Plasma kinetics and biodistribution of free cholesterol and cholesterol ester of a nanoemulsion that binds to LDL receptors in animals without and with atherosclerosis

Author(s)

Amanda Felippe Padoveze

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina (FM/SBD)
• Defense date: 2007-09-10

Examining board members

Raul Cavalcante Maranhao; Ligia Ferreira Gomes; Ernani Pinto Junior; Carlos Vicente Serrano Junior; Hermes Toros Xavier

• Advisor: Raul Cavalcante Maranhao

Abstract

I n previously studies, it was shown that free cholesterol (FC) and cholesterol ester (CE) of a cholesterol-rich nanoemulsion (LDE) behaves differently in patients with coronary artery disease (CAD). The FC plasma clearance and arterial deposition is greater than CE. In the present study we evaluate the plasma kinetics, estimated by the fractional clearance rate (FCR), and the tissue uptake of 3H-free cholesterol (3H FC) and of 14C cholesterol ester (14C - CE) of LDE by arterial segments and organs of rabbits with (n=13) and without atherosclerosis (n=17). Furthermore, it was evaluated the in vitro uptake of 3H FC and 14C - CE by rabbit aortic endothelial cells. Finally, it was evaluated the inhibition of the enzyme lecithin-cholesterol acyltransferase (LCAT), and indirectly, the FC esterification in rats non-treated (n=9) and treated with diazepam (n=9). In rabbits without atherosclerosis that received an standard diet there was no difference between the plasma clearance of 3H FC and 14C CE. In rabbits with hyperlipidemia and atherosclerosis induced by the cholesterol-rich diet the 3H - FC was removed faster than 14C - CE (p<0.05), however the arch aortic uptake of 14C CE was greater than of 3H - FC (0p<0.05). In both groups, liver, lungs, adrenals and spleen were the principal sites of LDE cholesterol uptake. The FCR and tissue uptake were smaller in rabbits with than those without atherosclerosis. In rabbit aortic endothelial cells the 3H - FC uptake was greater than 14C CE independently of incubated LDE mass (p<0.01). In control rats there was no difference on the arterial uptake of both cholesterol forms of LDE, but when the LCAT activity was diminished by the diazepam treatment, the arterial uptake of 3H FC were greater than 14C CE (p< 0.01). The hyperlipidemia and cholesterol stability alterations may lead to dissociation between lipoproteins FC and CE. This dissociation may increase the risk for atherosclerosis and likewise enhance the severity of atherosclerosis. (AU)