Effect of advanced glycosylation end products on diacylglycerol signaling pathway in cultured rat aortic smooth muscle cells.

Aim: To investigate whether diacylglycerol (Dia) signaling pathway is stimulated by advanced glycosylation end products (AGEP) and to determine effect of vitamin E and aminoguanidine on Dia level induced by AGEP in cultured rat aortic vascular smooth muscle cells (VSMC).

Methods: The effect of AGEP on Dia level in cultured VSMC was measured by radio-enzymatic assay. Quantitative measurements of [32P]phosphatidic acid were performed by thin-layer chromatography and autoradiography.

Results: The Dia level in VSMC incubated with AGEP-BSA was markedly increased in a concentration-dependent, biphasic manner. The early phase was rapid and transient, peaking at 15 s. The late phase reached the maximal level at 10 min and decayed slowly. The Dia levels in VSMC exposed to different concentrations of AGEP-BSA and AGEP-BSA glycosylated for various periods were greatly increased compared with control group. Vitamin E 50, 100 nmol.L-1 prevented the AGEP-BSA-stimulated elevation of Dia level in VSMC, from (940 +/- 43) pmol.L-1 to (599 +/- 38), (290 +/- 21) pmol.L-1, respectively. In aminoguanidine-treated AGEP-BSA groups, Dia level in the cells incubated with the same concentration of AGEP-BSA (100, 200 mg.L-1) were decreased to (260 +/- 8) and (289 +/- 10) pmol.L-1, respectively. Early glycosylated low-density lipoproteins (LDL) did not affect Dia level.

Conclusion: AGEP causes a robust stimulation of Dia signaling pathway in VSMC. Vitamin E and aminoguanidine attenuate the production of Dia.