Apocynin decreases AGEs-induced stimulation of NF-κB protein expression in vascular smooth muscle cells from GK rats

Abstract

Context: Elevated oxidative stress plays a key role in diabetes-associated vascular disease. Excessive production of reactive oxygen species via advanced glycation end products (AGEs) activates peroxisome proliferator-activated receptor gamma (PPARγ) and the transcription factor nuclear factor-kB (NF-κB) in aortic vascular smooth muscle cells (VSMCs). Apocynin, a drug with an antioxidant effect, has also been proposed as a therapeutic agent for atherosclerotic disease.

Objectives: This work investigates the effects of apocynin on the PPARγ and NF-κB protein expression evoked by AGEs in cultured VSMCs from Goto–Kakisaki (GK) rats, a non-obese insulin model of both insulin resistance and type 2 diabetes.

Materials and methods: VSMCs, isolated from aortas of GK and non-diabetic rats, were cultured. The expression of proteins was evaluated by Western blot. The blood glucose concentration was measured with a blood glucose test meter. The diabetes of GK rats was controlled by blood glucose and insulin determinations (non-fasting values). The serum insulin concentration was determined by radioimmunoassay.

Results: In VSMCs from non-diabetic and GK rats, apocynin (1 and 10 µM) abolished the protein overexpression of NF-κB induced by glycated bovine serum albumin (AGEs-BSA) incubation. However, apocynin (1 and 10 µM) enhanced the expression of PPARγ protein in the presence of AGEs-BSA (100 μg/mL) in VSMCs from non-diabetic, but not from GK rats.

Conclusion: These findings suggest that apocynin decreases the incidence of alterations in VSMCs induced by AGEs through the reduction of NF-κB and may represent an attractive therapeutic approach to treat diabetes mellitus.

• Advanced glycation end-product
• antioxidant
• diabetes mellitus
• PPARγ protein expression

Acknowledgements

This study is part of a Dissertation developed by C. O. Silva in order to obtain a Ph.D. degree in Biological Sciences while she was student at the Laboratoire de Biochimie, Hôpital Lapeyronie et Université Montpellier, Montpellier, France.

Declaration of interest

This study was supported by the French Research-National Education Ministry (LNHA 2993) and the CAPES-COFECUB (France-Brazil research cooperation) project number 296/99-I.