Paraoxonase 1 activity and phenotype distribution in premenopausal and postmenopausal women

Introduction: Postmenopausal women have higher risk of cardiovascular disease. One of the contributing factors could be reduced activity of antiatherogenic enzyme paraoxonase 1 (PON1). The aim of this study was to examine differences in the lipid status, paraoxonase and arylesterase PON1 activities and PON1 phenotype in women with regular menstrual cycle and in postmenopausal women. Materials and methods: The study included 51 women in reproductive age (25 in follicular and 26 in luteal phase of the menstrual cycle) and 23 women in postmenopause. Lipid parameters in sera were determined using original reagents and according to manufacturer protocol. PON1 activity in serum was assessed by spectrophotometric method with substrates: paraoxon and phenylacetate. PON1 phenotype was determined by double substrate method. Results: Compared to the women in follicular and luteal phase, postmenopausal women have significantly higher concentration of triglyceride [0.9 (0.7-1.3), 0.7 (0.6-1.0) vs. 1.5 (0.9-1.7) mmol/L; P = 0.002], cholesterol [5.10 (4.78-6.10), 5.05 (4.70-5.40) vs. 6.30 (5.73-7.23) mmol/L; P < 0.001], LDL [3.00 (2.56-3.63), 3.00 (2.70-3.70) vs. 3.90 (3.23-4.50) mmol/L; P < 0.001], and apolipoprotein B [0.88 (0.75-1.00), 0.79 (0.68-1.00) vs. 1.07 (0.901.24) mmol/L; P = 0.002]. PON1 basal [104 (66-260), 106 (63-250) vs. 93 (71-165) U/L; P = 0.847] and salt-stimulated paraoxonase activity [210 (131462), 211 (120-442) vs. 180 (139-296) U/L; P = 0.857] as well as arylesterase activity [74 (63-82), 70 (54-91) vs. 70 (60-81) kU/L; P = 0.906] and PON1 phenotype (P = 0.810) were not different in the study groups. Conclusion: There are no differences in PON1 activity and PON1 phenotype between women with regular menstrual cycle and postmenopausal women.