Increase of Anti-oxidative Capacity during Differentiation of 3T3-L1 Preadipocytes into Adipocytes

Cells have developed ingenious defense mechanisms in response to oxidative stress. Here, we evaluated changes in anti-oxidative capacity during differentiation of 3T3-L1 preadipocytes into adipocytes. When 3T3-L1 preadipocytes were treated with H₂O₂ (0.10-2.0 mM) for 21 h, cell viability decreased in response to H₂O₂ concentration, with an LD₅₀ of approximately 0.35 mM H₂O₂. In the cells undergoing differentiation at 2 and 6 d, LD₅₀ increased to 1.0 and >2.0 mM H₂O₂, respectively. These results indicate that resistance to oxidative stress dramatically increased with progression of differentiation of preadipocytes into adipocytes. Catalase activity and GSH content increased in the differentiated cells at 6 d, whereas superoxide dismutase and glutathione peroxidase activities were slightly lower in adipocytes than in preadipocytes. Moreover, knockdown of catalase or depletion of intracellular GSH enhanced the sensitivity to H₂O₂. When GSH was added to the cells depleted of intracellular GSH, the antioxidant capacity recovered. Autophagy was increased in differentiated adipocytes but was not affected by H₂O₂ treatment. Therefore, these results suggest that the increase in intracellular catalase activity and GSH content played a role in the increased anti-oxidative capacity of differentiated 3T3-L1 adipocytes.