| Research Abstract |
1. The c-DNA for cellular glutathione peroxidase (C-GPX) was inserted to an expression vector, and was transfected to T-47D cultured cell line. By limiting dilution method, clones that permanently express extra copies of C-GPX were established.
2. Serum level of protein carbonyl groups (PCGs) were increased in obese children, reflecting the enhanced oxidative stress in obesity.
3. Addition of SNAP, a nitric oxide (NO) donor, to the homogenate of KNRK cells resulted in inactivation of C-GPX by nitration. Combined stimulation of Lipopolysaccharide (LPS) and tumor necrosis factor (TNF) induced de novo expression of inducible nitric oxide synthase (iNOS)in KNRK cells. No production by such stimuli, as well as NO donor, leaded to a compensatory induction of C-GPX. Thus, enhanced NO production did not induce change in GPX activity in KNRK cells, due to a balanced induction and inactivation of C-GPX.
4. Serum extra cellular GPX (EC-GPX) and kidney C-GPX were increased in obese-diabetic rats. On the other hand, both EC-GPX and C-GPX in adipose tissue were suppressed by obesity. Troglitazone suppressed the expression of EC-GPX and C-GPX in adipose tissue. Troglitazone was a potent antioxidant. It suppressed the increased PCGs in obese animals. LPS injection induced iNOS in adipose tissue, but that was blocked by the co-administration of troglitazone.
5. Fully differentiated 3T3-L1 preadipocytes expressed iNOS after a combined stimulation of LPS, TNF and interferone (INF), resulting in increased NO production. The induction was blocked by co-incubation of troglitazone.
6. Serum EC-GPX was depleted in the rat fed with diet containing a phthalate derivative, a peroxisome proliferator. C-GPX was not affected. The enhanced oxidative stress, as evidenced by the increase in 4-hydroxy-2-nonenal, resulted in the inactivation of EC-GPX in kidney tissue.
|
