Effects of dietary defatted squid on cholesterol metabolism and hepatic lipogenesis in rats.
Male Sprague-Dawley rats were fed a cholesterol-free (Exp. 1) or cholesterol-supplemented (Exp. 2) diet containing 20% casein (control group) or 15% defatted squid and 5% casein (defatted squid group), as protein, for 14 d. Serum and hepatic cholesterol concentrations were lower in rats fed defatted squid than in those fed casein in both cholesterol-free (-20%, P < 0.05 and -15%, P < 0.05, respectively) and cholesterol-supplemented (-25%, P < 0.05 and -15%, P < 0.05, respectively) diets. Hepatic triglyceride concentration was lower in the defatted squid than in the control groups in both cholesterol-free (-51%, P< 0.05) and cholesterol-supplemented diets (-38%, P < 0.01). The activities of cytosolic fatty acid synthase and the NADPH-generating enzymes, malic enzyme and glucose-6-phosphate dehydrogenase, in the liver were lower in the defatted squid than in the control groups in both cholesterol-free (-21%, P< 0.01, -33%, P < 0.05, and -33%, P < 0.01, respectively) and cholesterol-supplemented diets (-34%, P < 0.05, -57%, P < 0.05, and -67%, P < 0.05, respectively). The activity of mitochondrial carnitine palmitoyltransferase in the liver was comparable between the control and defatted squid groups. The activity of Mg2+-dependent phosphatidate phosphohydrolase in the liver cytosol was lower in the defatted squid (-9%, P < 0.05) than in the control groups only in the cholesterol-free diet. Fecal excretion of total steroids was stimulated by the feeding of defatted squid in both cholesterol-free (+77%, P < 0.005) and cholesterol-supplemented diets (+29%, P < 0.01). These results suggest that the nonlipid fraction of squid exerts a hypocholesterolemic effect by increasing the excretion of total steroids in feces. The fraction also induces a triglyceride-lowering activity in the liver by decreasing hepatic lipogenesis.
Tanaka
K
K
Laboratory of Nutrition Chemistry, Siebold University of Nagasaki, Nishisonogi Gun, Japan. tanaka@sun.ac.jp
Ikeda
I
I
Yoshida
H
H
Imaizumi
K
K
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002364:Caseins / Q000008:administration & dosage; D002784:Cholesterol / Q000097:blood / Q000378:metabolism*; D002791:Cholesterol, Dietary / Q000008:administration & dosage / Q000494:pharmacology; D049832:Decapodiformes; D004032:Diet; D005243:Feces / Q000737:chemistry; D005247:Feeding Behavior / Q000187:drug effects; D006937:Hypercholesterolemia / Q000097:blood / Q000139:chemically induced / Q000201:enzymology / Q000378:metabolism*; D008055:Lipids / Q000032:analysis / Q000096:biosynthesis* / Q000097:blood; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013256:Steroids / Q000032:analysis / Q000378:metabolism; D014280:Triglycerides / Q000032:analysis
D002364:Caseins; D002791:Cholesterol, Dietary; D008055:Lipids; D013256:Steroids; D014280:Triglycerides; D002784:Cholesterol