Elsevier

Metabolism

Volume 52, Issue 12, December 2003, Pages 1558-1563
Metabolism

Preliminary report
Mechanisms involved in the stimulatory effect of advanced glycation end products on growth of rat aortic smooth muscle cells

https://doi.org/10.1016/j.metabol.2003.07.010Get rights and content

Abstract

Hyperglycemia is an important cause of accelerated atherosclerosis in diabetic patients. We examined the effect of hyperglycemia and advanced glycation end products (AGE) on proliferation of rat aortic smooth muscle cells (SMC) in culture; in vivo, this event is believed to contribute importantly to atherogenesis in diabetes mellitus. Glucose itself dose-dependently inhibited thymidine uptake by SMC, but AGE increased thymidine uptake, suggesting that SMC proliferation is accelerated by AGE. To examine possible mechanisms for this effect, we studied nuclear factor-kappa B (NF-κB) activation and the tyrosine phosphorylation pathway; AGE stimulated NF-κB activity, but phosphorylation of the platelet-derived growth factor (PDGF) receptor was unchanged. In Chinese hamster ovary (CHO) cells overexpressing galectin-3, an AGE receptor related to atherosclerosis, AGE increased thymidine uptake. This suggests SMC proliferation is enhanced by AGE via galectin-3. As pathways involving AGE-galectin-3 interaction thus may be involved in macroangiopathy, AGE appears to be important to the role of SMC in accelerated atherosclerosis associated with diabetes mellitus.

Section snippets

Culture of the cells

Rat aortic SMC were obtained from Wistar Kyoto rats (Charles River, Yokohama, Japan) using an explant method. The SMC were maintained in Dulbecco’s modified Eagle’s medium (DMEM; GIBCO BRL, Rockville, MD) containing penicillin (100 U/mL), streptomycin (100 mg/mL), and 10% fetal bovine serum (FBS).

Galectin-3-overexpressing CHO cells were maintained in DMEM containing penicillin (100 U/mL), streptomycin (100 mg/mL), geneticin (200 μg/mL), and 10% FBS.12

Experiments were performed in compliance

Effects of glucose concentration on cell numbers

As shown in Fig 1A, incubation with 25 mmol/L glucose significantly decreased numbers of rat aortic SMC compared with 5.6 mmol/L glucose (37.6 ± 1.33 × 104 v 49.5 ± 3.00 × 104/well; P < .05; n = 8). Other concentrations of glucose did not have significant effects.

Effects of glucose concentration on tritium-thymidine uptake

High glucose concentration dose-dependently inhibited FBS-stimulated tritium-thymidine uptake by rat aortic SMC compared with 5.6 mmol/L glucose (Fig 1B). Exposure to 10.5, 15.3, 20.1, and 25 mmol/L glucose significantly and

Discussion

To clarify the mechanisms of accelerated atherosclerosis in diabetes, we examined the effects of high-glucose or high-AGE environment on growth of cultured SMC. SMC are believed to migrate within the arterial wall from the media to the intima, where their proliferation contributes to intimal thickening as a component of atherosclerosis.11 Thymidine uptake by rat aortic SMC cultured in high glucose concentrations revealed a dose-dependent decrease despite the presence of serum. No osmotic effect

Acknowledgements

We are grateful to F. Watanabe and K. Amano for their expert assistance.

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