Expression of hepatic microsomal cholesterol 7 alpha-hydroxylase activity in lean and obese Zucker rats.
The activity of hepatic microsomal cholesterol 7 alpha-hydroxylase was studied in genetically obese and lean Zucker rats. The liver microsomal cholesterol 7 alpha-hydroxylase activity in fatty Zucker rats (fa/fa) is about 50% to 70% lower than that of the lean (Fa/-) rats of the same sex, when animals were sacrificed at the middle of the dark cycle. When rats were sacrificed at the middle of the light cycle, cholesterol 7 alpha-hydroxylase activity was the same as in the dark cycle in obese rats of both sexes, but was 65% lower in lean rats. However, cholesterol 7 alpha-hydroxylase activity was stimulated by the treatment with cholestyramine in both obese and lean rats. Our results suggested that the diurnal regulation of cholesterol 7 alpha-hydroxylase activity is lost in obese rats but was present under cholestyramine treatment in the genetically obese strain of rats.
Tang
P M
PM
Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, Rootstown 44272.
Finkelstein
J A
JA
Chiang
J Y
JY
D000818:Animals; D002790:Cholesterol 7-alpha-Hydroxylase / Q000378:metabolism*; D002792:Cholestyramine Resin / Q000494:pharmacology; D005260:Female; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D009765:Obesity / Q000378:metabolism*; D051381:Rats; D011924:Rats, Zucker / Q000378:metabolism; D012737:Sex Factors; D013045:Species Specificity; D013250:Steroid Hydroxylases / Q000378:metabolism*
D002792:Cholestyramine Resin; D013250:Steroid Hydroxylases; D002790:Cholesterol 7-alpha-Hydroxylase