Role of nitric oxide in the remodelling of extracellular matrix in myxomatous mitral valve degeneration of dogs and pigs

Myxomatous mitral valve degeneration (MMVD) or endocardiosis is a heart valve disease that occurs in many mammalian species, especially in humans, dogs and pigs. Nitric oxide (NO) plays an important role in the MMVD development. NO can be indirectly evaluated by the nitric-oxide synthase (NOS) expression and by the histochemical reaction of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d). The aim of this study was to evaluate NOS activity, by NADPH-d reaction, in the anterior leaflet of dogs with regular mitral valves and in those with MMVD, as well as in young swine and old females, comparing the reaction level with the degree of endocardiosis disease and also the histological alterations. Twelve mitral valves of dogs and 22 of swine were used for the research. All the valves were macroscopically analyzed for the occurrence or not of endocardiosis. They were fixed in a 4% paraformaldehyde, exposed to NADPH-d reaction, routinely processed and microscopically evaluated for the detection of mucopolysaccharides (MPS) deposition, collagen degeneration, fibrosis and level of endocardiosis. In dogs, relation was observed between higher intensity of the NADPH-d reaction, higher endocardiosis degree, MPS deposition as well as the collagen degeneration. No alteration in color was observed in pigs ́ valves during NADPH-d reaction. In conclusion, NO works in canine mitral valve remodeling extracellular matrix and plays an important role in endocardiosis disease. In swine, the lack of reaction reinforces the absence of macroscopical endocardiosis lesions, suggesting restrict NO action or major differences in the structures of swine valves.

Involvement of N-methyl-d-aspartate glutamate receptor and nitric oxide in cardiovascular responses to dynamic exercise in rats

Dynamic exercise evokes sustained cardiovascular responses, which are characterized by arterial pressure and heart rate increases. Although it is well accepted that there is central nervous system mediation of cardiovascular adjustments during exercise, information on the role of neural pathways and signaling mechanisms is limited. It has been reported that glutamate, by acting on NMDA receptors, evokes the release of nitric oxide through activation of neuronal nitric oxide synthase (nNOS) in the brain. In the present study, we tested the hypothesis that NMDA receptors and nNOS are involved in cardiovascular responses evoked by an acute bout of exercise on a rodent treadmill. Moreover, we investigated possible central sites mediating control of responses to exercise through the NMDA receptor-nitric oxide pathway. Intraperitoneal administration of the selective NMDA glutamate receptor antagonist dizocilpine maleate (MK-801) reduced both the arterial pressure and heart rate increase evoked by dynamic exercise. Intraperitoneal treatment with the preferential nNOS inhibitor 7-nitroindazole reduced exercise-evoked tachycardiac response without affecting the pressor response. Moreover, treadmill running increased NO formation in the medial prefrontal cortex (MPFC), bed nucleus of the stria teminalis (BNST) and periaqueductal gray (PAG), and this effect was inhibited by systemic pretreatment with MK-801. Our findings demonstrate that NMDA receptors and nNOS mediate the tachycardiac response to dynamic exercise, possibly through an NMDA receptor-NO signaling mechanism. However, NMDA receptors, but not nNOS, mediate the exercise-evoked pressor response. The present results also provide evidence that MPFC, BNST and PAG may modulate physiological adjustments during dynamic exercise through NMDA receptor-NO signaling. © 2013 Elsevier B.V.

Defensive-like behaviors and antinociception induced by NMDA injection into the periaqueductal gray of mice depend on nitric oxide synthesis

Glutamate NMDA receptor activation within the periaqueductal gray (PAG) leads to antinociceptive, autonomic and behavioral responses characterized as the fear reaction. Considering that NMDA receptor triggers activation of neuronal nitric oxide synthase (nNOS), enzyme that produces nitric oxide (NO), this study investigated the effects of intra-PAG infusions of NPLA (N omega-propyl-L-arginine), an nNOS inhibitor, on behavioral and antinociceptive responses induced by local injection of NMDA receptor agonist in mice. The behaviors measured were frequency of jumping and rearing as well as duration (in seconds) of running and freezing. Nociception was assessed during the second phase of the formalin test (injection of 50 mu l of formalin 2.5% into the dorsal surface of the right hind paw). Five to seven days after stereotaxic surgery for intracerebral cannula implantation, mice were injected with formalin into the paw, and 10 min later, they received intra-dPAG injection of NPLA (0, 0.2, or 0.4 nmol/0.1 mu l). Ten minutes later, they were injected with NMDA (N-methyl-D-aspartate: 0 or 0.04 nmol/0.1 mu l) into the same midbrain site and were immediately placed in glass holding cage for recording the defensive behavior and the time spent on licking the injected paw with formalin during a period of 10 min. Microinjections of NMDA significantly decreased nociception response and produced jumping, running, and freezing reactions. Intra-dPAG injections of NPLA (0.4 nmol) completely blocked the NMDA effects without affecting either behavioral or nociceptive responses in intra-dPAG saline-injected animals, except for the rearing frequency that was increased by the nNOS inhibitor. These results strongly suggest the involvement of NO within the PAG in the antinociceptive and defensive reactions induced by local glutamate NMDA receptor activation in this midbrain structure. (c) 2006 Elsevier B.V. All rights reserved.

Role of glutamate NMDA receptors and nitric oxide located within the periaqueductal gray on defensive behaviors in mice confronted by predator

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Role of nitric oxide and beta-adrenoceptors of the central nervous system on the salivary flow induced by pilocarpine injection into the lateral ventricle

Our studies have focused on the effect of L-NG-nitroarginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase (NOS), and L-arginine, the substrate of NOS, on salivary secretion induced by the administration of pilocarpine into the lateral cerebral ventricle (LV) of rats. The present study has also investigated the role of the beta-adrenergic agonists and antagonist injected into LV on the salivary secretion elicited by the injection of pilocarpine into LV. Male Holtzmann rats with a stainless-steel cannula implanted into the LV were used. The amount of salivary secretion was studied over a 7-min period after injection of pilocarpine, isoproterenol, propranolol, salbutamol, salmeterol, L-NAME and L-arginine. The injection of pilocarpine (10, 20, 40, 80 and 160 mug/mul) into LV produced a dose-dependent increase in salivary secretion. The injection of L-NAME (40 mug/mul) into LV alone produced an increase in salivary secretion. The injection of L-NAME into LV previous to the injection of pilocarpine produced an increase in salivary secretion. L-Arginine (30 mug/mul) injected alone into LV produced no change in salivary secretion. L-Arginine injected into LV attenuated pilocarpine-induced salivary secretion. The isoproterenol (40 nmol/mul) injected into LV increased into LV increased the salivary secretion. When injected previous to pilocarpine at a dose of 20 and 40 mug/mul, isoproterenol produced and additive effect on pilocarpine-induced salivary secretion. The 40-nmol/mul dose of propranolol injected alone or previous to pilocarpine into LV attenuated the pilocarpine-induced salivary secretion. The injection of salbutamol (40 nmol/mul), a specific beta-2 agonist, injected alone into LV produced no change in salivary secretion and when injected previous to pilocarpine produced and increase in salivary secretion. The 40-nmol/mul dose of salmeterol, a long-acting beta-2 agonist, injected into LV alone or previous to pilocarpine produced no change in salivary secretion. The results have shown that central injections of L-NAME and L-arginine interfere with the salivary secretion, which implies that might participate in pilocarpine-induced salivary secretion. The interaction between cholinergic and beta-adrenergic receptors of the central nervous system (CNS) for the control of salivary secretion can also be postulated. (C) 2002 Elsevier B.V. All rights reserved.

Antihypertensive responses elicited by central moxonidine in rats: Possible role of nitric oxide

In the present study, we investigated the effects of pretreatment with N-G-nitro-L-arginine methyl ester (L-NAME) (nitric oxide synthase inhibitor) injected intravenously (IV) on the hypotension, bradycardia, and vasodilation produced by moxonidine (alpha(2)-adrenergic/imidazoline receptor agonist) injected into the fourth brain ventricle (4th V) in rats submitted to acute hypertension that results from baroreflex blockade by bilateral injections of kynurenic acid (kyn, glutamatergic receptor antagonist) into the nucleus of the solitary tract (NTS) or in normotensive rats. Male Wistar rats (n = 5 to 7/group) anesthetized with IV urethane (1.0 g kg(-1) of body weight) and a-chloralose (60mg kg(-1) of body weight) were used. Bilateral injections of kyn (2.7 nmol 100 nL(-1)) into the NTS increased baseline mean arterial pressure (148 +/- 11 mm Hg, vs. control: 102 +/- 4mm Hg) and baseline heart rate (417 +/- 11 bpm, vs. control: 379 +/- 6 bpm). Moxonidine (20 nmol mu L-1) into the 4th V reduced mean arterial pressure and heart rate to similar levels in rats treated with kyn into the NTS (68 +/- 9 mm Hg and 359 +/- 7 bpm) or in control normotensive rats (66 +/- 7 mm Hg and 362 +/- 8 bpm, respectively). The pretreatment with L-NAME (2 5 mu mol kg-1, IV) attenuated the hypotension produced by moxonidine into the 4th V in rats treated with kyn (104 +/- 6 mm Hg) or in normotensive rats (95 +/- 8 mm Hg), without changing bradycardia. Moxonidine into the 4th V also reduced renal, mesenteric, and hindquarter vascular resistances in rats treated or not with kyn into the NTS and the pretreatment with L-NAME IV reduced these effects of moxonidine. Therefore, these data indicate that nitric oxide mechanisms are involved in hypotension and mesenteric, renal, and hindquarter vasodilation induced by central moxonidine in normotensive and in acute hypertensive rats.

Nitric oxide of the supraoptic nucleus influences the salivary secretion, sodium renal excretion, urinary volume and arterial blood pressure induced by pilocarpine

Male Holtzman rats weighting 200-250 g were anesthetized with zoletil 50 mg/Kg (tiletamine chloridrate 125.0 mg and zolazepan chloridrate 125.0 mg) into quadriceps muscle and stainless steel cannulas were implanted into their supraoptic nucleus (SON). We investigated the effects of the injection into the supraoptic nucleus (SON) of FK 409, a nitric oxide donor, and N(W-)nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor (NOS), on the salivary secretion, arterial blood pressure, sodium excretion and urinary volume induced by pilocarpine, which was injected into SON. The drugs were injected in 0.5 mul volume over 30-60 s. Controls was injected with a similar volume of 0.15 M NaCl. FK 409 and L-NAME were injected at doses of 20 mug/0.5 mul and 40 mug/0.5 mul. respectively. The amount of saliva secretion was studied over a five-minute period after injection of pilocarpine into SON. Injection of pilocarpine (10, 20, 40, 80, 160 mug/mul) into SON produced a dose-dependent increase in salivary secretion. L-NAME was injected into SON prior to the injection of pilocarpine into SON, producing an increase in salivary secretion due to the effect of pilocarpine. FK 409 injected into SON attenuating the increase in salivary secretion induced by pilocarpine. Mean arterial pressure (MAP) increase after injections of pilocarpine into the SON. L-NAME injected into the SON prior to injection of pilocarpine into SON increased the MAP. FK 409 injected into the SON prior to pilocarpine attenuated the effect of pilocarpine on MAP. Pilocarpine (0.5 mumol/0.5 mul) injected into the SON induced an increase in sodium and urinary excretion. L-NAME injected prior to pilocarpine into the SON increased the urinary sodium excretion and urinary volume induced by pilocarpine. FK 409 injected prior to pilocarpine into the SON decreased the sodium excretion and urinary volume induced by pilocarpine. All these roles of pilocarpine depend on the release of nitric oxide into the SON. In summary the present results show: a) SON is involved in pilocarpine-induced salivation; b) that mechanism involves increase in MAP, sodium excretion and urinary volume. (C) 2003 Elsevier B.V. All rights reserved.

Nitric oxide and L-type calcium channel influences the changes in arterial blood pressure and heart rate induced by central angiotesin II

We study the voltage dependent calcium channels and nitric oxide involvement in angiotensin II-induced pressor effect. The antipressor action of L-Type calcium channel antagonist, nifedipine, has been studied when it was injected into the third ventricle prior to angiotensin II. The influence of nitric oxide on nifedipine antipressor action has also been studied by utilizing N(W)-nitro-L-arginine methyl ester (LNAME) (40 mu g/0.2 mu l) a nitric oxide synthase inhibitor and L-arginine ( 20 mu g/0.2 mu l), a nitric oxide donor agent. Adult male Holtzman rats weighting 200-250 g, with cannulae implanted into the third ventricle were injected with angiotensin II. Angiotensin II produced an elevation in mean arterial pressure and a decreased in heart rate. Such effects were potentiated by the prior injection of LNAME. L-arginine and nifedipine blocked the effects of angiotensin II. These data showed the involvement of L-Type calcium channel and a free radical gas nitric oxide in the central control of angiotensin II-induced pressor effect. This suggested that L-Type calcium channel of the circunventricular structures of central nervous system participated in both short and long term neuronal actions of ANG II with the influence of nitrergic system.

Gastroprotective Effect of Serjania erecta Radlk (Sapindaceae): Involvement of Sensory Neurons, Endogenous Nonprotein Sulfhydryls, and Nitric Oxide

The present study reveals the pharmacological action of Serjania erecta Radlk. (Family Sapindaceae), an important medicinal plant species used in the Brazilian Pantanal against gastric pain. The methanolic (Me) and chloroformic (Se) extracts obtained from leaves of S. erecta were challenged by a very strong necrotizing agent in rodents, absolute ethanol. Se was also confronted with a nitric oxide synthase inhibitor (N(G)-nitro-l-arginine methyl ester), a capsaicin cation channel transient receptor potential vanilloid type 1 antagonist (ruthenium red), or a sulfhydryl-blocker (N-ethylmaleimide) to evaluate the participation of these cytoprotective factors in gastroprotection. In an in vivo experimental model, Me and Se presented several degrees of gastroprotective action without signs of acute toxicity. The best gastroprotective effect was restricted to all doses of Se. The mechanisms involving the gastroprotective action of Se are related to an augmented defense mechanism of the gastrointestinal mucosa consisting of sensory neurons, nitric oxide, and sulfhydryl groups that prevent and attenuate the ulcer process. The presence of polyisoprenoids in the Se explains the potent gastroprotective action of this medicinal species. Effective gastroprotective action and the absence of acute toxicity indicate this species may be a promising herbal drug against gastric disease.

Involvement of Glutathione, Sulfhydryl Compounds, Nitric Oxide, Vasoactive Intestinal Peptide, and Heat-Shock Protein-70 in the Gastroprotective Mechanism of Croton cajucara Benth. (Euphorbiaceae) Essential Oil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Nitric oxide in plants: a brief discussion on this multifunctional molecule

Diversos estudos vêm sendo realizados com a finalidade de aumentar o conhecimento sobre a ocorrência e a atividade do óxido nítrico (ON) nas plantas. Nesse sentido, a presente revisão objetivou abordar alguns aspectos referentes ao on nas plantas, tais como propriedades químicas, vias de síntese, efeitos fisiológicos, ação antioxidante, transdução do sinal, interação com hormônios vegetais e expressão gênica. Nos últimos anos, muitos avanços têm sido obtidos em relação à síntese de on e seus efeitos fisiológicos nas plantas. Porém, os mecanismos moleculares que fundamentam seus efeitos permanecem pouco compreendidos. É sinalizada uma investigação em detalhes sobre as estreitas interações entre ON, Ca2+, ADP-ribose cíclica (cADPR) e proteínas quinases. Além disso, ainda não foi possível identificar uma enzima vegetal que apresente atividade semelhante à da óxido nítrico sintase (NOS). A elucidação de tais aspectos representa um desafio para futuros trabalhos.

The role of nitric oxide in regulation of the cardiovascular system in reptiles

The roles that nitric oxide (NO) plays in the cardiovascular system of reptiles are reviewed, with particular emphasis on its effects on central vascular blood flows in the systemic and pulmonary circulations. New data is presented that describes the effects on hemodynamic variables in varanid lizards of exogenously administered NO via the nitric oxide donor sodium nitroprusside (SNP) and, preliminary data on the effects of SNP inhibition of nitric oxide synthase (NOS) by L-nitroarginine methyl ester (L-NAME). Furthermore. on hemodynamic variables in the tegu lizard are presented. The findings are compared with previously published data from Our laboratory on three other species of reptiles: pythons (Skovgaard, N., Galli, G., Taylor, E.W., Conlon, J.M., Wang.. T., 2005. Hemodynamic effects of python neuropeptide gamma in the anesthetized python, Python regius. Regul. Pept. 18, 15-26), rattlesnakes (Galli, G., Skovgaard, N., Abe, A.S., Taylor, E.W., Wang, T., 2005. The role of nitric oxide in the regulation of the systemic and the pulmonary vasculature of the rattlesnake, Crotalus durissus terrificus. J. Comp. Physiol. 175B, 201-208) and turtles (Crossley, D.A., Wang, T., Altimiras, J., 2000. Role of nitric oxide in the systemic and pulmonary circulation of anesthetized turtles (Trachemys scripta). J. Exp. Zool. 286, 683-689). These five species of reptiles possess different combinations of division of the heart and structural complexity of the lungs. Comparison of their responses to NO donors and NOS inhibitors may reveal whether the potential contribution of NO to vascular tone correlates with pulmonary complexity and/or with blood pressure. All existing studies oil reptiles have clearly established a potential role for NO in regulating vascular tone in the systemic circulation and NO may be important for maintaining basal systemic vascular tone in varanid lizards, pythons and turtles, through a continuous release of NO. In contrast., the pulmonary circulation is less responsive to NO donors or NOS inhibitors, and it was only in pythons and varanid lizards that the lungs responded to SNP. Both species have a functionally separated heart, so it is possible that NO may exert a larger role in species with low pulmonary blood pressures, irrespective of lung complexity. (C) 2005 Elsevier B.V. All rights reserved.

Myenteric denervation in gastric carcinogenesis: Differential modulation of nitric oxide and annexin-A1

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of nitric oxide synthesis inhibitor or fluoxetine treatment on depression-like state and cardiovascular changes induced by chronic variable stress in rats

Comorbidity between mood disorders and cardiovascular disease has been described extensively. However, available antidepressants can have cardiovascular side effects. Treatment with selective inhibitors of neuronal nitric oxide synthase (nNOS) induces antidepressant effects, but whether the antidepressant-like effects of these drugs are followed by cardiovascular changes has not been previously investigated. Here, we tested in male rats exposed to chronic variable stress (CVS) the hypothesis that nNOS blockers are advantageous compared with conventional antidepressants in terms of cardiovascular side effects. We compared the effects of chronic treatment with the preferential nNOS inhibitor 7-nitroindazole (7-NI) with those evoked by the conventional antidepressant fluoxetine on alterations that are considered as markers of depression (immobility in the forced swimming test, FST, decreased body weight gain and increased plasma corticosterone concentration) and cardiovascular changes caused by CVS. Rats were exposed to a 14-day CVS protocol, while being concurrently treated daily with either 7-NI (30 mg/kg) or fluoxetine (10 mg/kg). Fluoxetine and 7-NI prevented the increase in immobility in the FST induced by CVS and reduced plasma corticosterone concentration in stressed rats. Both these treatments also prevented the CVS-evoked reduction of the depressor response to vasodilator agents and baroreflex changes. Fluoxetine and 7-NI-induced cardiovascular changes independent of stress exposure, including cardiac autonomic imbalance, increased intrinsic heart rate and vascular sympathetic modulation, a reduction of the pressor response to vasoconstrictor agents, and impairment of baroreflex activity. Altogether, these findings provide evidence that fluoxetine and 7-NI have similar effects on the depression-like state induced by CVS and on cardiovascular function.

Role of brain nitric oxide in the thermoregulation of broiler chicks

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)