Effect of age and feeding on cholesterol 27-hydroxylase in pigs
Date
1996
Authors
Wang, Xia
Major Professor
Advisor
Beitz, Donald C.
Committee Member
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Abstract
The objective of this study was to determined the responses of hepatic mitochondrial cholesterol 27-hydroxylase to nursing in three-week-old suckling piglets and to feeding in 7-week-old weaned piglets. In feeding studies, livers were collected from 59 piglets at 0, 1, 3, and 5 hours after nursing or feeding and from ad libitum-fed piglets. In development studies, livers were collected from 21 ad libitum-fed pigs, which were fetal, suckling, 7-week-old weaned piglets and 12-week-old pigs. Cholesterol 27-hydroxylase activity was determined by incubating isolated mitochondria with 4-¹⁴C-cholesterol and by isolating the 27- hydroxycholesterol via thin-layer chromatography. Fasting for 14 hours decreased cholesterol 27-hydroxylase from 1.071 to 0.162 pmol/min.mg protein in three-week-old suckling piglets and from 1.120 to 0.273 pmol/min.mg protein in seven-week-old weaned piglets. The cholesterol 27-hydroxylase activities increased within 5 hours after fasted piglets nursed or fed, attaining the activities of the ad libitum-fed piglets. Furthermore, fasting decreased the activity of cholesterol 27-hydroxylase was determined. Additionally, the stability of the cholesterol 27-hydroxylase from fresh liver were compared with that of frozen liver and frozen mitochondria homogenates. It was found that the cholesterol 27-hydroxylase was not stable to freezing/thawing. Finally, the effect of age on the activity of cholesterol 27- hydroxylase was investigated. No significant differences in cholesterol 27-hydroxylase activities were detected among pigs of different ages.
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thesis