Lymphatic Transport of Dietary Cholesterol Oxidation Products, Cholesterol and Triacylglycerols in Rats

Abstract

Rats were fed on a diet containing 0.5% cholesterol oxidation products (oxysterols) or 0.5% cholesterol for 30 min, and their lymph was collected for 7 h. The amount of each of the individual oxysterols absorbed in the lymph depended on the ingested amounts, but the recovery was the highest for 5alpha,6alpha-epoxycholesterol (10.5%), this being followed by 7-ketocholesterol (5.8%), cholestanetriol (5.2%), 7beta-hydroxycholesterol (4.8%), 7alpha-hydroxycholesterol (3.4%), 5beta,6beta-epoxycholesterol (2.2%), and 25-hydroxycholesterol (1.8%). A diet enriched with oxysterol, but not cholesterol, resulted in increased transport of triacylglycerols in the lymph. These results suggest that the absorption rate of oxysterols depends on the type, and indicate that the effect of dietary oxysterols on the lymphatic transport of triacylglycerols differs from that of dietary cholesterol. It therefore remains to be determined which oxysterol was responsible for the triacyglycerol transport.

Dietary cholesterol-oxidation products accumulate in serum and liver in apolipoprotein E-deficient mice, but do not accelerate atherosclerosis

“…Peak identification was confirmed by relative retention time and mass spectral comparison with authentic standards, as well as with the NIST/EPA/NIH mass spectral database library (NIST'02 ASC1 version, Gaithersburg, MD, USA). As reported elsewhere (Tomoyori et al 2002), oxysterols were grouped into seven 'time windows': group 1 17 -20 min (5a-cholestane); group 2 20-27 min (7a-hydroxycholesterol); group 3 27-29•7 min (7b-hydroxycholesterol, b-epoxycholesterol, a-epoxycholesterol); group 4 29•7-32 min (unidentified compounds); group 5 32-34•2 min (cholestanetriol); group 6 34•2-36•5 min (7-ketocholesterol, 25-hydroxycholesterol); group 7 36•5-42•5 min (27-hydroxycholesterol). Several variables including ions monitored, relative retention time, correlation coefficient for calibration curves, response factors for the monitored ions, detection limit and CV for repeated injections have been reported elsewhere (Tomoyori et al 2002).…”

Oxysterols in biological systems: sources, metabolism and pathophysiological relevance

“…However, studies of the delivery of exogenous oxysterols to humans and animals have demonstrated little to no accumulation in host tissues. Depending on the specific oxysterol, this may reflect either a poor rate of absorption or an efficient hepatic conversion to more polar metabolites which are excreted (reviewed elsewhere 1,2 and supported by more recent studies [6][7][8][9][10][11] ).…”

A Comparison of the Potential Unfavorable Effects of Oxycholesterol and Oxyphytosterol in Mice: Different Effects, on Cerebral 24S-Hydroxychoelsterol and Serum Triacylglycerols Levels

“…7,8) The diet was based on the AIN-93G diet formulation, 14) as previously described. 9) The mice were individually housed in a temperature-controlled room at 21-23 C with a light-dark cycle (light on 8:00-20:00).…”

“…[6][7][8] These sterol oxidation products are transported to the circulation via the lymphatic system after being absorbed by the small intestine. 6,8,9) It is expected that each oxysterol has a different biological effect in the body, but this remains to be elucidated.…”