In the present study, the effects of thymosin alpha(1) on lipid peroxi
dation were studied in an in vivo model of experimental hypercholester
olemia. In groups II-IV, rabbits were fed a high-cholesterol diet 2% (
w/w) for 10 weeks. Thereafter, rabbits in group III were fed a normal
diet for another 14 days and those in group IV were given a normal die
t plus 25 mu g/kg thymosin alpha(1) intraperitoneally every other day
for the same period. At the end of this period, plasma and erythrocyte
lipid levels and susceptibility of erythrocytes to lipid peroxidation
were determined in all groups. Hypercholesterolemic rabbits had high
plasma and erythrocyte lipid peroxide (TBARS) levels compared to contr
ol animals fed a normal diet. Plasma and erythrocyte TEARS levels sign
ificantly decreased in the thymosin-alpha 1-injected rabbits. In thymo
sin-alpha(1)-treated animals (group IV), most of the lipid plaques wer
e replaced by fibrous tissue. These findings suggest that thymosin alp
ha(1) may have some beneficial effects on the treatment of atheroscler
osis by normalizing blood lipid levels and by substantially protecting
endothelial cells against free radical injury.