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De Luca LA, Laurin M, Menani JV. Control of fluid intake in dehydrated rats and evolution of sodium appetite. Physiol Behav 2024; 284:114642. [PMID: 39032667 DOI: 10.1016/j.physbeh.2024.114642] [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: 12/17/2023] [Revised: 07/04/2024] [Accepted: 07/17/2024] [Indexed: 07/23/2024]
Abstract
The objective of the present work is to examine from a new perspective the existence of causal factors not predicted by the classical theory that thirst and sodium appetite are two distinct motivations. For example, we ask why water deprivation induces sodium appetite, thirst is not "water appetite", and intracellular dehydration potentially causes sodium appetite. Contrary to the classical theory, we suggest that thirst first, and sodium appetite second, designate a temporal sequence underlying the same motivation. The single motivation becomes an "intervenient variable" a concept borrowed from the literature, fully explained in the text, between causes of dehydration (extracellular, intracellular, or both together), and respective behavioral responses subserved by hindbrain-dependent inhibition (e.g., lateral parabrachial nucleus) and forebrain facilitation (e.g., angiotensin II). A corollary is homology between rat sodium appetite and marine teleost thirst-like motivation that we name "protodipsia". The homology argument rests on similarities between behavior (salty water intake) and respective neuroanatomical as well as functional mechanisms. Tetrapod origin in a marine environment provides additional support for the homology. The single motivation hypothesis is also consistent with ingestive behaviors in nature given similarities (e.g., thirst producing brackish water intake) between the behavior of the laboratory rat and wild animals, rodents included. The hypotheses of single motivation and homology might explain why hyperosmotic rats, or eventually any other hyperosmotic tetrapod, shows paradoxical signs of sodium appetite. They might also explain how ingestive behaviors determined by dehydration and subserved by hindbrain inhibitory mechanisms contributed to tetrapod transition from sea to land.
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Affiliation(s)
- Laurival A De Luca
- Department of Physiology & Pathology, School of Dentistry, São Paulo State University (UNESP), 14801-903 Araraquara, São Paulo, Brazil.
| | - Michel Laurin
- CR2P, UMR 7207, CNRS/MNHN/SU, Muséum National d'Histoire Naturelle, Bâtiment de Géologie, CP 48, F-75231 Paris cedex 05, France
| | - José Vanderlei Menani
- Department of Physiology & Pathology, School of Dentistry, São Paulo State University (UNESP), 14801-903 Araraquara, São Paulo, Brazil
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Sodium Homeostasis, a Balance Necessary for Life. Nutrients 2023; 15:nu15020395. [PMID: 36678265 PMCID: PMC9862583 DOI: 10.3390/nu15020395] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 01/09/2023] [Accepted: 01/10/2023] [Indexed: 01/15/2023] Open
Abstract
Body sodium (Na) levels must be maintained within a narrow range for the correct functioning of the organism (Na homeostasis). Na disorders include not only elevated levels of this solute (hypernatremia), as in diabetes insipidus, but also reduced levels (hyponatremia), as in cerebral salt wasting syndrome. The balance in body Na levels therefore requires a delicate equilibrium to be maintained between the ingestion and excretion of Na. Salt (NaCl) intake is processed by receptors in the tongue and digestive system, which transmit the information to the nucleus of the solitary tract via a neural pathway (chorda tympani/vagus nerves) and to circumventricular organs, including the subfornical organ and area postrema, via a humoral pathway (blood/cerebrospinal fluid). Circuits are formed that stimulate or inhibit homeostatic Na intake involving participation of the parabrachial nucleus, pre-locus coeruleus, medial tuberomammillary nuclei, median eminence, paraventricular and supraoptic nuclei, and other structures with reward properties such as the bed nucleus of the stria terminalis, central amygdala, and ventral tegmental area. Finally, the kidney uses neural signals (e.g., renal sympathetic nerves) and vascular (e.g., renal perfusion pressure) and humoral (e.g., renin-angiotensin-aldosterone system, cardiac natriuretic peptides, antidiuretic hormone, and oxytocin) factors to promote Na excretion or retention and thereby maintain extracellular fluid volume. All these intake and excretion processes are modulated by chemical messengers, many of which (e.g., aldosterone, angiotensin II, and oxytocin) have effects that are coordinated at peripheral and central level to ensure Na homeostasis.
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Porcari CY, Cambiasso MJ, Mecawi AS, Caeiro XE, Antunes-Rodrigues J, Vivas LM, Godino A. 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] [Key Words] [MESH Headings] [Grants] [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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Affiliation(s)
- Cintia Y Porcari
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Friuli 2434, Barrio Parque Vélez Sarsfield, Casilla de Correo, 389-5000, 5016, Córdoba, Provincia de Córdoba, Argentina
| | - María J Cambiasso
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Friuli 2434, Barrio Parque Vélez Sarsfield, Casilla de Correo, 389-5000, 5016, Córdoba, Provincia de Córdoba, Argentina
- Departamento de Biología Bucal, Facultad de Odontología, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - André S Mecawi
- Laboratory of Molecular Neuroendocrinology, Department of Biophysics, Paulista Medical School, Federal University of São Paulo, São Paulo, Brazil
| | - Ximena E Caeiro
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Friuli 2434, Barrio Parque Vélez Sarsfield, Casilla de Correo, 389-5000, 5016, Córdoba, Provincia de Córdoba, Argentina
| | - José Antunes-Rodrigues
- Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Sao Paulo, Brazil
| | - Laura M Vivas
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Friuli 2434, Barrio Parque Vélez Sarsfield, Casilla de Correo, 389-5000, 5016, Córdoba, Provincia de Córdoba, Argentina
- Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Andrea Godino
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Friuli 2434, Barrio Parque Vélez Sarsfield, Casilla de Correo, 389-5000, 5016, Córdoba, Provincia de Córdoba, Argentina.
- Facultad de Psicología, Universidad Nacional de Córdoba, Córdoba, Argentina.
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The ability of baroreflex activation to improve blood pressure and resistance vessel function in spontaneously hypertensive rats is dependent on stimulation parameters. Hypertens Res 2021; 44:932-940. [PMID: 33707760 DOI: 10.1038/s41440-021-00639-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 01/26/2021] [Accepted: 01/31/2021] [Indexed: 02/03/2023]
Abstract
Baroreflex activation by electric stimulation of the carotid sinus (CS) effectively lowers blood pressure. However, the degree to which differences between stimulation protocols impinge on cardiovascular outcomes has not been defined. To address this, we examined the effects of short- and long-duration (SD and LD) CS stimulation on hemodynamic and vascular function in spontaneously hypertensive rats (SHRs). We fit animals with miniature electrical stimulators coupled to electrodes positioned around the left CS nerve that delivered intermittent 5/25 s ON/OFF (SD) or 20/20 s ON/OFF (LD) square pulses (1 ms, 3 V, 30 Hz) continuously applied for 48 h in conscious animals. A sham-operated control group was also studied. We measured mean arterial pressure (MAP), systolic blood pressure variability (SBPV), heart rate (HR), and heart rate variability (HRV) for 60 min before stimulation, 24 h into the protocol, and 60 min after stimulation had stopped. SD stimulation reversibly lowered MAP and HR during stimulation. LD stimulation evoked a decrease in MAP that was sustained even after stimulation was stopped. Neither SD nor LD had any effect on SBPV or HRV when recorded after stimulation, indicating no adaptation in autonomic activity. Both the contractile response to phenylephrine and the relaxation response to acetylcholine were increased in mesenteric resistance vessels isolated from LD-stimulated rats only. In conclusion, the ability of baroreflex activation to modulate hemodynamics and induce lasting vascular adaptation is critically dependent on the electrical parameters and duration of CS stimulation.
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Dutra SGV, Paterson A, Monteiro LRN, Greenwood MP, Greenwood MP, Amaral LS, Melo MR, Colombari DSA, Colombari E, Reis LC, Hindmarch CCT, Elias LLK, Antunes-Rodrigues J, Murphy D, Mecawi AS. Physiological and Transcriptomic Changes in the Hypothalamic-Neurohypophysial System after 24 h of Furosemide-Induced Sodium Depletion. Neuroendocrinology 2021; 111:70-86. [PMID: 31955161 DOI: 10.1159/000505997] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 01/17/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS Furosemide is a loop diuretic widely used in clinical practice for the treatment of oedema and hypertension. The aim of this study was to determine physiological and molecular changes in the hypothalamic-neurohypophysial system as a consequence of furosemide-induced sodium depletion. METHODS Male rats were sodium depleted by acute furosemide injection (10 and 30 mg/kg) followed by access to low sodium diet and distilled water for 24 h. The renal and behavioural consequences were evaluated, while blood and brains were collected to evaluate the neuroendocrine and gene expression responses. RESULTS Furosemide treatment acutely increases urinary sodium and water excretion. After 24 h, water and food intake were reduced, while plasma angiotensin II and corticosterone were increased. After hypertonic saline presentation, sodium-depleted rats showed higher preference for salt. Interrogation using RNA sequencing revealed the expression of 94 genes significantly altered in the hypothalamic paraventricular nucleus (PVN) of sodium-depleted rats (31 upregulated and 63 downregulated). Out of 9 genes chosen, 5 were validated by quantitative PCR in the PVN (upregulated: Ephx2, Ndnf and Vwf; downregulated: Caprin2 and Opn3). The same genes were also assessed in the supraoptic nucleus (SON, upregulated: Tnnt1, Mis18a, Nr1d1 and Dbp; downregulated: Caprin2 and Opn3). As a result of these plastic transcriptome changes, vasopressin expression was decreased in PVN and SON, whilst vasopressin and oxytocin levels were reduced in plasma. CONCLUSIONS We thus have identified novel genes that might regulate vasopressin gene expression in the hypothalamus controlling the magnocellular neurons secretory response to body sodium depletion and consequently hypotonic stress.
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Affiliation(s)
- Sabrina G V Dutra
- Department of Physiological Sciences, Federal Rural University of Rio de Janeiro, Seropédica, Brazil
| | - Alex Paterson
- Molecular Neuroendocrinology Research Group, Translational Health Sciences, Bristol Medical School, Bristol, United Kingdom
| | - Livia R N Monteiro
- Department of Physiological Sciences, Federal Rural University of Rio de Janeiro, Seropédica, Brazil
| | - Michael P Greenwood
- Molecular Neuroendocrinology Research Group, Translational Health Sciences, Bristol Medical School, Bristol, United Kingdom
| | - Mingkwan P Greenwood
- Molecular Neuroendocrinology Research Group, Translational Health Sciences, Bristol Medical School, Bristol, United Kingdom
| | - Ludimila S Amaral
- Department of Physiological Sciences, Federal Rural University of Rio de Janeiro, Seropédica, Brazil
| | - Mariana R Melo
- Department of Physiology and Pathology, School of Dentistry, UNESP, São Paulo State University, Araraquara, Brazil
| | - Débora S A Colombari
- Department of Physiology and Pathology, School of Dentistry, UNESP, São Paulo State University, Araraquara, Brazil
| | - Eduardo Colombari
- Department of Physiology and Pathology, School of Dentistry, UNESP, São Paulo State University, Araraquara, Brazil
| | - Luís C Reis
- Department of Physiological Sciences, Federal Rural University of Rio de Janeiro, Seropédica, Brazil
| | - Charles C T Hindmarch
- Queen's Cardiopulmonary Unit, Department of Medicine, Translational Institute of Medicine, Queen's University, Kingston, Ontario, Canada
| | - Lucila L K Elias
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - José Antunes-Rodrigues
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - David Murphy
- Molecular Neuroendocrinology Research Group, Translational Health Sciences, Bristol Medical School, Bristol, United Kingdom
| | - Andre S Mecawi
- Department of Physiological Sciences, Federal Rural University of Rio de Janeiro, Seropédica, Brazil,
- Laboratory of Neuroendocrinology, Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil,
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Domingos-Souza G, Santos-Almeida FM, Meschiari CA, Ferreira NS, Pereira CA, Martinez D, Dias DPM, Silva LEV, Castania JA, Tostes RC, Fazan R. Electrical stimulation of the carotid sinus lowers arterial pressure and improves heart rate variability in L-NAME hypertensive conscious rats. Hypertens Res 2020; 43:1057-1067. [PMID: 32358534 DOI: 10.1038/s41440-020-0448-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 03/03/2020] [Accepted: 03/26/2020] [Indexed: 11/09/2022]
Abstract
We evaluated the effects of long-term (48 h) electrical stimulation of the carotid sinus (CS) in hypertensive rats. L-NAME-treated (10 days) Wistar rats were implanted with a catheter in the femoral artery and a miniaturized electrical stimulator attached to electrodes positioned around the left CS, encompassing the CS nerve. One day after implantation, arterial pressure (AP) was directly recorded in conscious animals for 60 min. Square pulses (1 ms, 3 V, 30 Hz) were applied intermittently (20/20 s ON/OFF) to the CS for 48 h. After the end of stimulation, AP was recorded again. Nonstimulated rats (control group) and rats without electrodes around the CS (sham-operated) were also studied. Next, the animals were decapitated, and segments of mesenteric resistance arteries were removed to study vascular function. After the stimulation period, AP was 16 ± 5 mmHg lower in the stimulated group, whereas sham-operated and control rats showed similar AP between the first and second recording periods. Heart rate variability (HRV) evaluated using time and frequency domain tools and a nonlinear approach (symbolic analysis) suggested that hypertensive rats with electrodes around the CS, stimulated or not, exhibited a shift in cardiac sympathovagal balance towards parasympathetic tone. The relaxation response to acetylcholine in endothelium-intact mesenteric arteries was enhanced in rats that underwent CS stimulation for 48 h. In conclusion, long-term CS stimulation is effective in reducing AP levels, improving HRV and increasing mesenteric vascular relaxation in L-NAME hypertensive rats. Moreover, only the presence of electrodes around the CS is effective in eliciting changes in HRV similar to those observed in stimulated rats.
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Affiliation(s)
- Gean Domingos-Souza
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil. .,Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, 65211, USA.
| | | | - César Arruda Meschiari
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.,Health and Sports Science Center, Federal University of Acre, Rio Branco, AC, Brazil
| | - Nathanne S Ferreira
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Camila A Pereira
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Diana Martinez
- Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, 65211, USA
| | | | - Luiz Eduardo Virgílio Silva
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Jaci Airton Castania
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Rita C Tostes
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Rubens Fazan
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
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Porcari CY, Debarba LK, Amigone JL, Caeiro XE, Reis LC, Cunha TM, Mecawi AS, Elias LL, Antunes-Rodrigues J, Vivas L, Godino A. Brain osmo-sodium sensitive channels and the onset of sodium appetite. Horm Behav 2020; 118:104658. [PMID: 31874139 DOI: 10.1016/j.yhbeh.2019.104658] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 11/14/2019] [Accepted: 12/17/2019] [Indexed: 01/13/2023]
Abstract
The aim of the present study was to determine whether the TRPV1 channel is involved in the onset of sodium appetite. For this purpose, we used TRPV1-knockout mice to investigate sodium depletion-induced drinking at different times (2/24 h) after furosemide administration combined with a low sodium diet (FURO-LSD). In sodium depleted wild type and TRPV1 KO (SD-WT/SD-TPRV1-KO) mice, we also evaluated the participation of other sodium sensors, such as TPRV4, NaX and angiotensin AT1-receptors (by RT-PCR), as well as investigating the pattern of neural activation shown by Fos immunoreactivity, in different nuclei involved in hydromineral regulation. TPRV1 SD-KO mice revealed an increased sodium preference, ingesting a higher hypertonic cocktail in comparison with SD-WT mice. Our results also showed in SD-WT animals that SFO-Trpv4 expression increased 2 h after FURO-LSD, compared to other groups, thus supporting a role of SFO-Trpv4 channels during the hyponatremic state. However, the SD-TPRV1-KO animals did not show this early increase, and maybe as a consequence drank more hypertonic cocktail. Regarding the SFO-NaX channel expression, in both genotypes our findings revealed a reduction 24 h after FURO-LSD. In addition, there was an increase in the OVLT-NaX expression of SD-WT 24 h after FURO-LSD, suggesting the participation of OVLT-NaX channels in the appearance of sodium appetite, possibly as an anticipatory response in order to limit sodium intake and to induce thirst. Our work demonstrates changes in the expression of different osmo‑sodium-sensitive channels at specific nuclei, related to the body sodium status in order to stimulate an adequate drinking.
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Affiliation(s)
- C Y Porcari
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Córdoba, Argentina
| | - L K Debarba
- Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Sao Paulo, Brazil
| | - J L Amigone
- Sección de Bioquímica Clínica, Hospital Privado, Córdoba, Argentina
| | - X E Caeiro
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Córdoba, Argentina
| | - L C Reis
- Department of Physiological Sciences, Institute of Biological and Health Sciences, Federal Rural University of Rio de Janeiro, Seropédica, Brazil
| | - T M Cunha
- Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Sao Paulo, Brazil
| | - A S Mecawi
- Laboratory of Molecular Neuroendocrinology, Department of Biophysics, Paulista Medical School, Federal University of São Paulo, São Paulo, Brazil
| | - L L Elias
- Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Sao Paulo, Brazil
| | - J Antunes-Rodrigues
- Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Sao Paulo, Brazil
| | - L Vivas
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Córdoba, Argentina; Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - A Godino
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Córdoba, Argentina; Facultad de Psicología, Universidad Nacional de Córdoba, Córdoba, Argentina.
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Porcari CY, Araujo IG, Urzedo-Rodrigues L, De Luca LA, Menani JV, Caeiro XE, Imboden H, Antunes-Rodrigues J, Reis LC, Vivas L, Godino A, Mecawi AS. Whole body sodium depletion modifies AT1 mRNA expression and serotonin content in the dorsal raphe nucleus. J Neuroendocrinol 2019; 31:e12703. [PMID: 30803087 DOI: 10.1111/jne.12703] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 02/19/2019] [Accepted: 02/21/2019] [Indexed: 01/10/2023]
Abstract
Angiotensin II (Ang II) acts on Ang II type 1 (AT1) receptors located in the organum vasculosum and subfornical organ (SFO) of the lamina terminalis as a main facilitatory mechanism of sodium appetite. The brain serotonin (5-HT) system with soma located in the dorsal raphe nucleus (DRN) provides a main inhibitory mechanism. In the present study, we first investigated the existence of Ang II AT1 receptors in serotonergic DRN neurones. Then, we examined whether whole body sodium depletion affects the gene expression of the AT1a receptor subtype and the presumed functional significance of AT1 receptors. Using confocal microscopy, we found that tryptophan hydroxylase-2 and serotonin neurones express AT1 receptors in the DRN. Immunofluorescence quantification showed a significant reduction in 5-HT content but no change in AT1 receptor expression or AT1/5-HT colocalisation in the DRN after sodium depletion. Whole body sodium depletion also significantly increased Agtr1a mRNA expression in the SFO and DRN. Oral treatment with the AT1 receptor antagonist losartan reversed the changes in Agtr1a expression in the SFO but not the DRN. Losartan injection into either the DRN or the mesencephalic aqueduct had no influence on sodium depletion-induced 0.3 mol L-1 NaCl intake. The results indicate the expression of Agtr1a mRNA in the DRN and SFO as a marker of sodium depletion. They also suggest that serotonergic DRN neurones are targets for Ang II. However, the function of their AT1 receptors remains elusive.
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Affiliation(s)
- Cintia Yamila Porcari
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Córdoba, Argentina
| | - Iracema Gomes Araujo
- Department of Physiological Sciences, Institute of Biological and Health Sciences, Federal Rural University of Rio de Janeiro, Seropedica, Brazil
| | - Lilia Urzedo-Rodrigues
- Department of Physiology and Pathology, School of Dentistry-FOAr, São Paulo State University, UNESP, Araraquara, Brazil
| | - Laurival Antonio De Luca
- Department of Physiology and Pathology, School of Dentistry-FOAr, São Paulo State University, UNESP, Araraquara, Brazil
| | - José Vanderlei Menani
- Department of Physiology and Pathology, School of Dentistry-FOAr, São Paulo State University, UNESP, Araraquara, Brazil
| | - Ximena Elizabeth Caeiro
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Córdoba, Argentina
| | - Hans Imboden
- Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - José Antunes-Rodrigues
- Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, Brazil
| | - Luís Carlos Reis
- Department of Physiological Sciences, Institute of Biological and Health Sciences, Federal Rural University of Rio de Janeiro, Seropedica, Brazil
| | - Laura Vivas
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Córdoba, Argentina
- Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Andrea Godino
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Córdoba, Argentina
- Facultad de Psicología, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - André Souza Mecawi
- Department of Biophysics, Paulista School of Medicine, Federal University of São Paulo, São Paulo, Brazil
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Early oxytocin inhibition of salt intake after furosemide treatment in rats? Physiol Behav 2017; 173:34-41. [PMID: 28131863 DOI: 10.1016/j.physbeh.2017.01.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 01/24/2017] [Accepted: 01/24/2017] [Indexed: 11/23/2022]
Abstract
Body fluid homeostasis requires a complex suite of physiological and behavioral processes. Understanding of the role of the central nervous system (CNS) in integrating these processes has been advanced by research employing immunohistochemical techniques to assess responses to a variety of body fluid challenges. Such techniques have revealed sex/estrogen differences in CNS activation in response to hypotension and hypernatremia. In contrast, it has been difficult to conclusively identify specific CNS areas and neurotransmitter systems that are activated by hyponatremia using these techniques. In part, this difficulty is due to the temporal disconnect between the physiological effects of treatments commonly used to deplete body sodium and the behavioral response to such depletion. In some methods, sodium ingestion is delayed in association with increased oxytocin (OT), suggesting an inhibitory role for OT in sodium intake. Urinary sodium loss increases within an hour after treatment with furosemide, a natriuretic-diuretic, but sodium intake is delayed for 18-24h. Accordingly, we hypothesized that acute furosemide-induced sodium loss activates centrally-projecting OT neurons which provide an initial inhibition of sodium intake, and tested this hypothesis in ovariectomized Sprague-Dawley rats with or without estrogen using immunohistochemical methods. Neuronal activation in the hypothalamic paraventricular nuclei (PVN) after administration of furosemide corresponded to the timing of the physiological effects. The activation was not different in estrogen-treated rats, nor did estrogen alter the initial suppression of sodium intake. However, virtually no fos immunoreactive (fos-IR) neurons in the parvocellular PVN were also immunolabeled for OT. Thus, acute sodium loss after furosemide produces neural activation and an early inhibition of sodium intake that does not appear to involve activation of centrally-projecting OT neurons and is not influenced by estrogen.
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Domingos-Souza G, Meschiari CA, Buzelle SL, Callera JC, Antunes-Rodrigues J. Sodium and water intake are not affected by GABAC receptor activation in the lateral parabrachial nucleus of sodium-depleted rats. J Chem Neuroanat 2016; 74:47-54. [PMID: 26970564 DOI: 10.1016/j.jchemneu.2016.03.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 02/13/2016] [Accepted: 03/05/2016] [Indexed: 11/16/2022]
Abstract
The activation of GABAergic receptors, GABAA and GABAB, in the lateral parabrachial nucleus (LPBN) increases water and sodium intake in satiated and fluid-depleted rats. The present study investigated the presence of the GABAC receptor in the LPBN, its involvement in water and sodium intake, and its effects on cardiovascular parameters during the acute fluid depletion induced by furosemide combined with captopril (Furo/Cap). One group of male Wistar rats (290-300g) with bilateral stainless steel LPBN cannulas was used to test the effects of a GABAC receptor agonist and antagonist on the fluid intake and cardiovascular parameters. We investigated the effects of bilateral LPBN injections of trans-4-aminocrotonic acid (TACA) on the intake of water and 0.3M NaCl induced by acute fluid depletion (subcutaneous injection of Furo/Cap). c-Fos expression increased (P<0.05), suggesting LPBN neuronal activation. The injection of different doses of TACA (0.5, 2.0 and 160 nmol) in the LPBN did not change the sodium or water intake in Furo/Cap-treated rats (P>0.05). Treatment with the GABAC receptor antagonist (Z)-3-[(aminoiminomethyl)thio]prop-2-enoic acid sulfate (ZAPA, 10nmol) or with ZAPA (10nmol) plus TACA (160nmol) did not change the sodium or water intake compared with that for vehicle (saline) (P>0.05). Bilateral injections of the GABAC agonist in the LPBN of Furo/Cap-treated rats did not affect the mean arterial pressure (MAP) or heart rate (HR). The GABAC receptor expression in the LPBN was confirmed by the presence of a 50kDa band. Although LPBN neurons might express GABAC receptors, their activation produced no change in water and sodium intake or in the cardiovascular parameters in the acute fluid depletion rats. Therefore, the GABAC receptors in the LPBN might not interfere with fluid and blood pressure regulation.
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Affiliation(s)
- Gean Domingos-Souza
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.
| | - Cesar Arruda Meschiari
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Samyra Lopes Buzelle
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - João Carlos Callera
- Department of Basic Sciences, School of Dentistry, UNESP - Universidade Estadual Paulista, Rodovia, Araçatuba, SP, Brazil
| | - José Antunes-Rodrigues
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
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Godino A, Abate P, Amigone J, Vivas L, Molina J. Prenatal binge-like alcohol exposure alters brain and systemic responses to reach sodium and water balance. Neuroscience 2015; 311:92-104. [DOI: 10.1016/j.neuroscience.2015.10.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 09/28/2015] [Accepted: 10/02/2015] [Indexed: 01/19/2023]
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