OBJECTIVETo explore the oxidative modification effect and its mechanism of low density lipoprotein (LDL) in hyperlipidemia (HL) rats after treating with tetrahydrobiopterin (BH4).

METHODSFifty four 8-week-old male Wistar rats were used, these 54 rats were randomly divided into control group, high fat diet group (HL group), high fat diet and injected BH4 group (HL + BH4 group), and 18 in each group. The BH4 levels of blood fats and blood serum and its metabolites, the aortic reactive oxygen species, the end product malondialdehyde (MDA) and the LDL oxidation level were all determined by killing 6 experimental rats in each group at the first 8, 16, and 24 weeks of age respectively.

RESULTSTreating with BH4 after 8 and 16 weeks, there was no significant difference in serum lipids among three groups (P > 0. 05); but ROS and MDA decreased significantly (P < 0.01); compared with control and HL groups, the BH4 level of HL + BH4 group increased a lot (P < 0.01); compared with control group, the BH4 content reduced obviously in aortic homogenate of HL group (P < 0.01), but the total petrin levels (TB = BH4 + BH2 + B) had no significant difference (P > 0.05); the serum TBARS formation increased gradually with the increase of week-ages, but compared with HL group, the serum TBARS formation of HL + BH4 group reduced significantly (P < 0. 01).

CONCLUSIONTreating with BH4 can reduced the LDL oxidation, the mechanism may be related to the correct of NOS uncoupling, the reduce of ROS generation and the decrease of LDL lipid peroxidation.