The role of thymosin F5 on anemia in hypercholesterolemic rabbits.

New Zealand White rabbits were made hypercholesterolemic by feeding a high cholesterol diet (20 g/kg diet) for 3 months. Plasma cholesterol concentrations were monitored as a function of time. At the end of 3 months, the plasma lipid levels, the whole blood, erythrocyte and haemoglobin-bound 2,3-DPG levels and leucocyte counts increased, whereas erythrocyte counts, hematocrit and haemoglobin levels decreased significantly in hypercholesterolemic rabbits. At the end of 3 months, the rabbits in the experimental group were divided into two groups. The first group was fed a standard diet for 21 days. The second group received 0.5 mg/kg thymosin F5 injection i.p. every other day for 21 days. After this period, the plasma lipid levels, the whole blood, erythrocyte and haemoglobin-bound 2,3-DPG levels, erythrocyte and leucocyte counts, hematocrit and haemoglobin levels were measured. Rabbits fed diets supplemented with thymosin F5 had markedly lower plasma lipid levels, erythrocyte counts, hematocrit and haemoglobin levels and enhanced leucocyte counts, but did not have significantly less whole blood, erythrocyte and haemoglobin-bound 2,3-DPG levels. We conclude that thymosin F5 has lipid-lowering effects in hypercholesterolemic rabbits. The data further suggest that effects of thymosin F5 on haematological parameters are due to the cholesterol decrease and not to the direct regulatory mechanism.