Diurnal rhythm of thein vivoacetate metabolism to CO₂and nonsaponifiable lipids by neonatal chick

Abstract

The in vivo incorporation of acetate into nonsaponifiable lipids was studied in different tissues from 14-day-old chick. Total nonsaponifiable lipids (nmol/30 min/g tissue) were mainly synthesized in testicles and liver. The in vivo CO2 production from acetate by 1-day-old chick did not exhibit diurnal variations. However, in 14-day-old chick, a maximal value was observed in the middle of the light period, while a minimal value was found 9 h after the start of the dark period. No significant diurnal differences were detected in the in vivo acetate incorporation into nonsaponifiable lipids by liver and duodenal mucosa from 1-day-old chick. Nevertheless, a clear diurnal rhythm was found in liver and duodenal mucosa from 14-day-old chick, but not in brain and kidney from animals of the same age. Distribution of radioactivity from (1-14C)acetate among the different constituents of the nonsaponifiable fraction has been also studied at 3-h intervals. Cholesterol was the major sterol formed from acetate by chick liver at any time of day. In duodenal mucosa and kidney, maximal values in the percentage of cholesterol synthesized were observed during the light period.

Metabolic Transformations of U-14C-Resistant and U-14C-Gelatinized Bean Starch in Rat Liver and Body

“…The specific radioactivity in free fatty acids and cholesterol esters was also higher in rats fed label resistant starch (Table 10). There is evidence that acetic and butyric acids may be incorporated into free fatty acids, cholesterol, triglycerides, and phospholipids (Arce et al, 1993;Snoswell et al, 1982;Latymer and Woodley, 1983). Although no significant changes in total labeled lipids were detected in the carcass (Table 3), 14 C increased significantly in the cholesterol and free fatty acid fractions 18 h after gavage in rats fed resistant starch compared to rats fed gelatinized starch (Tables 11 and 12).…”

Cyclic fluctuations of 3‐hydroxy‐3‐methylglutaryl‐CoA reductase in aortic smooth muscle cell cultures

“…The rate of cholesterol biosynthesis from different tissues was shown to have a diurnal rhythm many years ago (2)(3)(4). These rhythmic changes are associated with changes in HMG-CoA reductase activity (1,2,5,6).…”