Extracellular superoxide dismutase in tissues from obese (ob/ob) mice

We have examined the protein content and gene expression of three superoxid e dismutase (SOD) isoenzymes in eight tissues from obese ob/ob mice, partic ularly placing the focus on extracellular-SOD (EC-SOD) in the white adipose tissue (WAT). Obesity significantly increased EC-SOD level in liver, kidne y, testis, gastrocnemius muscle, WAT; brown adipose tissue (BAT), and plasm a, but significantly decreased the isoenzyme level in lung. Tumor necrosis factor-cc and interleukin-lp contents in WAT were significantly higher in o bese mice than in lean control mice. Immunohistochemically, both WAT and BA T from obese mice could be stained deeply with anti-mouse EC-SOD antibody c ompared with those from lean mice. Each primary culture per se almost time- dependently enhanced EC-SOD production, and overtly expressed its mRNA. The loss of heparin-binding affinity of EC-SOD type C with high affinity for h eparin occurred in kidney of obese mice. These results suggest that the phy siological importance of this SOD isoenzyme in WAT may be a compensatory ad aptation to oxidative stress.