Nitric oxide-donating atorvastatin attenuates neutrophil recruitment during vascular inflammation independent of changes in plasma cholesterol.

PURPOSE: Polymorphonuclear neutrophils, the first leukocytes to infiltrate the inflamed tissue, can make important contributions to vascular inflammatory processes driving the development of atherosclerosis. We herein investigated the effects of atorvastatin and NCX 6560 (a nitric oxide (NO)-donating atorvastatin derivative that has completed a successful phase 1b study) on neutrophilic inflammation in carotid arteries of normocholesterolemic rabbits subjected to perivascular collar placement. METHODS: Atorvastatin or NCX 6560 were administered orally (5 mg/kg/day or equimolar dose) to New Zealand White rabbits for 6 days, followed by collar implantation 1 h after the last dose. Twenty-four hours later carotids were harvested for neutrophil quantification by immunostaining. RESULTS: Treatment with NCX 6560 was associated with a lower neutrophil infiltration (-39.5 %), while atorvastatin did not affect neutrophil content. The result was independent of effects on plasma cholesterol or differences in atorvastatin bioavailability, which suggests an important role of NO-related mechanisms in mediating this effect. Consistent with these in vivo findings, in vitro studies showed that NCX 6560, as compared to atorvastatin, had greater inhibitory activity on processes involved in neutrophil recruitment, such as migration in response to IL-8 and IL-8 release by endothelial cells and by neutrophils themselves. Pretreatment with NCX 6560, but not with atorvastatin, reduced the ability of neutrophil supernatants to promote monocyte chemotaxis, a well-known pro-inflammatory activity of neutrophils. CONCLUSION: Experimental data suggest a potential role of NO-releasing statins in the control of the vascular inflammatory process mediated by polymorphonuclear neutrophils.

Transgenic expression and activation of PGC-1α protect dopaminergic neurons in the MPTP mouse model of Parkinson's disease.

Mitochondrial dysfunction and oxidative stress occur in Parkinson's disease (PD), but little is known about the molecular mechanisms controlling these events. Peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) is a transcriptional coactivator that is a master regulator of oxidative stress and mitochondrial metabolism. We show here that transgenic mice overexpressing PGC-1α in dopaminergic neurons are resistant against cell degeneration induced by the neurotoxin MPTP. The increase in neuronal viability was accompanied by elevated levels of mitochondrial antioxidants SOD2 and Trx2 in the substantia nigra of transgenic mice. PGC-1α overexpression also protected against MPTP-induced striatal loss of dopamine, and mitochondria from PGC-1α transgenic mice showed an increased respiratory control ratio compared with wild-type animals. To modulate PGC-1α, we employed the small molecular compound, resveratrol (RSV) that protected dopaminergic neurons against the MPTP-induced cell degeneration almost to the same extent as after PGC-1α overexpression. As studied in vitro, RSV activated PGC-1α in dopaminergic SN4741 cells via the deacetylase SIRT1, and enhanced PGC-1α gene transcription with increases in SOD2 and Trx2. Taken together, the results reveal an important function of PGC-1α in dopaminergic neurons to combat oxidative stress and increase neuronal viability. RSV and other compounds acting via SIRT1/PGC-1α may prove useful as neuroprotective agents in PD and possibly in other neurological disorders.

Nicotine-induced fibroblast growth factor-2 restores the age-related decline of precursor cell proliferation in the subventricular zone of rat brain.

Precursor cell proliferation is present in the subventricular zone (SVZ) of the lateral ventricles and the subgranular zone (SGZ) of the dentate gyrus of the hippocampus of adult rat and persists during aging although at reduced levels. Previous studies have shown that acute intermittent nicotine treatment significantly increases fibroblast growth factor-2 (FGF-2) expression in several brain regions of aged rats. The aim of the present investigation was to test the hypothesis that nicotine-induced expression of FGF-2 may restore the age-related decline of precursor cell proliferation. It was first demonstrated that nicotine treatment increases both mRNA and protein FGF-2 in the SVZ of aged male rats (18 months old). The effect of nicotine on precursor cell proliferation in the SVZ was studied by i.p. injection of 5-bromo-2'-deoxyuridine (BrdU) 40 mg/kg to label dividing cells. The nicotine treatment was found to significantly enhance precursor cell proliferation in the SVZ. This increase was sufficiently large to restore the age-related decline of proliferating precursor cells observed in aged rats to that found in young adult rats (3 months old). FGF-2 was expressed in GFAP-positive cells and may act via its receptor FGFR1 that was found expressed in nestin-positive cells of the SVZ. The data obtained demonstrated that the age-related decline of precursor cell proliferation may be counteracted by activating a trophic mechanism mediated by FGF-2.

Fibroblast growth factor-2 and its receptor expression in proliferating precursor cells of the subventricular zone in the adult rat brain.

Several findings have suggested the existence in the subventricular zone (SVZ) from sagittal sections of adult rat brain of a trophic mechanism, mediated by fibroblast growth factor-2 (FGF-2) and its multiple high-affinity FGF receptors (FGFRs), regulating neurogenesis mainly by controlling precursor cell proliferation. However, no clear data are available on the expression of FGF-2 and FGFRs in proliferating precursor cells of the SVZ. To address these questions we examined FGF-2 mRNA and its FGFR mRNA expression in proliferating precursor cells of the SVZ by using a double labeling procedure, combining in situ hybridization for FGF-2 and its FGFR mRNA with immunohistochemistry for bromodeoxyuridine (BrdU), a marker for proliferating cells. The results showed that FGFR1 and FGFR2 mRNAs were expressed in BrdU-labeled proliferating precursor cells, whereas FGFR3 and FGF-2 mRNAs were not, suggesting that in the SVZ the proliferating precursor cells express FGFR1 or FGFR2 and they may respond to FGF-2 released by non-proliferating cells. The FGFR4 mRNA was not found expressed in the SVZ. In the future, by identifying the cell types expressing FGFRs, it will be possible to gain insight into the functional activity of FGF2 within the SVZ.

Resveratrol reduces oxidative stress and cell death and increases mitochondrial antioxidants and XIAP in PC6.3-cells.

Resveratrol, a polyphenol derived e.g. from red grapes, has been shown to mediate several positive biological actions such as protection of cells against oxidative stress. It can also influence cell signaling, but the mechanisms behind its antioxidant properties are largely unknown. Here we show that RSV reduces oxidative stress and enhances cell survival in PC6.3 cells depending on the concentration. In these cells, RSV increased the levels of antioxidants, SOD2 and TRX2, and of X chromosome-linked inhibitor of apoptosis protein. RSV also activated NFκB signaling as shown using luciferase reporter constructs. These findings show that RSV regulates oxidative stress and mitochondrial antioxidants in neuronal cells. This may contribute to cell protection in various brain disorders.

A1 receptors mediate adenosine inhibitory effects in mouse ileum via activation of potassium channels.

AIMS: We investigated the effects induced by exogenous adenosine on the spontaneous contractile activity of the longitudinal muscle of a mouse ileum, the receptor subtypes activated, the involvement of enteric nerves and whether opening of K+ channels was a downstream event leading to the observed effects. MAIN METHODS: Mechanical responses of the mouse ileal longitudinal muscle to adenosine were examined in vitro as changes in isometric tension. KEY FINDINGS: Adenosine caused a concentration-dependent reduction of the spontaneous contraction amplitude of the ileal longitudinal muscle up to its complete disappearance. This effect induced was markedly reduced by an A1 receptor antagonist, but not by A2 and A3 receptor antagonists and mimicked only by the A1 receptor agonist. Adenosine uptake inhibitors did not change adenosine potency. A1 receptor expression was detected at the smooth muscle level. Adenosine responses were insensitive to tetrodotoxin, atropine or nitric oxide synthase inhibitor. Tetraethylammonium and iberiotoxin, BK(Ca) channel blockers, significantly reduced adenosine effects, whilst 4-aminopyridine, a K(v) blocker, apamin, a small conductance Ca2+-activated K+ (SK(Ca)) channel blocker, charybdotoxin, an intermediate conductance Ca2+-activated K+ (IK(Ca)) and BK(Ca) channel blocker, or glibenclamide, an ATP-sensitive K+ channel blocker, had no effects. The combination of apamin plus iberiotoxin caused a reduction of the purinergic effects greater than iberiotoxin alone. SIGNIFICANCE: Adenosine acts as an inhibitory modulator of the contractility of mouse ileal longitudinal muscle through postjunctional A1 receptors, which in turn would induce opening of BK(Ca) and SK(Ca) potassium channels. This study would provide new insight in the pharmacology of purinergic receptors involved in the modulation of the gastrointestinal contractility.