Previously we demonstrated a marked sex difference In the metabolism of chylomicrons In adult rats. In males, radlolabeled chylomicrons displayed a longer dwell time on endothelial surfaces, which resulted In a decreased chylomlcron uptake by the liver. The Increased rate of chylomlcron metabolism In females was associated with Increased postheparln llpoproteln lipase activity. In the present study, we have Investigated the effects of physiological doses of sex steroid hormones on the metabolism of chylomicrons and postheparln llpoprotein lipase activity. No sex differences were found In prepubertal animals. We also found no difference In chylomlcron metabolism in control female, castrated female, estrogen-treated female, castrated male, and estrogen-treated male rats. However, control male, testosterone-treated male, and testosterone-treated female rats showed Increased endothelial binding of chylomicrons and decreased chylomlcron uptake by the liver. Postheparln llpoproteln lipase activity also was decreased by testosterone administration. In parallel with the alterations In chylomlcron metabolism, serum high density llpoprotein levels In male rats decreased with testosterone administration. These results Indicate that the differences In chylomlcron metabolism, postheparin llpoproteln lipase activities, and serum high density llpoprotein levels observed between male and female rats are due to testosterone.
Arteriosclerosis – Wolters Kluwer Health
Published: Jul 1, 1990