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Effects of Capsaicin on Lipid Metabolism in RatsFed a High Fat Diet1TERUO KAWADA, KOH-ICHIRO HAGIHARA ANDKAZUO IW AIL aboratory of N utritional C hem istry, D epartm ent of FoodS cie nce a nd T ech no lo gy, F acu lty o f A gric ulture, K yo toU niv er sity , S ak yo -k u, K yo to 6 06 , J ap an

ABSTRACT Effects of capsaicin, a pungent principle of hot red pepper, werestu died in exp erim en ts usin g m ale rats fed a d iet co ntain in g 3 0% lard . C ap saicin w assu pp lem en te d at 0.0 14 % o f th e d iet. T he lev el o f serum trig ly crid ew as lo wer w hencapsaicin w as present in the diet than w hen it w as not. L evels of serum cholesteroland pre-j3-lipoprotein w ere not affected by the supplem entation of capsaicin. T hep eriren al ad ip ose tissu e w eig ht w as lo wer w hen cap saic in w as p resen t in th e diet th anw hen it w as n ot. H ep atic en zyme a ctiv itie s o f g lu cose-6 -p ho sp hate d ehy dro gen aseand adipose lipoprotein lipase w ere low er in rats fed the 30 % lard diet than in thosefed a nonpurified diet. A ctivities of these tw o enzym es w ere higher w hen capsaicinwas added to the diet than when it was not. Hepatic acetyl-CoA carboxylase, /3-hyd roxyacyl -CoA dehyd rogena se , a nd adipos e hormone -s en siti ve lip as e a cti vi tie s we renot affected by capsaicin feeding. L ipid absorption w as not affected by the supplem en tation o f cap saicin . T he pe riren al ad ip ose tissu e w eig ht and serum trig ly crid ewere decreased as the level of capsaicin in the diet increased up to 0.021% . Theseresults su gg est th at cap sa icin stim ulates lip id m ob ilizatio n from ad ip ose tissu e a ndlow ers th e p erirenal ad ipo se tissue w eigh t an d serum trig ly crid eco nce ntratio n inlard-fed rats. J. Nutr. 116: 1272-1278, 1986.INDEXING KEY W ORDS capsaicin lipid metabolism adipose tissuese rum trig ly c rid e h ig h fa t d ie t

Capsaicin is a pungent principle of hot appear to lower blood cholesterol (6-8).red pepper that has been studied because of Recent studies have shown that capsaicinits im portance in spices, food additives and exerts a lipotropic effect sim ilar to that ofdrugs, w hich was recently reviewed by Suzuki choline in rats (9, 10) and decreases totaland Iwai (1). The structure of capsaicin has serum , m yocardial and aortic cholesterolb ee n e sta blish ed a sN - (4 -h yd ro xy -3 -m eth ox y- le ve ls in tu rk ey s (1 1).benzyl)-8-methylnon-frans-6-enamide (2, 3). The information about the effects ofW e have demonstrated that capsaicin is capsaicin on lipid metabolism is lim ited,readily transpo rted through the gastrointes- and the m ech anism of the effe ct of capsaicintinal tract and is absorbed via nonactive is not clear. The present study investigatestransport into the portal vein. M ost of the the effect of capsaicin on lipid metabolismabsorbed capsaicin is excreted as m etabolites in rats fed a high fat diet,via the urine within 48 h in rats (4, 5).trip pffpH- nf Hiptarv pnm nn 1986 American Institute of Nutrition. Received for publication:tne * i t dietary compo- w March985AKeptedorpub lication:2February98 6On lipid' metabolism have received 'Supported by a gram-in-aid ( to K . Iwai) f or Scientific R esearch frommuch attention. For example, Vegetable the M in*ry f E ducation, S cience and C ulture, Japan. This a rticle is i nr e the s eries "Formation and Metabolism of Pungent Principle of C apsicumproteins, dietary fiber and essential oils Fruits."

1272

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EFFECTS OF CAPSA ICI N ON L IPI D M ETABOL ISM I N RA TS 1273MATERIALS AND METHODS

Anima ls a nd diets. Wista r ma le ra ts(175-185 g body wt, Shizuoka AgriculturalCooperative Assoc. for Laboratory Animals,Hamamatsu, Japan) were individually housedin stainless steel wire-bottom cages in aroom maintained at 22-24 Cwith about50% relative humidity. The room was lightedfrom 0600 to 1800. Rats were fed each dietfor 10 d. In all experiments, rats were fed acommercial nonpurified diet (MF, OrientalYeast Co., Tokyo, Japan) (12) for 3 d to al lowthem to adjust to the new envi ronment andthen were starved for 1 d before startingexperiments. Water was provided ad libitum.The composition of experimental diets isgiven in table 1. A nonpurified diet (MF,Oriental Yeast Co., Tokyo, Japan) (12) wasalso fed to one group of rats. H igh fat dietcontained only 10% casein, considered to bea low but adequate level since rats wereadul ts. Capsaicin, the puri ty of which wasdetermined as over 99% by the high-performance thin-layer chromatographymethod as described elsewhere (13), waspurchased from E. M erck (Darmstadt, WestGermany). Two experiments were conducted.I n the first experiment, there were threedietary treatments: 1) nonpuri fied, 2) 30%lard, and 3) 30% lard plus 0.014% capsaicin.The dose of capsaicin used in this study wasrelated to that usually ingested by ruralThai people (14). The same energy intakefor the rats of three groups was maintainedby adjusting the feed intake (about 15.4 g ofnonpurified diet per rat, or about 10.5 g ofthe 30% lard or 30% lard plus 0.014%capsaicin diets per rat) . The feed intake washigher in the nonpuri fied diet group than inthe lard diets because of differences inenergy density of the diets. T he energyintakes of the three groups fed ad l ibi tumwereevealed in preliminary experiments.Rats were fed each diet for 10 d. There were15 rats per group. I n experiment 2, therewere four dietary treatments: 1 ) 30% lard,2) 30% la rd plus 0.007% ca psa icin, 3) 30%lard plus 0.014% capsaicin and 4) 30%lard plus 0.021% capsaicin. The additionalamount of capsaicin in each experimentaldiet replaced starch as in experiment 1. Thesame energy intake for the rat of the fourgroups was maintained by adjusting the

TABLE 1Compos it io n o f e xp er iment a l d ie ts 1Ingredients H igh fat diet

Casein2Starch2Sucrose2Lard2Soybean oil3M ineral mixture1V itamin mixture5Cellulose2Capsaicin6

104010305212'Nonpuri fied diet was commercial (MF, OrientalYeast Co. , Tokyo, Japan) (12). 2Oriental Yeast Co. ,Tokyo, Japan. 3Wako Pure Chemical I nd., Osaka,Japan. 'Supplied in mill igrams/kilogram diet (exceptas noted) : CaHPOH2O, 2.91 g; KHzPO,, 5.14 g;NaH2PO

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1274 KAWADA, HAGI HARA AND I WAI(1 5). T he fe ca l samp le s w ere d rie d, w eig he dand pu lverized. F ecal lipids w ere extractedby the method of Folch et al. (21).

Chem ica l a ssa y. S erum trig lycrid ewasa na ly ze d e nz ym ic ally u sin g a c ommerc ia llyavailab le k it (Trig lycrideG -TestW ako , WakoChem . Ind., Osaka, Japan). Serum ketonebodies were also assayed enzymically bythe m ethod of W illiam son et al. (16). Serumfre e fa tty a cid and cho le ste ro l w ere meas ure daccording to the method of Itaya and Ui(1 7), a nd Pea rs on e t a l. (1 8), re sp ec tiv ely . T heana ly sis o f s erum lip op ro te in w as p erfo rmedaccord ing to the m ethod of N arayan et al. (19)as m odified by M aruyam a and Kobori (20).Liver lipids w ere extracted by the m ethod ofFolch et al. (21). Liver total lipids were det erm ined g ravimet ri ca ll y. L iv er t ri gl ycride ,free fatty acid and cholesterol were m easured as described above for serum . DNA ofperirenal adipose tissue w as determ ined bythe method of Leyva and Kelley (22).Enzym e assay. Acetyl-C oA carboxylase(ACC ; EC 6 .4 .1 .2 ), g lu co se -6 -p ho sp ha te d e-

h yd ro ge na se (G -6 -PDH ; EC 1 .1 .1 .4 9) a nd j3 -hydrox yacyl-C oA dehydrogen ase (HADH;E C 1.1 .1.35) in the liver w ere assa yed by themethods of Nakanishi and Numa (23),K ornberg and H orecker (24) and O sum i andH ashim oto (25), respectively. H orm one-se nsitiv e lip ase (H SL ) a nd lip op ro te in lip as e(LPL ; EC 3 .1 .1 .3 4) a ctiv itie s o f th e p eri re na ladip ose tissue w ere estim ated as describe dby Rizack (26) and Salam an and Robinson(27), respectively.S ta tistica l a na lysis. In exp erim en t 1 , S tudent's

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EFFECTS OF CAPSA ICI N ON L IPI D M ETABOL ISM I N RA TS 1275RESULTS

E xp er ime nt 1 . Ta ble s 2 a nd 3 summa r ize dthe resul ts of experiment 1. There were nodi fferences in gain of body weight or l iverweight due to diet. Capsaicin supplementation tended to reduce epididymal adiposetissue weight and signi ficantly reducedperi renal adipose tissue weight (P < 0.01).The peri renal adipose cel l weight was notaffected by the supplementation of capsaicin.The l ipid f rom the diets was wel l absorbedin each group, and the absorption rate wasnot affected by the supplementation ofcapsaicin. Serum triglyc ridewas lower inrats fed the purified diet containing capsaicinthan in rats fed the same diet withoutcapsaicin. There was no difference in serumtriglyc ridebetween the group fed the non-puri fied diet and the groups fed the high fatplus capsaicin diet. Serum free fatty acidwas not altered by dietary treatment. Serumpre- /3-l ipoprotein was not different due todiet. L iver total lipid, triglyc rideandcholesterol in high fat diet groups werehigher than in the nonpuri fied diet groups.Activity of l iver acetyl-CoA carboxylase,the rate- limi ting enzyme of fatty acid synthesis (31), was lower in rats fed the high fatdiet than in those fed the nonpuri fied diet.L iver G-6-PDH activi ty was signi ficantlylower in rats fed the high fat diet withoutcapsaicin than in those fed the nonpurif ied

diet. G -6-PDH activity was higher in ratsfed capsaicin than in those fed the same dietwithout capsaicin (P < 0.02). The liverHADH activity was higher in rats fed thetwo high fat diets than in rats fed the non-puri fied diet. The supplementation of capsaicin to the high fat diet did not inf luenceenzyme activi ties of l iver ACC and HADH,and peri renal adipose HSL but increasedliver G-6-PDH and perirenal LPL activities.Exper iment 2. Since it ha s been found inexperiment 1 that the supplementation ofcapsaicin affects the perirenal adipose tissueweight and serum triglyc rideoncentration,the relationship between the supplementation of capsaicin and metabolic parameterswas investigated. Body weight gain was notsignificantly different among the four groups.There was a significant correlation betweenperirenal adipose tissue weight (% of bodywt) and the dose-amount of capsaicin (r= -0.738, P < 0.001) (fig. 1). A similarrelationship was also observed between theserum triglycrideconcentration and thedose-amount of capsaicin (r = -0.444, P< 0.02) (fig. 2).

DISCUSSIONRats fed the nonpurified diet gainedalmost tw ice as much weight as those fed

the lard diet. The ratio of protein to energyin the nonpuri fied diet was 3.5 times that inT ABL E 3E ffec ts o f ca psa ic in a dmin is tr a tio n o n va r iou s e nzyme a ctivitie s in r a t liver a nd p er ir en al a dip os e tissu e'

P-value, high fatHigh fat plus vs. high fat plusNonpurified High fat 0.014% capsaicin capsaicin*LiverAcetyl-CoAcarboxylase,mu/gliverGlucose-6-phosphatedehydrogenase,U/gliver0-Hydroxyacyl-CoAdehydrogenase,mu/gliverPerirenaladiposeissueHormone-sensitivelipase, freeattyacidnmo l/n g DNA p erLipoprotein lipase, free fattycidimol/iigDNA per h199.01.0439.73.2223.0

14.90.632.90.25

1.474.70.7653.04.9220.5

5.00.11.80.170.377.41.0953.54.4525.5

10.20.052.90.16

0.7NSJ