Apolipoprotein A5 and Hypertriglyceridemia in Prague Hypertriglyceridemic Rats

M. KADLECOVÁ, S. HOJNÁ, R. BOHUSLAVOVÁ1, J. A. HUBÁČEK1, J. ZICHA, J. KUNEŠ

Institute of Physiology AS CR and Cardiovascular Research Center, 1Institute for Clinical and Experimental Medicine, Prague, Czech Republic

Received September 5, 2005
Accepted October 3, 2005
On-line October 17, 2005

Summary
High plasma triglyceride (TG) level is a major independent risk factor of coronary heart disease. A newly identified Apolipoprotein A5 (Apoa5) gene has been shown to play an important role in determining plasma TG concentrations in humans and mice. Prague hereditary hypertriglyceridemic (HTG) rats are a useful model of human hypertriglyceridemia and other symptoms of metabolic syndrome. Thus, the variation of Apoa5 gene and its expression were studied in this strain under normal conditions and after chronic fructose loading. Lewis and Wistar rats served as normotriglyceridemic controls. Plasma TG were significantly higher in HTG rats in comparison with both control strains. Sequence analysis of the rat Apoa5 gene revealed the existence of two introns. However, screening of the coding regions and intron-exon boundaries of Apoa5 gene did not indicate any mutation of this gene in HTG rats in comparison with Lewis and Wistar ones. Under the basal conditions the expression of Apoa5 was lower in all age groups of HTG rats compared to Wistar animals. Furthermore, during chronic fructose loading there were no significant changes of Apoa5 expression in HTG rats, although plasma TG levels rose 3-4 times within first two days of fructose loading and were increased during the whole period of fructose treatment. In conclusion, Apoa5 does not seem to be a genetic determinant of hypertriglyceridemia in HTG rats. The absence of significant changes in Apoa5 gene expression during chronic fructose-induced TG elevation excludes its major role in mechanisms compensating severe hypertriglyceridemia.


Key words
Hypertriglyceridemia • Metabolic syndrome • Apolipoprotein A5 • Genetic analysis • Gene expression • Chronic fructose loading • Rat