA-fed group (76.3 ± 1.65 days) was significantly shorter than that of the control group (81.6 ± 0.88 days). The results of this study may not be applicable to humans. Future studies will be necessary to elucidate the mechanism underlying this phenomenon.

PERIPHERAL TISSUE DISTRIBUTION OF ORPHANIN FQ PRECUSOR mRNA IN STROKE-PRONE SPONTANEOUSLY HYPERTENSIVE RATS

The heptadecapeptide orphanin FQ (OFQ) is a recently discovered neuropeptide that exhibits structural features reminiscent of the opioid peptides and that is an endogenous ligant to a G protein-coupled receptor sequentially related to the opioid receptors. OFQ was originally isolated from brain, but the presence of OFQ in peripheral tissues, especially in cardiovascular system, has not been clarified. The present study was designed to investigate the peripheral tissue distribution of OFQ precusor mRNA in stroke-prone spontaneously hypertensive rats (SHRSP) and compare the difference of OFQ precusor mRNA expression in aorta or cultured vascular smooth muscle cells (VSMCs) between SHRSP and wistar-Kyoto normotensive (WKY) rats. By using quantitative reverse transcription-polymerase chain reaction (RT-PCR), OFQ precusor mRNA was detected in aorta and ovary at high levels comparable with the amounts found in brain. Moderate expression was found in testis, while a little OFQ precusor mRNA could be detected in atrium. All other peripheral tissues examined from SHRSP, including ventricle, liver, lung and kidney, showed no expression of OFQ precusor mRNA. In the vascular system, OFQ precusor mRNA was expressed in aorta, pulmonary artery, renal artery and vein at high levels comparable with the amounts found in brain. We also found that OFQ precusor mRNA levels were much higher in aorta or cultured VSMCs from SHRSP than those from WKY rats. In conclusion, the present study has shown that OFQ precusor mRNA is present in some peripheral tissues, especially in cardiovascular and reproductive system, suggesting that OFQ possibly involves in the regulation of cardiovascular and reproductive functions.

Effect of Zhongfeng Naodeping Granule on Hippocampal Excitatory Amino Acid and Neuron of Stroke-Prone Spontaneously Hypertensive Rats with Hemorrhagic Apoplexy

Objective: To observe the effects ofZhongfeng Naodeping Granule (ZFNDPG) onhemorrhagic apoplexy. Methods: The strokeprone spontaneously hypertensive rats(SHRsp ) were used to study effects ofZFNDPG on hemorrhage apoplexy. Excitatoryamino acid (EAA) concentration in hippocampus sector, neuronal density and ultrastructural changes in hippocampal CAI sector weremeasured. Results: In pathological modelgroup glutamate (Gin) and aspartate (Asp)concentration elevated obviously. With theZFNDPG treating SHRsp of hemorrhagicapoplexy, Gin and Asp concentration in hippocampal sector could be markedly inhibited,compared with model group, P < 0.05-0. 01. Neuronal morphology was observed:neurone injury was mild and neuronal densityincreased in hippocampal CA1 sector of treatment group, compared with model group, P< 0. 01. Electron microscopy showed t edema,degeneration and necrosis caused by hemorrhagic apoplexy were improved after theZFNDPG treatment. Conclusions: Effects ofprotecting neurone for SHRsp on hemorrhagicapoplexy might be associated with thatZFNDPG inhibited concentration of EAA.

Effect of Hypertension on Hearing Function,LDH and ChE of the Cochlea in Older Rats

The relationship between the hypertension and the aging process of hearing organ was investigated Twenty Wistar 3-month old rats and 20 Wistar 12-month old rats, 20 spontaneously hypertensive rat stroke-prone (SHRSP) 3-month old rats and 20 SHRSP 12-month old rats free of middle ear infections as observed under otomicroscopy, with normal tympanic membrane and auricle reflex, were selected to be divided into two experimental groups and two control groups respectively The tail artery blood pressure was measured non-invasively The threshold of auditory brainstem response (ABR) was measured by Spirit TM evoked potential meter The LDH and ChE staining in the inner ear was performed and the optical density was analyzed by the HPIAS analysis system The results showed that there was no difference in the ABR thresholds, the activities of LDH and ChE between Wistar 3-month old group and SHRSP 3-month old group ( P >0 05) The mean value of ABR threshold and the activities of LDH and ChE in the Wistar 12-month old group at relevant sections were significantly greater than those in the two 3-month old groups ( P< 0 05), whereas the mean value of ABR threshold and the activities of LDH and ChE in the SHRSP 12-month old group at relevant sections were significantly higher than those in the 3-month old control group ( P< 0 01) It was concluded that presbycusis existed in the Wistar 12-month old group rats The glycogenosis and the abnormal secretion of neural transmitter were discerned after hypertension All the above factors may worsen the aging of the hearing system

Comparison Between the Effects of 2-Selenium Bridged β-Cyclodextrin and Ebselen on Treating SHRsp Stroke

A glutathione peroxidase（GPX） mimic, 2-selenium bridged β-cyclodextrin（2-SeCD）, was synthesized. In order to examine its role and mechanism in treating stroke we chose stroke-prone spontaneously hypertensive rats（SHRsp） as animal model. 56 SHRsps of 8-week olds were randomly divided into several groups： test groups （low, moderate, high dose of 2-SeCD） and control groups（positive and negative）. After onset of the stroke, the rats in test groups were orally administrated with different amounts of 2-SeCD, the positive control group with ebselen, and the negative control group with drinking water. The treatment lasted two weeks, followed by observation of the rats for 10 days, meanwhile blood pressure, biochemical parameters of plasma, and the contents of nitric oxide（NO） and malondialdehyde（MDA） in plasma and brain were determined. The results show that there were significant differences in contents of NO and MDA in plasma and brain between the test groups（high, moderate dose of 2-SeCD） and negative control group. The NO contents of the test groups were obviously higher than that of the negative control group （P〈0.01）. The MDA contents of the test groups（high, moderate dose of 2-SeCD） were obviously lower than that of the negative control group（P〈0.01）. The mechanism of 2-SeCD in treating stroke was discussed, which maybe related to the increase of NO and the decrease of MDA in plasma and brain tissue, but the exact mechanism should be further studied. Moreover, the tendencies of changes in systolic blood pressure, contents of NO and MDA, and other physiological parameters for the test groups were shown to be much better than the corresponding parameters for the positive group（the group with ebselen）（P〈0.05）, indicating that the treatment effect of 2-SeCD is better than that of ebselen.

高钙摄取对易卒中自发性高血压大鼠的血压和细胞内pH，Na~＋－H~＋交换活性的

本文观察到易卒中自发性高血压大鼠接受高钙（３％）饮食６周后抑制了血压上升，胞浆游离钙浓度降低和血浆钙升高，细胞内ｐＨ也产生改变，接近正常对照的ＷＫＹ大鼠。本文对细胞内ｐＨ，Ｎａ＋－Ｈ＋交换，胞浆游离钙浓度与血压的关系进行了讨论。

淫羊藿总黄酮甙对小鼠纤溶系统及对卒中死亡的影响

用126_Ⅰ标记的纤维蛋白测定淫羊藿总黄酮甙(TFG)对小鼠巨噬细胞(M)纤溶活性的影响,用专一发色底物法测定在TFG作用下小鼠M的纤溶酶原激活剂(PA)的活性。结果表明TFG能使小鼠M中PA的活性显著增加,酶活性相当于0.731 IU/ml(P<0.01)。鼠M纤溶活性也显著增强,给药组的纤溶活性是对照组的2.8倍(P<0.01)。SHRsp大鼠体内实验表明,TFG能显著降低SHRsp大鼠死亡率,并能抑制其血压的升高。对照组大鼠中风死亡率为90％,给药组死亡率5％。

心钠素对卒中易感型自发性高血压大鼠血浆和脑组织加压素的影响

为研究心钠素(ANF)和精氨酸加压素(AVP)的相互作用在原发性高血压发病中的意义,对卒中易感型自发性高血压大鼠(SHRsp)和对照大鼠(WKY)侧脑室(icv)或静脉(iv)注射人ANF-(99-126)观察其对血浆、下丘脑和垂体AVP含量以及平均动脉压(MAP)和尿量(UV)、尿钠(U_(Na)V)排泌的影响。静脉注射ANF后10min,SHRsp和WKY大鼠的MAP分别下降9.4％和12.2％(P<0.05),UV分别增加9和20倍(P<0.01),U_(Na)V增加16和29倍(P<0.01)。侧脑室注射ANF对两种大鼠的MAP、UV和U_(Na)V排泌均无明显作用。静脉或侧脑室注射ANF均使两种大鼠的血浆AVP水平明显下降,其中SHRsp的血浆AVP浓度下降程度(iv,-58％;icv,-31％)弱于WKY大鼠(iv,-80％;icv,-65％),下丘脑AVP含量在两种大鼠中都明显增加,而垂体AVP含量无明显变化。 结果表明,人ANF-(99-126)有明显的抑制AVP释放和降压、利尿、利纳作用,而SHRsp对这些作用的敏感性都降低,提示SHRsp对ABF的反应减弱可能在自发性高血压大鼠的发病中具有一定的意义。

延髓孤束核微量注射可乐宁对自发性高血压大鼠血压和心房钠尿因子的影响

将卒中型自发性高血压大鼠(SHR_(sp))和正常血压对照大鼠(WKY)随机分为可乐宁、α_1受体拮抗剂育亨宾加可乐宁及对照组,进行孤束核(NTS)内微量注射。实验观察到,在SHR_(sp)中,可乐宁的降压效应及外周 ANF 释放减少的效应比 WKY 大鼠更明显。阻断α_2受体后,在 WKY 大鼠中,可乐宁的降压效应被完全阻断,而在 SHR_(sp)仅部分被阻断;两种大鼠的外周 ANF 与对照组相比无明显差异。可乐宁组两种大鼠的血浆儿茶酚胺水平明显降低,育亨宾可阻断该反应。以上结果提示,ANF 未参与 NTS 内微量注射可乐宁引起的降压效应,在 SHR_(sp),ANF 释放的减少可能为血压依赖的代偿反应;可乐宁通过α_2受体介导抑制外周儿茶酚胺的释放。

高糖摄入对易卒中型自发性高血压大鼠胰岛素抗性的影响

易卒中型自发性高血压大鼠(SHRsp)的饮水中添加10%葡萄糖喂养4周,其血糖水平增加、胰岛素抗性恶化。同时血压明显升高,交感神经系统兴奋性增加,血胆固醇及甘油三酯增加,心脏重量和相对重量增加、心肌血管紧张素Ⅱ水平增加。相关分析表明胰岛素水平与体重、血压、血胆固醇、去甲肾上腺素、心脏重量和相对重量呈显著正相关。提示高糖摄取可增加心血管病危险因子,其机制与胰岛素抗性恶化有关。

海鱼鱼油和胆固醇对卒中型自发性高血压大鼠血压和脑卒中作用的比较

予高盐下卒中型自发性高血压大鼠 (SHRsp)饲料中分别补充海鱼鱼油 [含二十碳五烯酸 (EPA)和二十碳六烯酸 (DHA) ]和胆固醇 ,发现两种饲料能不同程度地降低血压和脑卒中发生率 。