OBJECTIVETo detect whether the activation of nuclear factor-kappa B (NF-kappaB) in endothelial cells induced by mm-LDL can promote platelet-derived growth factor-B (PDGF-B) expression in vitro, and whether it is also present in hypercholesterolemic rats in vivo, influence of age on NF-kappaB and PDGF-B signal transduction pathway.

METHODSEstablished hypercholesterolemic rat model by feeding with a high-cholesterol ration. The activation of NF-kappaB in aortic endothelial cells was identified by immunohistochemical staining, the expression of PDGF-B mRNA and PDGF-B protein were examined using in situ hybridization and immunohistochemistry respectively.

RESULTSIn comparison with the control rats, a positive immunostaining of NF-kappaB in nuclei of aortic endothelial cells of the experimental rats was detected after a high cholesterol ration for 6 weeks. The number of endothelial cells expressing PDGF-B mRNA increased and the intensity was dependent upon the duration of high-cholesterol intake. NF-kappaB translocation (0.461 +/- 0.075 vs. 0.350 +/- 0.094, P < 0.05) and PDGF-B expression in 10-month old Wistar rats were more remarkable than that of 2-month old rats after having cholesterol for 16 weeks. Immunohistochemical staining for PDGF-B gave a similar result (0.230 +/- 0.040 vs. 0.185 +/- 0.037, P < 0.001).

CONCLUSIONSHypercholesterolemia is capable of activating nuclear translocation of NF-kappaB and promoting expression of PDGF-B in rat aortic endothelial cells in vivo, this coincided with the results obtained in ox-LDL or mm-LDL experiments on endothelial cells in vitro. This phenomenon is much more evident in 10-month old rats which indicates that age might have a close relationship with NF-kappaB - PDGF-B signal transduction pathway.