nitroarginine and Atherosclerosis

To investigate the effects of non-neuronal muscarinic receptors (NNMR) stimulation on atherosclerosis and endothelial cells activation.. Atherosclerosis model was established in ApoE-/- mice by a high fat diet for 7 weeks. During the experimental periods, animals were received a low (7 mg/kg/d) or a high (21 mg/kg/d) dose of arecoline by gavage. At the termination of the treatments, serum total cholesterol and NO levels were measured, and the aorta morphology was analyzed by hematoxylin and eosin staining. The gene expression of monocyte chemoattractant protein-1 (MCP-1) and adhesion molecules in the thoracic aortas was determined by RT-PCR, and the MCP-1 protein expression and NF-κB activity were detected by Western blot analysis. NO production, MCP-1 secretion in cultured rat aortic endothelial cells (RAECs), and monocyte-endothelium adhesion assay were also performed after arecoline treatments.. Arecoline efficiently decreased atherosclerotic plaque areas, increased serum nitric oxide (NO) content, suppressed the mRNA and protein expression of MCP-1, and modulated the IκB-α degradation and P65 phosphorylation in the aortae of ApoE-/- mice. Furthermore, arecoline promoted NO production and suppressed MCP-1 secretion in cultured RAECs after ox-LDL exposure, and either atropine or NG-nitro-L-arginine methylester could abrogate these effects. Arecoline also significantly inhibited the adherence of U937 monocytes to the ox-LDL injured human umbilical vein endothelial cells, which could be abolished by atropine.. Our results indicate that arecoline attenuates the progression of atherosclerosis and inhibits endothelial cells activation and adherence by stimulating endothelial NNMR. These effects, at least in part, are due to its modulation on NF-κB activity.

Topics: Animals; Aorta; Apolipoproteins E; Arecoline; Atherosclerosis; Cell Adhesion Molecules; Chemokine CCL2; Cholesterol; Disease Progression; Endothelial Cells; Endothelium, Vascular; Human Umbilical Vein Endothelial Cells; Humans; I-kappa B Proteins; Lipoproteins, LDL; Mice; Mice, Knockout; Monocytes; NF-KappaB Inhibitor alpha; Nitric Oxide; Nitroarginine; Rats; Receptors, Muscarinic; Transcription Factor RelA

Previously [Histochem J 1997;29:279-286], we found that sympathectomy induced neointima formation in ear but not cerebral arteries of genetically hyperlipidemic rabbits. To clarify the influence of sympathetic nerves in atherosclerosis, and whether their influence involves vascular NO activity, we studied groups of normocholesterolemic intact (NI) and sympathectomized (NS), and hypercholesterolemic intact (HI) and sympathectomized (HS) rabbits (diet/6-hydroxydopamine for 79 days). Segments of basilar (BA) and femoral (FA) arteries were studied histochemically, to evaluate differentiation (anti-desmin, anti-vimentin, anti-h-caldesmon, and nuclear dye), by confocal microscopy, and by in vitro myography. In BAs, staining of NI and NS groups was similar. In hypercholesterolemic groups, a small neointima developed, more frequently in HS segments where smooth muscle cells (SMCs) positive for all antibodies appeared to be migrating into the neointima. In FAs, SMCs stained for the three antibodies in the NI group, but we observed desmin- and h-caldesmon-negative, vimentin-positive cells in some external medial layers of the NS, HI and HS groups, identical to adventitial fibroblasts. Large neointimas of the HS group contained vimentin-positive and largely desmin- and h-caldesmon-negative cells. Relaxation of BA or FA segments to acetylcholine was not decreased by sympathectomy. Sympathectomy increased the contraction of resting FAs to nitro-L-arginine (p = 0.0379). Thus, sympathectomy aggravates the tendency for FA SMCs to migrate and dedifferentiate, increasing atherosclerotic lesions, without decreasing NO activity, but has only minor effects on BAs.

Topics: Acetylcholine; Animals; Atherosclerosis; Basilar Artery; Cell Differentiation; Cell Movement; Cell Proliferation; Disease Models, Animal; Dose-Response Relationship, Drug; Enzyme Inhibitors; Femoral Artery; Hypercholesterolemia; Male; Nitric Oxide; Nitric Oxide Synthase; Nitroarginine; Oxidopamine; Rabbits; Sympathectomy, Chemical; Tunica Intima; Tunica Media; Vasodilator Agents

There is increasing evidence that Chlamydia pneumoniae is linked to atherosclerosis and thrombosis. In this regard, we have recently shown that C. pneumoniae stimulates platelet aggregation and secretion, which may play an important role in the progress of atherosclerosis and in thrombotic vascular occlusion. The aims of the present study were to investigate the effects of C. pneumoniae on platelet-mediated formation of reactive oxygen species (ROS) and oxidation of low-density lipoprotein (LDL) in vitro. ROS production was registered as changes in 2',7'-dichlorofluorescin- fluorescence in platelets with flow cytometry. LDL-oxidation was determined by measuring thiobarbituric acid reactive substances (TBARs). We found that C. pneumoniae stimulated platelet production of ROS. Polymyxin B treatment of C. pneumoniae, but not elevated temperature, abolished the stimulatory effects on platelet ROS-production, which suggests that chlamydial lipopolysaccharide has an important role. Inhibition of nitric oxide synthase with nitro-L-arginine, lipoxygenase with 5,8,11-eicosatriynoic acid and protein kinase C with GF 109203X significantly lowered the production of radicals. In contrast, inhibition of NADPH-oxidase with di-phenyleneiodonium (DPI) did not affect the C. pneumoniae induced ROS-production. These findings suggest that the activities of nitric oxide synthase and lipoxygenase are the sources for ROS and that the generation is dependent of the activity of protein kinase C. The C. pneumoniae-induced ROS-production in platelets was associated with an extensive oxidation of LDL, which was significantly higher compared to the effect obtained by separate exposure of LDL to C. pneumoniae or platelets. In conclusion, C. pneumoniae interaction with platelets leading to aggregation, ROS-production and oxidative damage on LDL, may play a crucial role in the development of atherosclerotic cardiovascular disease.

Topics: Atherosclerosis; Blood Platelets; Cells, Cultured; Chlamydophila pneumoniae; Enzyme Inhibitors; Fatty Acids, Unsaturated; Flow Cytometry; Fluoresceins; Humans; Indoles; Lipopolysaccharides; Lipoproteins, LDL; Lipoxygenase; Lipoxygenase Inhibitors; Maleimides; Nitric Oxide Synthase; Nitroarginine; Oxygen; Polymerase Chain Reaction; Polymyxin B; Protein Kinase C; Reactive Oxygen Species; Signal Transduction; Temperature; Thiobarbituric Acid Reactive Substances; Thrombosis