4-hydroxy-2-nonenal and Hypercholesterolemia

Hypercholesterolemia induces erectile dysfunction (ED) mostly by increasing oxidative stress and impairing endothelial function in the penis, but the mechanisms regulating reactive oxygen species (ROS) production in the penis are not understood.. We evaluated whether hypercholesterolemia activates nicotinamide adenine dinucleotide phosphate (NAD[P]H) oxidase in the penis, providing an initial source of ROS to induce endothelial nitric oxide synthase (eNOS) uncoupling and endothelial dysfunction resulting in ED.. Low-density-lipoprotein receptor (LDLR)-null mice were fed Western diet for 4 weeks to induce early-stage hyperlipidemia. Wild type (WT) mice fed regular chow served as controls. Mice received NAD(P)H oxidase inhibitor apocynin (10 mM in drinking water) or vehicle. Erectile function was assessed in response to cavernous nerve electrical stimulation. Markers of endothelial function (phospho [P]-vasodilator-stimulated-protein [VASP]-Ser-239), oxidative stress (4-hydroxy-2-nonenal [HNE]), sources of ROS (eNOS uncoupling and NAD[P]H oxidase subunits p67(phox) , p47(phox) , and gp91(phox) ), P-eNOS-Ser-1177, and eNOS were measured by Western blot in penes.. The main outcome measures are the molecular mechanisms of ROS generation and endothelial dysfunction in hypercholesterolemia-induced ED.. Erectile response was significantly (P<0.05) reduced in hypercholesterolemic LDLR-null mice compared with WT mice. Relative to WT mice, hypercholesterolemia increased (P<0.05) protein expressions of NAD(P)H oxidase subunits p67(phox) , p47(phox) and gp91(phox) , eNOS uncoupling, and 4-HNE-modified proteins, and reduced (P<0.05) P-VASP-Ser-239 expression in the penis. Apocynin treatment of LDLR-null mice preserved (P<0.05) maximal intracavernosal pressure, and reversed (P<0.05) the abnormalities in protein expressions of gp67(phox) and gp47(phox) , 4-HNE, P-VASP-Ser-239, and eNOS uncoupling in the penis. Apocynin treatment of WT mice did not affect any of these parameters. Protein expressions of P-eNOS-Ser-1177 and total eNOS were unaffected by hypercholesterolemia.. Activated NAD(P)H oxidase in the penis is an initial source of oxidative stress resulting in eNOS uncoupling, thus providing a mechanism of eNOS uncoupling and endothelial dysfunction in hypercholesterolemia-induced ED.

Topics: Acetophenones; Aldehydes; Animals; Cell Adhesion Molecules; Cholesterol, Dietary; Disease Models, Animal; Endothelium, Vascular; Enzyme Inhibitors; Erectile Dysfunction; Hypercholesterolemia; Male; Mice; Microfilament Proteins; NADPH Oxidases; Nitric Oxide Synthase Type III; Penis; Phosphoproteins; Reactive Oxygen Species

Rabbits were fed a diet containing 1% cholesterol for 8 weeks and the levels of iron and oxidized lipids in liver analysed using atomic absorption spectroscopy and gas chromatography-mass spectrometry. A non-significant trend to an increase in iron level, but significant increases in the lipid peroxidation products, F(2)-isoprostanes and the cholesterol oxidation products 7 beta hydroxycholesterol, 7 ketocholesterol and cholesterol 5,6-alpha epoxide were detected in the liver of the cholesterol-fed rabbits. Histological analysis showed greater accumulation of lipids by Sudan red labelling in hepatocytes of zone I than zones II and III of the liver acinus. The increase in lipids coincided with an increase in iron staining in macrophages around liver microvessels and increased immunostaining to melanotransferrin and the lipid peroxidation product, 4-hydroxynonenal (4-HNE), in zone 1. The results are suggestive of microvascular damage associated with iron accumulation and oxidative stress in the liver during hypercholesterolemia.

Topics: Aldehydes; Animals; Cholesterol; Cholesterol, Dietary; Hypercholesterolemia; Iron; Lipid Metabolism; Liver; Microscopy, Electron; Microscopy, Polarization; Microvessels; Oxidative Stress; Rabbits

To determine whether oxidized LDL enhances atherogenesis by promoting monocyte recruitment into the vascular intima, we investigated whether LDL accumulation and oxidation precede intimal accumulation of monocytes in human fetal aortas (from spontaneous abortions and premature newborns who died within 12 h; fetal age 6.2+/-1.3 mo). For this purpose, a systematic assessment of fatty streak formation was carried out in fetal aortas from normocholesterolemic mothers (n = 22), hypercholesterolemic mothers (n = 33), and mothers who were hypercholesterolemic only during pregnancy (n = 27). Fetal plasma cholesterol levels showed a strong inverse correlation with fetal age (R = -0.88, P < 0.0001). In fetuses younger than 6 mo, fetal plasma cholesterol levels correlated with maternal ones (R = 0.86, P = 0.001), whereas in older fetuses no such correlation existed. Fetal aortas from hypercholesterolemic mothers and mothers with temporary hypercholesterolemia contained significantly more and larger lesions (758,651+/-87,449 and 451,255+/-37,448 micron2 per section, respectively; mean+/-SD) than aortas from normocholesterolemic mothers (61,862+/-9,555 micron2; P < 0.00005). Serial sections of the arch, thoracic, and abdominal aortas were immunostained for recognized markers of atherosclerosis: macrophages, apo B, and two different oxidation-specific epitopes (malondialdehyde- and 4-hydroxynonenal-lysine). Of the atherogenic sites that showed positive immunostaining for at least one of these markers, 58.6% were established lesions containing both macrophage/foam cells and oxidized LDL (OxLDL). 17.3% of all sites contained only native LDL, and 13.3% contained only OxLDL without monocyte/ macrophages. In contrast, only 4.3% of sites contained isolated monocytes in the absence of native or oxidized LDL. In addition, 6.3% of sites contained LDL and macrophages but few oxidation-specific epitopes. These results demonstrate that LDL oxidation and formation of fatty streaks occurs already during fetal development, and that both phenomena are greatly enhanced by maternal hypercholesterolemia. The fact that in very early lesions LDL and OxLDL are frequently found in the absence of monocyte/macrophages, whereas the opposite is rare, suggests that intimal LDL accumulation and oxidation contributes to monocyte recruitment in vivo.

Topics: Adult; Aldehydes; Aorta; Apolipoproteins B; Arteriosclerosis; Cholesterol; Female; Fetal Diseases; Humans; Hypercholesterolemia; Lipid Peroxidation; Lipoproteins; Macrophages; Malondialdehyde; Pregnancy; Pregnancy Complications, Hematologic