European Journal of Pharmacology 620 (2009) 84–89

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European Journal of Pharmacology

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Cardiovascular Pharmacology

Sesamin improves endothelial dysfunction in renovascular hypertensive rats fed witha high-fat, high-sucrose diet

Xiang Kong, Jie-ren Yang ⁎, Li-qun Guo, Ying Xiong, Xiang-qi Wu, Kai Huang, Yong ZhouDepartment of Pharmacology, Third-Grade Pharmacology Laboratory of State Administration of Traditional Chinese Medicine, Wannan Medical College, 10 Weiliu Road, Wuhu 241001,Anhui Province, China

⁎ Corresponding author. Tel.: +86 553 3932464.E-mail address: wnmcyaoli@sina.com (J. Yang).

0014-2999/$ – see front matter © 2009 Elsevier B.V. Adoi:10.1016/j.ejphar.2009.08.023

a b s t r a c t

a r t i c l e i n f o

Article history:Received 10 May 2009Received in revised form 3 July 2009Accepted 6 August 2009Available online 20 August 2009

Keywords:Endothelial dysfunctionEndothelial nitric oxide synthaseNADPH oxidaseSesamin

The present study was designed to evaluate the possible in vivo protective effects of sesamin onhypertension and endothelial function in two-kidney, one-clip renovascular hypertensive rats fed with ahigh-fat, high-sucrose diet (2K1C rats on HFS diet). Sesamin was orally administered for 8 weeks in 2K1C ratson HFS diet. Then, the serum malondialdehyde level was determined. The protein expression of endothelialnitric oxide synthase (eNOS), nitrotyrosine and nicotinamide adenine dinucleotide phosphate (NADPH)oxidase subunit p47phox in aortas was detected by Western blotting. Vasorelaxation response toacetylcholine and nitroprusside, and functional assessment of nitric oxide (NO) bioactivity were alsodetermined in aortic rings. Sesamin treatment reduced systolic blood pressure, improved vasodilatationinduced by acetylcholine and enhanced NO bioactivity in the thoracic aortas. These changes were associatedwith increased eNOS, decreased malondialdehyde content, and reduced nitrotyrosine and p47phox proteinexpression. All these results suggest that chronic treatment with sesamin reduces hypertension andimproves endothelial dysfunction through upregulation of eNOS expression and reduction of NO oxidativeinactivation in 2K1C rats on HFS diet.

© 2009 Elsevier B.V. All rights reserved.

1. Introduction

It is well known that diminished nitric oxide (NO) production and/or increased reactive oxygen species, in particular superoxide-induced oxidative inactivation may lead to decrease NO availability,contributing to endothelial dysfunction and maintenance of hyper-tension. Several studies have shown that endothelial nitric oxidesynthase (eNOS) expression and/or NO concentration are significantlyincreased although endothelium-dependent vasorelaxation is de-creased in spontaneously hypertensive (SHR), stroke-prone sponta-neously hypertensive (SHRSP), and two-kidney, one-clip renovascularhypertensive rats (Hong et al., 2000; Ülker et al., 2003a,b; McIntyreet al., 1999; García-Saura et al., 2005). These results suggest that onlyinactivation of NO is responsible for endothelial dysfunction in thesemodels. However, Ma et al. (2001) reported that severe endothelialdysfunction occurred and caused not only an increase in NOinactivation, but also a decrease in its production from eNOS inSHRSP supplemented with a high-salt, high-fat diet. In fact, a linkbetween high-fat or high-fat, high-sucrose (HFS) diet mediatedoxidative stress and a decrease in NO concentration has been recentlydemonstrated (Rodríguez et al., 2002; Yamamoto and Oue, 2006).Chronic consumption of HFS diet induces dyslipidemia and hyperten-

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sion in genetically normal rats. Endothelial dysfunction in thismodel isassociated with NO inactivation and downregulation of eNOSexpression (Roberts et al., 2005, 2006; Bourgoin et al., 2008). Thus,we hypothesized that NO inactivation in combination with decreasedeNOS expression could contribute to endothelial dysfunction in two-kidney, one-clip renovascular hypertensive rats fed with a HFS diet(2K1C rats on HFS diet).

Sesamin, one of the major lignan in sesame seeds has received agreat deal of interest. The literatures reported that sesamin hashypolipidemic (Gu et al., 1998) and antihypertensive effect (Matsu-mura et al., 1995, 1998; Kita et al., 1995). Recent works demonstratedthat sesamin metabolites induced a vasorelaxation in vitro (Nakanoet al., 2006) and sesamin feeding enhanced endothelium-dependentrelaxation in deoxycorticosterone acetate (DOCA)-salt hypertensiverats (Nakano et al., 2003). Konan et al. (2008) reported that theaqueous extract of leaves from sesame induced dose-dependentvasorelaxation in guinea-pig aortas. Nevertheless, the underlyingmechanisms of in vivo protective effects of sesamin on blood pressureand endothelial function are not completely understood. In a series ofrecent studies, Nakano et al. (2003, 2008) suggested that sesamindecreased superoxide production and suppressed mRNA expressionof nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inaortas from DOCA-salt hypertensive rats. Lee et al. (2004) reportedthat sesamin increased NO concentration and induced eNOS mRNAand protein expression in the medium of human umbilical veinendothelial cells. Moreover, sesamin metabolite-induced relaxations

85X. Kong et al. / European Journal of Pharmacology 620 (2009) 84–89

in isolated rat aortic rings were attenuated by pretreatment with NG-nitro-L-arginine (L-NOARG, a NOS inhibitor) (Nakano et al., 2006). Theaqueous extract of leaves from sesame caused relaxation wasattenuated in the presence of the L-NOARG (Konan et al., 2008).These results suggested that the effects of sesamin on biosynthesisand/or reduced superoxide-mediated inactivation of NO may beinvolved in its protective action.

Therefore, the purpose of this study was to evaluate the effects ofsesamin in the development of hypertension and endothelialdysfunction in 2K1C rats on HFS diet. In addition, we further examinedthe roles of eNOS, NADPH oxidase subunit p47phox, and nitrotyrosine(the footprint of NO interaction with reactive oxygen species)expression in sesamin-mediated protection.

2. Materials and methods

2.1. Drugs and reagents

Sesamin (>94% purity) was provided by Tianyi Lvbao TechnologyCo., Ltd. (Wuhu, China)with an inventionpatent number ZL03113181.6of China to extract sesamin. Its structure is shown in Fig. 1. Norepi-nephrine, phenylephrine, acetylcholine (an endothelium-dependentvasodilator), nitroprusside (an endothelium-independent vasodilator),and NG-nitro-L-arginine methyl ester (L-NAME, an inhibitor of NOS)were purchased from Sigma (St. Louis, MO, USA). Total cholesteroland triglyceride assay kits were purchased from Rongsheng Biotech-nology Co. (Shanghai, China). Malondialdehyde analysis kit wasobtained from Jiancheng Institute of Biotechnology (Nanjing, China).The composition of Krebs solution was as follows (in mM): NaCl 118.3,KCl 4.7, CaCl2 2.5, KH2PO4 1.2, MgSO4 1.2, NaHCO3 25, and glucose 11.1.

2.2. Animals, diet and surgery

Thirty-six 6–7 week old (weighing 200–240 g) male Sprague–Dawley rats [Certificate No: SCXK(jing) 2007-0001] were purchasedfrom Weitong Lihua Experimental Animal Co., Ltd. (Beijing, China).The rats were housed in individual cages at 24–26 °C with a 12-h light–dark cycle, and acclimatized to these conditions for 1 week.The investigation conformed to the Guide for the Care and Use ofLaboratory Animals published by the US National Institutes of Health(NIH publication No. 85-23, revised 1996).

Rat chow [Certificate No: SCXK(jun) 2002-018] was purchasedfrom the Experimental Animal Center at the Academy of MilitaryMedical Sciences of PLA in Beijing. High-fat, high-sucrose (HFS) dietwas prepared as described previously (Xu et al., 2006) with slightmodification, and composed of 18% protein, 22% fat (containing 15%lard oil and 2% cholesterin), 46% carbohydrate (containing 25%sucrose), and standard vitamins and mineral mix. Specifically, thepercent distribution of calories and caloric density for the two dietswere as follows: 28% protein, 13% fat, 59% carbohydrate and 3.1 kcal/gfor the standard diet, and 16% protein, 44% fat, 40% carbohydrate and4.5 kcal/g for the HFS diet.

Rats were anesthetized with 3% sodium pentobarbital (30mg/kg, i.p.) after the acclimatization period. 2K1C renovascular hypertensionwas induced as described previously (Ono et al., 1989). Briefly, a U-shaped silver clip (0.25 mm internal diameter) was placed around the

Fig. 1. The structure of sesamin.

left renal artery in 28 rats through a midline laparotomy. Sham-operated rats underwent the same procedure, except that the clipwas not applied. The wound was closed in layers, and penicillinG (100,000 U/kg) was administered intramuscularly for 3 days.

2.3. Experimental design

Seven days after surgery, the 2K1C and Sham-operated ratsreceived the HFS and standard diet, respectively. Systolic bloodpressure (SBP) was measured in conscious rats using the tail-cuffmethod (ALC-NIBP, Alcott Biotech, Shanghai, China) after the animalswere maintained in a warm chamber for about 10 min. Before the firstmeasurement of SBP, rats were trained for 3 days to adapt to theprocedure. SBP values were derived from an average of 5 measure-ments per animal. Five weeks after placement of the clip, 22hypertensive rats (SBP greater than 160 mm Hg) were randomlyassigned to three groups, namely a model group (2K1C on HFS, n=8),and two treatment groups (Ses 120 and Ses 60 groups, received thesame HFS diet, given sesamin by gavage at the daily dose of 120 or60 mg/kg, n=7 each). In addition, the sham-operated group (withstandard diet, n=8) was set up. Sesamin was suspended in 0.5%carboxymethylcellulose sodium and orally administrated at 9:00–10:00 AM everyday for 8 weeks in two treatment groups. Untreatedgroups received an equal volume of carboxymethylcellulose sodiumas control.

At the end of the experiment, the rats were fasted overnight andanesthetized by an intraperitoneal injection of sodium pentobarbital.Blood samples were drawn from abdominal aorta, centrifuged toobtain serum, and kept at−20 °C until assayed. Thoracic aortas of ratswere carefully removed, cleaned of adhering tissue, and divided intotwo parts. One part contained the descending thoracic aorta whichwere cut into two transverse rings (3–4 mm in length) used forvascular reactivity experiments, and the other was quickly frozen inliquid nitrogen and stored −80 °C until processed.

2.4. Vascular reactivity studies

Aortic rings were mounted between two steel hooks, randomlysuspended in two tissue baths containing 10 mL Krebs solution at37 °C, and continuously bubbled with carbogen. Changes in isometrictension were detected by JZ101 force transducers (Xinhang ElectricApparatus, Gaobeidian, China) and recorded via a MedLab U/8Cpolygraph (Medease Science and Technology, Nanjing, China). Pre-load (2 g) was applied to the rings, and the vessels were allowed toequilibrate for 60 min (with 4 washouts). The rings were stimulatedwith norepinephrine (3×10−7 M) to evaluate their viability, thenserially washed to baseline and equilibrated once again. Subsequently,in the first bath, the concentration-relaxation response curves toacetylcholine (10−8 to 10−4 M) and nitroprusside (10−9 to 10−6 M)were performed in rings, which were precontracted by phenylephrine(10−6 M). The relaxant responses to acetylcholine and nitroprussidewere calculated as a percentage of the response to phenylephrine. Inthe second bath, rings were also precontracted with 10−6 Mphenylephrine, and then incubated with 10−4 M L-NAME. Underthese conditions, the contraction induced by L-NAME resulting from aloss of physiological NO in aortas was observed. Thus, the plateauphase of L-NAME-induced contraction was measured and expressedas a percentage of the phenylephrine-induced contraction to reflectNO bioactivity.

2.5. Determination of lipid and malondialdehyde levels

The serum levels of total cholesterol and triglyceride weredetermined by enzymatic colorimetric reaction with commercialdiagnostic kits. Malondialdehyde, a degrading product of lipidperoxidation known as thiobarbituric acid reactive substances, was

86 X. Kong et al. / European Journal of Pharmacology 620 (2009) 84–89

also determined in serum according to the thiobarbituric acidmethods (Wang et al., 2009).

2.6. Western blot analysis

Western blotting was performed in the aortas from each group todetect eNOS, p47phox and nitrotyrosine protein levels as previouslydescribed (Roberts et al., 2006; López-Sepúlveda et al., 2008). Proteinsof aortic homogenates were separated by electrophoresis on a sodiumdodecyl sulfate polyacrylamide gel. The proteins were transferredelectrophoretically to polyvinylidene difluoride membranes, thenincubated with primary polyclonal anti-eNOS (Boster Biotechnology,Wuhan, China), polyclonal anti-p47phox, and monoclonal anti-nitro-tyrosine antibodies (SantaCruz Biotechnology, Santa Cruz, USA)overnight and with the correspondent secondary peroxidase conju-gated antibodies. The blots were visualized using enhanced chemi-luminescence kit (Pierce, Rockford, IL) and evaluated bydensitometry. The intensity of the bands was normalized to that ofβ-actin detected by polyclonal antibody and values are presented asrelative density.

2.7. Statistical analysis

Data were expressed as mean±S.E.M. For statistical analysis, weused one-way ANOVA followed by Newman–Keuls tests. P<0.05 wasconsidered statistically significant.

3. Results

3.1. Systolic blood pressure and lipid levels

Before clipping the left renal artery, no significant difference inbasal level of SBP was observed among all experimental groups. Asshown in Table 1, SBP and serum lipid levels in themodel group (2K1Crats on HFS diet) were significantly higher than those in the shamgroup. Daily oral administration of both 120 and 60 mg/kg sesamininduced a progressive reduction in SBP (reduced 17% and 11% at theend of 8 weeks, P<0.01 versus model rats). Moreover, treatment with120 mg/kg sesamin obviously attenuated the elevation of serum totalcholesterol and triglyceride levels (P<0.01 versus model rats). Theseresults confirmed previous evidence that sesamin has hypolipidemicand antihypertensive effects.

3.2. In vitro vascular activity

Acetylcholine elicited a concentration-dependent relaxation inphenylephrine-precontracted aortic rings from all experimentalgroups. Acetylcholine-induced vasorelaxation was significantly de-creased (by 18, 23 and 28% for 10−6, 10−5 and 10−4 M acetylcholine,respectively; P<0.05 or P<0.01) in the model group compared withthe sham group. The aortic rings obtained from the 120 mg/kgsesamin treated group showed significant increase in vasodilatationinduced by acetylcholine as compared to those from the model group

Table 1Effects of sesamin on systolic blood pressure and lipid metabolism.

Group n SBP (mm Hg) TG(mmol/L)

TC(mmol/L)

5 weeks 9 weeks 13 weeks

Sham 8 114±6.4 115±6.6 118±4.8 1.03±0.22 1.64±0.44Model 8 174±4.9d 175±8.0d 179±5.1d 2.05±0.52d 3.42±0.90d

Ses 120 7 172±6.3d 155±6.7bd 142±7.6bd 1.34±0.33b 2.41±0.54ac

Ses 60 7 171±6.8d 164±7.4ad 153±9.0bd 1.63±0.23d 2.87±0.46d

Values are expressed as mean±S.E.M. aP<0.05, bP<0.01 vs. model group. cP<0.05,dP<0.01 vs. sham group. SBP: systolic blood pressure, TC: triglyceride, TG: totalcholesterol.

(Fig. 2A). The endothelium-independent vasorelaxation induced bysodium nitroprusside was not different among all experimentalgroups (Fig. 2B).

The addition of L-NAME to phenylephrine-precontracted aorticrings induced further vasoconstriction. The magnitude of L-NAME-induced responses was diminished in 2K1C rats on HFS diet ascompared to the sham group, indicating a reduced bioactive NOformation in the model group. A significant improvement of NObioactivity was found in the sesamin 120 mg/kg treated group (Fig. 3).

3.3. Serum level of malondialdehyde

As shown in Fig. 4, an increase of serum malondialdehyde contentconfirmed that oxidative damage had been induced in 2K1C rats onHFS diet. The level of malondialdehyde in the sesamin 120 mg/kgtreated group was significantly lower than those in the model group(P<0.05 versus model rats).

3.4. Protein expression of eNOS in rat aortas

Compared with the sham rats, 2K1C rats on HFS diet exhibited asignificant reduction of eNOS protein expression in aortic tissues.Treatment with 120 mg/kg sesamin was able to enhance proteinexpression of eNOS in aortas (Fig. 5).

3.5. Protein expression of nitrotyrosine and p47phox in rat aortas

As shown in Fig. 6, p47phox and nitrotyrosine protein expression inaortic tissues were significantly higher in the model group comparedwith the sham group. These abnormalities were essentially reversedby treatment with 120 mg/kg sesamin for 8 weeks.

4. Discussion

The major conclusions to be drawn from this study were thatchronic treatment with sesamin significantly reduced SBP andimproved acetylcholine-induced vasorelaxation in 2K1C rats on HFSdiet. This effects seem to be related to restore NO bioactivity throughupregulation of eNOS and suppression of p47phox and nitrotyrosineprotein expression.

Among the various endothelium-derived molecules, NO has beendemonstrated to play a key role in the regulation of vascular tone andblood pressure. In rat aortas, specially in SHR and 2K1C, endothelium-dependent vasodilatation relies almost entirely on the endothelialrelease of NO (Rodriguez-Rodriguez et al., 2007; Callera et al., 2000;Kong et al., 2009). In the present study, 2K1C rats on HFS diet wereaccompanied by a reduced aortic relaxant response to acetylcholine.Indeed, aortic rings from the model group showed diminishedbioactivity of NO, which was assessed on the basis of the magnitudeof L-NAME (an inhibitor of NOS)-induced vasoconstriction. Further-more, the relaxant response to the NO donor nitroprusside wascomparable among the sham and the model groups. Taken together,these data indicated that endothelial dysfunction in 2K1C rats on HFSdiet occurred and was characterized by impaired the endothelium-dependent relaxation and NO inactivation. In addition, we found thatsesamin treatment improved the aortic endothelial dysfunction in2K1C rats on HFS diet. It is of note that endothelial function plays animportant role in the modulation of blood pressure. Thus, the rise inNO bioactivity and NO-mediated vasodilatation after sesamin treat-ment, could, in part, account for the observed amelioration ofhypertension. These results confirmed and extended previousevidence about the improvement in endothelial function of sesaminin hypertensive rats (Nakano et al., 2003). Several potential mechan-isms would be involved in the sesamin-induced increase of NObioactivity, such as changes in the expression of eNOS, changes in the

Fig. 2. Effects of sesamin on the vascular relaxant responses induced by acetylcholine (A) and nitroprusside (B) in aortic rings precontracted by 10−6 M phenylephrine. Values aremean±S.E.M. n=5 to 6 rings from different rats. ⁎P<0.05, ⁎⁎P<0.01 vs. model group. †P<0.05, ††P<0.01 vs. sham group.

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vascular levels of superoxide and thus superoxide-mediated NOinactivation.

NO is generatedwithinnormal endotheliumbyeNOS fromL-arginine.Similar to previous reports (Lee et al., 1999; Roberts et al., 2005), atthe age of 13 weeks we have found lower eNOS protein expressionlevels in aortas from themodel groupwhen comparedwith the shamgroup. Long-term administration of sesamin was able to increaseeNOS expression in this animal model. Several recent findings (Leeet al., 2004; Nakano et al., 2006), i.e., sesamin induced eNOS mRNAand protein expression and enhanced NOS activity in humanumbilical vein endothelial cells, sesamin metabolites induced NO-dependent vasorelaxation, and sesamin feeding had no antihyper-tensive action in chronically L-NOARG-treated rats or DOCA-salt-treated eNOS−/− mice, supported this conclusion. The resultssuggested that the improvement of endothelial function and NObioactivity after sesamin treatment might be attributed, at least inpart, to a quantitative eNOS restoration, since the protein expressionof eNOS were increased in aortas from 2K1C rats on HFS diet.

Excessive release of oxygen radicals, if not controlled by theendogenous antioxidant systems, can lead to lipid peroxidation.Oxidant stress is evidenced by significantly higher malondialdehydelevel in serum of 2K1C rats on HFS diet compared to the sham rats. Thesuperoxide inactivates NO, thereby diminishing its halflife, and leadsto generate peroxynitrite. Peroxynitrite, a highly reactive andcytotoxic radical attacks and denatures lipids, nucleic acids, and

Fig. 3. Effects of sesamin on bioactive NO production in aortic rings. (A) Representative recordaortic rings from sham, model and sesamin 120 mg/kg treated rats, respectively. (B) Averapercentage of increased tension induced by L-NAME vs. the plateau value induced by phen

proteins (Halliwell, 1997). Peroxynitrite reacts with tyrosine residuesto produce nitrotyrosine, which is frequently used as a stable footprintof superoxide-mediated inactivation of NO. The elevation of aorticnitrotyrosine abundance in 2K1C rats on HFS diet was found hereinand closely resembled the earlier findings in SHRSP on high-salt, high-fat diet (Ma et al., 2001), SHR (Hong et al., 2000) and HFS diet-inducedhypertensive rats (Roberts et al., 2000). Indeed, the increasednitrotyrosine protein expression and malondialdehyde level fromthe model group were tangible evidence for the presence of oxidativestress leading to enhanced NO inactivation. The NADPH oxidase hasrecently been characterized in several cell lines and shown to be oneof the main sources of vascular superoxide (Ülker et al., 2003a,b).Upregulation of this oxidase, in particular p47phox (a cytoplasmicsubunit of NADPH oxidase), can contribute to the pathogenesis ofoxidative stress in several animal models of acquired and genetichypertension (Vaziri and Ni, 2005; Sánchez et al., 2006; Yu et al.,2008; López-Sepúlveda et al., 2008). In our experimental conditions,we also found upregulation of p47phox protein expression in thevascular tissues of 2K1C rats on HFS diet. Taken together, theincreased p47phox expression could raise superoxide production andthereby contributed to the elevation of nitrotyrosine expression andNO inactivation in this animal model. Several reports have recentlysuggested that sesamin feeding decreased aortic superoxide produc-tion and mRNA expression of NADPH oxidase subunits (p22phox,gp91phox, Nox1 and Nox4) in DOCA-salt hypertensive rats (Nakano

ing for 10−4 M L-NAME-induced vasocontraction in phenylephrine (PE)-precontractedged values (mean±S.E.M. n=5 to 6 rings from different rats) were calculated as theylephrine. ⁎P<0.05 vs. model group. †P<0.05, ††P<0.01 vs. sham group.

Fig. 4. Effects of sesamin on serum malondialdehyde concentration in rats from eachgroup. Values are mean±S.E.M. n=7–8. ⁎P<0.05 vs. model group. ††P<0.01 vs. shamgroup. MDA: malondialdehyde.

Fig. 6. Effects of sesamin on the protein expression of p47phox and nitrotyrosine in aortictissues byWestern blotting. Histograms represent densitometric values normalized to thecorrespondingβ-actin (n=4). ⁎P<0.05, ⁎⁎P<0.01 vs.model group. †P<0.05, ††P<0.01 vs.sham group.

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et al., 2003; Nakano et al., 2008). In the present study, we showed thatsesamin was effective to decrease serum malondialdehyde level andreduce expression of p47phox and nitrotyrosine in aortas from 2K1Crats on HFS diet. These results suggested that another cause of theeffect of sesamin on improving the endothelial dysfunction and NObioactivity is due to its antioxidative activity, which might have comefrom downregulation of p47phox expression and subsequent suppres-sion of NO oxidative inactivation.

In addition, oxidative stress results in depletion of the NOS cofactortetrahydrobiopterin and in uncoupling of the NOS. The latter events,in turn, reduce NO production and promote superoxide generation byNOS (Roberts et al., 2006; Landmesser et al., 2003). Supplementationwith tetrahydrobiopterin significantly reduced SBP in SHR whichmight be mediated through its direct antioxidant activity and/ordecreasing oxygen free radical production from NOS (Hong et al.,2000). d'Uscio et al. (2003) reported that treatment with antiox-idative vitamin C increased vascular tetrahydrobiopterin levels andNOS activity. Thus, the possibility of sesamin-induced increase inaortic NO bioactivity from protecting uncoupling of the NOS and itscofactor tetrahydrobiopterin from oxidative stress could be assumed.Nevertheless, further experiments should be carried out to evaluatethese mechanisms.

In our investigation, we also demonstrated that chronic treatmentwith 120 mg/kg sesamin decreased serum total cholesterol andtriglyceride levels in rats. These effects were related to the sesaminproperties of inhibiting lipid metabolism, such as desaturation in thebiosynthesis of polyunsaturated fatty acid and cholesterol absorption(Shimizu et al., 1991; Hirose et al., 1991). The underlying mechanismis that sesamin could inhibit the HMG-CoA reductase (Hirose et al.,1991), which is the rate-limiting enzyme in the cholesterol biosyn-thetic pathway.

Fig. 5. Effects of sesamin on the protein expression of eNOS in aortic tissues byWesternblotting. Histogram represents densitometric values normalized to the correspondingβ-actin (n=4). ⁎P<0.05 vs. model group. †P<0.05, ††P<0.01 vs. sham group.

In summary, our results demonstrated that orally administratedsesamin by gavage for 8weeks reduced the elevated blood pressure andimproved the vascular endothelial function in 2K1C rats fed with a HFSdiet. These effects, at least in part, were associatedwith enhanced eNOSexpression and reduced NO inactivation.

Acknowledgments

This workwas supported by grants from the Key Program of NaturalScience Foundation of Education Department of Anhui Province (No:2006kj099A) and the Program of Universities Excellent Young TalentFoundation of Anhui Province (No: 2009SQRZ184).

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