Effects of caloric restriction and gender on rat serum paraoxonase 1 activity.

Paraoxonase 1 (PON1) associates to specific high-density lipoproteins (HDLs)--those containing apolipoprotein A-I (apoA-I) and apolipoprotein J (apoJ)--and is largely responsible for their antiatherogenic properties. Caloric restriction (CR) has been shown to reduce major atherosclerotic risk factors. The aims of this work were to study PON1 activity response to CR (40% over 14 weeks) and to elucidate whether there are adaptive differences related to gender. Serum and liver paraoxonase and arylesterase activities, serum triglyceride, total and HDL cholesterol concentrations, serum PON1, apoA-I and apoJ contents and liver PON1 mRNA levels were measured. No effects of CR or gender were observed in triglyceride, total cholesterol concentration and PON1 mRNA levels. HDL cholesterol was higher in female rats than in male rats and increased with CR only in the latter animals. Serum PON1 activities tended to be higher in female rats and dropped with CR, with females showing the biggest decrease. Serum PON1 content was higher in female rats and decreased in both genders with CR, whereas apoA-I and apoJ contents, which were higher in female rats too, decreased only in the former animals, accounting for the high PON1 activity decrease observed in these animals. In conclusion, the short-term CR-associated reduction of serum PON1 activity and PON1, apoA-I and apoJ levels points toward a reduced stability of HDL-PON1 complexes and/or HDL particle levels responsible for PON1 transport and function in the blood. Moreover, the variations in PON1 activity and apolipoprotein levels show gender-related differences that are indicative of a different adaptive strategy of male and female rats when faced with a period of food restriction.