Paraoxonase 1 status and interactions between Q192R functional genotypes by smoking contribute significantly to total plasma radical trapping antioxidant potential.

The measurement of the total radical trapping antioxidant potential (TRAP) is a general marker of peripheral blood antioxidant defenses. Paraoxonase 1 (PON1) is a potent antioxidant, which protects against lipid peroxidation. The study aimed to examine the relation between TRAP levels and PON1 activity, PON1 Q192R functional genotypes, smoking, interactions between PON1 genotypes and smoking, and mood disorders, while adjusting for effects of ethnicity, marital status, body mass index (BMI) and gender. The analyses were performed in 197 controls and 136 subjects with mood disorders. TRAP levels were significantly associated with higher plasma PON1 activity, the RR functional genotype, non smoking by RR carriers, male gender and a higher BMI. TRAP levels were significantly lower in patients with mood disorders than in controls, but this association was no longer significant after considering the effects of the above predictors. The risk in the subgroup with low TRAP levels is increased by a smoking X RR genotype interaction and decreased by male gender, the RR genotype, and higher BMI and PON1 activity. Plasma PON1 activity, the PON1 Q192R functional genotypes and specific interactions between this genotype and smoking contribute significantly to TRAP levels. Gender and BMI also appear to influence TRAP levels.