Coenzyme Q10 prevents high glucose-induced oxidative stress in human umbilical vein endothelial cells.

Hyperglycemia-induced oxidative stress plays a crucial role in the pathogenesis of vascular complications in diabetes. Although some clinical evidences suggest the use of an antioxidant reagent coenzyme Q10 in diabetes with hypertension, the direct effect of coenzyme Q10 on the endothelial functions has not been examined. In the present study, we therefore investigated the protective effect of coenzyme Q10 against high glucose-induced oxidative stress in human umbilical vein endothelial cells (HUVEC). HUVEC exposed to high glucose (30 mM) exhibited abnormal properties, including the morphological and biochemical features of apoptosis, overproduction of reactive oxygen species, activation of protein kinase Cbeta2, and increase in endothelial nitric oxide synthase expression. Treatment with coenzyme Q10 strongly inhibited these changes in HUVEC under high glucose condition. In addition, coenzyme Q10 inhibited high glucose-induced cleavage of poly(ADP-ribose) polymerase, an endogenous caspase-3 substrate. These results suggest that coenzyme Q10 prevents reactive oxygen species-induced apoptosis through inhibition of the mitochondria-dependent caspase-3 pathway. Moreover, consistent with previous reports, high glucose caused upregulation of intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) in HUVEC, and promoted the adhesion of U937 monocytic cells. Coenzyme Q10 displayed potent inhibitory effects against these endothelial abnormalities. Thus, we provide the first evidence that coenzyme Q10 has a beneficial effect in protecting against the endothelial dysfunction by high glucose-induced oxidative stress in vitro.

Antiangiogenic activity of beta-eudesmol in vitro and in vivo.

Abnormal angiogenesis is implicated in various diseases including cancer and diabetic retinopathy. In this study, we examined the effect of beta-eudesmol, a sesquiterpenoid alcohol isolated from Atractylodes lancea rhizome, on angiogenesis in vitro and in vivo. Proliferation of porcine brain microvascular endothelial cells and human umbilical vein endothelial cells (HUVEC) was inhibited by beta-eudesmol (50-100 microM). It also inhibited the HUVEC migration stimulated by basic fibroblast growth factor (bFGF) and the tube formation by HUVEC in Matrigel. beta-eudesmol (100 microM) blocked the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 induced by bFGF or vascular endothelial growth factor. Furthermore, beta-eudesmol significantly inhibited angiogenesis in subcutaneously implanted Matrigel plugs in mice and in adjuvant-induced granuloma in mice. These results indicate that beta-eudesmol inhibits angiogenesis, at least in part, through the blockade of the ERK signaling pathway. We considered that beta-eudesmol may aid the development of drugs to treat angiogenic diseases.

Nicotinic enhancement of proliferation in bovine and porcine cerebral microvascular endothelial cells.

Nicotinic acetylcholine receptors are found in microvascular endothelial cells. To reveal the functional role in cerebral angiogenic processes, we studied the nicotinic modulation of proliferation activity in cultured bovine and porcine cerebral microvascular endothelial cells. The proliferation activity was determined by an increase in the number of cells present in culture dishes. When the bovine cerebral endothelial cells at different passages were cultured in the presence of nicotine (10 nM), the proliferation activities were significantly increased in the cells at passage 1 and passage 3, but not at passage 4. Reverse transcriptase-polymerase chain reaction studies demonstrated that the expression of mRNAs coding for alpha3 nicotinic receptor subunit was significantly reduced in the bovine cerebral endothelial cells at passage 4, compared with that at passage 1. The proliferation of porcine cerebral endothelial cells (passage 1) was enhanced by acetylcholine (10 nM-100 microM) in the presence of atropine, a muscarinic antagonist, and this enhancing effect was inhibited by hexamethonium (100 microM, a nicotinic antagonist). The stimulation by acetylcholine (1 microM, with atropine) or nicotine (10 nM) induced the phosphorylation of a mitogen-activated protein (MAP) kinase (extracellular-signal regulated kinase: ERK) in the serum-starved endothelial cells. In the presence of PD98059 (2 microM, a MAP kinase kinase inhibitor) and atropine, acetylcholine (1 microM) failed to enhance the proliferation of porcine cerebral endothelial cells. These results demonstrate that nicotinic stimulation promotes the proliferation of bovine and porcine cerebral microvascular endothelial cells, at least in part, through the MAP kinase activation.