Effects of Capsaicin on Lipid Metabolism in Rats Fed a High Fat Diet1

TERUO KAWADA, KOH-ICHIRO HAGIHARA AND KAZUO IWAI Laboratory of Nutritional Chemistry, Department of Food Science and Technology, Faculty of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606, Japan

ABSTRACT Effects of capsaicin, a pungent principle of hot red pepper, were studied in experiments using male rats fed a diet containing 30 % lard. Capsaicin was supplemented at 0.014 % of the diet. The level of serum triglycéridewas lower when Downloaded from capsaicin was present in the diet than when it was not. Levels of serum cholesterol and pre-j3-lipoprotein were not affected by the supplementation of capsaicin. The perirenal adipose tissue weight was lower when capsaicin was present in the diet than when it was not. Hepatic enzyme activities of glucose-6-phosphate dehydrogenase and adipose lipoprotein lipase were lower in rats fed the 30 % lard diet than in those fed a nonpurified diet. Activities of these two enzymes were higher when capsaicin jn.nutrition.org was added to the diet than when it was not. Hepatic acetyl-CoA carboxylase, /3- hydroxyacyl-CoA dehydrogenase, and adipose hormone-sensitive lipase activities were not affected by capsaicin feeding. Lipid absorption was not affected by the supple

mentation of capsaicin. The perirenal adipose tissue weight and serum triglycéride by on March 4, 2009 were decreased as the level of capsaicin in the diet increased up to 0.021%. These results suggest that capsaicin stimulates lipid mobilization from adipose tissue and lowers the perirenal adipose tissue weight and serum triglycérideconcentration in lard-fed rats. J. Nutr. 116: 1272-1278, 1986. INDEXING KEY WORDS capsaicin •lipid metabolism •adipose tissue serum triglycéride •high fat diet

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 capsaicin its importance in spices, food additives and exerts a lipotropic effect similar to that of drugs, which was recently reviewed by Suzuki choline in rats (9, 10) and decreases total and Iwai (1). The structure of capsaicin has serum, myocardial and aortic cholesterol been established as N-(4-hydroxy-3-methoxy- levels in turkeys (11). benzyl)-8-methylnon-frans-6-enamide (2, 3). The information about the effects of We have demonstrated that capsaicin is capsaicin on lipid metabolism is limited, readily transported through the gastrointes- and the mechanism of the effect of capsaicin tinal tract and is absorbed via nonactive is not clear. The present study investigates transport into the portal vein. Most of the the effect of capsaicin on lipid metabolism absorbed capsaicin is excreted as metabolites in rats fed a high fat diet, via the urine within 48 h in rats (4, 5). tnetrip pffpH-«* i nft dietaryHiptarv compo-pnmnn w®March19861985AmericanAKeptedInstituteforpublication:of Nutrition.12FebruaryReceived for1986publication: On lipid' metabolism have received 'Supported by a gram-in-aid (to K. Iwai) for Scientific Researchfrom much attention. For example, Vegetable the Min¡*ryof Education, Science and Culture, Japan. This article is in r e the series "Formation and Metabolism of Pungent Principle of Capsicum proteins, dietary fiber and essential oils Fruits."

1272 EFFECTS OF CAPSAICIN ON LIPID METABOLISM IN RATS 1273

MATERIALS AND METHODS TABLE 1 Composition of experimental diets1 Animals and diets. Wistar male rats (175-185 g body wt, Shizuoka Agricultural Ingredients High fat diet Cooperative Assoc. for Laboratory Animals, Hamamatsu, Japan) were individually housed in stainless steel wire-bottom cages in a Casein2 10 room maintained at 22-24 °Cwith about Starch2 40 Sucrose2 50 % relative humidity. The room was lighted 10 Lard2 30 from 0600 to 1800. Rats were fed each diet Soybean oil3 5 for 10 d. In all experiments, rats were fed a Mineral mixture1 2 commercial nonpurified diet (MF, Oriental Vitamin mixture5 1 Yeast Co., Tokyo, Japan) (12) for 3 d to allow Cellulose2 2 them to adjust to the new environment and Capsaicin6 then were starved for 1 d before starting 'Nonpurified diet was commercial (MF, Oriental experiments. Water was provided ad libitum. Yeast Co., Tokyo, Japan) (12). 2Oriental Yeast Co., The composition of experimental diets is Tokyo, Japan. 3Wako Pure Chemical Ind., Osaka, given in table 1. A nonpurified diet (MF, Japan. 'Supplied in milligrams/kilogram diet (except Downloaded from Oriental Yeast Co., Tokyo, Japan) (12) was as noted): CaHPO«•2H2O, 2.91 g; KHzPO,, 5.14 g; also fed to one group of rats. High fat diet NaH2PO<; 1.87 g; NaCl, 0.93 g; calcium lactate, 7.02 g; iron citrate, 0.64 g; MgSO,, 1.43 g; ZnCo3, 22; contained only 10% casein, considered to be MnSO, •4-6H2O, 24; CuSO4 •5H2O, 6; KI, 2. 'Sup a low but adequate level since rats were plied in milligrams/kilogram diet: thiamin •HC1, 12; adults. Capsaicin, the purity of which was riboflavin, 40; pyridoxine •HC1, 8; vitamin B-12, 0.005; determined as over 99% by the high- ascorbic acid, 300; D-biotin, 0.2; menadione, 52; folie jn.nutrition.org performance thin-layer chromatography acid, 2; D-calcium pantothenate, 50; p-aminobenzoic method as described elsewhere (13), was acid, 50; nicotinic acid, 60; inositol, 60; choline chlo purchased from E. Merck (Darmstadt, West ride, 2000; all-rac-a-tocopheryl acetate, 50 and in iu/kilogram diet: retinyl acetate, 5000; cholecalciferol,

Germany). Two experiments were conducted. 2500. "Added at 0.014% of diet in place of equal by on March 4, 2009 In the first experiment, there were three weight of starch in high fat plus capsaicin diet. Pur dietary treatments: 1) nonpurified, 2) 30% chased from E. Merck, Darmstad, West Germany. lard, and 3) 30% lard plus 0.014% capsaicin. The dose of capsaicin used in this study was related to that usually ingested by rural feed intake (10.5 ±0.2 g/d per rat in each Thai people (14). The same energy intake group, mean ±SD). Thirty rats were used for the rats of three groups was maintained in this experiment. by adjusting the feed intake (about 15.4 g of Sample collection. At the end of experi nonpurified diet per rat, or about 10.5 g of ments, rats were fasted for 16 h and lightly the 30% lard or 30% lard plus 0.014% anesthetized with pentobarbital. Blood was capsaicin diets per rat). The feed intake was collected by heart puncture for analyses of higher in the nonpurified diet group than in serum lipids, glucose, ketone bodies and the lard diets because of differences in lipoprotein. Immediately after blood sam energy density of the diets. The energy pling, the liver was excised, washed in intakes of the three groups fed ad libitum chilled saline solution, blotted and cooled •wererevealed in preliminary experiments. on crushed ice. A part of the liver was used Rats were fed each diet for 10 d. There were for the assay of enzyme activities and the 15 rats per group. In experiment 2, there rest of the liver was kept at -30°C until were four dietary treatments: 1) 30% lard, analysis of lipid components. Pedreñaladi 2) 30% lard plus 0.007% capsaicin, 3) 30% pose tissue was excised, rinsed, blotted and lard plus 0.014% capsaicin and 4) 30% weighed. A part of adipose tissue was used lard plus 0.021% capsaicin. The additional for the enzyme assay and the measurement amount of capsaicin in each experimental of adipose cell weight. The intestinal absorp diet replaced starch as in experiment 1. The tion rate of dietary lipid was monitored for same energy intake for the rat of the four 3 d, from d 5-7 of experiment 1, and deter groups was maintained by adjusting the mined by the method of balance experiments 1274 KAWADA, HAGIHARA AND IWAI

(15). The fecal samples were dried, weighed hydrogenase (G-6-PDH; EC 1.1.1.49) and j3- and pulverized. Fecal lipids were extracted hydroxyacyl-CoA dehydrogenase (HADH; by the method of Folch et al. (21). EC 1.1.1.35) in the liver were assayed by the Chemical assay. Serum triglycéridewas methods of Nakanishi and Numa (23), analyzed enzymically using a commercially Kornberg and Horecker (24) and Osumi and available kit (TriglycérideG-TestWako, Wako Hashimoto (25), respectively. Hormone- Chem. Ind., Osaka, Japan). Serum ketone sensitive lipase (HSL) and lipoprotein lipase bodies were also assayed enzymically by (LPL; EC 3.1.1.34) activities of the perirenal the method of Williamson et al. (16). Serum adipose tissue were estimated as described free fatty acid and cholesterol were measured by Rizack (26) and Salaman and Robinson according to the method of Itaya and Ui (27), respectively. Statistical analysis. In experiment 1, Stu (17), and Pearson et al. (18), respectively. The dent's <-test was used for statistical evalua analysis of serum lipoprotein was performed according to the method of Narayan et al. (19) tion of the two means. Populations were as modified by Maruyama and Kobori (20). tested using analysis of variance. When the Liver lipids were extracted by the method of F-test was significant at P < 0.05, compari son was made using Aspin-Welch method Folch et al. (21). Liver total lipids were de Downloaded from termined gravimetrically. Liver triglycéride, (28). In experiment 2, group means were tested by using standard one-way analysis of free fatty acid and cholesterol were meas variance techniques (28) and Duncan's Mul ured as described above for serum. DNA of perirenal adipose tissue was determined by tiple-Range test (29). These calculations the method of Leyva and Kelley (22). were performed on a NEC PC-8801 mkll

Enzyme assay. Acetyl-CoA carboxylase microcomputer (NEC Co., Tokyo, Japan) jn.nutrition.org (ACC; EC 6.4.1.2), glucose-6-phosphate de- using Nss-BASIC program (30). by on March 4, 2009 TABLE 2 Effects oj capsaicin in rats fed high fat diets with and without capsaicin (experiment I)1

Dietary treatments P-value, high fat High fat plus vs. high fat plus Nonpurified High fat 0.014% capsaicin capsaicin2

CaloriedGain intake, cal/10 0.035.7± 0.718.8± 1.318.5± dLiverin body weight, g/10 1.65.30± 0.75.29± 1.65.70± gEpididymalweight, 0.131.16± 0.172.22± 0.091.93± gPerirenal fat pad weight, 0.070.36± 0.142.23± 0.091.69± gPerirenal fat pad weight, 0.0643.6± 0.1443.8± 0.1344.2± 0.01NSNS< DNAFat cell weight, mg//jg 0.199.6± 0.198.4± 0.398.9± %SerumTriglycéride,absorption rate, 0.026.1± 0.141.7± 0.129.3±

mg/dlFree 1.46.30± 4.46.51± 3.46.45± 0.05NSNSNSNSNSNSNSNSNS mg/diKetonefatty acid, 0.2798.7± 0.31141.5± 0.46147.9± ¡anol/dlCholesterol,bodies, 3.3104.9± 4.1140.3± 4.0140.2± mg/dlGlucose, 2.8153.7± 12.1103.0± 5.7118.9± mg/dl(Pre-/3 8.00.39± 5.70.40± 6.50.38± lipoprotein4LiverTotal+ ß)/a 0.0256.6± 0.0182.5± 0.0177.7±

liverTriglycéride,lipid, mg/g 1.89.20± 3.527.8± 2.724.4± liverFree mg/g 0.443.95± 1.74.35± 1.14.34± liverCholesterol,fatty acid, mg/g 0.183.73± 0.084.58± 0.094.85± mg/g liver549.0 ±0.06547.2 ±0.07548.6 ±0.17NS3NSNSNS< 'Mean ±SEMof 15 rats. ^he statistical significance of differences was calculated by the methods described in Materials and Methods. 3NS, not significant. 4(Pre-/3 lipoprotein + 0 lipoprotein)/« lipoprotein. EFFECTS OF CAPSAICIN ON LIPID METABOLISM IN RATS 1275

RESULTS diet. G-6-PDH activity was higher in rats fed capsaicin than in those fed the same diet Experiment 1. Tables 2 and 3 summarized without capsaicin (P < 0.02). The liver the results of experiment 1. There were no HADH activity was higher in rats fed the differences in gain of body weight or liver two high fat diets than in rats fed the non- weight due to diet. Capsaicin supplementa purified diet. The supplementation of cap tion tended to reduce epididymal adipose saicin to the high fat diet did not influence tissue weight and significantly reduced enzyme activities of liver ACC and HADH, perirenal adipose tissue weight (P < 0.01). and perirenal adipose HSL but increased The perirenal adipose cell weight was not liver G-6-PDH and perirenal LPL activities. affected by the supplementation of capsaicin. Experiment 2. Since it has been found in The lipid from the diets was well absorbed experiment 1 that the supplementation of in each group, and the absorption rate was capsaicin affects the perirenal adipose tissue not affected by the supplementation of weight and serum triglycérideconcentration, capsaicin. Serum triglycéridewas lower in the relationship between the supplementa rats fed the purified diet containing capsaicin tion of capsaicin and metabolic parameters than in rats fed the same diet without was investigated. Body weight gain was not Downloaded from capsaicin. There was no difference in serum significantly different among the four groups. triglycéridebetween the group fed the non- There was a significant correlation between purified diet and the groups fed the high fat perirenal adipose tissue weight (% of body plus capsaicin diet. Serum free fatty acid wt) and the dose-amount of capsaicin (r was not altered by dietary treatment. Serum = -0.738, P < 0.001) (fig. 1). A similar pre-/3-lipoprotein was not different due to

relationship was also observed between the jn.nutrition.org diet. Liver total lipid, triglycéride and serum triglycérideconcentration and the cholesterol in high fat diet groups were dose-amount of capsaicin (r = -0.444, P higher than in the nonpurified diet groups. < 0.02) (fig. 2). Activity of liver acetyl-CoA carboxylase, the rate-limiting enzyme of fatty acid syn by on March 4, 2009 DISCUSSION thesis (31), was lower in rats fed the high fat diet than in those fed the nonpurified diet. Rats fed the nonpurified diet gained Liver G-6-PDH activity was significantly almost twice as much weight as those fed lower in rats fed the high fat diet without the lard diet. The ratio of protein to energy capsaicin than in those fed the nonpurified in the nonpurified diet was 3.5 times that in

TABLE 3 Effects of capsaicin administration on various enzyme activities in rat liver and perirenal adipose tissue'

P-value, high fat High fat plus vs. high fat plus Nonpurified High fat 0.014% capsaicin capsaicin*

LiverAcetyl-CoA carboxylase,mu/g liverGlucose-6-phosphate 14.9± 5.0± 10.2± dehydrogenase,U/g liver0-Hydroxyacyl-CoA 0.63± 0.1± 0.05± 0.02NSNS< dehydrogenase,mu/g liverPerirenal 2.9± 1.8± 2.9± tissueHormone-sensitiveadipose fattyacid lipase, free hLipoproteinnmol/ng DNA per 0.25± 0.17± 0.16± acid¡imol/iiglipase, free fatty DNA per h199.01.0439.73.2223.0± 1.474.70.7653.04.9220.5±0.377.41.0953.54.4525.5±0.7NSJ< 0.01 'Mean ±SEMof 10 rats. 8The statistical significance of differences was calculated by the methods described in Materials and Methods. 3NS, not significant. 1276 KAWADA, HAGIHARA AND IWAI

before additional perirenal cells are produced (fat pad weight gain). It was reported that the absorption of lipid in rat intestine is inhibited by capsaicin 1-°*adipose^ (33). however, in the present study the gastrointestinal absorption of lipid was not bodytissue%( inhibited by capsaicin as shown by the balance study method. Similar results were OBgoo«k0» also obtained by Sambaiah et al. (9). The data in table 2 indicate that the decrease of lipid accumulation in adipose tissue is not due to the decrease of gastrointestinal ab sorption of lipid in rats fed the high fat plus capsaicin diet. The previous study using turkeys fed a high cholesterol diet for 23 d showed that capsaicin decreased total serum cholesterol (11), but there was no influence of capsaicin Downloaded from 1a on the serum cholesterol in the present study 0.2 using rats fed a diet without supplemental cholesterol for 10 d. The discrepant results may be due to differences in cholesterol

n-aTbTP*™bcT( intake or in animal species. jn.nutrition.org 14 21 Capsaicin concentration in diet (»10%) Fig. l Dose-response of capsaicin on perirenal adipose tissue weight. Values are means ±SEMfor 50 - by on March 4, 2009 individual values from 12 (0% capsaicin concentration in diet), 4 (0.007%), 10 (0.014%) or 4 (0.021%) rats. Means not sharing a common superscript letter are sig nificantly different at P < 0.05. 40*»*E the lard diet. Therefore, the rats fed the nonpurified diet might be so much more efficient in using the energy consumed, and 30^^OKEE the energy might be deposited as muscle. The results of the present study showed that when similar amounts of diet were con 20S10n.m.-LabIbcTcT sumed the weight of perirenal adipose tissue and the serum triglycérideconcentration were lower in rats fed the diet containing capsaicin than in those fed the diet without capsaicin. This effect on serum triglycéride concentration was not in conflict with the results reported by Sambaiah and Satyan- arayana (32) in rats fed ad libitum a diet 14 21 containing 10% fructose and 0.015% cap Capsaicin concentration in diet(«10 %) saicin for 6 wk. Perirenal fat pad weights were different Fig. 2 Dose-response of capsaicin on serum tri in the three groups. On the other hand, the glycérideconcentration. Values are means ±SEMfor individual values from 12 (0% capsaicin concentration cell weights were similar in the three groups. in diet), 4 (0.007%), 10 (0.014%) or 4 (0.021%) rats. These results suggest that existing perirenal Means not sharing a common superscript letter are sig cells are filled up with lipid (similar weight) nificantly different at P < 0.05. EFFECTS OF CAPSAICIN ON LIPID METABOLISM IN RATS 1277

It has been shown that the ingestion of fat •LITERATURE CITED markedly inhibits hepatic lipogenesis (34, 1. Suzuki, T. & Iwai, K. (1984) Constituents of 35). In the present experiments, ACC (a red pepper species: chemistry, biochemistry, phar rate-limiting enzyme of fatty acid synthesis) macology, and food science of the pungent princi (31) and G-6-PDH activities in rats fed the ple of Capsicum species. In: The Alkaloids, vol. 23 high fat diet were also lower than in rats fed (Brossi, A., éd.),pp. 227-299, Academic Press, New York. the nonpurified diet. However, as seen in 2. Nelson, E. K. & Dawson, L. E. (1923) The con table 3, activities of both lipogenic enzymes stitution of capsaicin, the pungent principle of were not inhibited by capsaicin, a result in Capsicum. (III). J. Am. Chem. Soc. 45, 2170-2181. opposition to that in fructose-fed rats (32). 3. Crombie, L., Dandegaonker, S. H. & Simpson, K. B. (1955) Amides of vegetable origin. Part The mechanism of action of capsaicin on A: Synthesis of capsaicin. J. Chem. Soc. (Jan- lipid metabolism in rats fed fructose is March) 1025-1027. therefore different from that of rats fed lard. 4. Kawada, T., Suzuki, T., Takahashi, M. & Iwai, K. Serum triglycérideconcentration of rats fed (1984) Gastrointestinal absorption and metabo lism of capsaicin and dihydrocapsaicin in rats. the high fat plus capsaicin diet was in Toxicol. Appi. Pharmacol. 72, 449-456. versely related to the capsaicin level of the 5. Kawada, T. & Iwai, K. (1985) In vivo and in diet. Consequently, these results indicate vitro metabolism of dihydrocapsaicin, a pungent Downloaded from that consumption of capsaicin facilitates principle of hot pepper, in rats. Agrie. Biol. Chem. lipid metabolism in rats fed a high fat diet. 49, 441-448. The stimulation of lipid metabolism by cap 6. Carroll, K. K. & Hamilton, R. M. G. (1975) Effect of dietary protein and carbohydrate on saicin is supported by the results obtained in plasma cholesterol levels in relation to athero perirenal adipose tissue weight, serum tri sclerosis. J. Food Sci. 40, 18-24. 7. Kiriyama, S., Okizaki, S. & Yoshida, A. (1960)

glycérideconcentration and adipose LPL jn.nutrition.org Hypocholesterolemic effect of polysaccharides and activity. polysaccharide-rich foodstuffs in cholesterol-fed There was no difference in serum ketone rats. J. Nutr. 97, 382-388. bodies, pre-j3-lipoprotein and liver lipids 8. Bordia, A., Verma, S. K., Vyas, A. K. & Bhu, N. between high fat and high fat plus capsaicin (1977) Effect of essential oil of onion and garlic groups. These results suggest that the surplus on experimental atherosclerosis in rabbits. Athero by on March 4, 2009 sclerosis 26, 379-386. energy of the nutrients consumed with or 9. Sambaiah, K., Satyanarayana, M. N. & Rao, without capsaicin accumulates in adipose M. V. L. (1978) Effect of red pepper (chillies) tissue as lipid (triglycéride).Previous studies and capsaicin on fat absorption and liver fat in have shown that a free fatty acid was incor rats. Nutr. Rep. Int. 18, 521-529. 10. Sambaiah, K. & Satyanarayana, M. N. (1982) porated into an organ in proportion to the Lipotrope-like activity of red pepper. J. Food Sci. concentration of the fatty acid outside the Technol. 19, 30-31. organ (36, 37), and the rate of oxidation of 11. Ki, P., Negulesco, J. A. & Murnane, M. (1982) that fatty acid automatically increased in Decreased total serum, myocardial and aortic the organ as its concentration increased (38, cholesterol levels following capsaicin treatment. IRCS Med. Sci. Libr. Compend. 10, 446-447. 39). Thus, it is possible that stimulation of 12. Tani, M. & Iwai, K. (1984) Some nutritional lipid metabolism by capsaicin is attributable effects of folate-binding protein in bovine milk on to fat mobilization from adipose tissue How the bioavailability of folate to rats. J. Nutr. 114, ever, its stimulation might not be accom 778-785. panied by the induction of lipase, because 13. Suzuki, T, Kawada, T. & Iwai, K. (1980) Ef fective separation of capsaicin and its analogues by HSL activity was not different between high reversed-phase high-performance thin-layer chro- fat and high fat plus capsaicin groups matography. J. Chromatogr. 198, 217-223. (table 3). Detailed study on the stimulation 14. Interdepartment Committee on Nutrition for Na mechanism of capsaicin on lipid metabolism tional Defense (1962) Nutrition Survey—The Kingdom of Thailand, pp. 57-59, US Government is now in progress. Printing Office, Washington, DC. 15. Smyth, D. H. (1974) Methods of studying intes tinal absorption. In: Biomembrane, vol. 4A (D. H. ACKNOWLEDGMENT Smyth, éd.),pp. 241-283, Plenum Press, London. 16. Williamson, D. H., Mellanby, J. & Krebs, H. A. We thank Tatsuo Watanabe in this labora (1962) Enzymic determination of D(-)-beta- tory for his assistance in the experimental hydroxybutyric acid and acetoacetic acid in blood. work. Biochem. J. 82, 90-96. 1278 KAWADA, HAGIHARA AND IWAI

17. Itaya, K. & Ui, M. (1965) Colorimetrie deter tistical Methods, 7th ed., Iowa State University mination of fatty acids in biological fluids. J. Press, Ames, IA. Lipid Res. 6, 16-20. 29. Duncan, D. B. (1955) Multiple range and mul 18. Pearson, S., Stern, S. & McCavack, T. H. (1953) tiple F-tests. Biometrics 11, 1-42. A rapid, accurate method for the determination of 30. Ishii, S. (1983) Programs of Statistical Methods total cholesterol in serum. Anal. Chem. 25, for Biologists by N88-BASIC.Baifukan Co., Tokyo, 813-814. Japan. 19. Narayan, K., Creinin, H. L. & Kummerow, F. A. 31. Numa, S., Bortz, W. M. & Lynen, F. (1965) (1966) Disc electrophoresis of rat plasma lipo- Regulation of fatty acid synthesis at the acetyl- proteins. J. Lipid Res. 7, 150-157. CoA carboxylation step. Adv. Enzyme Regul. 3, 20. Maruyama, M. & Kobori, H. (1972) Quantita 407-423. tive determination of the serum lipoproteins by gel 32. Sambaiah, K. & Satyanarayana, M. N. (1982) electrophoretic separation. Seibutsu Butsuri Influence of red pepper and capsaicin on body Kagaku (in Japanese) Iti. 243-245. composition and lipogenesis in rats. J. Biosci. 4, 21. Folch, J., Lees, M. & Sloane-Stanley, G. H. 425-430. (1957) A simple method for the isolation and 33. Nopanitaya, W. (1973) Long term effects of purification of total lipids from animal tissues. J. capsaicin on fat absorption and the growth of the Biol. Chem. 226, 497-509. rat. Growth 37, 269-279. 22. Leyva, A. & Kelley, W. N. (1974) Measurement 34. Dupont, J. (1965) Relationship between utili of DNA in cultured human cells. Anal. Biochem. zation of fat and synthesis of cholesterol and total lipid in young female rats. J. Am. Oil Chem. Soc.

62, 173-179. Downloaded from 42, 903-909. 23. Nakanishi, S. & Numa, S. (1970) Purification of rat liver acetyl coenzyme A carboxylase and 35. Lowenstein, J. M. (1972) Is insulin involved in immunochemical studies on its synthesis and regulating the rats of fatty acid synthesis. In: degradation. Eur. J. Biochem. 16, 161-173. Handbook of Physiology, sect. 7, Endocrinology vol. 7, (Steiner, D. F., ed.), pp. 415-424, American 24. Kornberg, A. & Horecker, B. L. (1955) Glu- cose-6-phosphate dehydrogenase. In: Methods in Physiological Society, Washington, DC. 36. Fine, M. B. & Williams, R. H. (1960) Effect of

Enzymology, vol. 1 (Colowick, S. P. & Kaplan, jn.nutrition.org N. O., eds.), pp. 323-327, Academic Press, New fasting, adrenaline, glucose, and insulin on uptake of nonesterified fatty acids. Am. J. Physiol. ¿99, York. 403-406. 25. Osumi, T. & Hashimoto, T. (1978) Enhance 37. Evans, J. R., Opie, H. & Shipp, J. C. (1963) ment of fatty acyl-CoA oxidizing activity in rat Metabolism of palmitic acid in perfused rat heart. liver peroxisomes by di-(2-ethylhexyl)-phthalate J. Am. J. Physiol. 205, 766-770. by on March 4, 2009 Biochem. 83, 1361-1365. 38. Fritz, I. B. (1961) Factors influencing the rates 26. Rizack, M. A. (1961) An epinephrine-sensitive of long-chain fatty acid oxidation and synthesis in lipolytic activity in adipose tissue J. Biol. Chem. mammalian systems. Physiol. Rev. 41, 52-129. 236, 657-662. 39. Eaton, P. & Steinberg, D. (1961) Effects of 27. Salaman, M. & Robinson, D. S. (1966) Clear medium fatty acid concentration, epinephrine, ing-factor lipase in adipose tissue Biochem. J. 99, and glucose on palmitate-l-C1