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Baumer-Harrison C, Patel S, Scott KA, Krause EG, de Kloet AD. Optical perturbation of Agtr1a-containing neurons and afferents within the caudal nucleus of the solitary tract modulates sodium intake. Physiol Behav 2024; 284:114624. [PMID: 38959991 DOI: 10.1016/j.physbeh.2024.114624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 06/30/2024] [Accepted: 06/30/2024] [Indexed: 07/05/2024]
Abstract
Angiotensin-II (Ang-II) production is driven by deviations in blood volume and osmolality, and serves the role of regulating blood pressure and fluid intake to maintain cardiovascular and hydromineral homeostasis. These actions are mediated by Ang-II acting on its type 1a receptor (AT1aR) within the central nervous system and periphery. Of relevance, AT1aR are expressed on sensory afferents responsible for conveying cardiovascular information to the nucleus of the solitary tract (NTS). We have previously determined that optical excitation of neurons and vagal afferents within the NTS that express AT1aR (referred to as NTSAT1aR) mimics the perception of increased vascular stretch and induces compensatory responses to restore blood pressure. Here, we test whether NTSAT1aR are also involved in the modulation of water and sodium intake. We directed the light-sensitive excitatory channelrhodopsin-2 (ChR2) or inhibitory halorhodopsin (Halo) to Agtr1a-containing neurons and measured water and sodium chloride (NaCl) intake in the presence and absence of optical stimulation within the NTS during various challenges to fluid homeostasis. Optical perturbation of NTSAT1aR modulates NaCl intake, such that excitation attenuates, whereas inhibition increases intake. This effect is only observed in the water-deprived condition, suggesting that NTSAT1aR are involved in the regulation of sodium intake during an imbalance in both the intracellular and extracellular fluid compartments. Furthermore, optical excitation of NTSAT1aR increases c-Fos expression within oxytocinergic neurons of the paraventricular nucleus of the hypothalamus (PVN), indicating that the regulation of sodium intake by NTSAT1aR may be mediated by oxytocin. Collectively, these results reveal that NTSAT1aR are sufficient and necessary to modulate sodium intake relative to perceived changes in vascular stretch.
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Affiliation(s)
- Caitlin Baumer-Harrison
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL, 32611, United States; Center for Integrative Cardiovascular and Metabolic Diseases, University of Florida, Gainesville, FL, 32611, United States; Center for Smell and Taste, University of Florida, Gainesville, FL, 32611, United States; Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, United States.
| | - Sagar Patel
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL, 32611, United States
| | - Karen A Scott
- Center for Integrative Cardiovascular and Metabolic Diseases, University of Florida, Gainesville, FL, 32611, United States; Department of Pharmacodynamics, College of Pharmacy, University of Florida, 32611, United States; Neuroscience Institute, Georgia State University, Atlanta, GA, 30302, United States
| | - Eric G Krause
- Center for Integrative Cardiovascular and Metabolic Diseases, University of Florida, Gainesville, FL, 32611, United States; Department of Pharmacodynamics, College of Pharmacy, University of Florida, 32611, United States; Neuroscience Institute, Georgia State University, Atlanta, GA, 30302, United States
| | - Annette D de Kloet
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL, 32611, United States; Center for Integrative Cardiovascular and Metabolic Diseases, University of Florida, Gainesville, FL, 32611, United States; Center for Smell and Taste, University of Florida, Gainesville, FL, 32611, United States; Neuroscience Institute, Georgia State University, Atlanta, GA, 30302, United States
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Melo LM, de Barros WA, de Fátima Â, Giusti FCV, Giusti-Paiva A. Exposure to the psychedelic substance 25 H-NBOMe disrupts maternal care in lactating rats and subsequently impairs the social play behavior of the offspring. Behav Brain Res 2024; 465:114924. [PMID: 38423256 DOI: 10.1016/j.bbr.2024.114924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 02/08/2024] [Accepted: 02/25/2024] [Indexed: 03/02/2024]
Abstract
Given the critical role of maternal care in the neurodevelopment of offspring, this study aimed to investigate the effects of the psychedelic substance 25 H-NBOMe on maternal behavior in lactating rats and its subsequent impact on the social and neurodevelopmental behavior of the offspring. We administered two different dosages of 25 H-NBOMe (0.3 mg/kg and 1.0 mg/kg; i,p,) to lactating rats and observed changes in maternal behaviors, such as nest-building and pup retrieval, and in offspring behaviors, including social play. Behavioral assessments were complemented by physiological measurements to rule out general health or nutritional decline. 25 H-NBOMe significantly disrupted maternal behaviors, including nest-building and pup retrieval, without affecting the weight of dams or offspring. Offspring of exposed dams exhibited reduced social play behavior. Higher doses led to more pronounced disruptions, while lower doses, despite not visibly affecting maternal behavior, still impacted offspring behavior, suggesting potential direct effects of 25 H-NBOMe. The study highlights the potential risks associated with the use of 25 H-NBOMe during lactation, emphasizing its detrimental impact on maternal care and offspring development. These findings contribute to understanding the neurobiological effects of psychedelic substances during critical developmental periods and underscore the importance of avoiding their use.
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Affiliation(s)
- Lidia M Melo
- Programa de Pós-Graduação Multicêntrico em Ciências Fisiológicas, Instituto de Ciências Biomédicas, Universidade Federal de Alfenas (Unifal-MG), Alfenas, MG, Brazil
| | - Wellington A de Barros
- Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Ângelo de Fátima
- Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | | | - Alexandre Giusti-Paiva
- Departamento de Ciências Fisiológicas, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
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Molecular neurobiological markers in the onset of sodium appetite. Sci Rep 2022; 12:14224. [PMID: 35987984 PMCID: PMC9392805 DOI: 10.1038/s41598-022-18220-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 08/08/2022] [Indexed: 12/02/2022] Open
Abstract
Sodium appetite is a motivational state involving homeostatic behavior, seeking the ingest of salty substances after sodium loss. There is a temporal dissociation between sodium depletion (SD) and the appearance of sodium appetite. However, the responsible mechanisms for this delay remain poorly elucidated. In the present study, we measured the temporal changes at two and 24 h after SD in the gene expression of key elements within excitatory, inhibitory, and sensory areas implicated in the signaling pathways involved in the onset of sodium appetite. In SD rats, we observed that the expression of critical components within the brain control circuit of sodium appetite, including Angiotensin-type-1 receptor (Agtr1a), Oxytocin-(OXT-NP)-neurophysin-I, and serotonergic-(5HT)-type-2c receptor (Htr2c) were modulated by SD, regardless of time. However, we observed reduced phosphorylation of mitogen-activated protein kinases (MAPK) at the paraventricular nucleus (PVN) and increased oxytocin receptor (Oxtr) mRNA expression at the anteroventral of the third ventricle area (AV3V), at two hours after SD, when sodium appetite is inapparent. At twenty-four hours after SD, when sodium appetite is released, we observed a reduction in the mRNA expression of the transient receptor potential channel 1gene (Trpv1) and Oxtr in the AV3V and the dorsal raphe nucleus, respectively. The results indicate that SD exerts a coordinated timing effect, promoting the appearance of sodium appetite through changes in MAPK activity and lower Trpv1 channel and Oxtr expression that trigger sodium consumption to reestablish the hydroelectrolytic homeostasis.
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Rapid stimulation of sodium intake combining aldosterone into the 4th ventricle and the blockade of the lateral parabrachial nucleus. Neuroscience 2017; 346:94-101. [DOI: 10.1016/j.neuroscience.2017.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 01/04/2017] [Accepted: 01/04/2017] [Indexed: 12/17/2022]
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5
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Importance of the lateral parabrachial nucleus to sodium balance in fluid-depleted rats. Neurosci Res 2016; 111:41-7. [DOI: 10.1016/j.neures.2016.05.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 05/13/2016] [Accepted: 05/17/2016] [Indexed: 11/23/2022]
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Andrade CAF, Andrade-Franzé GMF, De Paula PM, De Luca LA, Menani JV. Role of α2-adrenoceptors in the lateral parabrachial nucleus in the control of body fluid homeostasis. Braz J Med Biol Res 2014; 47:11-8. [PMID: 24519089 PMCID: PMC3932968 DOI: 10.1590/1414-431x20133308] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 10/15/2013] [Indexed: 12/03/2022] Open
Abstract
Central α2-adrenoceptors and the pontine lateral parabrachial nucleus
(LPBN) are involved in the control of sodium and water intake. Bilateral injections
of moxonidine (α2-adrenergic/imidazoline receptor agonist) or
noradrenaline into the LPBN strongly increases 0.3 M NaCl intake induced by a
combined treatment of furosemide plus captopril. Injection of moxonidine into the
LPBN also increases hypertonic NaCl and water intake and reduces oxytocin secretion,
urinary sodium, and water excreted by cell-dehydrated rats, causing a positive sodium
and water balance, which suggests that moxonidine injected into the LPBN deactivates
mechanisms that restrain body fluid volume expansion. Pretreatment with specific
α2-adrenoceptor antagonists injected into the LPBN abolishes the
behavioral and renal effects of moxonidine or noradrenaline injected into the same
area, suggesting that these effects depend on activation of LPBN
α2-adrenoceptors. In fluid-depleted rats, the palatability of sodium is
reduced by ingestion of hypertonic NaCl, limiting intake. However, in rats treated
with moxonidine injected into the LPBN, the NaCl palatability remains high, even
after ingestion of significant amounts of 0.3 M NaCl. The changes in behavioral and
renal responses produced by activation of α2-adrenoceptors in the LPBN are
probably a consequence of reduction of oxytocin secretion and blockade of inhibitory
signals that affect sodium palatability. In this review, a model is proposed to show
how activation of α2-adrenoceptors in the LPBN may affect palatability
and, consequently, ingestion of sodium as well as renal sodium excretion.
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Affiliation(s)
- C A F Andrade
- Departamento de Fisiologia e Patologia, Faculdade de Odontologia, Universidade Estadual Paulista, AraraquaraSP, Brasil, Departamento de Fisiologia e Patologia, Faculdade de Odontologia, Universidade Estadual Paulista, Araraquara, SP, Brasil
| | - G M F Andrade-Franzé
- Departamento de Fisiologia e Patologia, Faculdade de Odontologia, Universidade Estadual Paulista, AraraquaraSP, Brasil, Departamento de Fisiologia e Patologia, Faculdade de Odontologia, Universidade Estadual Paulista, Araraquara, SP, Brasil
| | - P M De Paula
- Departamento de Fisiologia e Patologia, Faculdade de Odontologia, Universidade Estadual Paulista, AraraquaraSP, Brasil, Departamento de Fisiologia e Patologia, Faculdade de Odontologia, Universidade Estadual Paulista, Araraquara, SP, Brasil
| | - L A De Luca
- Departamento de Fisiologia e Patologia, Faculdade de Odontologia, Universidade Estadual Paulista, AraraquaraSP, Brasil, Departamento de Fisiologia e Patologia, Faculdade de Odontologia, Universidade Estadual Paulista, Araraquara, SP, Brasil
| | - J V Menani
- Departamento de Fisiologia e Patologia, Faculdade de Odontologia, Universidade Estadual Paulista, AraraquaraSP, Brasil, Departamento de Fisiologia e Patologia, Faculdade de Odontologia, Universidade Estadual Paulista, Araraquara, SP, Brasil
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Kimura EH, De Oliveira LB, Menani JV, Callera JC. Baclofen into the lateral parabrachial nucleus induces hypertonic sodium chloride intake during cell dehydration. Behav Brain Funct 2013; 9:17. [PMID: 23642235 PMCID: PMC3679877 DOI: 10.1186/1744-9081-9-17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 04/23/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Activation of GABA(B) receptors with baclofen into the lateral parabrachial nucleus (LPBN) induces ingestion of water and 0.3 M NaCl in fluid replete rats. However, up to now, no study has investigated the effects of baclofen injected alone or combined with GABA(B) receptor antagonist into the LPBN on water and 0.3 M NaCl intake in rats with increased plasma osmolarity (rats treated with an intragastric load of 2 M NaCl). Male Wistar rats with stainless steel cannulas implanted bilaterally into the LPBN were used. RESULTS In fluid replete rats, baclofen (0.5 nmol/0.2 μl), bilaterally injected into the LPBN, induced ingestion of 0.3 M NaCl (14.3 ± 4.1 vs. saline: 0.2 ± 0.2 ml/210 min) and water (7.1 ± 2.9 vs. saline: 0.6 ± 0.5 ml/210 min). In cell-dehydrated rats, bilateral injections of baclofen (0.5 and 1.0 nmol/0.2 μl) into the LPBN induced an increase of 0.3 M NaCl intake (15.6 ± 5.7 and 21.5 ± 3.5 ml/210 min, respectively, vs. saline: 1.7 ± 0.8 ml/210 min) and an early inhibition of water intake (3.5 ± 1.4 and 6.7 ± 2.1 ml/150 min, respectively, vs. saline: 9.2 ± 1.4 ml/150 min). The pretreatment of the LPBN with 2-hydroxysaclofen (GABA(B) antagonist, 5 nmol/0.2 μl) potentiated the effect of baclofen on 0.3 M NaCl intake in the first 90 min of test and did not modify the inhibition of water intake induced by baclofen in cell-dehydrated rats. Baclofen injected into the LPBN did not affect blood pressure and heart rate. CONCLUSIONS Thus, injection of baclofen into the LPBN in cell-dehydrated rats induced ingestion of 0.3 M NaCl and inhibition of water intake, suggesting that even in a hyperosmotic situation, the blockade of LPBN inhibitory mechanisms with baclofen is enough to drive rats to drink hypertonic NaCl, an effect independent of changes in blood pressure.
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Affiliation(s)
- Everton H Kimura
- Department of Basic Sciences, School of Dentistry, UNESP - Univ. Estadual Paulista, Rodovia Marechal Rondom, km 527, Araçatuba, São Paulo 16018-805, Brazil
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Antunes-Rodrigues J, Ruginsk SG, Mecawi AS, Margatho LO, Cruz JC, Vilhena-Franco T, Reis WL, Ventura RR, Reis LC, Vivas LM, Elias LLK. Mapping and signaling of neural pathways involved in the regulation of hydromineral homeostasis. Braz J Med Biol Res 2013; 46:327-38. [PMID: 23579631 PMCID: PMC3854407 DOI: 10.1590/1414-431x20132788] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 02/05/2013] [Indexed: 11/22/2022] Open
Abstract
Several forebrain and brainstem neurochemical circuitries interact with
peripheral neural and humoral signals to collaboratively maintain both the
volume and osmolality of extracellular fluids. Although much progress has been
made over the past decades in the understanding of complex mechanisms underlying
neuroendocrine control of hydromineral homeostasis, several issues still remain
to be clarified. The use of techniques such as molecular biology, neuronal
tracing, electrophysiology, immunohistochemistry, and microinfusions has
significantly improved our ability to identify neuronal phenotypes and their
signals, including those related to neuron-glia interactions. Accordingly,
neurons have been shown to produce and release a large number of chemical
mediators (neurotransmitters, neurohormones and neuromodulators) into the
interstitial space, which include not only classic neurotransmitters, such as
acetylcholine, amines (noradrenaline, serotonin) and amino acids (glutamate,
GABA), but also gaseous (nitric oxide, carbon monoxide and hydrogen sulfide) and
lipid-derived (endocannabinoids) mediators. This efferent response, initiated
within the neuronal environment, recruits several peripheral effectors, such as
hormones (glucocorticoids, angiotensin II, estrogen), which in turn modulate
central nervous system responsiveness to systemic challenges. Therefore, in this
review, we shall evaluate in an integrated manner the physiological control of
body fluid homeostasis from the molecular aspects to the systemic and integrated
responses.
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Affiliation(s)
- J Antunes-Rodrigues
- Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil.
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Andrade C, Margatho L, Andrade-Franzé G, De Luca L, Antunes-Rodrigues J, Menani J. Moxonidine into the lateral parabrachial nucleus reduces renal and hormonal responses to cell dehydration. Neuroscience 2012; 208:69-78. [DOI: 10.1016/j.neuroscience.2012.02.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Revised: 02/07/2012] [Accepted: 02/07/2012] [Indexed: 11/27/2022]
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De Oliveira LB, Kimura EH, Callera JC, De Luca LA, Colombari DSA, Menani JV. Baclofen into the lateral parabrachial nucleus induces hypertonic sodium chloride and sucrose intake in rats. Neuroscience 2011; 183:160-70. [PMID: 21419196 DOI: 10.1016/j.neuroscience.2011.02.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 01/12/2011] [Accepted: 02/08/2011] [Indexed: 11/30/2022]
Abstract
GABA(A) and GABA(B) receptors are present in the lateral parabrachial nucleus (LPBN), a pontine area involved with inhibitory mechanisms related to the control of sodium appetite. Activation of GABA(A) receptors in the LPBN induces strong ingestion of 0.3 M sodium chloride (NaCl) in normonatremic and euhydrated rats. In the present study, we investigated the effects of the GABA(B) receptor agonist baclofen, injected alone or combined with GABA(A) or GABA(B) receptor antagonists into the LPBN on 0.3 M NaCl, water, 0.06 M sucrose and food intake in normonatremic and euhydrated rats. Male Holtzman rats with stainless steel cannulas implanted bilaterally in the LPBN were used. In normonatremic and euhydrated rats, bilateral injections of baclofen (0.5 nmol/0.2 μl) into the LPBN induced 0.3 M NaCl (24.0±3.1 vs. saline: 2.0±0.8 ml/240 min) and water intake (10.6±1.4 vs. saline: 3.5±0.7 ml/240 min) in a two-bottle test. Injections of GABA(B) receptor antagonists CGP 35348 (50 nmol/0.2 μl) or 2-hydroxysaclofen (5 nmol/0.2 μl) or GABA(A) receptor antagonist bicuculline (1.6 nmol/0.2 μl) into the LPBN reduced 0.3 M NaCl (14.1±4.7 ml/240 min; 9.97±2.5 ml/210 min; 8.8±5.9 ml/240 min, respectively) and water intake induced by baclofen injected into the LPBN. Baclofen (0.5 nmol/0.2 μl) injected into the LPBN also induced 0.06 M sucrose intake (21.8±5.9 vs. saline: 5.0±2.6 ml/180 min). Urinary volume and sodium excretion had a tendency to decrease after baclofen injection into the LPBN, whereas arterial pressure and food intake were not affected. The results show that baclofen injected into the LPBN, in normonatremic and euhydrated rats, produces a natriorexigenic effect dependent on GABA(A) and GABA(B) receptor activation. The natriorexigenic effect is not secondary to alterations in blood pressure or sodium urinary excretion. In addition, baclofen injected into the LPBN also induces 0.06 M sucrose intake.
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Affiliation(s)
- L B De Oliveira
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, São Paulo, Brazil.
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de Arruda Camargo GMP, de Arruda Camargo LA, Saad WA. On a possible dual role for the lateral septal area 5-HT1A receptor system in the regulation of water intake and urinary excretion. Behav Brain Res 2010; 215:122-8. [DOI: 10.1016/j.bbr.2010.07.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 07/07/2010] [Accepted: 07/09/2010] [Indexed: 11/29/2022]
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Godino A, Margatho LO, Caeiro XE, Antunes-Rodrigues J, Vivas L. Activation of lateral parabrachial afferent pathways and endocrine responses during sodium appetite regulation. Exp Neurol 2010; 221:275-84. [DOI: 10.1016/j.expneurol.2009.11.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 10/05/2009] [Accepted: 11/03/2009] [Indexed: 11/29/2022]
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Margatho LO, Godino A, Oliveira FRT, Vivas L, Antunes-Rodrigues J. Lateral parabrachial afferent areas and serotonin mechanisms activated by volume expansion. J Neurosci Res 2008; 86:3613-21. [DOI: 10.1002/jnr.21806] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Villa PDS, Menani JV, Camargo GMPDA, Camargo LADA, Saad WA. Activation of the serotonergic 5-HT1A receptor in the paraventricular nucleus of the hypothalamus inhibits water intake and increases urinary excretion in water-deprived rats. ACTA ACUST UNITED AC 2008; 150:14-20. [DOI: 10.1016/j.regpep.2008.05.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Revised: 04/30/2008] [Accepted: 05/04/2008] [Indexed: 11/30/2022]
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Cedraz-Mercez PL, Mecawi AS, Lepletier A, Araújo IG, Costa-e-Sousa RH, Rocha FF, Olivares EL, Medeiros MA, Reis LC. Noradrenergic stimulation within midbrain raphe increases electrolyte excretion in rats. Exp Physiol 2007; 92:923-31. [PMID: 17591682 DOI: 10.1113/expphysiol.2007.037317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The present study was carried out to assess the influence of noradrenergic stimulation of the midbrain dorsal (DRN) and median raphe nuclei (MRN) on urinary volume and electrolyte excretion in hydrated rats. Wistar rats were implanted with a guide cannula into the MRN or DRN and then submitted to two intragastric administrations of water in order to attain an increased diuresis. The following treatments were performed. (1) Intra-DRN microinjections of saline (0.2 microl), alpha(1)-adrenergic agonist phenylephrine (PHE, 0.49 and 4.9 nmol in 0.2 microl), alpha(2)-adrenergic antagonist idazoxan (IDZ, 0.42 and 4.2 nmol in 0.2 microl) or the alpha(1)-adrenergic antagonist prazosin (PRZ, 0.24 and 2.4 nmol in 0.2 microl). (2) Intra-MRN microinjections of saline, IDZ (4.2 nmol in 0.2 microl), PHE (4.9 nmol in 0.2 microl) or PRZ (2.4 nmol in 0.2 microl). Urine samples were subsequently collected over 120 min at 20 min intervals for photometric measurement of sodium and potassium. Intra-DRN administration of PHE and IDZ significantly increased the urinary volume, natriuresis and kaliuresis. Intra-DRN microinjection of a higher dose of PRZ reduced the urinary volume and both sodium and potassium excretion. Intra-MRN microinjections of PHE, IDZ or PRZ did not induce any significant effect on urinary volume or electrolyte excretion. These data suggest that the increase of tonic excitatory noradrenergic input conveyed to DRN influences the hydroelectrolyte homeostasis, possibly through 5-HTergic circuitry.
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Affiliation(s)
- P L Cedraz-Mercez
- Department of Physiological Sciences, Biology Institute, Federal Rural University of Rio de Janeiro, BR465, Km 7, 23890-000, Seropédica, RJ, Brazil
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Ruginsk SG, Oliveira FRT, Margatho LO, Vivas L, Elias LLK, Antunes-Rodrigues J. Glucocorticoid modulation of neuronal activity and hormone secretion induced by blood volume expansion. Exp Neurol 2007; 206:192-200. [PMID: 17553493 DOI: 10.1016/j.expneurol.2007.04.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2007] [Revised: 04/02/2007] [Accepted: 04/07/2007] [Indexed: 11/29/2022]
Abstract
The present study evaluated the involvement of glucocorticoid in the activation of vasopressinergic and oxytocinergic neurons of hypothalamic nuclei and plasma levels of vasopressin (AVP), oxytocin (OT), atrial natriuretic peptide (ANP) and corticosterone (CORT) in response to both isotonic and hypertonic blood volume expansion (BVE). Rats were subjected to isotonic (0.15 M NaCl, 2 ml/100 g b.w., i.v.) or hypertonic (0.30 M NaCl, 2 ml/100 g b.w., i.v.) BVE with or without pre-treatment with dexamethasone (1 mg/kg, i.p.). Results showed that isotonic BVE increased OT, ANP and CORT, and decreased AVP plasma levels. On the other hand, hypertonic BVE enhanced AVP, ANP, OT, and CORT plasma concentrations. Both hypertonic and isotonic BVE induced an increase in the number of Fos-OT double-labeled magnocellular neurons in the PVN and SON. Pre-treatment with dexamethasone reduced OT secretion, as well as Fos-OT immunoreactive neurons in response to both isotonic and hypertonic BVE. We also observed that dexamethasone pre-treatment had no effect on AVP secretion in response to hypertonic BVE, although this effect was associated with a blockade of Fos expression in the vasopressinergic magnocellular neurons in the PVN and SON. In conclusion, these data suggest that, not only the rapid OT release from storages, but also the oxytocinergic cellular activation induced by BVE are modulated by glucocorticoids. However, this pattern of response was not observed for AVP cells, suggesting that dexamethasone is not likely to influence rapid release of AVP but seems to modulate the activation of these neurons in response to hypertonic BVE.
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Affiliation(s)
- S G Ruginsk
- Departamento de Fisiologia, Faculdade de Medicina de Ribeirao Preto, Universidade de São Paulo, Brazil
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