NONO2P, a novel nitric oxide donor, causes vasorelaxation through NO/sGC/PKG pathway, K+ channels opening and SERCA activation.

BACKGROUND & AIMS: The treatment of cardiovascular diseases (CVD) could greatly benefit from using nitric oxide (NO) donors. This study aimed to investigate the mechanisms of action of NONO2P that contribute to the observed responses in the mesenteric artery. The hypothesis was that NONO2P would have similar pharmacological actions to sodium nitroprusside (SNP) and NO. METHODS: Male Wistar rats were euthanized to isolate the superior mesenteric artery for isometric tension recordings. NO levels were measured using the DAF-FM/DA dye, and cyclic guanosine monophosphate (cGMP) levels were determined using a cGMP-ELISA Kit. RESULTS: NONO2P presented a similar maximum efficacy to SNP. The free radical of NO (NO•) scavengers (PTIO; 100 µM and hydroxocobalamin; 30 µM) and nitroxyl anion (NO-) scavenger (L-cysteine; 3 mM) decreased relaxations promoted by NONO2P. The presence of the specific soluble guanylyl cyclase (sGC) inhibitor (ODQ; 10 µM) nearly abolished the vasorelaxation. The cGMP-dependent protein kinase (PKG) inhibition (KT5823; 1 µM) attenuated the NONO2P relaxant effect. The vasorelaxant response was significantly attenuated by blocking inward rectifying K+ channels (Kir), voltage-operated K+ channels (KV), and large conductance Ca2+-activated K+ channels (BKCa). NONO2P-induced relaxation was attenuated by cyclopiazonic acid (10 µM), indicating that sarcoplasmic reticulum Ca2+-ATPase (SERCA) activation is involved in this relaxation. Moreover, NONO2P increased NO levels in endothelial cells and cGMP production. CONCLUSIONS: NONO2P induces vasorelaxation with the same magnitude as SNP, releasing NO• and NO-. Its vasorelaxant effect involves sGC, PKG, K+ channels opening, and SERCA activation, suggesting its potential as a therapeutic option for CVD.

Ru(II) based dual nitric oxide donors: electrochemical and photochemical reactivities and vasorelaxant effect with no cytotoxicity.

The synthesized complexes, cis-[Ru(NO)(NO2)(phen)2](PF6)2 (NONO2P) and cis-[Ru(NO)(NO2)(bpy)2](PF6)2 (NONO2B), were characterized by using elemental analysis, voltammetry and electronic and vibrational spectroscopy. Under electrochemical and photochemical stimulation in an aqueous medium, there are indications of the formation of complexes, which suggests that the nitro and nitrosyl groups are converted into nitric oxide. Both compounds do not show cytotoxic activity against human umbilical vein endothelial cells (HUVECs). The cis-[Ru(NO)(NO2)(phen)2](PF6)2 complex presented vasorelaxation activity in superior mesenteric arteries from Wistar rats: the biphasic concentration-response curve indicates two sites of action. In the presence of NO scavengers, we observed an impaired relaxing effect induced by NONO2P, suggesting that the vasorelaxant effect is due to NO production from this compound.

Thiocarbonyl-bound metallonitrosyl complexes with visible-light induced DNA cleavage and promising vasodilation activity.

Nitric oxide has been involved in many key biological processes such as vasodilation, platelet aggregation, apoptosis, memory function, and this has drawn attention to the development of exogenous NO donors. Metallonitrosyl complexes are an important class of these compounds. Here, two new ruthenium nitrosyl complexes containing a thiocarbonyl ligand, with the formula cis-[Ru(phen)2(L)(NO)](PF6)3 (phen = phenantroline, L = thiourea or thiobenzamide), were synthesized and characterized by electronic spectroscopy, FTIR, NMR, mass spectrometry and voltammetric techniques. Theoretical calculations using Density Functional Theory (DFT) and Time-dependent Density Functional Theory (TD-DFT) were also used and further supported the characterizations of these complexes. An efficient release of nitric oxide by blue light was validated using a NO/HNO probe: 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, known as cPTIO. Interestingly, the complex containing thiourea cleaved DNA even in the dark, while both complexes showed great DNA photocleavage activity in blue light. This process might work mainly through NO and hydroxyl radical production. Additionally, these complexes showed promising vasodilator activity, whose mechanism of action was investigated using N-Nitro-l-arginine methyl ester hydrochloride (L-NAME) and 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) and compared to sodium nitroprusside. Both compounds were indeed NO-mediated heme-dependent activators of soluble guanylate cyclase. Additionally, they did not show any significant cytotoxicity against cancer cell lines U87 and GBM02. Altogether, these results supported both complexes having potential pharmacological applications that deserve further studies.

Methamphetamine Induces Anhedonic-Like Behavior and Impairs Frontal Cortical Energetics in Mice.

INTRODUCTION: We recently showed that a single high dose of methamphetamine (METH) induces a persistent frontal cortical monoamine depletion that is accompanied by helpless-like behavior in mice. However, brain metabolic alterations underlying both neurochemical and mood alterations remain unknown. AIMS: Herein, we aimed at characterizing frontal cortical metabolic alterations associated with early negative mood behavior triggered by METH. Adult C57BL/6 mice were injected with METH (30 mg/kg, i.p.), and their frontal cortical metabolic status was characterized after probing their mood and anxiety-related phenotypes 3 days postinjection. RESULTS: Methamphetamine induced depressive-like behavior, as indicated by the decreased grooming time in the splash test and by a transient decrease in sucrose preference. At this time, METH did not alter anxiety-like behavior or motor functions. Depolarization-induced glucose uptake was reduced in frontocortical slices from METH-treated mice compared to controls. Consistently, astrocytic glucose transporter (GluT1) density was lower in the METH group. A proton high rotation magic angle spinning (HRMAS) spectroscopic approach revealed that METH induced a significant decrease in N-acetyl aspartate (NAA) and glutamate levels, suggesting that METH decreased neuronal glutamatergic function in frontal cortex. CONCLUSIONS: We report, for the first time, that a single METH injection triggers early self-care and hedonic deficits and impairs frontal cortical energetics in mice.

Non-nitric oxide based metallovasodilators: synthesis, reactivity and biological studies.

There is an increasing number of compounds developed to target one or more pathways involved in vasodilation. Some studies conducted with azaindole and indazole derivatives showed cardiovascular activity associated with these compounds. Fast and easy structural modification of these organic molecules can be achieved using metal complexes promoting a much larger spatial change than organic strategies, potentially leading to novel drugs. Here, we have prepared a series of complexes with a formula cis-[RuCl(L)(bpy)(2)]PF(6), where L = 7-azaindole (ain), 5-azaindole (5-ain), 4-azaindole (4-ain), indazole (indz), benzimidazole (bzim) or quinoline (qui), which were characterized by spectroscopic and electrochemical techniques (CV, DPV). These compounds showed reasonable stability exhibiting photoreactivity only at low wavelength along with superoxide scavenger activity. Cytotoxicity assays indicated their low activity preliminarily supporting in vivo application. Interestingly, vasodilation assays conducted in rat aorta exhibited great activity that largely improved compared to free ligands and even better than the well-studied organic compound (BAY 41-42272), with IC(50) reaching 55 nM. These results have validated this strategy opening new opportunities to further develop cardiovascular agents based on metallo-bicyclic rings.

A single neurotoxic dose of methamphetamine induces a long-lasting depressive-like behaviour in mice.

Methamphetamine (METH) triggers a disruption of the monoaminergic system and METH abuse leads to negative emotional states including depressive symptoms during drug withdrawal. However, it is currently unknown if the acute toxic dosage of METH also causes a long-lasting depressive phenotype and persistent monoaminergic deficits. Thus, we now assessed the depressive-like behaviour in mice at early and long-term periods following a single high METH dose (30 mg/kg, i.p.). METH did not alter the motor function and procedural memory of mice as assessed by swimming speed and escape latency to find the platform in a cued version of the water maze task. However, METH significantly increased the immobility time in the tail suspension test at 3 and 49 days post-administration. This depressive-like profile induced by METH was accompanied by a marked depletion of frontostriatal dopaminergic and serotonergic neurotransmission, indicated by a reduction in the levels of dopamine, DOPAC and HVA, tyrosine hydroxylase and serotonin, observed at both 3 and 49 days post-administration. In parallel, another neurochemical feature of depression--astroglial dysfunction--was unaffected in the cortex and the striatal levels of the astrocytic protein marker, glial fibrillary acidic protein, were only transiently increased at 3 days. These findings demonstrate for the first time that a single high dose of METH induces long-lasting depressive-like behaviour in mice associated with a persistent disruption of frontostriatal dopaminergic and serotonergic homoeostasis.

Detection and quantification of Leptospira interrogans in hamster and rat kidney samples: immunofluorescent imprints versus real-time PCR.

A major limitation in the clinical management and experimental research of leptospirosis is the poor performance of the available methods for the direct detection of leptospires. In this study, we compared real-time PCR (qPCR), targeting the lipL32 gene, with the immunofluorescent imprint method (IM) for the detection and quantification of leptospires in kidney samples from the rat and hamster experimental models of leptospirosis. Using a virulent strain of Leptospira interrogans serovar Copenhageni, a chronic infection was established in the rat model, which were euthanized 28 days post-infection, while the hamster model simulated an acute infection and the hamsters were euthanized eight days after inoculation. Leptospires in the kidney samples were detected using culture isolation, qPCR and the IM, and quantified using qPCR and the IM. In both the acute and chronic infection models, the correlation between quantification by qPCR and the IM was found to be positive and statistically significant (P<0.05). Therefore, this study demonstrates that the IM is a viable alternative for not only the detection but also the quantification of leptospires, particularly when the use of qPCR is not feasible.