Investigation of serum paraoxonase 1 (PON1) activity in postprandial lipemia

Postprandial dyslipidemia (PPD) considered as a risk factor for cardiovascular diseases results in alteration of many biochemical parameters. Especially, increasing triglyceride levels accompanied with decreasing high density lipoprotein (HDL) levels were associated with PPD. Paraoxonase-1 (PON1) is present in HDL structure. PON1 decreases the oxidative stress in atherosclerotic lesions by preventing the HDL and LDL against to oxidation. The aim of the present study is to determine PON1 enzyme activities by measuring paraoxonase, arylesterase and lactonase activities in healthy subjects after oral trigliseride tolerans test (OTTT) by considering OTTT response. Study group included 96 healthy subjects (45 female and 51 male with age range of 18-55 years). Study group was divided into three groups according to the area under curve (AUC) values calculated by using triglyceride levels at the fasting state and at 2nd, 4th and 6th hours after the high fat diet (OTTT). PON1 enzyme activities and other parameters in lower OTTT response group were compared to that of the upper group. Atherogenic lipid profile, increased total cholesterol and LDL-C and decreased HDL-C levels, was observed in subjects with the upper group men when compared to the lower group. PON1 enzyme activity levels were determined by spectrofotometric methods. PON1 lactonase activity was significantly lower in men than that of women (P<0.05). On the other hand, PON1 lactonase activity showed time-depended increase during OTTT in both sex. PON1 arylesterase activity in subjects with the upper group was significantly higher than that of the lower groups (P<0.022) in women.It was concluded that, subjects with upper response group to OTTT had atherogenic lipid profile. PON1 enzyme activities showed different response, generally by increasing, in postprandial period during OTTT. It may be related to response to increased oxidant stress in this period. All these observed changes may be associated with some degree increased atherogenic tendency, especially in men with disturbed response to OTTT.