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Fernandes-Costa F, de Lima Flôr AF, Falcão MSF, de Moura Balarini C, de Brito Alves JL, de Andrade Braga V, de Campos Cruz J. Central interaction between nitric oxide, lactate and glial cells to modulate water and sodium intake in rats. Brain Res Bull 2022; 186:1-7. [PMID: 35487385 DOI: 10.1016/j.brainresbull.2022.04.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 04/07/2022] [Accepted: 04/23/2022] [Indexed: 12/23/2022]
Abstract
The "astrocyte-to-neuron lactate shuttle" (ANLS) mechanism is part of the central inhibitory pathway to modulate sodium intake. An interaction between the GABAergic neurons and nitric oxide (NO) in the subfornical organ (SFO) in salt-appetite inhibition has been suggested. In addition, NO is a key molecule involved in astrocytic energy metabolism and lactate production. In the present study, we hypothesized there is an interaction between astrocytic lactate and central NO to negatively modulate water and sodium intake through the ANLS mechanism. The results showed that central Nω-nitro-L-arginine methyl ester (L-NAME, NO-synthase inhibition) induced an increase in water and sodium intake. These responses were attenuated by previous central microinjection of fluorocitrate (FCt, a reversible glial inhibitor). Interestingly, L-NAME-induced water and sodium intake were also decreased by previous microinjection of lactate but did not change after inhibition of the ANLS mechanism by α-cyano 4-hydroxycinnamic acid (α-CHCA), an inhibitor of the MCT lactate transporter. Our results suggest a central interaction between NO, glial cells, and lactate to modulate water and sodium intake.
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Affiliation(s)
| | | | | | | | | | | | - Josiane de Campos Cruz
- Biotechnology Center, Department of Biotechnology, Federal University of Paraiba, João Pessoa, Brazil; Department of Physiology and Pathology, Federal University of Paraiba, João Pessoa, Brazil; Department of Nutrition, Federal University of Paraiba, João Pessoa, Brazil; Department of Biotechnology, Federal University of Paraiba, João Pessoa, Brazil.
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El-Haddad MA, Desai M, Gayle D, Ross MG. In Utero Development of Fetal Thirst and Appetite: Potential for Programming. ACTA ACUST UNITED AC 2016; 11:123-30. [PMID: 15051031 DOI: 10.1016/j.jsgi.2003.12.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Thirst and appetite-mediated ingestive behavior develop and are likely programmed in utero, thus preparing for newborn and adult ingestive behavior. Fetal swallowing activity is markedly different from that of the adult, as spontaneous fetal swallowing occurs at a markedly (six-fold) higher rate compared with spontaneous adult drinking activity. This high rate of fetal swallowing is critical for the regulation of amniotic fluid volume and the development of the fetal gastrointestinal tract. Disordered fetal swallowing has been associated with both a decrease (oligohydramnios) and increase (polyhydramnios) in amniotic fluid volume. Both conditions are associated with a significant increase in perinatal morbidity and mortality, and limited treatment modalities are currently available. The mechanisms underlying the high rate of human fetal swallowing are regulated, in part, by tonic activity of central angiotensin II, glutamate N-methyl-D-aspartate receptors, and neuronal nitric oxide synthase. Fetal hypertonicity-mediated dipsogenesis is likely programmed in utero, as offspring of water-restricted ewes demonstrate a programmed syndrome of plasma hypertonicity, with significant hematologic and cardiovascular alterations. Similar to dipsogenic mechanisms, peripheral and central fetal orexic mechanisms also develop in utero, as demonstrated by increased fetal swallowing after both oral sucrose infusion and central injection of neuropeptide Y. The role of leptin in regulating fetal ingestive behavior is interesting because, contrary to actions in adults, leptin does not suppress fetal ingestive behavior. Teleologically, this may be of value during the newborn period, as unopposed appetite stimulatory mechanisms may facilitate rapid fetal and newborn weight gain. An adverse intrauterine environment, with altered fetal orexic factors during the critical developmental period of fetal life, may alter the normal setpoints of appetitive behavior and potentially lead to programming of adulthood hyperphagia and obesity. Further research is needed to delineate the mechanistic relationship between the intrauterine environment and the development of the setpoints of adult appetite and thirst.
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Affiliation(s)
- M A El-Haddad
- Perinatal Research Laboratories, Harbor/UCLA Medical Center, UCLA School of Medicine, Los Angeles, California, USA.
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Reis WL, Saad WA, Camargo LA, Elias LL, Antunes-Rodrigues J. Central nitrergic system regulation of neuroendocrine secretion, fluid intake and blood pressure induced by angiotensin-II. Behav Brain Funct 2010; 6:64. [PMID: 20974001 PMCID: PMC2987978 DOI: 10.1186/1744-9081-6-64] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Accepted: 10/25/2010] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Nitric oxide (NO) synthesis has been described in several circumventricular and hypothalamic structures in the central nervous system that are implicated in mediating central angiotensin-II (ANG-II) actions during water deprivation and hypovolemia. Neuroendocrine and cardiovascular responses, drinking behavior, and urinary excretions were examined following central angiotensinergic stimulation in awake freely-moving rats pretreated with intracerebroventricular injections of Nω-nitro-L-arginine methyl ester (L-NAME, 40 μg), an inhibitor of NO synthase, and L-arginine (20 ug), a precursor of NO. RESULTS Injections of L-NAME or ANG-II produced an increase in plasma vasopressin (VP), oxytocin (OT) and atrial natriuretic peptide (ANP) levels, an increase in water and sodium intake, mean arterial blood pressure and sodium excretion, and a reduction of urinary volume. L-NAME pretreatment enhanced the ANG-II response, while L-arginine attenuated VP and OT release, thirst, appetite for sodium, antidiuresis, and natriuresis, as well as pressor responses induced by ANG-II. DISCUSSION AND CONCLUSION Thus, the central nitrergic system participates in the angiotensinergic responses evoked by water deprivation and hypovolemia to refrain neurohypophysial secretion, hydromineral balance, and blood pressure homeostasis.
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Affiliation(s)
- Wagner L Reis
- Department of Physiology, School of Dentistry, Paulista State University of Araraquara, UNESP Araraquara São Paulo, Brazil
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Saad WA, Camargo LADA, Guarda IFMS, Santos TAFBD. Subfornical organ mediates pressor effect of angiotensin: Influence of nitric oxide synthase inhibitors, AT1 and AT2 angiotensin antagonist's receptors. ACTA ACUST UNITED AC 2008; 2:326-31. [DOI: 10.1016/j.jash.2008.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2008] [Revised: 04/03/2008] [Accepted: 04/10/2008] [Indexed: 11/29/2022]
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Saad WA, . IFM, . LADA, . TAF, . WAS. Effects of Nitric Oxide and Arginine Vasopressin on Water Intake Induced by Central Angiotensin II. Part 1. JOURNAL OF MEDICAL SCIENCES 2007. [DOI: 10.3923/jms.2007.845.849] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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. WAS, . IFM, . LADA, . C, . TAF, . SS, . WAS. Nitrergic Pathways and L-Type Calcium Channel of MnPO Influencing Cardiovascular Homeostasis. JOURNAL OF MEDICAL SCIENCES 2006. [DOI: 10.3923/jms.2006.597.602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Saad WA, . IFM, . LADA, . WAS, . RSG, . TAS, . SS. Endothelial and Neuronal Nitric Oxide Synthase Inhibitors Influences Angiotensin II Pressor Effect in Central Nervous System. INT J PHARMACOL 2006. [DOI: 10.3923/ijp.2006.341.347] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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El-Haddad MA, Chao CR, Ross MG. N-methyl-D-aspartate glutamate receptor mediates spontaneous and angiotensin II-stimulated ovine fetal swallowing. ACTA ACUST UNITED AC 2005; 12:504-9. [PMID: 16202927 DOI: 10.1016/j.jsgi.2005.06.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2004] [Indexed: 11/16/2022]
Abstract
BACKGROUND In adult rats, N-methyl-D-aspartate (NMDA) receptors have been implicated in the central control of body fluid homeostasis, as intracerebroventricular (ICV) injection of NMDA receptor antagonists suppresses stimulated drinking behavior. Fetal swallowing occurs at a significantly higher rate as compared to adult drinking, contributing to amniotic fluid volume regulation and fetal gastrointestinal development. The aim of present study was to determine the role of central NMDA receptors in the modulation of fetal swallowing activity. METHODS Eight time-dated pregnant ewes and fetuses were chronically prepared with fetal vascular and ICV catheters, electrocorticogram (ECoG), and esophageal electromyogram electrodes and studied at 130 +/- 1 days' gestation. Following an initial 2-hour baseline period (time 2 h), the NMDA receptor antagonist, dizocipline (1 mg), was injected ICV. At time 4 h, the dose of dizocipline was repeated, together with angiotensin II (AngII, 6.4 microg). Fetal swallowing was monitored for 2 hours after each injection. Four of these fetuses also received an identical control study (on an alternate day) in which dizocipline was replaced with artificial cerebrospinal fluid (aCSF). RESULTS ICV dizocipline injection nearly abolished spontaneous fetal swallowing activities (0.6 +/- 0.1 to 0.2 +/- 0.1 swallows/min; P < .001). ICV AngII in the presence of dizocipline did not demonstrate a dipsogenic effect on fetal swallowing (0.1 +/- 0.1; P < .001). In the control study, ICV injection of aCSF did not change fetal swallowing activity (1.0 +/- 0.1 swallows/min), while ICV AngII resulted in a significant increase in fetal swallowing (2.0 +/- 0.1 swallows/min; P < .001). CONCLUSIONS This study demonstrates that central NMDA-glutamate receptor-mediated activity contributes to the high rate of spontaneous and AngII-stimulated fetal swallowing. We speculate that reduced NMDA receptor expression within the forebrain dipsogenic neurons may account for observed differences in drinking activities between the fetus/neonate and the adult.
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Affiliation(s)
- Mostafa A El-Haddad
- Perinatal Research Laboratories, Harbor/UCLA Medical Center, School of Medicine, Los Angeles, California, USA
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Ma R, Zhu GQ, Wang W. Interaction of central Ang II and NO on the cardiac sympathetic afferent reflex in dogs. Auton Neurosci 2005; 118:51-60. [PMID: 15795177 DOI: 10.1016/j.autneu.2004.12.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2004] [Revised: 12/21/2004] [Accepted: 12/30/2004] [Indexed: 02/06/2023]
Abstract
The aim of this study was to test the hypothesis that the central angiotensin II (Ang II) and nitric oxide (NO) systems interact to modulate the cardiac sympathetic afferent reflex (CSAR). All dogs were anesthetized with alpha-chloralose (100 mg/kg, iv). They were sino-aortic baroreceptor denervated and vagotomized throughout the experiment renal sympathetic nerve activity responses to cardiac sympathetic afferent stimulation and the central gain of the CSAR were measured. Three protocols were performed: (1) intracerebroventricular injection (icv, 3 microg/h or 6 microg/h) of Ang II with and without N(omega)-nitro-L-arginine methyl ester (L-NAME) (icv, 1 mg/kg), (2) L-NAME (icv) with and without Ang II (icv, 6 microg/h), and (3) administration of the specific neural NO synthase (nNOS) inhibitor, S-Methyl-L-thiocitrulline (MeTC) (icv, 0.1 or 1 mM, 0.5 ml in 5 min) with and without pretreatment with the angiotensin type 1 receptor antagonist, losartan (icv, 0.125 mg/kg). The primary findings were (1) Ang II alone did not significantly affect the central sensitivity of the CSAR. However, Ang II with L-NAME enhanced this reflex, (2) even though L-NAME alone augmented the CSAR, this excitatory effect was further potentiated in the presence of Ang II and (3) MeTC significantly enhanced the central sensitivity of the CSAR. However, this enhancement did not occur after pretreatment with losartan. These data suggest that Ang II interacts with NO in the brain to modulate the CSAR and that inhibition of NO is required for facilitation of the CSAR by Ang II.
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Affiliation(s)
- Rong Ma
- Department of Cellular and Integrative Physiology, University of Nebraska College of Medicine, 985850 Nebraska Medical Center Omaha, NE 68198-5850, USA
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Abrão Saad W, Guarda IFMS, Camargo LADA, Garcia G, Gutierrez LI, Abrão Saad W, Simões S, Saad Guarda R. 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. Life Sci 2004; 75:685-97. [PMID: 15172178 DOI: 10.1016/j.lfs.2004.01.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2003] [Accepted: 01/14/2004] [Indexed: 11/26/2022]
Abstract
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 microg/0.5 microl), a nitric oxide (NO) donor, and N(W)-nitro-L-arginine methyl ester (L-NAME) 40 microg/0.5 microl, 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.
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Affiliation(s)
- Wilson Abrão Saad
- Department of Anesthesiology, 9 de Julho Medical Hospital, São Paulo, Brazil.
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Schwimmer H, Gerstberger R, Horowitz M. Nitric oxide and angiotensin II: neuromodulation of thermoregulation during combined heat and hypohydration stress. Brain Res 2004; 1006:177-89. [PMID: 15051521 DOI: 10.1016/j.brainres.2004.01.064] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/07/2004] [Indexed: 11/22/2022]
Abstract
We investigated the central role of nitric oxide and AngII on thermoregulation in rats (Rattus norvegicus, Sabra strain,) undergoing heat-stress in euhydration or hypohydration (water deprivation, -10% b.wgt). Experimental rats received AngII (100 pm), 7-nitroindazole-an antagonist of neuronal nitric oxide synthase (7NI-100 nm), or AngII+7NI in a 5-microl bolus intracerebroventricularly (i.c.v.) under light chloroform anesthesia; untreated control rats received saline or DMSO (5%). We used three experimental paradigms: (1) heat defense responses [salivation (STsh), vasodilatation (VTsh) temperature thresholds and heat-endurance] in conscious, heat-stressed (39 degrees C) rats; (2) Western immunoblotting to detect AngII AT(1) and AT(2) receptors and nNOS protein expression; (3) real-time PCR to measure gene transcripts. In the in vivo experiment, 7NI decreased thermoregulatory thresholds, namely, NO had a reciprocal effect that was more pronounced during hypohydration (e.g. euhydration: STsh: -0.7+/-0.01 degrees C, hypohydration: -0.9+/-0.18 degrees C, p<0.05). AngII decreased STsh by 0.9+/-0.18 degrees C (p<0.05) upon euhydration but increased it in hypohydration (+1.7+/-0.28 degrees C, p<0.05). A novel finding was the involvement of AT(2) receptors in thermoregulation, which was more pronounced upon hypohydration. The response to NO was mediated via AT(1) and AT(2) receptors signaling, as well as independently. A synthesis of the results from all experimental paradigms suggests (1) a dominant influence (decrease) of NO on AT(1) receptors, thereby changing AT(1)/AT(2) receptor ratio and their signaling pathway; primarily upon hypohydration; (2) an influence of AngII (increase) on receptor density, more pronounced during hypohydration, at both gene transcription and translation levels; and (3) an effect of AngII on nNOS protein levels, implying a mutual effect of AngII and NO.
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MESH Headings
- Analysis of Variance
- Angiotensin II/antagonists & inhibitors
- Angiotensin II/physiology
- Angiotensin II Type 1 Receptor Blockers
- Angiotensin II Type 2 Receptor Blockers
- Animals
- Blotting, Western/methods
- Body Temperature/drug effects
- Body Temperature Regulation/drug effects
- Body Temperature Regulation/physiology
- Body Weight/drug effects
- Cell Membrane/drug effects
- Cell Membrane/metabolism
- Cell Nucleus/drug effects
- Cell Nucleus/metabolism
- Dehydration/physiopathology
- Drug Interactions
- Enzyme Inhibitors/pharmacology
- Heat Stress Disorders/physiopathology
- Indazoles/pharmacology
- Injections, Intraventricular/methods
- Losartan/pharmacology
- Male
- Nitric Oxide/physiology
- RNA, Messenger/biosynthesis
- Rats
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Angiotensin, Type 2/genetics
- Receptor, Angiotensin, Type 2/metabolism
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Salivation/drug effects
- Salivation/physiology
- Vasodilation/drug effects
- Vasodilation/physiology
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Affiliation(s)
- H Schwimmer
- Division of Physiology, Hadassah School of Dental Medicine, The Hebrew University, POB 12272, Jerusalem 91120, Israel.
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Saad WA, de Arruda Camargo LA, Guarda IFMS, dos Santos TAFB, Guarda RS, Saad WA, Simões S, Rodrigues JA. Interaction between supraoptic nucleus and septal area in the control of water, sodium intake and arterial blood pressure induced by injection of angiotensin II. Pharmacol Biochem Behav 2004; 77:667-74. [PMID: 15099911 DOI: 10.1016/j.pbb.2004.01.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2003] [Revised: 12/05/2003] [Accepted: 01/08/2004] [Indexed: 11/15/2022]
Abstract
We investigated the effects of injection into the supraoptic nucleus (SON) of losartanand PD 123319 (nonpeptide AT(1) and AT(2)-angiotensin II [ANG II] receptor antagonists, respectively); d(CH(2))(5)-Tyr(Me)-AVP (AVPA; an arginine-vasopressin [AVP] V(1) receptor antagonist), FK 409 (a nitric oxide [NO] donor), and N(W)-nitro-l-arginine methyl ester (l-NAME; an NO synthase inhibitor) on water intake, sodium chloride 3% (NaCl) intake and arterial blood pressure induced by injection of ANG II into the lateral septal area (LSA). Male Holtzman rats (250-300 g) were implanted with cannulae into SON and LSA unilaterally. The drugs were injected in 0.5 microl over 30-60 s. Controls were injected with a similar volume of 0.15 M NaCl. ANG II was injected at a dose of 10 pmol. ANG II antagonists and AVPA were injected at doses of 80 nmol. FK 409 and l-NAME were injected at doses of 20 and 40 microg, respectively. Water and NaCl intake was measured over a 2-h period. Prior administration of losartan into the SON decreased water and NaCl intake induced by injection of ANG II. While there was a decrease in water intake, ANG II-induced NaCl intake was significantly increased following injection of AVPA. FK 409 injection decreased water intake and sodium intake induced by ANG II. l-NAME alone increased water and sodium intake and induced a pressor effect. l-NAME-potentiated water and sodium intake induced by ANG II. PD 123319 produced no changes in water or sodium intake induced by ANG II. The prior administration of losartan or AVPA decreased mean arterial pressure (MAP) induced by ANG II. PD 123319 decreased the pressor effect of ANG II to a lesser degree than losartan. FK 409 decreased the pressor effect of ANG II while l-NAME potentiated it. These results suggest that both ANG II AT(1) and AVP V(1) receptors and NO within the SON may be involved in water intake, NaCl intake and the pressor response were induced by activation of ANG II receptors within the LSA. These results do not support the involvement of LSA AT(2) receptors in the mediation of water and NaCl intake responses induced by ANG II, but influence the pressor response.
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Affiliation(s)
- Wilson Abrão Saad
- Department of Physiology and Pathology, School of Dentistry, Paulista State University, UNESP, UNIARA, Araraquara, São Paulo, Brazil
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Yamaguchi K, Hama H. A study on the mechanism by which sodium nitroprusside, a nitric oxide donor, applied to the anteroventral third ventricular region provokes facilitation of vasopressin secretion in conscious rats. Brain Res 2003; 968:35-43. [PMID: 12644262 DOI: 10.1016/s0006-8993(02)04246-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We reported previously that sodium nitroprusside (SNP) applied to the anteroventral third ventricular region (AV3V), a pivotal area for autonomic functions, facilitates vasopressin (AVP) secretion in conscious rats. The aim of this study was to pursue the problems of whether nitric oxide (NO) generated from the agent may be responsible for the phenomenon, and whether it may be mediated by cyclic guanosine monophosphate (cGMP), the biosynthesis of which could reportedly be activated by NO. The infusion of SNP into the AV3V of conscious rats produced dose-related increases in plasma AVP, the maximal responses of which appeared at 5 min. Blood pressure and heart rate tended to rise at 15 min. The plasma osmolality, sodium, potassium or chloride did not show marked alteration following the SNP administration. Although the SNP solution was hypertonic and hypernatremic, AV3V application of hypertonic saline with a relatively higher osmolality and an equal sodium level was significantly less effective in augmenting plasma AVP. When injected into the lateral ventricle, SNP did not change plasma AVP and reduced arterial pressure, different from the results provoked by the AV3V application. The rise in plasma AVP in response to the AV3V application of SNP was diminished by preadministration of hemoglobin, a scavenger of NO, that did not affect the responses of the other variables. In contrast, pretreatment with methylene blue, an agent capable of antagonizing the potency of NO to activate guanylate cyclase, did not attenuate but potentiated the responses of both plasma AVP and arterial pressure to the AV3V infusion of SNP. Hemoglobin or methylene blue given alone into the AV3V did not affect any of the variables monitored. On the other hand, the AV3V injection of 8-bromo cGMP, a stable analogue of cGMP, was not potent for causing a significant rise in plasma AVP, in contrast to the notable AVP-enhancing effect of 8-bromo cAMP. Arterial pressure and heart rate were elevated by both of these agents, whereas the remaining variables were not altered. Histological inspection indicated that the infusion sites of the drugs in the AV3V had included areas such as the organum vasculosum of the lamina terminalis, median preoptic nucleus, medial preoptic nucleus and periventricular nucleus. On the basis of these results, we concluded that the AVP secretion prompted by the AV3V application of SNP may be attributable to NO, whereas its well-known ability to stimulate guanylate cyclase activity may hardly contribute to this phenomenon.
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Affiliation(s)
- Ken'ichi Yamaguchi
- Department of Homeostatic Regulation and Development, Niigata University Graduate School of Medical and Dental Sciences, Niigata City, Japan.
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Saad WA, Guarda IFMS, Guarda RS, Camargo LADA, dos Santos TAFB, Saad WA, Simões S. Role of nitric oxide and beta-adrenoceptors of the central nervous system on the salivary flow induced by pilocarpine injection into the lateral ventricle. Pharmacol Biochem Behav 2002; 72:229-35. [PMID: 11900793 DOI: 10.1016/s0091-3057(01)00760-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
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 Holtzman 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 microg/microl) into LV produced a dose-dependent increase in salivary secretion. The injection of L-NAME (40 microg/microl) 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 microg/microl) injected alone into LV produced no change in salivary secretion. L-Arginine injected into LV attenuated pilocarpine-induced salivary secretion. The isoproterenol (40 nmol/microl) injected into LV increased the salivary secretion. When injected previous to pilocarpine at a dose of 20 and 40 microg/microl, isoproterenol produced an additive effect on pilocarpine-induced salivary secretion. The 40-nmol/microl dose of propranolol injected alone or previous to pilocarpine into LV attenuated the pilocarpine-induced salivary secretion. The injection of salbutamol (40 nmol/microl), a specific beta-2 agonist, injected alone into LV produced no change in salivary secretion and when injected previous to pilocarpine produced an increase in salivary secretion. The 40-nmol/microl 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.
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Affiliation(s)
- Wilson Abrão Saad
- Department of Physiology and Pathology, School of Dentistry, Paulista State University, UNESP, Araraquara, SP, Brazil
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El-Haddad MA, Chao CR, Ma SX, Ross MG. Neuronal NO modulates spontaneous and ANG II-stimulated fetal swallowing behavior in the near-term ovine fetus. Am J Physiol Regul Integr Comp Physiol 2002; 282:R1521-7. [PMID: 11959696 DOI: 10.1152/ajpregu.00229.2001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Spontaneous fetal swallowing occurs at a markedly higher rate compared with spontaneous adult drinking activity. This high rate of fetal swallowing is critical for amniotic fluid volume regulation. Central NO is critical for maintaining the normal rate of fetal swallowing, as nonselective inhibition of NO (with central N(G)-nitro-L-arginine methyl ester) suppresses spontaneous and angiotensin II (ANG II)-stimulated swallowing. We sought to differentiate the contributions of central endothelial vs. neuronal NO in the regulation of spontaneous and stimulated fetal swallowing, using a selective neuronal NO synthase (nNOS) inhibitor. Six time-dated pregnant ewes and fetuses were chronically prepared with fetal vascular and intracerebroventricular (i.c.v.) catheters and electrocorticogram (ECoG) and esophageal electromyogram electrodes and studied at 130 +/- 1 days of gestation. After an initial 2-h baseline period (0-2 h), the selective nNOS inhibitor N-propyl-L-arginine (NPLA) was injected i.c.v. (2-4 h). At 4 h, the dose of NPLA was repeated, together with ANG II, and fetal swallowing was monitored for a final 2 h. Four fetuses also received an identical control study (on an alternate day) in which NPLA was replaced with artificial cerebrospinal fluid (aCSF). Suppression of nNOS by i.c.v. NPLA significantly reduced mean (+/- SE) spontaneous fetal swallowing (1.35 +/- 0.12 to 0.50 +/- 0.07 swallows/min; P < 0.001). Injection of ANG II in the presence of NPLA had no dipsogenic effect on fetal swallowing (0.68 +/- 0.09 swallows/min). In the aCSF study, i.c.v. aCSF did not change fetal swallowing (0.93 +/- 0.10 vs. 0.95 +/- 0.09 swallows/min), whereas i.c.v. ANG II resulted in a significant increase in the rate of fetal swallowing (2.0 +/- 0.04 swallows/min; P = 0.001). We speculate that the suppressive dipsogenic effects of central NPLA indicate that spontaneous and ANG II- stimulated fetal swallowing is dependent on central nNOS activity.
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Affiliation(s)
- Mostafa A El-Haddad
- Perinatal Research Laboratories, Harbor/University of California at Los Angeles Medical Center, University of California at Los Angeles School of Medicine, Torrance, California 90902, USA.
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Saad WA, Guarda IFMS, Camargo LADA, dos Santos TAFB, Saad WA, Simões S, Guarda RS. Novel evidence that nitric oxide of the medial septal area influences the salivary secretion induced by pilocarpine. Life Sci 2002; 70:2403-12. [PMID: 12150204 DOI: 10.1016/s0024-3205(02)01531-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Our studies have focused on the effect of injection of L-NAME and sodium nitroprussiate (SNP) on the salivary secretion, arterial blood pressure, sodium excretion and urinary volume induced by pilocarpine which was injected into the medial septal area (MSA). Rats were anesthetized with urethane (1.25 g/kg b. wt.) and a stainless steel cannula was implanted into their MSA. The amount of saliva secretion was studied over a five-minute period after injection of pilocarpine into MSA. Injection of pilocarpine (10, 20, 40, 80, 160 microg/microl) into MSA produced a dose-dependent increase in salivary secretion. L-NG-nitro arginine methyl-esther (L-NAME) (40 microg/microl), a nitric oxide (NO) synthase inhibitor, was injected into MSA prior to the injection of pilocarpine into MSA, producing an increase in salivary secretion due to the effect of pilocarpine. Sodium nitroprussiate (SNP) (30 microg/microl) was injected into MSA prior to the injection of pilocarpine into MSA attenuating the increase in salivary secretion induced by pilocarpine. Medial arterial pressure (MAP) increase after injections of pilocarpine into the MSA. L-NAME injected into the MSA prior to injection of pilocarpine into MSA increased the MAP. SNP injected into the MSA prior to pilocarpine attenuated the effect of pilocarpine on MAP. Pilocarpine (40 ug/ul) injected into the MAS induced an increase in sodium and urinary excretion. L-NAME injected prior to pilocarpine into the MSA increased the urinary sodium excretion and urinary volume induced by pilocarpine. SNP injected prior to pilocarpine into the MSA decreased the sodium excretion and urinary volume induced by pilocarpine. All these roles of pilocarpine depend on the release of nitric oxide into the MSA. We may also conclude that the MSA is involved with the cholinergic excitatory mechanism that induce salivary secretion, increase in MAP and increase in sodium excretion and urinary volume.
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Affiliation(s)
- Wilson Abrão Saad
- Department of Physiology and Pathology School of Dentistry, Paulista State University, UNESP Araraquara, SP Brazil.
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Song D, Liu H, Sharkey KA, Lee SS. Hyperdynamic circulation in portal-hypertensive rats is dependent on central c-fos gene expression. Hepatology 2002; 35:159-66. [PMID: 11786972 DOI: 10.1053/jhep.2002.30417] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Portal hypertension is associated with hyperdynamic circulation, but the pathogenesis remains unclear. To clarify the role of central cardiovascular regulatory mechanisms, several protocols were conducted in rats with portal hypertension due to portal vein stenosis (PVS). Neuronal activation was quantified by immunohistochemical staining for Fos, the protein product of the c-fos gene. Fos expression in several brain nuclei with cardiovascular-regulatory roles was examined at 1, 3, 5, and 10 days following PVS surgery. This was correlated with development of cardiovascular changes measured at the same time points. Finally, Fos expression in the nucleus tractus solitarius (NTS) was blocked by local microinjection of c-fos antisense oligonucleotides twice daily for 5 days following PVS. The results showed that Fos-positive neurons were significantly increased in the paraventricular nucleus of hypothalamus, supraoptic nucleus, ventrolateral medulla, and NTS, detectable at day 1 and persistently increased at every day examined in the PVS rats. However, the hyperdynamic circulation developed between days 3 to 5. Administration of c-fos antisense oligonucleotides eliminated the hyperdynamic circulation in PVS rats, but had no effect on sham-operated controls. We conclude that the activation of central cardiovascular-regulatory nuclei, through a c-fos-dependent pathway, is necessary for development of hyperdynamic circulation in portal-hypertensive rats.
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Affiliation(s)
- Daisheng Song
- Liver Unit, Gastroenterology Research Group, and Neuroscience Research Group, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
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El-Haddad MA, Chao CR, Sayed AA, El-Haddad H, Ross MG. Effects of central angiotensin II receptor antagonism on fetal swallowing and cardiovascular activity. Am J Obstet Gynecol 2001; 185:828-33. [PMID: 11641660 DOI: 10.1067/mob.2001.117310] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Fetal plasma angiotensin II levels are 10 times the levels found in adults. Despite these high levels, central injection of angiotensin II may stimulate fetal swallowing and increase fetal arterial blood pressure. We postulated that the high rate of spontaneous fetal swallowing and normal fetal pressor regulation may be dependent, in part, on central angiotensin II. In view of the potential dipsogenic role of both type 1 and type 2 angiotensin II receptors, we examined the central effect of the nonselective angiotensin II receptor antagonist saralasin on fetal swallowing and cardiovascular responses. STUDY DESIGN Six time-dated pregnant ewes and fetuses were chronically prepared with fetal vascular and intracerebroventricular catheters, electrocorticograms, and esophageal electromyogram electrodes and studied at 130 +/- 1 days' gestation. After an initial 2-hour baseline period (0 to 2 hours), saralasin (1 mL, 64 microg) was injected intracerebroventricularly (2 to 4 hours). After 4 hours the dose of saralasin was repeated together with angiotensin II (1 mL, 6.4 microg), and the fetuses were monitored for a final 2 hours. Four fetuses also underwent an identical control study (on an alternate day) in which saralasin was replaced with artificial cerebrospinal fluid. RESULTS Blockade of central angiotensin II receptors by intracerebroventricular saralasin significantly reduced mean (+/- SEM) spontaneous fetal swallowing (1.3 +/- 0.1 to 0.4 +/- 0.1 swallows per minute; P <.001) but did not alter fetal mean blood pressure (50 +/- 5 versus 56 +/- 5 mm Hg). Intracerebroventricular angiotensin II, in the presence of saralasin, did not affect swallowing (0.6 +/- 0.1 swallows per minute) or fetal blood pressure. In the control study, intracerebroventricular artificial cerebrospinal fluid did not change fetal swallowing (0.9 +/- 0.1 versus 1.0 +/- 0.1 swallows per minute), whereas intracerebroventricular angiotensin II significantly increased swallowing activity (1.0 +/- 0.1 versus 2.0 +/- 0.1 swallows per minute; P <.001) and fetal blood pressure (51 +/- 2 to 59 +/- 3 mm Hg; P =.003). CONCLUSIONS Tonic activity of central angiotensin II receptor stimulation contributed to the high rate of basal ovine fetal swallowing but not fetal basal blood pressure. Angiotensin II-mediated fetal dipsogenic and pressor responses are a result of specific angiotensin II receptor binding in central brain regions. These results indicate that fetal exposure to angiotensin II antagonists or angiotensin-converting enzyme inhibitors may have adverse effects on fetal and amniotic fluid homeostasis.
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Affiliation(s)
- M A El-Haddad
- Perinatal Research Laboratories, Harbor-University of California Los Angeles Medical Center, UCLA School of Medicine, Torrance, CA 90502, USA
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Steiner AA, Branco LG. Carbon monoxide is the heme oxygenase product with a pyretic action: evidence for a cGMP signaling pathway. Am J Physiol Regul Integr Comp Physiol 2001; 280:R448-57. [PMID: 11208574 DOI: 10.1152/ajpregu.2001.280.2.r448] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have recently reported that the central heme oxygenase (HO) pathway has an important role in the genesis of lipopolysaccharide fever. However, the HO product involved, i.e., biliverdine, free iron, or carbon monoxide (CO), has not yet been identified with certainty. Therefore, in the present study, we tested the thermoregulatory effects of all HO products. Body core temperature (T(c)) and gross activity of awake, freely moving rats was measured by biotelemetry. Intracerebroventricular administration of heme-lysinate (152 nmol), which induces the HO pathway, evoked a marked increase in T(c), a response that was attenuated by intracerebroventricular pretreatment with the HO inhibitor zinc deuteroporphyrin 2,4-bis glycol (200 nmol), indicating that an HO product has a pyretic action in the central nervous system (CNS) of rats. Besides, heme-lysinate also increased gross activity, but no correlation was found between this effect and the increase in T(c). Moreover, intracerebroventricular biliverdine or iron salts at 152 nmol, a dose at which heme-lysinate was effective in increasing T(c), produced no change in T(c). Accordingly, intracerebroventricular treatment with the iron chelator deferoxamine elicited no change in basal T(c) and did not affect heme-induced pyresis. However, heme-induced pyresis was completely prevented by the soluble guanylate cyclase (sGC) inhibitor 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxaline-1-one. Because biliverdine and iron had no thermoregulatory effects and CO produces most of its actions via sGC, these data strongly imply that CO is the only HO product with a pyretic action in the CNS.
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Affiliation(s)
- A A Steiner
- Departamento de Morfologia, Estomatologia e Fisiologia, Faculdade de Odontologia de Ribeirão Preto, Universidade de São Paulo, 14040-904 Ribeirão Preto, São Paulo, Brazil
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Guilhaume SS, Corrêa FM. Effect of NMDA-induced lesion of the subfornical organ on the angiotensin II binding sites density and acetylcholinesterase or NADPH-diphorase activities in the lamina terminalis of the rat brain. Cell Mol Neurobiol 2001; 21:81-90. [PMID: 11440200 DOI: 10.1023/a:1007125413308] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
1. Neural angiotensinergic circuitry located in the lamina terminalis has been proposed to be involved in blood pressure regulation and fluid homeostasis. 2. ANG II binding sites have been described to be localized throughout the lamina terminalis including the subfornical organ (SFO), the median preoptic nucleus (MnPO), and the organum vasculosum lamina terminalis (OVLT). 3. The present experiment was designed to investigate the ANG II binding sites localization in the lamina terminalis. For this purpose, we have compared the ANG II binding sites, acetylcholinesterase, and NADPH-diaphorase distributions throughout the lamina terminalis. Additionally, we have studied the effect of the preferential lesion of SFO neuronal cell bodies by local injection of NMDA on the ANG II binding sites density in different areas of the lamina terminalis. 4. Male Wistar rats were anesthetized, immobilized in a stereotaxic apparatus, and 500 nl of saline or 250 nmol NMDA was injected into the SFO. 5. Animals were sacrificed 1 week later, the brain was removed, frozen, and sagittal 16 microm slices were cut in a cryostat. Alternate brain slices were incubated with [125I]-Sar1-ANG II for receptor autoradiography or histochemically stained for visualization of acetylcholinesterase and NADPH-diaphorase activities. Binding capacity was determined by computerized quantitative densitometry of autoradiograms. The intensity of histochemical reactions was measured as relative units obtained by computerized densitometry processing of the brain slices stained for either activity. 6. Acetylcholinesterase staining was mainly located in the SFO, with faint staining reaction in other areas of the lamina terminalis. NADPH-diaphorase staining was homogeneously distributed throughout the lamina terminalis. A significant positive correlation was observed between acetylcholinesterase and NADPH-diaphorase stainings in the SFO of control and NMDA-lesioned rats. 7. ANG II binding sites were localized throughout the lamina terminalis. A significant positive correlation was observed between the density of ANG II binding sites and the intensity of acetylcholinesterase or NADPH-diaphorase staining in the SFO of control and NMDA-lesioned rats. 8. The distribution of the NADPH-diaphorase staining was found to closely match the distribution of the ANG II binding sites in the lamina terminalis. 9. Neuronal lesion of the SFO caused significant reductions in the density of ANG II biding sites in the SFO (-68%) and the MnPO (-48%). No changes were observed either in the OVLT or outside the lamina terminalis in the superior colliculus. 10. The present results indicate the following: first, the presence of high levels of acetylcholinesterase staining in the SFO and of NADPH-diaphorase throughout the lamina terminalis; second, that ANG II binding sites in the SFO and possibly in the MnPO are localized in neuronal cell bodies; third, that SFO lesion did not affect the expression of ANG II binding sites in the OVLT, thus suggesting that these binding sites correspond to different angiotensinergic system: and finally, the existence of a striking correlation between the distribution of the ANG II binding sites and NADPH-diaphorase throughout the lamina terminalis, thus suggesting a interrelation between angiotensinergic and nitrergic systems in the lamina terminalis.
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Affiliation(s)
- S S Guilhaume
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Brazil
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Kadekaro M, Summy-Long JY. Centrally produced nitric oxide and the regulation of body fluid and blood pressure homeostases. Clin Exp Pharmacol Physiol 2000; 27:450-9. [PMID: 10831252 DOI: 10.1046/j.1440-1681.2000.03264.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. Nitric oxide (NO) tonically inhibits the basal release of vasopressin and oxytocin into plasma. 2. Nitric oxide inhibition on vasopressin secretion is removed, while that on oxytocin is enhanced, during water deprivation, hypovolaemia, moderate osmotic stimulation and angiotensin (Ang)II. This results in a preferential release of vasopressin over oxytocin that promotes conservation of water. 3. Nitric oxide facilitates drinking behaviour stimulated by water deprivation, osmotic stimulation, haemorrhage and AngII. Together with the hormonal response, NO produces a positive water balance during reductions in intracellular and intravascular volumes. 4. Nitric oxide produced within the central nervous system maintains resting arterial blood pressure partially by attenuating the pressor actions of AngII and prostaglandins. 5. Central production of NO is enhanced during osmotic stimulation to counterbalance the salt-induced pressor response. 6. Paradoxically, central production of NO is also enhanced during haemorrhage, presumably to maintain peripheral vasodilation and blood flow to vital organs.
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Affiliation(s)
- M Kadekaro
- Division of Neurosurgery, The University of Texas Medical Branch at Galveston, 77555-0517, USA.
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22
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El-Haddad MA, Chao CR, Ma SX, Ross MG. Nitric oxide modulates angiotensin II-induced drinking behavior in the near-term ovine fetus. Am J Obstet Gynecol 2000; 182:713-9. [PMID: 10739535 DOI: 10.1067/mob.2000.104227] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Human and ovine fetuses demonstrate an enhanced rate of spontaneous and angiotensin II-stimulated swallowing. Angiotensin II and nitric oxide synthase have been localized to thirst centers in the brain. This study was performed to determine whether central nitric oxide contributes to the regulation of angiotensin II-induced fetal swallowing. STUDY DESIGN Six pregnant ewes with near-term singleton fetuses were chronically prepared with fetal vascular and lateral ventricle catheters and electrocorticogram and esophageal electromyogram electrodes. After a 2-hour control period, fetuses were administered serial lateral ventricle injections (1 mL) of angiotensin II (3.2 microg; time, 2 hours) and N omega-nitro-L -arginine methyl ester (3 mg; time, 3 hours) and a repeat angiotensin II injection (3.2 microg; time, 5 hours). All fetuses received an additional control study of lateral ventricle injections of artificial cerebrospinal fluid on a previous day. RESULTS Angiotensin II injection significantly increased mean +/- SEM fetal swallowing (0.9 +/- 0.1 to 2.7 +/- 0.4 swallows/min). N omega-nitro-L -arginine methyl ester significantly decreased fetal swallowing to below the basal rate (0.4 +/- 0.1 swallows/min), and swallowing did not increase with the second angiotensin II dose (in the presence of nitric oxide blockade). CONCLUSIONS These results demonstrate that inhibition of central nitric oxide suppresses fetal swallowing behavior in response to central angiotensin II. We speculate that tonic nitric oxide facilitates angiotensin II swallowing stimulation by maintenance of glutamate activation of hypothalamic N -methyl-D -aspartate receptors.
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Affiliation(s)
- M A El-Haddad
- Perinatal Research Laboratories, Harbor-University of California, Los Angeles Medical Center, University of California, Los Angeles School of Medicine, Torrance, CA 90502, USA
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Saad WA, Camargo LA, Saad R, Pereira AF, Simões S. Effect of injection of L-NAME on drinking response. Braz J Med Biol Res 1999; 32:1413-6. [PMID: 10559843 DOI: 10.1590/s0100-879x1999001100012] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The drinking behavior responses to centrally administered N G-nitro-L-arginine methyl ester (L-NAME; 10, 20 or 40 microg/microl), an inhibitor of nitric oxide synthase, were studied in satiated rats, with cannulae stereotaxically implanted into the lateral ventricle (LV) and subfornical organ (SFO). Water intake increased in all animals after angiotensin II (ANG II) injection into the LV, with values of 14.2 +/- 1.4 ml/h. After injection of L-NAME at doses of 10, 20 or 40 microg/microl into the SFO before injection of ANG II (12 ng/microl) into the LV, water intake decreased progressively and reached basal levels after treatment with 0.15 M NaCl and with the highest dose of L-NAME (i.e., 40 microg). The water intake obtained after 40 microg/microl L-NAME was 0.8 +/- 0.01 ml/h. Also, the injection of L-NAME, 10, 20 or 40 microg/microl, into the LV progressively reduced the water intake induced by hypertonic saline, with values of 5.3 +/- 0.8, 3.2 +/- 0.8 and 0.7 +/- 0.01 ml/h, respectively. These results indicate that nitric oxide is involved in the regulation of drinking behavior induced by centrally administered ANG II and cellular dehydration and that the nitric oxide of the SFO plays an important role in this regulation.
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Affiliation(s)
- W A Saad
- Departamento de Fisiologia, Faculdade de Odontologia, Universidade Estadual Paulista, Araraquara, SP, Brasil.
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El-Haddad MA, Chao CR, Ma SX, Ross MG. Nitric oxide modulates spontaneous swallowing behavior in near-term ovine fetus. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:R981-6. [PMID: 10516235 DOI: 10.1152/ajpregu.1999.277.4.r981] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Human and ovine fetuses demonstrate an enhanced rate of swallowing, an activity critical for amniotic fluid regulation. Fetal swallowing may be modulated by both systemic and central factors. Nitric oxide (NO) is a central neuromodulator that has been localized to brain regions regulating thirst and swallowing. We sought to determine if NO contributes to the regulation of spontaneous ovine fetal swallowing. Six time-dated pregnant ewes with singleton fetuses (129 +/- 1 day) were chronically prepared with fetal vascular and lateral ventricle catheters and electrocorticogram (ECoG) and esophageal electromyogram electrodes. After a 2-h control period, fetuses were given lateral ventricle injection of NO synthase inhibitor nitro-L-arginine methyl ester (L-NAME) and monitored for 2 h. NO precursor L-arginine was then injected into the lateral ventricle, and fetuses were monitored for a final 2 h. All fetuses received an additional control study of fetal swallowing before and after lateral ventricle injection of artificial cerebrospinal fluid (aCSF). Data were analyzed with repeated-measures ANOVA and paired t-test (P < 0.05). Suppression of a central NO with central L-NAME significantly reduced mean (+/-SE) spontaneous fetal swallowing (1.2 +/- 0.1-0.6 +/- 0.1 swallows/min low-voltage ECoG; P < 0.01). Restoration of central NO by L-arginine significantly increased fetal swallowing to pre-L-NAME levels (1.2 +/- 0.1 swallows/min low voltage). There were no changes in fetal swallowing during the control study of aCSF. Fetal ECoG activity and blood pressure did not change during the study or control aCSF injection. We conclude that NO is an important neuromodulator of fetal swallowing activity. Central NO synthase activity may contribute to the heightened level of spontaneous fetal swallowing and thus amniotic fluid regulation.
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Affiliation(s)
- M A El-Haddad
- Perinatal Research Laboratories, Harbor/University of California Los Angeles Medical Center, Torrance, California 90502, USA
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Millatt LJ, Abdel-Rahman EM, Siragy HM. Angiotensin II and nitric oxide: a question of balance. REGULATORY PEPTIDES 1999; 81:1-10. [PMID: 10395403 DOI: 10.1016/s0167-0115(99)00027-0] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The vasoconstrictor peptide angiotensin II (Ang II) and the endogenous vasodilator nitric oxide (NO) have many antagonistic effects, as well as influencing each other's production and functioning. In the short-term, Ang II stimulates NO release, thus modulating the vasoconstrictor actions of the peptide. In the long-term, Ang II influences the expression of all three NO synthase (NOS) isoforms, while NO downregulates the Ang II Type I (AT1) receptor, contributing to the protective role of NO in the vasculature. Within the cardiovascular system, Ang II and NO also have antagonistic effects on vascular remodeling and apoptosis. In the kidney, the distribution of the NOS isoforms coincides with the sites of the components of the renin-angiotensin system. NO influences renin secretion from the kidney, and NO-Ang II interactions are important in the control of glomerular and tubular function. In the adrenal gland, NO has been shown to affect Ang II-induced aldosterone synthesis, while in the brain NO appears to influence Ang II-induced drinking behavior, although conflicting data have been reported. In this review, we focus on the diverse ways in which Ang II and NO interact, and on the importance of maintaining a balance between these two important mediators.
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Affiliation(s)
- L J Millatt
- Department of Anesthesiology, University of Virginia, Health Sciences Center, Charlottesville 22908, USA
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Calapai G, Marciano MC, Costantino G, Russo A, Corica F, Sautebin L, Di Rosa M, Caputi AP. Effects of water deprivation and angiotensin II intracerebroventricular administration on brain nitric oxide synthase activity. Eur J Pharmacol 1998; 360:147-54. [PMID: 9851581 DOI: 10.1016/s0014-2999(98)00672-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Intracranial administration of L-arginine causes a reduction of the water intake induced by water deprivation or by intracerebroventricular (i.c.v.) injection of angiotensin II (angiotensin II), through the release of nitric oxide (NO) in the central nervous system. We studied the effects of i.c.v. angiotensin II (120 ng/rat) in association with i.c.v. L-arginine (2.5-10 microg/rat) on blood pressure. We also studied the effects of both peripheral and central angiotensin II injection (1.5-6 mg kg(-1) i.p. and 30-120 ng rat(-1) i.c.v., respectively) on NO synthase activity in the cortex, diencephalon and brainstem, after water deprivation (24 h), conditions producing activation of the renin-angiotensin system. L-arginine dose dependently antagonized the increase in blood pressure induced by i.c.v. angiotensin II (P < 0.001). Peripheral administration of angiotensin II produced a dose-dependent reduction of NO synthase activity in the brainstem and cortex (P < 0.001), but not in the diencephalon. Water deprivation produced similar effects on brain NO synthase activity. Angiotensin II i.c.v. injection caused NO synthase activity reduction in all brain regions studied (P < 0.001). Our findings suggest that NO and angiotensin II could play opposite roles in brain regulation of blood pressure and drinking behaviour.
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Affiliation(s)
- G Calapai
- Institute of Pharmacology, School of Medicine, University of Messina, Italy
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Abstract
Angiotensin (ANG) II is a powerful and phylogenetically widespread stimulus to thirst and sodium appetite. When it is injected directly into sensitive areas of the brain, it causes an immediate increase in water intake followed by a slower increase in NaCl intake. Drinking is vigorous, highly motivated, and rapidly completed. The amounts of water taken within 15 min or so of injection can exceed what the animal would spontaneously drink in the course of its normal activities over 24 h. The increase in NaCl intake is slower in onset, more persistent, and affected by experience. Increases in circulating ANG II have similar effects on drinking, although these may be partly obscured by accompanying rises in blood pressure. The circumventricular organs, median preoptic nucleus, and tissue surrounding the anteroventral third ventricle in the lamina terminalis (AV3V region) provide the neuroanatomic focus for thirst, sodium appetite, and cardiovascular control, making extensive connections with the hypothalamus, limbic system, and brain stem. The AV3V region is well provided with angiotensinergic nerve endings and angiotensin AT1 receptors, the receptor type responsible for acute responses to ANG II, and it responds vigorously to the dipsogenic action of ANG II. The nucleus tractus solitarius and other structures in the brain stem form part of a negative-feedback system for blood volume control, responding to baroreceptor and volume receptor information from the circulation and sending ascending noradrenergic and other projections to the AV3V region. The subfornical organ, organum vasculosum of the lamina terminalis and area postrema contain ANG II-sensitive receptors that allow circulating ANG II to interact with central nervous structures involved in hypovolemic thirst and sodium appetite and blood pressure control. Angiotensin peptides generated inside the blood-brain barrier may act as conventional neurotransmitters or, in view of the many instances of anatomic separation between sites of production and receptors, they may act as paracrine agents at a distance from their point of release. An attractive speculation is that some are responsible for long-term changes in neuronal organization, especially of sodium appetite. Anatomic mismatches between sites of production and receptors are less evident in limbic and brain stem structures responsible for body fluid homeostasis and blood pressure control. Limbic structures are rich in other neuroactive peptides, some of which have powerful effects on drinking, and they and many of the classical nonpeptide neurotransmitters may interact with ANG II to augment or inhibit drinking behavior. Because ANG II immunoreactivity and binding are so widely distributed in the central nervous system, brain ANG II is unlikely to have a role as circumscribed as that of circulating ANG II. Angiotensin peptides generated from brain precursors may also be involved in functions that have little immediate effect on body fluid homeostasis and blood pressure control, such as cell differentiation, regeneration and remodeling, or learning and memory. Analysis of the mechanisms of increased drinking caused by drugs and experimental procedures that activate the renal renin-angiotensin system, and clinical conditions in which renal renin secretion is increased, have provided evidence that endogenously released renal renin can generate enough circulating ANG II to stimulate drinking. But it is also certain that other mechanisms of thirst and sodium appetite still operate when the effects of circulating ANG II are blocked or absent, although it is not known whether this is also true for angiotensin peptides formed in the brain. Whether ANG II should be regarded primarily as a hormone released in hypovolemia helping to defend the blood volume, a neurotransmitter or paracrine agent with a privileged role in the neural pathways for thirst and sodium appetite of all kinds, a neural organizer especially in sodium appetit
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Zhu B, Herbert J. Calcium channels mediate angiotensin II-induced drinking behaviour and c-fos expression in the brain. Brain Res 1997; 778:206-14. [PMID: 9462893 DOI: 10.1016/s0006-8993(97)01091-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
It is widely accepted that calcium ions are critically important in both short- and/or long-lasting responses of neurons to a stimulus. We have shown previously that NMDA receptors play a role in dipsogenic responses and c-fos expression induced by intracerebroventricular (i.c.v.) infusion of angiotensin II (Ang II). Since NMDA receptors are known to be linked to receptor-operated calcium channels, this study determined whether voltage dependent calcium channels are also involved in Ang II-induced behavioural (drinking) and endocrine responses as well as c-fos expression. The antidipsogenic actions of three L-type calcium channel antagonists, nifedipine, diltiazem and verapamil on Ang II-induced drinking behaviour were studied. These bind to the dihydropyridine, phenylalkylamine and benzothiazepine sites respectively. Rats (Lister-hooded) pre-treated i.c.v. with either 25 or 100 microg nifedipine, followed by 25 pmol Ang II, drank significantly less water than controls during the first 15 min after infusion. However, rats pre-treated with i.c.v. 100 microg diltiazem or verapamil showed no change in Ang II-induced drinking behaviour. The antidipsogenic actions of N- and P-type calcium channel antagonists omega-conotoxin GVIA and omega-conotoxin MVIIC were also evaluated. Rats pre-treated with 5 pmol or 20 pmol omega-conotoxin GVIA did show a slight but not significant suppression of water intake, particularly after the higher dose. Rats pre-treated with omega-conotoxin MVIIC drank almost the same amount of water as those pre-treated with saline. Nifedipine was found to suppress both Ang II-induced corticosterone release and c-fos expression in the following areas: organum vasculosum of the lamina terminalis (OVLT), median preoptic nucleus (MNPO), hypothalamic paraventricular nucleus (PVN) and supraoptic nucleus (SON). The results described in this paper provide evidence that calcium channels play important roles in the Ang II-induced behavioural and endocrine responses, and in the expression of the immediate-early gene c-fos. This suggests that an L-type calcium channel may participate both short- and longer-term neuronal actions of Ang II.
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Affiliation(s)
- B Zhu
- Department of Anatomy and MRC Cambridge Centre for Brain Repair, University of Cambridge, UK
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