L-Type calcium channels mediate water intake induced by angiotensin injection into median preoptic nucleus

Calcium ions are widely accepted as critically important in responses of neurons to a stimulus. We have show previously the central involvement of angiotensin II (ANGII) in water intake. This study determined whether voltage-dependent calcium channels are involved in ANGII-induced behavioral drinking implicating nitrergic mechanism. The antidipsogenic actions of L-type calcium channel antagonists nifedipine, on ANGII-induced drinking behavior were studied when it is injected into the median preoptic nucleus (MnPO). The influence of nitric oxide (NO) on nifedipine antidipsogenic action was also studied by utilizing the N-W-nitro-L-arginine methyl ester (L-NAME) a constitutive nitric oxide synthase inhibitor constitutive (cNOSI) and 7-nitroindazol (7-NIT) a specific neuronal nitric oxide synthase inhibitor (nNOSI) and L-arginine a NO donor. Rats 200-250 g, with cannulae implanted into MnPO, pre-treated into MnPO with either nifedipine, followed by ANGII, drank significantly less water than controls during the first 15 min after injection. However, L-NAME potentiated the dipsogenic effect of ANGII that is blocked by prior injection of nifedipine and L-arginine. 7-NIT injected prior to ANGII into MnPO also potentiated the dipsogenic effect of ANGII but with a less intensity than L-NAME that it is also blocked by prior injection of nifedipine. The results described in this paper provide evidence that calcium channels play important roles in the ANGII-induced behavioral water intake. The structures containing NO in the brain such as MnPO include both endothelial cells and neurons might be responsible for the influence of nifedipine on dipsogenic effect of ANGII. These data shows the correlation between L-type calcium channel and a free radical gas NO produced endogenously from amino acids L-arginine by endothelial and neuronal NO synthase in the control of ANGII-dipsogenic effect. This suggests that an L-type calcium channel participates in both short- and longer-term neuronal actions of ANGII by nitrergic way. (c) 2006 Elsevier B.V. All rights reserved.

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.

Lateral hypothalamus lesions influences water and salt intake, and sodium and urine excretion, and arterial blood pressure induced by L-NAME and FK 409 injections into median preoptic nucleus in conscious rats

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 submitted an electrolytic lesion of the lateral hypothalamus (LH) and a stainless steel cannula was implanted into their median preoptic nucleus (MnPO). We investigated the effects of the injection into the (MnPO) of FK 409 (20 mug/0.5 mul), a nitric oxide (NO) donor, and N-W-nitro-L-arginine methyl ester (L-NAME) 40 mug/0.5 mul, a nitric oxide synthase inhibitor (NOSI), on the water and sodium appetite and the natriuretic, diuretic and cardiovascular effects induced by injection of L-NAME and FK 409 injected into MnPO in rats with LH lesions. Controls were injected with a similar volume of 0.15 M NaCl. L-NAME injected into MnPO produced an increase in water and sodium intake and in sodium and urine excretion and increase de mean arterial pressure (MAP). FK 409 injected into MnPO did not produce any change in the hydro electrolytic and cardiovascular parameters in LH-sham and lesioned rats. FK 409 injected before L-NAME attenuated its effects. These data show that electrolytic lesion of the LH reduces fluid and sodium intake as well as sodium and urine excretion, and the pressor effect induced by L-NAME. LH involvement with NO of the MnPO excitatory and inhibitory mechanisms related to water and sodium intake, sodium excretion and cardiovascular control is suggested. (C) 2004 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.

Alterações vasculares em ratos obesos por dieta rica em gordura: papel da Via L-arginina/NO Endotelial

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

Antioxidative action of methanolic extract and buthanolic fraction of Vochysia tucanorum Mart. in the gastroprotection

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

Perinatal lead exposure affects nitric oxide and cyclooxygenase pathways in aorta of weaned rats

Perinatal Pb exposure may modulate arterial tone through nitric oxide (NO) and cyclooxygenase products. To investigate this, Wistar dams received 1000 ppm of Pb or sodium acetate (control) in drinking water during pregnancy and lactation. Curves were constructed in phenylephrine-precontracted intact and/or denuded rings of thoracic aortas of weaned (23-day-old) male pups from their responses to N-omega-nitro-L-arginine methyl ester (L-NAME, NO synthase inhibitor) and ACh in the absence or presence of indomethacin (10(-5)M, cyclooxygenase inhibitor) or L-NAME (3 x 10(-7)M and 3 x 10(-4)M). Blood lead concentration and systolic blood pressure (SBP) were higher in intoxicated than control pups (blood lead mu g/dl: control < 3.0, Pb 58.7 +/- 6.5*; SBP mmHg: control 111.4 +/- 2.3, Pb 135.5 +/- 2.4*). In L-NAME-treated rings maximal responses increased in Pb-exposed rats, and were higher in intact than in denuded aortas (contraction [% of phenylephrine] intact: control 184.3 +/- 23.7, Pb 289.1 +/- 18.3*; denuded: control 125.1 +/- 4.5, Pb 154.8 +/- 13.3*). ACh-induced relaxation in intact aortas from Pb-exposed rats presented rightward shift in L-NAME presence (EC50 x 10(-7)M: control 1.32 [0.33-5.18], Pb 4.88 [3.56-6.69]*) but moved left under indomethacin (EC50 x 10(-7)M: control 8.95 [3.47-23.07], Pb 0.97 [0.38-2.43]*). *p < 0.05 significant relative to the respective control; N = 7-9. Endothelium removal abolished ACh-induced relaxation. Perinatal Pb exposure caused hypertension associated with alterations in the production and/or release of basal and stimulated endothelium-derived relaxing factors-NO and constricting cyclooxygenase products. These findings may help explain the contribution of NO and cyclooxygenase products to the etiology and/or maintenance of Pb-induced hypertension and could ultimately lead to therapeutic advantages in plumbism.

Orchidectomy enhances the effects of phenylephrine in rat isolated portal vein

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

Gastroprotective mechanisms of Citrus lemon (Rutaceae) essential oil and its majority compounds limonene and beta-pinene: Involvement of heat-shock protein-70, vasoactive intestinal peptide, glutathione, sulfhydryl compounds, nitric oxide and prostaglandin E-2

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

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)

Role of central nitric oxide in behavioral thermoregulation of toads during hypoxia

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The effect of L-arginine on guinea-pig and rabbit airway smooth muscle function in vitro

We have investigated the effects of L-arginine, D-arginine and L-lysine on airway smooth muscle responsiveness to spasmogens in vitro. Both L-arginine and D-arginine (100 mM) significantly reduced the contractile potency and maximal contractile response to histamine but not to methacholine or potassium chloride in guinea-pig epithelium-denuded isolated trachea. Similarly, the contractile response to histamine was significantly reduced by L-arginine (100 mM) in rabbit epithelium-denuded isolated bronchus. The amino acid L-lysine (100 mM) failed to significantly alter the contractile potency of histamine in guinea-pig isolated trachea (P>0.05). In guinea-pig isolated trachea precontracted with histamine, both L-arginine and D-arginine produced a concentration-dependent relaxation which was not significantly altered by epithelium removal or by the presence of the nitric oxide synthase inhibitor, NG-nitro L-arginine methyl ester (L-NAME; 50 µM). Thus, at very high concentrations, arginine exhibit a non-competitive antagonism of histamine-induced contraction of isolated airway preparations that was independent of the generation of nitric oxide and was not dependent on charge. These observations confirm previous studies of cutaneous permeability responses and of contractile responses of guinea-pig isolated ileal smooth muscle. Taken together, the data suggest that high concentrations of arginine can exert an anti-histamine effect.

Pulmonary neutrophil recruitment and bronchial reactivity in formaldehyde-exposed rats are modulated by mast cells and differentially by neuropeptides and nitric oxide

We have used a pharmacological approach to study the mechanisms underlying the rat lung injury and the airway reactivity changes induced by inhalation of formaldehyde (FA) (1% formalin solution, 90 min once a day, 4 days). The reactivity of isolated tracheae and intrapulmonary bronchi were assessed in dose-response curves to methacholine (MCh). Local and systemic inflammatory phenomena were evaluated in terms of leukocyte countings in bronchoalveolar lavage (BAL) fluid, blood, bone marrow lavage and spleen. Whereas the tracheal reactivity to MCh did not change, a significant bronchial hyporesponsiveness (BHR) was found after FA inhalation as compared with naive rats. Also, FA exposure significantly increased the total cell numbers in BAL, in peripheral blood and in the spleen, but did not modify the counts in bone marrow. Capsaicin hindered the increase of leukocyte number recovered in BAL fluid after FA exposure. Both compound 48/80 and indomethacin were able to prevent the lung neutrophil influx after FA, but indomethacin had no effect on that of mononuclear cells. Following FA inhalation, the treatment with sodium cromoglycate (SCG), but not with the nitric oxide (NO) synthase inhibitor L-NAME, significantly reduced the total cell number in BAL. Compound 48/80, L-NAME and SCG significantly prevented BHR to MCh after FA inhalation, whereas capsaicin was inactive in this regard. on the other hand, indomethacin exacerbated BHR. These data suggest that after FA inhalation, the resulting lung leukocyte influx and BHR may involve nitric oxide, airway sensory fibers and mast cell-derived mediators. The effect of NO seemed to be largely restricted to the bronchial tonus, whereas neuropeptides appeared to be linked to the inflammatory response, therefore indicating that the mechanisms responsible for the changes of airway responsiveness caused by FA may be separate from those underlying its inflammatory lung effects. (c) 2005 Elsevier B.V. All rights reserved.

Effect of NωNLA or dexamethasone on vascular hyporeactivity induced by E. coli endotoxin in sham and adrenalectomized rats

Induction of iNOS by bacterial products is considered to be part of the defense mechanism against infection. However, it has been suggested that the bacterial-induced NO-overproduction may be involved in the vascular hyporeactivity and in septic shock. It is well known that glucocorticoids prevent the induction of iNOS by Etx in rats. In the present study, dexamethasone diminished but not abolished Etx-induced vascular hyporeactivity in rats. Our results showed that the inhibition of iNOS protects sham rats against the lethal shock produced by Etx, but, in Adx rats, the NωNLA, an iNOS inhibitor, did not reduce Etx-induced mortality. Interestingly, the lack of glucocorticoid impaired the protective effect of NωNLA against Etx-induced hyporeactivity and shock in rats. A conceivable pharmacological approach to protect tissues against deleterious effect of excessive NO production includes inhibition of the iNOS, because the absence of glucocorticoid may increase the iNOS gene expression, with NO-overproduction induced by Etx, suggesting that the glucocorticoids might be of therapeutic value for the treatment of hyporeactivity and shock triggered by sepsis.