effects of low-dose ketanserin on atherosclerosis in rats and rabbits

Effects of low-dose ketanserin on atherosclerosisin rats and rabbits

Yong-Sheng Yu, He-Hui Xie, Ling Li, Shu-Wei Song, Ping Han, Guo-Jun Cai, andDing-Feng Su

Abstract: The present study was designed to test the hypothesis that a small dose of ketanserin, which enhances baroreflex ac-tivity, prevents the early lesions of atherosclerosis. In experiment 1, baroreflex sensitivity (BRS) was measured in 31 spontane-ously hypertensive rats (SHRs) in a conscious state using a computerized blood pressure monitoring system. Four weeks later,the rats were administered vitamin D3 and fed a high-cholesterol diet for 8 weeks to induce atherosclerosis. Then their heartsand aortae were removed for pathological examination. A negative correlation was found between BRS and the scores of coro-nary (r = –0.460, P < 0.01) and aortic atherosclerosis (r = –0.448, P < 0.05) in SHR. In experiment 2, SHRs were divided into 3groups (n = 10 in each group) and received a dose of ketanserin of 0.3, 1.0, and 3.0 mg/kg (i.g.), respectively. At the smallestdose (0.3 mg/kg), ketanserin did not lower blood pressure but enhanced BRS. In experiment 3, SHRs were administered vitaminD3, fed a high-cholesterol diet, and simultaneously treated with low-dose ketanserin. The atherosclerosis scores of the treatmentgroup were significantly lower than those of the control group (coronary score: 0.90 ± 0.14 vs. 1.76 ± 0.27, P < 0.05; aorticscores: 1.00 ± 0.39 vs. 2.18 ± 0.41, P < 0.05). In experiment 4, male New Zealand White rabbits were fed a high-cholesteroldiet and treated with low-dose ketanserin at the same time. The atherosclerosis scores of the treatment group were significantlylower than those of the control group (aortic scores: 0.26 ± 0.20 vs. 0.60 ± 0.31, P < 0.05). In conclusion, the present study dem-onstrated, for the first time, that low-dose ketanserin prevented the development of atherosclerosis independent of its blood pres-sure lowering action in SHRs and New Zealand White rabbits at least in part via enhancement of arterial baroreflex function.

Key words: atherosclerosis, baroreflex, spontaneously hypertensive rats, rabbit, ketanserin.

Resume : La presente etude a eu pour objectif de verifier l’hypothese qu’une faible dose de ketanserine, qui stimule l’activitedu baroreflexe, a prevenu les lesions precoces de l’atherosclerose. Dans l’experience 1, on a mesure la sensibilite du baroreflexe(SBR) chez 31 rats spontanement hypertendus (RSH) eveilles, en utilisant un systeme informatise de surveillance de la pressionarterielle. Quatre semaines plus tard, on a administre de la vitamine D3 aux rats, et on les a soumis a une diete riche en choleste-rol pendant 8 semaines pour induire l’atherosclerose. On a ensuite preleve les cœurs et les aortes pour les soumettre a un exa-men pathologique. On a trouve une correlation negative entre la SBR et les scores coronaire (r = 0,460, P < 0,01) et aortique(r = –0,448,P 0< 0,05) de l’atherosclerose. Dans l’experience 2, on a divise les RSH en trois groupes (n = 10 danschaque groupe) et on leur a administre une dose de ketanserine de 0,3, 1,0 et 3,0 mg/kg (i.g.) respectivement. A la plusfaible dose (0,3 mg/kg), la ketanserine n’a pas abaisse la PA, mais a augmente la SBR. Dans l’experience 3, on a admi-nistre de la vitamine D3 aux RSH et on les a soumis a la diete riche en cholesterol, en plus de les traiter avec la faibledose de ketanserine. Les scores d’atherosclerose du groupe traite ont ete significativement plus faibles que ceux dugroupe temoin (scores coronaires : 0,90 ± 0,14 par rapport a 1,76 ± 0,27, P < 0,05 ; scores aortiques 1,00 ± 0,39 parrapport a 2,18 ± 0,41, P < 0,05). Dans l’experience 4, on a soumis des lapins neo-zelandais blancs males (NZB) a ladiete riche en cholesterol et on les a traites simultanement avec la faible dose de ketanserine. Les scores de l’athero-sclerose du groupe traite ont ete significativement plus faibles que ceux du groupe temoin (scores aortiques : 0,26 ±0,20 contre 0,60 ± 0,31, P < 0,05). En conclusion, cette etude est la premiere a demontrer qu’une faible dose de ketan-serine a prevenu le developpement de l’atherosclerose, independamment de son action d’abaissement de la PA, chez lesRSH et les lapins NZB, en partie du moins, en stimulant la fonction du baroreflexe arteriel.

Mots-cles : atherosclerose, baroreflexe, rats spontanement hypertendus, lapin, ketanserine.

[Traduit par la Redaction]

IntroductionThe function of arterial baroreflex (ABR), also expressed

by baroreflex sensitivity (BRS), contributes importantly tothe regulation of cardiovascular activities. The dysfunctionof ABR has been linked to increased cardiovascular variabil-ity, severe end-organ damage in hypertension, poor progno-sis in acute myocardial infarction, and chronic heart failure(La Rovere et al. 1988; Mortara et al. 1997; Shan, et al.1999; Su and Miao 2005). In our previous studies, it wasfound that ABR dysfunction promoted the development ofatherosclerosis in aortae and coronary arteries in rats (Cai etal. 2005). It is well accepted that atherosclerosis is more fre-

Received 7 February 2010. Accepted 25 May 2010. Publishedon the NRC Research Press Web site at cjpp.nrc.ca on23 October 2010.

Y.-S. Yu, H.-H. Xie, L. Li, S.-W. Song, P. Han, G.-J. Cai,and D.-F. Su.1 Department of Pharmacology, Second MilitaryMedical University, Shanghai 200433, P.R. China.

1Corresponding author (e-mail: [email protected]).

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Can. J. Physiol. Pharmacol. 88: 1054–1060 (2010) doi:10.1139/Y10-079 Published by NRC Research Press

quent and more severe in hypertensive compared with nor-motensive people (Bronte-Stewart and Heptinstall 1954; De-ming et al. 1958; Koletsky et al. 1968; Hollander et al.1976). However, it is not clear whether the function ofABR plays an important role in the severity of atherosclero-sis in hypertension independent of blood pressure.

Ketanserin is an antihypertensive drug with affinity forboth 5-HT2A and a1 receptors (Van Nueten et al. 1981; Re-imann and Frolich 1983). Among many antihypertensiveagents and other drugs, ketanserin possessed the best effecton enhancement of the function of ABR in many kinds ofanimal models studied in our laboratory. It enhanced thefunction of ABR in spontaneously hypertensive rats (SHRs)independently of its blood pressure lowering effect when ad-ministered as a small dose of ketenserin (Fu et al. 2004).However, it is not clear whether low-dose ketanserin mightprevent the development of atherosclerosis.

The present work was therefore designed to answer theabove 2 questions in SHRs and New Zealand White (NZW)rabbits.

Materials and methods

Animals and drug administrationSHRs of either sex (180–240 g; 12–16 weeks) and male

NZW rabbits (2.3–2.8 kg) were provided by the experimen-tal animal center of the Second Military Medical University,Shanghai. All animals were entrained to controlled tempera-ture (23–25 8C), 12 h light : 12 h dark cycles (light: 0800–2000; darkness: 2000–0800), and free access to food and tapwater. All animals used in this work received humane carein compliance with institutional animal care guidelines ap-proved by the Local Institutional Committee. All surgicaland experimental procedures were in accordance with insti-tutional animal care guidelines.

Ketanserin (Janssen Pharmaceutica, Beerse, Belgium) wasmixed into a high-cholesterol diet. The consumption of rator rabbit chow containing ketanserin was previously deter-mined (Fu et al. 2004). The concentration of drug in thechow was calculated according to chow consumption. Thecontrol group received the same diet without the drug.

Blood pressure measurementSystolic blood pressure (SBP), diastolic blood pressure

(DBP), and heart period (HP) were recorded continuouslyas previously described (Laude et al. 2008). Briefly, ratswere anesthetized with a combination of ketamine (40 mg/kg, i.p.) and diazepam (6 mg/kg, i.p.). A floating polyethy-lene catheter was inserted into the lower abdominal aortavia the left femoral artery for BP measurement, and anothercatheter was indwelled in the left femoral vein for intrave-nous injection. The catheters were exteriorized through theinterscapular skin. After a 2 day recovery period, the ani-mals were placed in individual cylindrical cages with foodand water for BP recording. The aortic catheter was con-nected to a BP transducer via a rotating swivel that allowedthe animals to move freely in the cage. After about a 14 hhabituation, the BP signals were digitized by a microcom-puter, and beat-to-beat SBP, DBP, and HP values were de-termined online. The mean values of these parametersduring the 24 h period were calculated and served as SBP,

DBP, and HP for study. The SD of the mean was calculatedand defined as the quantitative parameter of BP variability(BPV) and HP variability (HPV).

BRS measurementUnder the above-mentioned BP recording conditions, BRS

was measured in conscious rat as previously described(Zhang et al. 2008; El-Mas and Abdel-Rahman 2009). A bo-lus injection of phenylephrine was given to induce BP eleva-tion. The dose of phenylephrine was adjusted to raise SBPby 20–40 mm Hg. There was a delay (about 1 s) betweenthe elevation of BP (stimulus) and the prolongation of HP(response) for arterial baroreflex. In rat, the heart rate isabout 5 or 6 beats/s. So HP was plotted against SBP for lin-ear regression analysis for 2–8 shifts (calculated by com-puter); the slope with the largest correlation coefficient ofHP–SBP was defined as BRS. The mean of the 2 measure-ments with a proper dose served as the final result.

Induction of atherosclerosis and pathological study inSHRs

After a single dose of vitamin D3 (600 000 units/kg, i.p.),the rats were fed a high-cholesterol diet (normal diet supple-mented with 3% cholesterol, 0.5% cholic acid, 0.2% 6-propyl-2-thiouracil, 5% sucrose, 10% lard) for 8 weeks to in-duce atherosclerosis. At the end of the 8 week treatment withthe high-cholesterol diet, the rats were anesthetized by phen-tobarbital. The hearts were fixed and removed for freezingsection preparation and stained with Oil Red O and hematox-ylin. The aortae were fixed and stained with Oil Red O forgross detection under a stereological microscope. Theplaque/lumen ratio of coronary arteries was calculated underthe microscope by image analysis software programmed bythe Academy of Science of China (Beijing, China), and 10arteries were observed in each section. The scores of coro-nary and aortic atherosclerosis were determined according tothe criteria shown in Table 1 (Cai et al. 2005). The datacollection from histological sections was performed by oneobserver in a blind fashion using coded slides.

Induction of atherosclerosis and pathological study inrabbits

The NZW rabbits were fed a high-cholesterol diet (normaldiet supplemented with 0.5% cholesterol, 2.5% yolk powder,4% lard) for 8 weeks to induce atherosclerosis. The extent ofatherosclerosis was then assessed in the longitudinally openedaortae that were stained with Oil Red O to visualize the lesionarea. The positive areas stained by Oil Red O were photo-graphed and measured by computer-assisted planimetry withthe powerful software Leica Qwin, in which the ratio of thearea of atherosclerosis to the whole aortic area was obtained.

Determination of serum level of lipids in SHRsSerum was separated from blood samples, and total cho-

lesterol, triglycerides, low-density lipoprotein cholesterol,and high-density lipoprotein cholesterol were measured byusing corresponding kits supplied by Boehringer Mannheim(Boehringer Mannheim, France S.A.S., Lyon, France).

Experiment 1BRS, SBP, and DBP were measured in SHRs in a con-

Yu et al. 1055

Published by NRC Research Press

scious state with a computerized blood pressure monitoringsystem. Four weeks later, the rats were administered a singledose of vitamin D3 (600 000 units/kg, i.p.) and fed a high-cholesterol diet for 8 weeks to induce atherosclerosis. Thentheir hearts and aorta were removed for pathological exami-nation, and the atherosclerosis score was determined. Therelationship between BP, BRS, and the atherosclerosisscores were analyzed. Then the multiple regression analysiswas applied among BRS, BP, and the atherosclerosis scores.

Experiment 2Spontaneously hypertensive rats aged 8–12 months were

divided into 3 groups (n = 10 in each group), and the ratsreceived a dose of ketanserin of 0.3, 1.0, and 3.0 mg/kg(i.g.), respectively. BP was recorded for a period of 1 h,and BRS was measured using the above-mentioned methods.These values were taken as the basal control values. A sin-gle dose of ketanserin was given via intragastric catheter.About 30 min after drug administration, BP was recordedfor another 1 h period, and BRS was determined again.

Experiment 3Atherosclerosis was induced by vitamin D3 and the high-

cholesterol diet for 8 weeks in SHRs. Simultaneously, therats were randomized into 2 groups, where one group wastreated with a low dose of ketanserin (0.3 mg�kg–1�day–1)and the other group served as the control. Eight weeks later,the hearts and aortae of rats were removed for pathologicalexamination, and the atherosclerosis score was determined.In addition, blood samples were collected for the measure-ment of serum lipids.

Experiment 4Atherosclerosis was induced in 18 male NZW rabbits by

the high-cholesterol diet for 8 weeks. The rabbits were alsorandomly divided into 2 groups (n = 9 in each group). Onegroup was treated with ketanserin (0.3 mg�kg–1�day–1), andthe other group served as the control. On day 46, the labelsof 4 rabbits were lost, and these 4 rabbits were excluded.Eight weeks later, the aortae of rabbits were removed forpathological examination, and the extent of atherosclerosiswas obtained by computer-assisted planimetry.

Statistical analysisData are expressed as means ± SD. In experiment 1, the

relationships between hemodynamic parameters and athero-sclerosis score were analyzed by classic univariate correla-tion analysis. Stepwise multiple regression analysis was

performed to study the independent effect of hemodynamicparameters on the atherosclerosis score. In experiment 2,the comparisons between parameters pre- and post-drug ad-ministration were made by paired Student’s t tests. In ex-periments 3 and 4, comparisons between 2 groups weremade by Wilcoxon signed-rank test and unpaired Student’st test, respectively. The F value to enter and F value to re-move were set to P < 0.05 and P > 0.10, respectively. Re-sults with P < 0.05 were considered statistically significant.Statistical analysis was performed by using SPSS for Win-dows, version 11.0.0 (SPSS, Inc. 2009).

Results

BRS, BP, and atherosclerosis in SHRsIn experiment 1, 24 h blood pressure and HP were measured

in conscious SHRs (n = 31). The hemodynamic parameters andscores of coronary and aortic atherosclerosis are shown in Ta-ble 2. A positive correlation was found between SBP or DBPand the plaque/lumen ratio of coronary artery or aortic athero-sclerosis scores, and a negative correlation was found betweenBRS and the plaque/lumen ratio of coronary artery or aorticatherosclerosis scores in these rats (Fig. 1A, 1B).

The relative importance of the effect of BRS and BP toatherosclerosis in coronary artery and aorta was assessed bymultiple regression analysis (Table 3). It was found that SBPwas independently correlated with the coronary atherosclero-sis score (b = 0.543, P < 0.01) and aortic atherosclerosis score(b = 0.501, P < 0.01). BRS was independently correlated with

Table 1. The criteria scores of aortic and coronary atherosclerosis in rats.

Atherosclerosis criteria

Score Aorta Coronary artery0 Smooth endothelium without dyeing and plaque Smooth endothelium without infiltration of lipids0.5 Extensive dyeing of red without ridgy plaque Mild infiltration of lipids1.0 Visible ridgy plaques, dotted about, area <1.5 mm2 Plaque/lumen ratio <1/41.5 Visible ridgy plaques, 1.5 mm2 < area < 3 mm2 Plaque/lumen ratio 1/4 to 1/32.0 Visible ridgy plaques, area >3 mm2 Plaque/lumen ratio 1/3 to 1/23.0 Plaque confluence, area >3 mm2 Plaque/lumen ratio >1/24.0 Endothelium nearly covered with plaque Lumen nearly blocked by plaque

Table 2. Hemodynamic parameters and athero-sclerosis scores in spontaneously hypertensiverats (n = 31).

Parameter Mean ± SDSBP (mm Hg) 178±16DBP (mm Hg) 123±12HP (ms) 176±18SBPV (mm Hg) 12.89±5.01DBPV (mm Hg) 8.77±2.06HPV (ms) 14.04±4.73BRS (ms/mm Hg) 0.34±0.19Coronary artery score 1.61±0.51Aorta score 1.48±0.62

Note: SBP, systolic blood pressure; DBP, diastolicblood pressure; HP, heart period; SBPV, systolic bloodpressure variability; DBPV, diastolic blood pressurevariability; HPV, heart period variability; BRS, barore-flex sensitivity.

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the coronary atherosclerosis score (b = –0.339, P < 0.05) andaortic atherosclerosis score (b = –0.335, P < 0.05).

Effects of ketanserin on BP, HP, and BRS in SHRsThe effects of ketanserin on SBP, DBP, HP, SBPV,

DBPV, HPV, and BRS in conscious SHRs are summarizedin Table 4. It was found that a single dose of ketanserin de-creased SBP and DBP dose dependently and significantly ata dose of 1.0–3 mg/kg. Ketanserin significantly decreasedsystolic BPV and diastolic BPV and enhanced BRS in all 3

dose groups of SHRs. The results show that low-dose ketan-serin (0.3 mg/kg) enhanced BRS, but did not lower BP.

Effects of low-dose ketanserin on atherosclerosis in SHRsIn experiment 2, low-dose ketanserin was used to reduce

the atherosclerosis in SHRs. The results showed that thescores of the atherosclerosis that developed in the treatedgroup (n = 10) (coronary score: 0.90 ± 0.14, aortic score:1.00 ± 0.39) were lower than that of the untreated group (n= 14) (coronary score: 1.76 ± 0.27, aortic score: 2.18 ± 0.41,P < 0.01) (Fig. 2A, 2B). Blood samples were collected tomeasure serum total cholesterol, triglycerides, low-densitylipoprotein cholesterol, and high-density lipoprotein choles-terol. There was no significant difference between 2 groups(Fig. 2C).

Effect of low-dose ketanserin on atherosclerosis in NZWrabbits

In experiment 3, a low dose of ketanserin was used totreat the atherosclerosis in NZW rabbits. The results showedthat the area of atherosclerosis in the treated group (area:

Fig. 1. Relationship between hemodynamic parameters and the plaque/lumen ratio of coronary arteries (left, A) or aortic score of athero-sclerosis (right, B) in spontaneously hypertensive rats (n = 31). SBP, systolic blood pressure; DBP, diastolic blood pressure; BRS, baroreflexsensitivity.

Table 3. The standardized partial regression coefficients (b) be-tween SBP, BRS, and atherosclerosis score in spontaneouslyhypertensive rats.

Coronary atherosclerosisscore

Aortic atherosclerosisscore

SBP 0.543** 0.501**BRS –0.339* –0.335*

Note: SBP, systolic blood pressure; BRS, baroreflex sensitivity. *,P < 0.05; **, P < 0.01, multiple regression analysis.

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Table 4. Effects of ketanserin on SBP, DBP, HP, SBPV, DBPV, HPV, and BRS in spontaneously hypertensive rats.

Ketanserindose (mg/kg) SBP (mm Hg) DBP (mm Hg) HP (ms) SBPV (mm Hg) DBPV (mm Hg) HPV (ms) BRS (ms/mm Hg)0.3

Before 176±17 126±12 177±14 12.0±1.8 8.7±2.1 14.39±5.01 0.31±0.17After 173±19 121±13 179±11 10.1±1.4** 6.6±1.9* 15.03±4.42 0.65±0.13**

1.0Before 170±9.7 124±9.0 173±10 12.5±1.5 8.3±2.2 14.11±5.32 0.34±0.13After 160±7.5* 117±11 177±7.3 9.4±1.1** 6.9±1.8* 14.52±4.93 0.69±0.15**

3.0Before 180±10 129±10 173±16 11.8±1.9 8.9±1.9 14.96±5.34 0.29±0.09After 158±9.1** 107±11** 176±12 9.1±1.2** 7.1±1.5* 16.11±4.18 0.58±0.14**

Note: Values are means ± SD. SHR, spontaneously hypertensive rats; SBP, systolic blood pressure; DBP, diastolic blood pressure; HP, heart period;SBPV, systolic blood pressure variability; DBPV, diastolic blood pressure variability; HPV, heart period variability; BRS, baroreflex sensitivity. *, P < 0.05;**, P < 0.01, after versus before ketanserin. n = 10 in each group.

Fig. 2. Effects of low-dose ketanserin on atherosclerosis in spontaneously hypertensive rats. Atherosclerosis was induced by vitamin D3 anda high-cholesterol diet for 8 weeks in spontaneously hypertensive rats. Simultaneously, they were randomly divided into 2 groups, whereone group (n = 10) was treated with low-dose ketanserin (0.3 mg�kg–1�day–1) and the other (n = 14) was untreated. (A) The mean athero-sclerosis scores in the control group and ketanserin group. (B) Atherosclerosis of coronary artery in the control group and ketanserin group.Staining with Oil Red O and hematoxylin; magnification 40� (*, P < 0.05). (C) Serum levels of lipids (TC, total cholesterol; TG, trigly-ceride; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol).



0.26% ± 0.20%) was less than that of the untreated group(area: 0.60% ± 0.31%, P < 0.05) (Fig. 3A, 3B).

DiscussionThe present work demonstrated, for the first time, that

low-dose ketanserin (0.3 mg�kg–1�day–1), which had no effecton BP, prevented the development of atherosclerosis inSHRs and NZW rabbits.

First of all, we are conscious that rats per se are not con-sidered valid models of atherosclerosis for a variety of rea-sons that are well documented. They do, however, developearly-stage lesions (fatty streaks). In terms of the data pre-sented in this paper, the development of atherosclerosismeans that these are early lesions.

Ketanserin is a drug that decreased BP dose dependentlybut enhanced BRS independently of dose; ketanserin didnot change BP and HP, but still enhanced BRS at the small-est dose (0.3 mg/kg). In our previous study, one action siteof ketanserin was located in the rostral ventrolateral me-dulla. After microinjection into the rostral ventrolateral me-dulla with ketanserin, a significant enhancement of BRS wasfound, and there were no modifications in basal BP and HP(Fu et al. 2006).

What is the mechanism underlying the beneficial effects oflow-dose ketanserin on atherosclerosis development independ-ent of its BP-lowering action? Based on the fact that a highserum level of lipids, such as cholesterol, triglycerides, orlow-density lipoprotein cholesterol, is a major risk factor ofatherosclerosis, it is reasonable to expect that the preventiveaction of ketanserin in atherosclerosis development would beattributable to its effects on the serum level of lipids. In thepresent work, we examined the serum lipids. However, it wasfound that total cholesterol, triglycerides, low-density lipopro-tein cholesterol, and high-density lipoprotein cholesterol wereall unchanged by ketanserin treatment in SHRs. Therefore, se-rum lipids are not involved in this process.

ABR dysfunction is a feature of atherosclerosis, and it hasbeen well recognized that BRS is impaired in humans andanimals who suffer from atherosclerosis (Angell-James1974; Vlachakis et al. 1976; Katsuda et al. 1992; Li et al.1996). Our previous studies demonstrated that ABR dys-function promoted the development of atherosclerosis inrats (Cai et al. 2005). In the present work, a negative rela-tionship was found between BRS and atherosclerosis scores,and multiple regression analysis showed that BRS was oneof the independent variables related to atherosclerosis scoresin SHRs. Furthermore, treatment with low-dose ketanserin,which had no effect on BP, but significantly enhanced BRS,prevented development of atherosclerosis in SHRs fed witha high-cholesterol diet.

Why could the enhancement of ABR function produce apreventive action in the development of atherosclerosis? Itmay be explained by 3 possibilities: (i) Restoration of im-paired endothelial function. Dysfunction of ABR gives riseto damage of endothelial function. Early structural changesof the aortic wall and degenerative changes in endothelialcells were found in sinoaortic-denerved (SAD) rats, a modelof dysfunction of ABR (Shen et al. 2006), and the endothe-lial dysfunction subsequently promoted the development ofatherosclerosis (Freiman et al. 1986; Platt et al. 2007). (ii)

Inhibition of inflammation. The relation between inflamma-tion and atherosclerosis development is certain (Ross 1999).Inflammation is involved in all phases of the atheroscleroticprocess. C-reactive protein and other inflammatory cyto-kines have been regarded as risk factors in the developmentof atherosclerosis. It was found that impaired ABR functionmight initiate inflammation reaction expressed by an in-crease in plasma TXB2, TNF-a, and IL-1b (Zhang et al.2003) and in aortic C-reactive protein in SAD rats (Cai etal. 2005). Recently, we found that ABR dysfunction led todecrease in vagal activity and endogenous acetylcholine.Consequently, the anti-inflammatory function of nicotinicacetylcholine receptor a7 was largely attenuated (C. Liuand D.-F. Su, unpublished data). (iii) Reduction of oxidativestress. Oxidative stress was also central in the pathogenesisof atherosclerosis. Reactive oxygen species were requiredfor low-density lipoprotein cholesterol oxidation, the keystep in the formation of early fatty streaks. It was foundthat tissue reactive oxygen species increased significantlyafter SAD (Zhang et al. 2003).

Fig. 3. Effects of low-dose ketanserin on atherosclerosis in NZWrabbits. Atherosclerosis was induced with a high-cholesterol diet for8 weeks in NZW rabbits. Simultaneously, they were randomly di-vided into 2 groups, where one group (n = 6) was treated with low-dose ketanserin (0.3 mg�kg–1�day–1) and the other (n = 8) was un-treated. (A) Mean area of atherosclerosis in the control group andketanserin group. (B) Atherosclerosis of aorta in the control groupand ketanserin group. Staining with Oil Red O (*, P < 0.05).

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Finally, some limitations in the present work should benoted. First, we lack direct evidence showing the beneficialeffects of low-dose ketanserin that contributed to its effectson ABR restoration. Second, we did not determine thechanges caused by ketanserin on production of inflammatorycytokines and parameters related to oxidative stress.

In conclusion, the present study demonstrated, for the firsttime, that BRS was one of the independent variables related toatherosclerosis in SHR and that low-dose ketanserin preventedthe development of atherosclerosis in SHRs and NZW rabbits.

AcknowledgementsThis work was supported by the National Natural Science

Foundation of China (30730106, 30772582) and the NationalScience and Technology Major Project (2009ZX09303-002).

ReferencesAngell-James, J.E. 1974. Arterial baroreceptor activity in rabbits with

experimental atherosclerosis. Circ. Res. 34: 27–39. PMID:4809347.Bronte-Stewart, B., and Heptinstall, R.H. 1954. The relationship

between experimental hypertension and cholesterol-inducedatheroma in rabbits. J. Pathol. Bacteriol. 68(2): 407–417.doi:10.1002/path.1700680214. PMID:14354546.

Cai, G.J., Miao, C.Y., Xie, H.H., Lu, L.H., and Su, D.F. 2005. Ar-terial baroreflex dysfunction promotes atherosclerosis in rats.Atherosclerosis, 183(1): 41–47. doi:10.1016/j.atherosclerosis.2005.03.037. PMID:15907853.

Deming, Q.B., Mosbach, E.H., Bevans, M., Daly, M.M., Abell,L.L., Martin, E., et al. 1958. Blood pressure, cholesterol contentof serum and tissues and atherogenesis in the rat. J. Exp. Med.107(4): 581–598. doi:10.1084/jem.107.4.581. PMID:13513919.

El-Mas, M.M., and Abdel-Rahman, A.A. 2009. Longitudinal as-sessment of the effects of oestrogen on blood pressure and car-diovascular autonomic activity in female rats. Clin. Exp.Pharmacol. Physiol. 36(10): 1002–1009. doi:10.1111/j.1440-1681.2009.05192.x. PMID:19413598.

Freiman, P.C., Mitchell, G.G., Heistad, D.D., Armstrong, M.L., andHarrison, D.G. 1986. Atherosclerosis impairs endothelium-de-pendent vascular relaxation to acetylcholine and thrombin in pri-mates. Circ. Res. 58(6): 783–789. PMID:3087655.

Fu, Y.J., Shu, H., Miao, C.Y., Wang, M.W., and Su, D.F. 2004.Restoration of baroreflex function by ketanserin is not bloodpressure dependent in conscious freely moving rats. J. Hyper-tens. 22(6): 165–172. doi:10.1097/00004872-200406000-00018.PMID:15167452.

Fu, Y.J., Wang, W.Z., Cai, G.J., Wang, M.W., and Su, D.F. 2006.Action site of ketanserin enhancing baroreflex function is withinthe rostral ventrolateral medulla in anesthetized rats. Auton.Neurosci. 124(1–2): 31–37. doi:10.1016/j.autneu.2005.11.001.PMID:16344003.

Hollander, W., Madoff, I., Paddock, J., and Kirkpatrick, B. 1976.Aggravation of atherosclerosis by hypertension in a subhumanprimate model with coarctation of the aorta. Circ. Res. 38(supplII): II-63–II-72. [PubMed: 817849.]

Katsuda, S., Hosomi, H., Shiomi, M., and Watanabe, Y. 1992. Im-paired baroreflex control of arterial pressure in WHHL rabbits.J. Vet. Med. Sci. 54(5): 983–987. PMID:1420582.

Koletsky, S., Roland, C., and Rivera-Velez, J.M. 1968. Rapid ac-celeration of atherosclerosis in hypertensive rats on high fatdiet. Exp. Mol. Pathol. 9(3): 322–338. doi:10.1016/0014-4800(68)90023-3. PMID:4952080.

La Rovere, M.T., Specchia, G., Mortara, A., and Schwartz, P.J.

1988. Baroreflex sensitivity, clinical correlates, and cardiovascu-lar mortality among patients with a first myocardial infarction.A prospective study. Circulation, 78(4): 816–824. PMID:3168190.

Laude, D., Baudrie, V., and Elghozi, J.L. 2008. Effects of atropineon the time and frequency domain estimates of blood pressureand heart rate variability in mice. Clin. Exp. Pharmacol. Physiol.35(4): 454–457. doi:10.1111/j.1440-1681.2008.04895.x. PMID:18307740.

Li, Z., Mao, H.Z., Abboud, F.M., and Chapleau, M.W. 1996. Oxy-gen-derived free radicals contribute to baroreceptor dysfunctionin atherosclerotic rabbits. Circ. Res. 79(4): 802–811. PMID:8831504.

Mortara, A., La Rovere, M.T., Pinna, G.D., Prpa, A., Maestri, R.,Febo, O., et al. 1997. Arterial baroreflex modulation of heartrate in chronic heart failure: clinical and hemodynamic corre-lates and prognostic implications. Circulation, 96(10): 3450–3458. PMID:9396441.

Platt, M.O., Ankeny, R.F., Shi, G.P., Weiss, D., Vega, J.D., Taylor,W.R., and Jo, H. 2007. Expression of cathepsin K is regulatedby shear stress in cultured endothelial cells and is increased inendothelium in human atherosclerosis. Am. J. Physiol. HeartCirc. Physiol. 292(3): 1479–1486. doi:10.1152/ajpheart.00954.2006. PMID:17098827.

Reimann, I.W., and Frolich, J.C. 1983. Mechanism of antihyperten-sive action of ketanserin in man. Br. Med. J. (Clin. Res. Ed.),287(6389): 381–383. doi:10.1136/bmj.287.6389.381-a. PMID:6135489.

Ross, R. 1999. Atherosclerosis — an inflammatory disease. N.Engl. J. Med. 340(2): 115–126. doi:10.1056/NEJM199901143400207. PMID:9887164.

Shan, Z.Z., Dai, S.M., and Su, D.F. 1999. Relationship betweenbaroreceptor reflex function and end-organ damage in sponta-neously hypertensive rats. Am. J. Physiol. 277(3 Pt. 2): H1200–H1206. PMID:10484442.

Shen, F.M., Zhang, S.H., Xie, H.H., Jing, Q., Wang, D.S., and Su,D.F. 2006. Early structural changes of aortic wall in sinoaortic-denervated rats. Clin. Exp. Pharmacol. Physiol. 33(4): 358–363.doi:10.1111/j.1440-1681.2006.04375.x. PMID:16620301.

SPSS, Inc. 2009. SPSS for Windows, version 11.0.0 [computer pro-gram]. SPSS, Inc., Chicago, Ill.

Su, D.F., and Miao, C.Y. 2005. Reduction of blood pressure varia-bility: a new strategy for the treatment of hypertension. TrendsPharmacol. Sci. 26(8): 388–390. doi:10.1016/j.tips.2005.06.003.PMID:15990175.

Van Nueten, J.M., Janssen, P.A., Van Beek, J., Xhonneux, R., Ver-beuren, T.J., and Vanhoutte, P.M. 1981. Vascular effects of ke-tanserin (R 41 468), a novel antagonist of 5-HT2 serotonergicreceptors. J. Pharmacol. Exp. Ther. 218(1): 217–230. PMID:6113280.

Vlachakis, N.D., Mendlowitz, M., and DeGuia DeGusman, D.1976. Diminished baroreceptor sensitivity in elderly hyperten-sives. Possible role of atherosclerosis. Atherosclerosis, 24(1–2):243–249. doi:10.1016/0021-9150(76)90079-4. PMID:942520.

Zhang, C., Chen, H., Xie, H.H., Shu, H., Yuan, W.J., and Su, D.F.2003. Inflammation is involved in the organ damage induced bysinoaortic denervation in rats. J. Hypertens. 21(11): 2019–2021.doi:10.1097/00004872-200311000-00024. PMID:14597843.

Zhang, W., Liu, A.J., Yi-Ming, W., Liu, J.G., Shen, F.M., and Su,D.F. 2008. Pressor and non-pressor effects of sodium loading onstroke in stroke-prone spontaneously hypertensive rats. Clin.Exp. Pharmacol. Physiol. 35(1): 83–88. doi:10.1111/j.1440-1681.2007.04746.x. PMID:18047633.



effects of low-dose ketanserin on atherosclerosis in rats and rabbits

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