ANTIOXIDANT ENZYMES AND ATHEROSCLEROSIS IN JAPANESE-QUAIL - HERITABILITY AND GENETIC CORRELATION ESTIMATES

OBJECTIVES: To estimate, in male quail susceptible to atherosclerotic plaque formation (SUS) fed a regular diet and an atherogenic diet, the genetic and phenotypic parameters associated with antioxidant enzymes and atherogenesis. DESIGN: Genetic parameters were estimated from var iance components of the analysis of variance on 70 males from 13 full- sib families. MAIN RESULTS: Under the regular diet, seven of 35 males developed mild atherosclerosis. Heritability was zero for atherosclero tic plaque score and plasma cholesterol level. Plaque score was highly correlated to plasma triglyceride level (r(p)=0.96) and liver fattine ss (r(p)=0.97), but only moderately to plasma cholesterol level (r(p)= 0.39). With the high cholesterol diet, plasma cholesterol level increa sed sixfold and became heritable (h(2)=0.4). Many males developed seve re atherosclerosis. Plaque score became associated more with plasma an d aortic cholesterol levels (r(p)=0.56 and 0.76, respectively) than wi th plasma triglyceride level (r(p)=0.54). Aortic glutathione reductase activity was negatively correlated with plaque score (r(p)=-0.42; r(g )=-0.51) and aortic cholesterol level (r(p)=-0.39; r(g)=-0.62). CONCLU SIONS: Plasma triglyceride level was an important factor affecting the development of fatty streaks and the early progression of atheroscler otic plaques. Without high levels of dietary cholesterol in the plasma and aorta, any early atherosclerotic plaques that developed did not p rogress further within the time-frame of the experiment. Aortic choles terol concentration and glutathione reductase activity were important factors in the advancement of severe plaque formation. Heritability of plaque score was high in the SUS line, and further selective breeding should increase the susceptibility of these quail to cholesterol-indu ced atherosclerosis.