Underlying anti-hypertensive mechanism of the Mizuhopecten yessoensis derived peptide NCW in spontaneously hypertensive rats via widely targeted kidney metabolomics

The angiotensin-converting enzyme(ACE)inhibitory peptide NCW derived from Mizuhopecten yessoensis has been demonstrated to have significant in vivo anti-hypertensive effects,however,its anti-hypertensive mechanism is still not fully clarified.This study established a UPLC-Q-TRAP-MS/MS-based widely targeted kidney metabolomics approach to explore the changes of kidney metabolic profiles and to clarify the antihypertensive mechanism of peptide NCW in spontaneously hypertensive rats(SHRs).Multivariate statistical analysis indicated that the kidney metabolic profiles were clearly separated between the SHR-NCW and SHRUntreated groups.A total of 85 metabolites were differentially regulated,and 16 metabolites were identified as potential kidney biomarkers,e.g.,3-hydroxybutyrate,malonic acid,deoxycytidine,and L-aspartic acid.The peptide NCW might regulate kidney metabolic disorder of SHRs to alleviate hypertension by suppressing inflammation and improving nitric oxide production under the regulation of linoleic acid metabolism,folate related pathways,synthesis and degradation of ketone bodies,pyrimidine metabolism,β-alanine metabolism,and retinal metabolism.

Epigallocatechin-3-gallate exerts antihypertensive effects and improves endothelial function in spontaneously hypertensive rats

Objective:To investigate the effect of epigallocatechin-3-gallate(EGCG)on endothelial dysfunction in spontaneously hypertensive rats(SHR).Methods:Wistar-Kyoto(WKY)rats and SHR were divided into four groups;WKY control,SHR control and SHR treated with EGCG(50 mg/kg/day)or losartan(10 mg/kg/day).The treatment was given daily for 4 weeks by oral gavage and the blood pressure was monitored by tail-cuff method every 3 days.Acetylcholineinduced endothelium-dependent relaxations were assessed in isolated phenylephrine-precontracted aortic rings at the end of treatment.The vascular levels of reactive oxygen species,nitric oxide,tetrahydrobiopterin,and cyclic guanosine monophosphate were also measured.Moreover,the expression of angiotensinⅡtype 1(AT_(1))receptor protein was determined.Results:The systolic blood pressure was significantly decreased in SHR treated with EGCG.The impaired endothelium-dependent relaxation was significantly improved in aortic ring isolated from the EGCG-treated SHR group.EGCG also significantly increased the levels of nitric oxide,tetrahydrobiopterin,and cyclic guanosine monophosphate,while decreasing the level of reactive oxygen species and the protein expression of AT_(1)receptor in SHR.Conclusions:EGCG attenuates endothelial dysfunction in SHR by decreasing oxidative stress and increasing vascular nitric oxide bioavailability,which may be modulated partly by inhibition of vascular AT_(1)receptors.An increase in endothelium-dependent relaxation may contribute to a decrease in blood pressure in hypertensive animals.

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).

Effects of continuous intermedin infusion on blood pressure and hemodynamic function in spontaneously hypertensive rats

Objective To examine the effects of exogenously administered intermedin （IMD,adrenomedullin-2） on arterial blood pressure,cardiac function and the cardiovascular IMD receptor system in spontaneously hypertensive rats （SHRs） as well as to investigate the associated mechanisms.Methods Thirteen week-old male rats were divided in Wistar Kyoto （WKY） group （n =12）,SHR group （n =12）,IMD group （SHRs infused with IMD 1-47 500 ng/kg per hour,n =12）,and ADM group （SHRs infused with adrenomedullin 500 ng/kg per hour,n =12）.Results A two-week continuous administration of low dose IMD 1-47 via mini-osmotic pumps markedly reduced blood pressure,the maximal rates of increase and decrease of left-ventricle pressure development （LV ± dp/dtmax）,left ventricular systolic pressure and heart rate in SHRs.Furthermore,IMD also inhibited protein over-expression of cardiovascular IMD receptors,myocardial Receptor Activity-Modifying Proteins （RAMP1 and RAMP2）,aortic RAMP1,RAMP2,RAMP3,and calcitonin receptor-like receptor （CRLR）;suppressed up-regulation of aortic RAMP1,RAMP2,RAMP3 and CRLR gene expression; and markedly elevated the mRNA abundance of myocardial atrial natriuretic peptide （ANP） and myocardial brain natriuretic peptide （BNP）.Additionally,IMD 1-47 administration in SHRs increased aortic cAMP concentration and reduced myocardial cAMP concentration.Conclusion These findings support the speculation that IMD,as a cardiovascular active peptide,is involved in blood pressure reduction and cardiac function amelioration during hypertension.The mechanism underlying this effect may involve IMD binding of a receptor complex formed by RAMPs and CRLR,and consequential regulation of cAMP levels and other cardiovascular active factors,such as ANP and BNP.

Antihypertensive Properties on Spontaneously Hypertensive Rats of Peptide Hydrolysates from Silkworm Pupae Protein

Peptide hydrolysates of silkworm pupae protein with molecular weight of less than 5000 Da were prepared by ultrafiltration. The extracted peptide hydrolysates of silkworm pupae protein had inhibitory action on angiotensin-I-converting enzyme activity in vitro. The hydrolysates were orally administered to spontaneously hypertensive rats (SHR) in one period and long-term (four weeks). The results showed that the systolic blood pressure (SBP) of the treatment groups decreased in a dose-related manner. After one oral administration of silkworm protein hydrolysates with doses of 60, 20 and 5 mg/kg, the SBP of SHR decreased by 21.5, 13.8, and 9.0 mmHg in 1.5 h. After four weeks of the treatment in 80 mg/kg, the SBP decreased by 25 mmHg, with the antihypertensive activity close to 4 mg/kg of captopril;the SBP of the 40 mg/kg dose group also decreased by 17.5 mmHg. The peptide hydrolysate did not affect the SBP in normal, non-hypertensive rats in one period and long-term treatments. The acute toxicity research showed that the peptide hydrolysates were safe and without side effects. This research would be helpful in exploring the silkworm protein peptides as functional components for the antihypertension treatment.

Effects of Total Flavonoids ofHippophae RhamnoidesL.on Intracellular Free Calciumin Cultured Vascular Smooth Muscle Cells of Spontaneously Hypertensive Rats and Wistar-Kyoto Rats

To explore the effects of total flavonoids of Hippophae rhamnoides L. （TFH） quercetin （Que） and isorhamnetin （Isor） on the intracellular free calcium （[Ca^2＋]） in vascular smooth muscle cells （VSMC） of spontaneously hypertensive rats （SHR） and Wistar-Kyoto rats （WKY）. Metheds： Fluo 3-acetoxymethylester（Fluo-3/AM） was used to observe the effects of TFH （100mg/L） and its essential monomers, namely Que （10^-4mol/L） and Isor （10^-4mol/L） on changes of [Ca^2＋]1 in cultured SHR and WKY VSMC （abbr. to Ca-SHR ＆ Ca-WKY） following exposure to high K^＋, norepinephrine （NE） and angiotensin Ⅱ （AngⅡ）, and to compare with the effects of verapamil （Ver）. Results： （1） TFH, Que and Isor had inhibitory effects on resting Ca-SHR （P〈0.05）, but had no significant effects on Ca-WKY （P〉0.05）. （2） High K^＋ could increase Ca-SHR more significantly than Ca-WKY （P〈0.05）; TFH, Que and Isor could inhibit the elevation of [Ca^2＋]1 induced by high K^＋ -depolarization, with the effects similar to that of Ver, and the effect on Ca-SHR was more significant than that on Ca-WKY （P〈0.05）. （3） NE and Ang Ⅱ could increase Ca-SHR more significantly than Ca-WKY （P〈0.05）, TFH, Que and Isor had remarkably inhibitory effect on the elevation of Ca-SHR and Ca-WKY induced by NE or Ang Ⅱ. （4） In the absence of extracellular Ca^2＋ , TFH, Que and Isor also had certain inhibitory effect on Ca-SHR and Ca-WKY induced by NE, and the effect on the former was more significant than that on the latter（P〈0.05）. Ceaclusiea： TFH, Que and Isor might decrease the levels of [Ca^2＋], in VSMCs by blocking both voltage-dependent calcium channels （VDC） and receptoroperated calcium channels （ROC） in physiological or pathological state, which may be one of the important mechanisms of their hypotensive and protective effects on target organs in patients with hypertension.

The Expression of VIP and SP in the Cochlea of Spontaneously Hypertensive Rats and Its Implication

To investigate the expression of vasoactive intestinal peptide (VIP) and substance P (SP) in the cochlea of spontaneously hypertensive rat (SHR), and to assess the function of VIP and SP in the cochlea following the damage of hypertension, hearing thresholds of ABR were observed and the fixative (4% paraformaldehyde) was pumped through the circulatory system. Adult Wistar rats (3 months, n=20) served as the control group and SHRs (3 months, n=20) as the hypertension group. Bullas were taken out and cochleas were irrigated in vitro with the same fixative. The number of base turn's spiral ganglions in the sections was counted. The expression of VIP and SP were detected by SABC method and the images of the sections were analyzed. The number of base turn's spiral ganglsons in the hypertension group was significantly less than in the normal group (P<0.01). VIP and SP were expressed in the spiral ganglion cytoplasma and stria vascularis of the two groups. There were no significant difference in the expression of VIP and SP in spiral ganglion cytoplasma (P>0.05) between the two groups. However, in stria vascularis the expression of VIP in the hypertension group was higher than in the normal group (P<0.05), and no significant difference in SP was found between the two groups. It was suggested that VIP not only contributed to the regulation of the cochlea microcirculation, but also made the neurotransmitter in the pathway of the auditory system. However, SP made only the neurotransmitter in the pathway of the auditory system.

Effect of Salvia Miltiorrhiza Bge on Left Ventricular Hypertrophy and the Expression of Tumor Necrosis Factor-α in Spontaneously Hypertensive Rats

The effects of salvia miltiorrhiza Bge (SMB) on left ventricular hypertrophy (LVH) and the expression of tumor necrosis factor-α (TNF-α) in the left ventricle of spontaneously hypertensive rats and the action mechanism were investigated. Normal Wistar-kyoto (WKY) rats were used as negative control, and spontaneously hypertensive rats (SHR) were randomly assigned to receive pla- cebo or SMB. SMB (1 g/kg·d) was injected intraperitoneally for 12 weeks. Systolic blood pressure (SBP) and left ventricular mass index (LVMI) were measured. HE, VG and immunohistochemical staining combined with computed morphometry were employed to evaluate the cardiomyocyte size, diameter, the collagen volume fraction (CVF), perivascular circumferential area (PVCA), and tumor necrosis factor-α (TNF-α) expression in the left ventricular tissue. The results showed, as compared with WKY rats, the SBP, LVMI, cardiomyocyte size, diameter, CVF, PCVA, and TNF-α expression were increased markedly in the 20-week-old spontaneously hypertensive rats. SMB decreased LVMI (P<0.01), size of cardiomyocytes (P<0.01), collagen volume fraction (P<0.01), perivascular circum- ferential area (P<0.01), and TNF-α expression (P<0.01), but had no effect on SBP (P>0.05). It was suggested that chronic administration of SMB could inhibit and reverse the development of LVH in spontaneously hypertensive rats independent of BP. TNF-α may be involved in the reversal mecha- nism of LVH by SMB.

Sesamin enhances nitric oxide bioactivity in aortas of spontaneously hypertensive rats

OBJECTIVE To explore the underlying mechanisms involved in the effect of sesamin on aortic NO bioactivity in spontaneously hypertensive rat(SHR).METHODS Sesamin was orally administered for consecutive 8 weeks in SHR.Systolic blood pressure(SBP)was measured using the tail-cuff method.The aortas were isolated and in vitro vascular reactivity studies were performed.Superoxide anion production in carotid arteries was assessed by dihydroethidium fluorescence staining.The protein expression of endothelial nitric oxide synthase(eNOS),phosphorylated eNOS(P-eNOS),dihydrofolate reductase(DHFR),nicotinamide adenine dinucleotide phosphate(NADPH)oxidase subunit p47 phox and copper,zinc-superoxide dismutase(Cu/Zn-SOD)in aortas was detected by Western blotting.The dimeric form of eNOS in aortas was determined by low-temperature SDS-PAGE.Aortic level of nitrotyrosine and activities of antioxidant enzymes,namely,total SOD(T-SOD),glutathione peroxidase(GPx)and catalase were also detected.RESULTS In SHR,sesamin treatment reduced SBP,improved vascular relaxation induced by acetylcholine and enhanced aortic NO bioactivity.Sesamin treatment enhanced NO biosynthesis in SHR aortas was due to upregulated P-eNOS and suppressed eNOS uncoupling,and the latter effect might be attributed to decreased nitrotyrosine and upregulated DHFR.Sesamin also reducd the NO oxidative inactivation and decreased the superoxide anion production through downregulation of p47 phox and amelioration of eNOS uncoupling.In addition,sesamin treatment did not alter the levels of GPx and catalase activity but obviously reduced the compensatory elevated T-SOD activity and Cu/Zn-SOD protein expression.CONCLUSION Chronic treatment with sesamin could reduce hypertension and improve endothelial dysfunction through enhancement of NO bioactivity in SHRs aortas.

Taurine supplementation in spontaneously hypertensive rats: Advantages and limitations for human applications

Taurine(2-aminoethanesulfonic acid) is a β-amino acid found in many tissues particularly brain, myocardium, and kidney. It plays several physiological roles including cardiac contraction, antioxidation, and blunting of hypertension. Though several lines of evidence indicate that dietary taurine can reduce hypertension in humans and in animal models, evidence that taurine supplementation reduces hypertension in humans has not been conclusive. One reason for the inconclusive nature of past studies may be that taurine having both positive and negative effects on cardiovascular system depending on when it is assessed, some effects may occur early, while others only appear later. Further, other consideration may play a role, e.g., taurine supplementation improves hypertension in spontaneously hypertensive rats on a low salt diet but fails to attenuate hypertension on a high salt diet. In humans, some epidemiologic studies indicate that people with high taurine and low salt diets display lower arterial pressure than those with low taurine and high salt diets. Differences in techniques for measuring arterial pressure, duration of treatment, and animal models likely affect the response in different studies. This review considers both the positive and negative effects of taurine on blood pressure in animal models and their applications for human interventions.

Telmisartan Attenuates the Growth of Epithelium-like Cells and Glomerular Injury in Spontaneously Hypertensive Rats

The abnormal growth of epithelium-like cells has been noticed in spontaneously hypertensive rats(SHRs)with hypertensive nephropathy.However,the characteristics of abnormal epithelium-like cells and their pathogenesis in hypertensive nephropathy are not fully understood.In the present study,we investigated the correlation of epithelium-like cells with glomerular injury,and the effects of early drug intervention with telmisartan,an anti-hypertensive drug,on the growth of epithelium-like cells.The results showed that the epithelium-like cells were obviously observed lining along the luminal surface of Bowman’s capsule in glomeruli,significantly resulting in the atrophy of the glomerular tuft.Some of the epithelium-like cells strongly expressed proliferating cell nuclear antigen(PCNA)and vimentin,indicating active cellular proliferation.The incidence of epithelium-like cells varied from 13.6%to 54.4%of glomeruli in 48-week-old SHRs,and from 5.1%to 18.0%of glomeruli in age-matched Wistar-Kyoto(WKY)rats(P<0.01).The linear regression analysis further confirmed an obvious correlation between the incidence of epithelium-like cells and the glomerular injury.Moreover,early intervention with telmisartan could dramatically attenuate the progression of epithelium-like cells growth.However,no significant effect of telmisartan on the established epithelium-like cells was observed.Taken together,we demonstrated the involvement of abnormal epithelium-like cells growth in glomerular injury during hypertensive nephropathy in SHRs,and firstly showed the positive effects of the anti-hypertensive drug on the progression of epithelium-like cells growth.

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.

Effect of Salvia Miltiorrhiza on Left Ventricular Hypertrophy and Cardiac Aldosterone in Spontaneously Hypertensive Rats

Chronic treatment with Salvia Miltiorrhiza preventing left ventricular hypertrophy (L VH) and its possible mechanism- inhibiting the action of cardiac aldosterone in spontaneously hypertensive rats (SHR) were investigated.Normotensive Wistar- kyoto (WKY ) rats and SHRs were used.Part of SHRs was treated with Salvia Miltiorrhiza for 12 weeks.Systolic blood pres- sure (SBP) and left ventricular mass index were measured.Sections of heart tissue were stained with HE method and Van Gieson method.Collagen volume fraction was determined in the leftven- tricle by automatically quantitative m orphometry.Cardiac aldosterone concentration was measured by radioimm unoassay.The results indicated thatcom pared with WKY rats,SHRs exhibited high- er SBP,left ventricular collagen volume fraction,and aldosterone concentration (all P<0 .0 5 ) . After the treatm ent with Salvia Miltiorrhiza,SBP,left ventricular collagen volum e fraction,and aldosterone concentration in SHR were decreased as compared with control group (P<0 .0 5 ) ex- cept SBP.It was concluded thatchronic treatment with Salvia Miltiorrhiza could preventleftven- tricular hypertrophy in SHR,significantly inhibit collagen compositions in left ventricle.The m echanism was probably related with the inhibition of the cardiac aldosterone action.

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.

Remodeled structure and reduced contractile responsiveness of ocular ciliary artery in spontaneously hypertensive rats

AIM: To investigate the alterations in both structure and contractile responsiveness of ocular ciliary artery(OCA) in spontaneously hypertensive rat(SHR).METHODS: In this experiment, 20-week-old male SHR and Wistar Kyoto rat(WKY) were studied. The heart rate(HR), the blood pressure(BP; the systolic BP and the diastolic BP) of rats with an electronic sphygmomanometer were measured. Vascular morphometry and isometric tension measurement were used to investigate the alterations in structure and contractility of OCA.RESULTS: A general narrowing of OCAs was observed in SHR compared to the control WYK. In SHR, the media of OCAs were thicker, the luminal diameters were smaller, and the media-to-lumen ratios were higher when compared with WKY(P<0.05). The contractions of OCAs evoked by norepinephrine were smaller in SHR compared to control(P<0.05). Then, OCAs were pretreated with iberiotoxin, L-NAME, or indomethacin 30 min before norepinephrineinduced contraction. Iberiotoxin(0.1 μmol/L) has not changed the norepinephrine-induced contractions in OCAs from both groups. However, L-NAME(100 μmol/L) increased the vasoconstrictions, the increased extents were similar in SHR and WKY(P>0.05). Indomethacin(10 μmol/L) decreased the contractions induced by norepinephrine in OCAs from WKY(P<0.05), but did not change those contractions in vessels from SHR(P>0.05).CONCLUSION: Our results demonstrate that the structure and function of OCAs are altered in hypertension. OCAs from SHR are remodeled with decreased lumen diameter and increased media-to-lumen ratio. Moreover, the contractile responsiveness of OCAs from SHR is diminished due to the disruption of vasoconstrictive effect of prostaglandins.

Effect of alpha-lipoic acid supplementation on blood pressure, renal oxidant-antioxidant status and renal damage in spontaneously hypertensive rats

Objective:To investigate the effect of alpha-lipoic acid(ALA)supplementation on systolic blood pressure(SBP),renal oxidant-antioxidant status and renal damage in spontaneously hypertensive rats(SHR)and SHR administered with Nω-nitro-L-arginine methyl ester(L-NAME).Methods:Male rats were divided into four groups(SHR,SHR+ALA,SHR+L-NAME,SHR+ALA+L-NAME).The respective group of rats was administered with ALA(100 mg/kg/day)from age 4 weeks to 28 weeks and L-NAME(25 mg/kg/day)from age 16 weeks to 28 weeks.SBP was measured every two weeks and twenty four hour urine was collected at 4 weeks,16 weeks and 28 weeks for estimation of protein,creatinine and N-acetyl-e end of 28 weeks,rats were sacrificed and blood and kidneys colα-Dglucosaminidase.At thlected for assessment of blood creatinine,kidney thiobarbituric acid reactive substances,protein carbonyls,superoxide dismutase,catalase,glutathione peroxidase,glutathione reductase,glutathione S-transferase,glutathione disulfide,glutathione,total antioxidant status and nitric oxide as well as histopathological examination.Results:ALA supplementation significantly reduced SBP of SHR and SHR+L-NAME rats when compared to their respective non-supplemented groups.Renal oxidant status markers including thiobarbituric acid reactive substances and protein carbonyls were significantly reduced on SHR and SHR+L-NAME rats supplemented with ALA at 28 weeks as well as ALA supplementation significantly increased renal antioxidants including superoxide dismutase,catalase,glutathione peroxidase,glutathione S-transferase,glutathione and glutathione/glutathione disulfide ratio at 28 weeks.No significant change in nitric oxide levels was observed between the ALA supplemented and non-supplemented groups.Renal dysfunction was ameliorated on ALA supplementation as evidenced by significant reduction in urine protein levels,N-acetyl-α-D-glucosaminidase activity and significant increase of creatinine clearance in SHR and SHR+L-NAME at 28 weeks.Renal histopathological examination showed that ALA supplementation prevented vascular damage in SHR and ameliorated glomerular damage in SHR+L-NAME at 28 weeks.Conclusions:ALA has hypotensive and renoprotective effects on both SHR and SHR+LNAME,which could be due to its ability to ameliorate oxidative stress in the kidneys.

The effects and mechanisms of total flavonoids of Cydonia oblonga Mill. on myocardial hypertrophy in spontaneously hypertensive rats

Aim To study the activity and mechanism of inhibition of myocardial hypertrophy of total flavonoids of Cydonia oblonga Mill. in spontaneously hypertensive rats. Methods Total flavonoids of COM （COMF） were sepa- rated and purified by the optimal process. SHtl were divided into 6 groups： SHR control group （SHR） , captopril group （SHR ＋ CAP, 25 μg · g^-1）, Eucommia ulmoides Oliver group （SHR ＋ EUO, 30 μg · g^-1）, low （SHR ＋ COMF-L, 40 μg · g^-1） ,middle （SHR ＋ COMF-M, 80 μg· g^-1） and high dose （SHR ＋ COMF-H, 160 μg · g^-1） of COMF groups. Wistar-Kyoto （WKY） rats （n= 8 ） were given distilled water as control The drugs were given by intragastric administration for 16 weeks. The histological and pathological examination of the heart were performed and organic damage were valued. The levels of Ang II and ALD in blood and heart were evaluated. The mRNA and protein expression of ACE, ACE2 and AT~ was determined by RT-PCR and Western blot to evaluate the effect of COMF on RAAS. Results Compared with SHR control group, HW, HW/BW, LVM and LVM/BW de- creased in SHR ＋ COMF-M and SHR ＋ COMF-H groups; Cadiomyocyte hypertrophy was inhibited in COMF groups; The concentration of Ang 11 and ALD in heart and blood decreased; ACE and AT1 mRNA and protein ex- pression in heart tissue decreased while ACE2 mRNA expression increased （P 〈 0.01 or P 〈 0.05） , Conclusion Total flavonoids of Cydonia oblonga Mill. showed the effect of inhibition of myocardial hypertrophy in spontaneously hypertensive rats and the mechanism was related to. inhibit the activity of Renin-angiotensin-aldosterone system.

Protective effect of sodium ferulate on cardiac hypertrophy in spontaneously hypertensive rats

OBJECTIVE To investigate the inhibitory effect and mechanism of sodium ferulate(SF)on myocardial hypertrophy in spontaneously hypertensive(SHR).METHODS Forty 14-week-old SHR male rats were randomly divided into model group(SHR,receive distilled water)and SF treatment groups(SF 20,40 and 80 mg·kg^-1 per day,respectively).Age-matched male Wistar-Kyoto(WKY)rats gavaged with distilled water served as controls.After 12 weeks of treatment,the effects of SF on cardiac hypertrophy were evaluated using echocardiographic measurement,pathological analysis and the expression of atrial natriuretic peptide(ANP),myosin heavy chainβ(β-MHC)-a gene related to myocardial hypertrophy.In order to explore the mechanism of SF on myocardial hypertrophy,the calcium-sensing receptor(CaSR),calcineurin(CaN),nuclear factor of activated T cell 3(NFAT3),phosphorylation NFAT3(p-NFAT3),zinc finger transcription factor(GATA4),phosphorylation GATA4(p-GATA4),protein kinase Cβ(PKC-β),Raf-1,extracellular regulated protein kinase 1/2(ERK 1/2),phosphorylation ERK1/2(p-ERK 1/2)and mitogen-activated protein kinase phosphatase-1(MKP-1)were detected.RESULTS The myocardial hypertrophy parameters,myocardial cell cross section area,left ventricular wall thickness and expression of ANP and β-MHC,CaSR,CaN,NFAT3,p-GATA4,PKC-β,Raf-1,and p-ERK 1/2 were significantly increased,while the left ventricular cavity was significantly smaller,expression of p-NFAT3 and MKP-1 were significantly decreased,meanwhile,the ultra⁃structure of cardiomyocytes was significantly damaged in 26-week-old SHR rats.Notably,SF significantly ameliorated myocardial hyper⁃trophy in 26-week-old SHR rats;suppressed the overexpression of ANP,β-MHC,CaSR,CaN,NFAT3,p-GATA4,PKC-β,Raf-1,and p-ERK 1/2 and increased the expression of p-NFAT3 and MKP-1.CONCLUSION SF can inhibit cardiac hypertrophy in SHR rats,and the mechanism may be related to the inhibition of CaSR mediated signaling pathway.

Chemical renal artery denervation with appropriate phenol in spontaneously hypertensive rats

Objective To explore the effectiveness of renal denervation (RDN) on blood pressure with the appropriate dosage of phenol/ethanol solution in spontaneously hypertensive rats (SHRs). Methods RDN was performed on the bilateral renal artery. Forty SHRs were divided into four groups according on the dosage of phenol (10% phenol in absolute ethanol): sham group, 0.5 mL phenol group, 1 mL phenol group and 1.5 mL phenol group (n = 10 in each group). Blood pressure was measured by tail-cuff plethysmography. Plasma creatinine was determined four weeks after the treatment. The kidneys and renal arteries were collected and processed for histological examination. Results A sustained decrease in systolic blood pressure (SBP) was only observed after the application of 1 mL phenol for four weeks, while SBP was lowered during the first week after RDN and increased in the following three weeks in the 0.5 mL and 1.5 mL phenol groups compared with the sham group. Renal norepinephrine (NE) was significantly decreased four weeks after RDN in the 1 mL and 1.5 mL phenol group compared with the sham group, but not in the 0.5 ml group. RDN with 1 mL phenol obviously reduced glomerular fibrosis. Histopathological analysis showed that tyrosine hydroxylase immunoreactivity was lower in the 1 mL and 1.5 mL phenol groups compared with the sham group. Moderate renal artery damage occurred in the 1.5 mL phenol group. Conclusion Chemical denervation with 1 ml phenol (10% phenol in absolute ethanol) effectively and safely damaged peripheral renal sympathetic nerves and contributed to the sustained reduction of blood pressure in SHRs.

Enrichment Discrimination Behavior in Spontaneously Hypertensive Rats

Objectives: 1) To reveal, among spontaneously hypertensive rats, subpopulations that diverge in attention to objects enriching an empty cross-maze;2) To evaluate effect of clinically efficient drug for treatment of attention deficiency atomoxetine on the attention to environmental cues in attentionally-low rats. Method: A novel paradigm that provides measure of attention towards enriching objects independent of general locomotor activity and spatial orientation is employed. The apparatus consists of 4-arm radial maze, two arms of which contain objects (enriched compartments). Animals exploring the objects typically stay longer in enriched parts of maze than in empty arms and have a higher score of enrichment discrimination ratio. Results: Frequency distribution of the enrichment discrimination ratio had clear bimodal shape that differed significantly from normal distribution suggesting the existence of subpopulations of attentionally-low and -high individuals. The attentionally-low phenotype did not show inferiority in spatial orientation as compared with attentionally-high phenotype. The phenotypes did not differ from each other in measures of locomo- tor activity and blood pressure. Atomoxetine (3 mg/kg, orally, once daily for 4 days) enhanced enrichment discrimina- tion in animals of attentionally-low phenotype. Single administration of the drug was ineffective. Conclusion: Popula- tion of spontaneously hypertensive rat includes two phenotypes of attentionally-low and -high individuals. Subchronic atomoxetine ameliorates attention to environmental cues in attentionally-low rats. The enrichment discrimination test could be useful in studies of neurobiology of attention deficit condition and for screening of novel drug candidates.