Previous studies suggest a role for sialic acid on platelet function. It was shown in such clinical syndromes as Bernaud-Surlier syndrome and Thromboasthenia. Platelets from those patients are known to be reduced sialic acid or lack of a certain glycoprotein (GP1-b). On the other hand increased glycoprotein or sialic acid were shown in some thrombogenic state (during ingestion of oral contraceptive drug and estrogen therapy for prostatic cancer patient).
It was known that almost those glycoprotein have sialic acid on out side of platelet membrane and give a negative charge to the platelet membrane and affect platelet function. We examined platelet sialic acid and sialidase activity (EC3. 2. 1. 18) in arteriosclerotic rat in order to clarify the relationship between arteriosclerosis and sialic acid change in platelet. At first we confirmed tipical atherosclerotic lesions with atheroma and carcification in aorta using H-E stein, von Gieson stein, Sudan stein and Kossa stein methods.
We performed glucose tolerance test, thyroid function test and lipid analysis. In this experimental rat showed abnormal glucose tolerance test with low responce of insulin and hypothyroid state due to intake propylthiouracil in experimental diet. Plasma sialic acid was slightly elevated in arteriosclerotic rat compaired with normal control rat but not statistically significant. Platelet sialic acid was significantly increased in arteriosclerotic rat. Platelet sialidase activity was significantly decreased in arteriosclerotic rat.
This data suggest that changes of sialic acid and sialidase activity may play a role on platelet function and accerate arteriosclerosis. But it was not clear wether this change of platelet sialic acid in our experiment was the result of angiopathy or primary metabolic disorder in this experimental condition.
