<bold>The aim of the study.</bold> Investigation of the effect of vertical banded gastroplasty (VBG), which is an effective method of treating patients with morbid obesity on serum paraoxonase (PON) activity.
<bold>Material and methods.</bold> Serum PON activity was measured in twenty eight morbidly obese patients 6 and 12 months after surgery. PON activity was also measured in the serum and liver of rats maintained on a restricted diet for one month.
<bold>Results.</bold> We found that VBG-induced significant reduction in body weight and serum PON activity at 6 and 12 months after surgery. Similar patterns of decreases in serum paraoxonase activity in obese patients after VBG were observed in A, AB and B paraoxonase/esterase phenotypes. After VBG, several clinically relevant events occurred: a) a decrease of serum triacylglycerol concentration was observed; b) no significant changes in total serum cholesterol and LDL-cholesterol concentrations were found; c) serum HDL-cholesterol concentration increased slightly.
Paraoxonase activity in the serum of rats maintained on a restricted diet, which induced approximately 30% and 50% of rat body weight and fat mass loss, respectively, was lower than in control animals.
<bold>Conclusions.</bold> This study indicates that after VBG significant decreases in serum paraoxonase activity occur in obese subjects. It is likely that less food ingestion and possibly a different type of food consumed by the obese subjects after VBG (compared to type of food consumed before surgery) may contribute to decreases in serum PON activity.