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Zhang Y, Pool AH, Wang T, Liu L, Kang E, Zhang B, Ding L, Frieda K, Palmiter R, Oka Y. Parallel neural pathways control sodium consumption and taste valence. Cell 2023; 186:5751-5765.e16. [PMID: 37989313 PMCID: PMC10761003 DOI: 10.1016/j.cell.2023.10.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 09/04/2023] [Accepted: 10/19/2023] [Indexed: 11/23/2023]
Abstract
The hedonic value of salt fundamentally changes depending on the internal state. High concentrations of salt induce innate aversion under sated states, whereas such aversive stimuli transform into appetitive ones under sodium depletion. Neural mechanisms underlying this state-dependent salt valence switch are poorly understood. Using transcriptomics state-to-cell-type mapping and neural manipulations, we show that positive and negative valences of salt are controlled by anatomically distinct neural circuits in the mammalian brain. The hindbrain interoceptive circuit regulates sodium-specific appetitive drive , whereas behavioral tolerance of aversive salts is encoded by a dedicated class of neurons in the forebrain lamina terminalis (LT) expressing prostaglandin E2 (PGE2) receptor, Ptger3. We show that these LT neurons regulate salt tolerance by selectively modulating aversive taste sensitivity, partly through a PGE2-Ptger3 axis. These results reveal the bimodal regulation of appetitive and tolerance signals toward salt, which together dictate the amount of sodium consumption under different internal states.
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Affiliation(s)
- Yameng Zhang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Allan-Hermann Pool
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA; Departments of Neuroscience and Anesthesia and Pain Management and Peter O'Donnell Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Tongtong Wang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Lu Liu
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Elin Kang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Bei Zhang
- Spatial Genomics, Inc., Pasadena, CA, USA
| | - Liang Ding
- Spatial Genomics, Inc., Pasadena, CA, USA
| | | | - Richard Palmiter
- Departments of Biochemistry and Genome Sciences, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Yuki Oka
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.
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2
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Mietlicki-Baase EG, Santollo J, Daniels D. Fluid intake, what's dopamine got to do with it? Physiol Behav 2021; 236:113418. [PMID: 33838203 DOI: 10.1016/j.physbeh.2021.113418] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 03/12/2021] [Accepted: 04/05/2021] [Indexed: 12/27/2022]
Abstract
Maintaining fluid balance is critical for life. The central components that control fluid intake are only partly understood. This contribution to the collection of papers highlighting work by members of the Society for the Study of Ingestive Behavior focuses on the role that dopamine has on fluid intake and describes the roles that various bioregulators can have on thirst and sodium appetite by influencing dopamine systems in the brain. The goal of the review is to highlight areas in need of more research and to propose a framework to guide that research. We hope that this framework will inspire researchers in the field to investigate these interesting questions in order to form a more complete understanding of how fluid intake is controlled.
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Affiliation(s)
- Elizabeth G Mietlicki-Baase
- Department of Exercise and Nutrition Sciences, University at Buffalo, State University of New York, Buffalo, NY 14214, United States; Center for Ingestive Behavior Research, University at Buffalo, State University of New York, Buffalo, NY 14260, United States
| | - Jessica Santollo
- Department of Biology, University of Kentucky, Lexington, KY 40506, United States
| | - Derek Daniels
- Center for Ingestive Behavior Research, University at Buffalo, State University of New York, Buffalo, NY 14260, United States; Department of Psychology, University at Buffalo, State University of New York, Buffalo, NY 14260, United States
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3
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Abstract
The homeostatic need for sodium is one of the strongest motivational drives known in animals. Although the brain regions involved in the sensory detection of sodium levels have been mapped relatively well, data about the neural basis of the motivational properties of salt appetite, including a role for midbrain dopamine cells, have been inconclusive. Here, we employed a combination of fiber photometry, behavioral pharmacology and c-Fos immunohistochemistry to study the involvement of the mesocorticolimbic dopamine system in salt appetite in rats. We observed that sodium deficiency affected the responses of dopaminergic midbrain neurons to salt tasting, suggesting that these neurons encode appetitive properties of sodium. We further observed a significant reduction in the consumption of salt after pharmacological inactivation of the nucleus accumbens (but not the medial prefrontal cortex), and microstructure analysis of licking behavior suggested that this was due to decreased motivation for, but not appreciation of salt. However, this was not dependent on dopaminergic neurotransmission in that area, as infusion of a dopamine receptor antagonist into the nucleus accumbens did not alter salt appetite. We conclude that the nucleus accumbens, but not medial prefrontal cortex, is important for the behavioral expression of salt appetite by mediating its motivational component, but that the switch in salt appreciation after sodium depletion, although detected by midbrain dopamine neurons, must arise from other areas.
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Fortin SM, Roitman MF. Physiological state tunes mesolimbic signaling: Lessons from sodium appetite and inspiration from Randall R. Sakai. Physiol Behav 2016; 178:21-27. [PMID: 27876640 DOI: 10.1016/j.physbeh.2016.11.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 10/31/2016] [Accepted: 11/18/2016] [Indexed: 12/22/2022]
Abstract
Sodium deficit poses a life-threatening challenge to body fluid homeostasis and generates a sodium appetite - the behavioral drive to ingest sodium. Dr. Randall R. Sakai greatly contributed to our understanding of the hormonal responses to negative sodium balance and to the central processing of these signals. Reactivity to the taste of sodium solutions and the motivation to seek and consume sodium changes dramatically with body fluid balance. Here, we review studies that collectively suggest that sodium deficit recruits the mesolimbic system to play a role in the behavioral expression of sodium appetite. The recruitment of the mesolimbic system likely contributes to intense sodium seeking and reinforces sodium consumption observed in deficient animals. Some of the hormones that are released in response to sodium deficit act directly on both dopamine and nucleus accumbens elements. Moreover, the taste of sodium in sodium deficient rats evokes a pattern of dopamine and nucleus accumbens activity that is similar to responses to rewarding stimuli. A very different pattern of activity is observed in non-deficient rats. Given the well-characterized endocrine response to sodium deficit and its central action, sodium appetite becomes an ideal model for understanding the role of mesolimbic signaling in reward, reinforcement and the generation of motivated behavior.
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Affiliation(s)
- Samantha M Fortin
- Department of Psychology and Graduate Program in Neuroscience, University of Illinois at Chicago, 1007 W Harrison St, Chicago, IL 60607, United States
| | - Mitchell F Roitman
- Department of Psychology and Graduate Program in Neuroscience, University of Illinois at Chicago, 1007 W Harrison St, Chicago, IL 60607, United States.
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5
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Abstract
Physiological regulation of sodium and water intake and output is required for the maintenance of homeostasis. The behavioral and neuroendocrine mechanisms that govern fluid and salt balance are highly interdependent, with acute and chronic alterations in renal output tightly balanced by appropriate changes in thirst and, to a lesser extent in humans, sodium appetite. In healthy individuals, these tightly coupled mechanisms maintain extracellular fluid volume and body tonicity within a narrow homeostatic range by initiating ingestive behaviors and the release of hormones necessary to conserve water and sodium within the body. In this review, the factors that determine output of sodium and fluid and those that determine "normal" input (i.e., matched to output) are addressed. For output, individual variability accompanied by dysregulation of homeostatic mechanisms may contribute to acute and/or chronic disease. To illustrate that point, the specific condition of salt-sensitive hypertension is discussed. For input, physical characteristics, physiological phenotypes, genetic and developmental influences, and cultural and environmental factors combine to result in a wide range of individual variability that, in humans, is compensated for by alterations in excretion.
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Affiliation(s)
- Anna E Stanhewicz
- A.E. Stanhewicz and W.L. Kenney are with the Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania, USA.
| | - W Larry Kenney
- A.E. Stanhewicz and W.L. Kenney are with the Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania, USA
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6
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Gold MS, Badgaiyan RD, Blum K. A Shared Molecular and Genetic Basis for Food and Drug Addiction: Overcoming Hypodopaminergic Trait/State by Incorporating Dopamine Agonistic Therapy in Psychiatry. Psychiatr Clin North Am 2015; 38:419-62. [PMID: 26300032 DOI: 10.1016/j.psc.2015.05.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
This article focuses on the shared molecular and neurogenetics of food and drug addiction tied to the understanding of reward deficiency syndrome. Reward deficiency syndrome describes a hypodopaminergic trait/state that provides a rationale for commonality in approaches for treating long-term reduced dopamine function across the reward brain regions. The identification of the role of DNA polymorphic associations with reward circuitry has resulted in new understanding of all addictive behaviors.
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Affiliation(s)
- Mark S Gold
- Departments of Psychiatry & Behavioral Sciences, Keck School of Medicine, University of Southern California, 1975 Zonal Avenue, Los Angeles, CA 90033, USA; Department of Psychiatry, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA; Rivermend Health Scientific Advisory Board, 2300 Windy Ridge Parkway South East, Suite 210S, Atlanta, GA 30339, USA; Drug Enforcement Administration (DEA) Educational Foundation, Washington, DC, USA.
| | - Rajendra D Badgaiyan
- Laboratory of Advanced Radiochemistry and Molecular and Functioning Imaging, Department of Psychiatry, College of Medicine, University of Minnesota, Minneapolis, MN, USA
| | - Kenneth Blum
- Department of Psychiatry, McKnight Brain Institute, University of Florida College of Medicine, Gainesville, FL, USA; Department of Psychiatry, Center for Clinical & Translational Science, Community Mental Health Institute, University of Vermont College of Medicine, University of Vermont, Burlington, VT, USA; Division of Applied Clinical Research, Dominion Diagnostics, LLC, 211 Circuit Drive, North Kingstown, RI 02852, USA; Rivermend Health Scientific Advisory Board, Atlanta, GA, USA
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Hurley SW, Johnson AK. The biopsychology of salt hunger and sodium deficiency. Pflugers Arch 2015; 467:445-56. [PMID: 25572931 PMCID: PMC4433288 DOI: 10.1007/s00424-014-1676-y] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/09/2014] [Accepted: 12/15/2014] [Indexed: 12/14/2022]
Abstract
Sodium is a necessary dietary macromineral that tended to be sparsely distributed in mankind's environment in the past. Evolutionary selection pressure shaped physiological mechanisms including hormonal systems and neural circuits that serve to promote sodium ingestion. Sodium deficiency triggers the activation of these hormonal systems and neural circuits to engage motivational processes that elicit a craving for salty substances and a state of reward when salty foods are consumed. Sodium deficiency also appears to be associated with aversive psychological states including anhedonia, impaired cognition, and fatigue. Under certain circumstances the psychological processes that promote salt intake can become powerful enough to cause "salt gluttony," or salt intake far in excess of physiological need. The present review discusses three aspects of the biopsychology of salt hunger and sodium deficiency: (1) the psychological processes that promote salt intake during sodium deficiency, (2) the effects of sodium deficiency on mood and cognition, and (3) the sensitization of sodium appetite as a possible cause of salt gluttony.
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Affiliation(s)
- Seth W. Hurley
- Department of Psychology, University of Iowa, Iowa City, IA
| | - Alan Kim Johnson
- Department of Psychology, University of Iowa, Iowa City, IA
- Department of Pharmacology, University of Iowa, Iowa City, IA
- Department of Health and Human Physiology, University of Iowa, Iowa City, IA
- Cardiovascular Center, University of Iowa, Iowa City, IA
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McKinley MJ. Adaptive appetites for salted and unsalted food in rats: differential effects of sodium depletion, DOCA, and dehydration. Am J Physiol Regul Integr Comp Physiol 2013; 304:R1149-60. [PMID: 23594615 DOI: 10.1152/ajpregu.00481.2012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Most ingested sodium is contained in food. The aim was to investigate whether sodium depletion, dehydration, or DOCA alters intakes of salted and unsalted foods by rats given choices of two foods: salted (0.2-0.5% Na) and unsalted food containing either similar or different other dietary components. Diuretic-induced (furosemide or acetazolamide, two treatments on successive days) sodium depletion always caused pronounced falls in intake of unsalted food within 24 h, continuing at least another 2 days (e.g., 20.9 ± 1.6 pretreatment to 14.8 ± 1.2, 10.6 ± 1.5, and 14.3 ± 1.3 g/day for 3 days of depletion). Intake and preference for salted food increased after 24-72 h (e.g., 6.5 ± 1.2 pretreatment to 7.1 ± 1.1, 16.4 ± 2.3, and 17.0 ± 1.5 g/day at 1, 2, and 3 days of depletion). Valsartan (10 mg/day) blocked the increased intake of salted food but not the reduced intake of unsalted food. DOCA (2 mg/day) caused equivalent increase and decrease in intakes of salted and unsalted food, respectively. Water-deprived rats reduced intake (e.g., 14.2 ± 3.1 to 3.2 ± 2.0 g/day) of and preference for salted food (e.g., 56 ± 13% to 21 ± 11%) after 2 days of dehydration but did not consistently reduce intake of unsalted food. Total food ingested/day fell in both sodium-depleted and dehydrated rats. Rats regulate intakes of different foods to balance sodium needs, osmoregulatory homeostasis, and energy requirements. Reduced appetite for unsalted food may be a homeostatic response to sodium depletion, which together with subsequent generation of appetite for salted food, drives animals to ingest sodium-containing food, thereby restoring sodium balance.
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Affiliation(s)
- M J McKinley
- Florey Neuroscience Institutes of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia.
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D'Aquila PS, Rossi R, Rizzi A, Galistu A. Possible role of dopamine D1-like and D2-like receptors in behavioural activation and “contingent” reward evaluation in sodium-replete and sodium-depleted rats licking for NaCl solutions. Pharmacol Biochem Behav 2012; 101:99-106. [DOI: 10.1016/j.pbb.2011.12.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 12/05/2011] [Accepted: 12/10/2011] [Indexed: 11/28/2022]
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Loriaux AL, Roitman JD, Roitman MF. Nucleus accumbens shell, but not core, tracks motivational value of salt. J Neurophysiol 2011; 106:1537-44. [PMID: 21697439 DOI: 10.1152/jn.00153.2011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To appropriately respond to an affective stimulus, we must be able to track its value across changes in both the external and internal environment. The nucleus accumbens (NAc) is a critical component of reward circuitry, but recent work suggests that the NAc encodes aversion as well as reward. It remains unknown whether differential NAc activity reflects flexible changes in stimulus value when it is altered due to a change in physiological state. We measured the activity of individual NAc neurons when rats were given intraoral infusions of a hypertonic salt solution (0.45 M NaCl) across multiple sessions in which motivational state was manipulated. This normally nonpreferred taste was made rewarding via sodium depletion, which resulted in a strong motivation to seek out and consume salt. Recordings were made in three conditions: while sodium replete (REP), during acute sodium depletion (DEP), and following replenishment of salt to normal sodium balance (POST). We found that NAc neurons in the shell and core subregions responded differently across the three conditions. In the shell, we observed overall increases in NAc activity when the salt solution was nonpreferred (REP) but decreases when the salt solution was preferred (DEP). In the core, overall activity was significantly altered only after sodium balance was restored (POST). The results lend further support to the selective encoding of affective stimuli by the NAc and suggest that NAc shell is particularly involved in flexibly encoding stimulus value based on motivational state.
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Affiliation(s)
- Amy L Loriaux
- Department of Psychology, University of Illinois at Chicago, Chicago, IL 60607, USA
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11
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Asico L, Zhang X, Jiang J, Cabrera D, Escano CS, Sibley DR, Wang X, Yang Y, Mannon R, Jones JE, Armando I, Jose PA. Lack of renal dopamine D5 receptors promotes hypertension. J Am Soc Nephrol 2010; 22:82-9. [PMID: 21051739 DOI: 10.1681/asn.2010050533] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Disruption of the dopamine D(5) receptor gene in mice increases BP and causes salt sensitivity. To determine the role of renal versus extrarenal D(5) receptors in BP regulation, we performed cross-renal transplantation experiments. BP was similar between wild-type mice and wild-type mice transplanted with wild-type kidneys, indicating that the transplantation procedure did not affect BP. BP was lower among D(5)(-/-) mice transplanted with wild-type kidneys than D(5)(-/-) kidneys, demonstrating that the renal D(5) receptors are important in BP control. BP was higher in wild-type mice transplanted with D(5)(-/-) kidneys than wild-type kidneys but not significantly different from syngenic transplanted D(5)(-/-) mice, indicating the importance of the kidney in the development of hypertension. On a high-salt diet, all mice with D(5)(-/-) kidneys excreted less sodium than mice with wild-type kidneys. Transplantation of a wild-type kidney into a D(5)(-/-) mouse decreased the renal expression of AT(1) receptors and Nox-2. Conversely, transplantation of a D(5)(-/-) kidney into a wild-type mouse increased the expression of both, suggesting that both renal and extrarenal factors are important in the regulation of AT(1) receptor and Nox-2 expression. These results highlight the role of renal D(5) receptors in BP homeostasis and the pathogenesis of hypertension.
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Affiliation(s)
- Laureano Asico
- Children's National Medical Center, Children's Research Institute, 111 Michigan Avenue NW, Washington, D.C., USA
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12
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Jose PA, Soares-da-Silva P, Eisner GM, Felder RA. Dopamine and G protein-coupled receptor kinase 4 in the kidney: role in blood pressure regulation. Biochim Biophys Acta Mol Basis Dis 2010; 1802:1259-67. [PMID: 20153824 DOI: 10.1016/j.bbadis.2010.02.004] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Revised: 02/05/2010] [Accepted: 02/07/2010] [Indexed: 12/11/2022]
Abstract
Complex interactions between genes and environment result in a sodium-induced elevation in blood pressure (salt sensitivity) and/or hypertension that lead to significant morbidity and mortality affecting up to 25% of the middle-aged adult population worldwide. Determining the etiology of genetic and/or environmentally-induced high blood pressure has been difficult because of the many interacting systems involved. Two main pathways have been implicated as principal determinants of blood pressure since they are located in the kidney (the key organ responsible for blood pressure regulation), and have profound effects on sodium balance: the dopaminergic and renin-angiotensin systems. These systems counteract or modulate each other, in concert with a host of intracellular second messenger pathways to regulate sodium and water balance. In particular, the G protein-coupled receptor kinase type 4 (GRK4) appears to play a key role in regulating dopaminergic-mediated natriuresis. Constitutively activated GRK4 gene variants (R65L, A142V, and A486V), by themselves or by their interaction with other genes involved in blood pressure regulation, are associated with essential hypertension and/or salt-sensitive hypertension in several ethnic groups. GRK4γ 142Vtransgenic mice are hypertensive on normal salt intake while GRK4γ 486V transgenic mice develop hypertension only with an increase in salt intake. GRK4 gene variants have been shown to hyperphosphorylate, desensitize, and internalize two members of the dopamine receptor family, the D(1) (D(1)R) and D(3) (D(3)R) dopamine receptors, but also increase the expression of a key receptor of the renin-angiotensin system, the angiotensin type 1 receptor (AT(1)R). Knowledge of the numerous blood pressure regulatory pathways involving angiotensin and dopamine may provide new therapeutic approaches to the pharmacological regulation of sodium excretion and ultimately blood pressure control.
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Affiliation(s)
- Pedro A Jose
- Children's National Medical Center, George Washington University for the Health Sciences, Washington, DC, USA.
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Krause EG, de Kloet AD, Sakai RR. Post-ingestive signals and satiation of water and sodium intake of male rats. Physiol Behav 2010; 99:657-62. [PMID: 20138075 DOI: 10.1016/j.physbeh.2010.01.030] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Revised: 01/23/2010] [Accepted: 01/26/2010] [Indexed: 11/30/2022]
Abstract
This study investigated the role of post-ingestive signals in the satiation of thirst or salt appetite. Post-ingestive signals, defined as those arising from the passage of fluid into the duodenum and proximal jejunum, were manipulated by implanting rats with gastric fistulas. After recovery, rats were water deprived and the following day gastric fistulas were opened (sham-drinking) or closed (control). Deprivation-induced thirst significantly increased water intake with sham-drinking rats consuming four-fold more than controls after 120 min access. Subsequently, rats were given sodium deficient chow for 48 h and the next day were administered furosemide and urine was collected. Twenty-four hours later, gastric fistulas were manipulated and rats were given water and 0.5M NaCl and intakes were measured. After 120 min of access, rats were sacrificed and plasma sodium (pNa) and plasma-renin-activity (PRA) were measured. Furosemide resulted in a loss of 2.2 mEq of sodium in urine and sham-drinking rats consumed significantly more water and 0.5M NaCl when compared to controls. At 120 min sham-drinking rats consumed 7.5 mEq of sodium nearly twice that of controls but had significantly lower pNa and significantly increased PRA. Interestingly, the ratio of water to 0.5M NaCl intake was similar in both groups, with each making a mixture of approximately 0.25 M NaCl. The results suggest that post-ingestive signals are necessary for the satiation of thirst and salt appetite.
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Affiliation(s)
- Eric G Krause
- University of Cincinnati, Department of Psychiatry, Cincinnati, OH 45237, USA.
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14
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Morris MJ, Na ES, Grippo AJ, Johnson AK. The effects of deoxycorticosterone-induced sodium appetite on hedonic behaviors in the rat. Behav Neurosci 2009; 120:571-9. [PMID: 16768609 DOI: 10.1037/0735-7044.120.3.571] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The authors tested the hypothesis that chronic treatment with a dose of deoxycorticosterone acetate (DOCA) known to elicit a robust sodium appetite can negatively affect the hedonic state of rats. Daily treatment with DOCA with no opportunity to ingest saline produced a rightward shift in the midpoint (effective current 50) of lateral hypothalamic self-stimulation (LHSS) current-response functions and reduced intakes of a palatable sucrose solution. Providing rats with 0.3 M saline during DOCA treatment prevented the rightward shift in LHSS response functions and the decrease in sucrose intake. The authors concluded that a chronic sodium appetite, with no opportunity to attenuate the appetite, can elicit a reduced responsiveness to reward.
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Affiliation(s)
- Michael J Morris
- Department of Psychology, Pharmacology, and Exercise Science, and Cardiovascular Center, University of Iowa, Iowa City, IA 52242-1407, USA
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Morris MJ, Na ES, Johnson AK. Salt craving: the psychobiology of pathogenic sodium intake. Physiol Behav 2008; 94:709-21. [PMID: 18514747 PMCID: PMC2491403 DOI: 10.1016/j.physbeh.2008.04.008] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Accepted: 04/02/2008] [Indexed: 01/22/2023]
Abstract
Ionic sodium, obtained from dietary sources usually in the form of sodium chloride (NaCl, common table salt) is essential to physiological function, and in humans salt is generally regarded as highly palatable. This marriage of pleasant taste and physiological utility might appear fortunate--an appealing taste helps to ensure that such a vital substance is ingested. However, the powerful mechanisms governing sodium retention and sodium balance are unfortunately best adapted for an environment in which few humans still exist. Our physiological and behavioral means for maintaining body sodium and fluid homeostasis evolved in hot climates where sources of dietary sodium were scarce. For many reasons, contemporary diets are high in salt and daily sodium intakes are excessive. High sodium consumption can have pathological consequences. Although there are a number of obstacles to limiting salt ingestion, high sodium intake, like smoking, is a modifiable behavioral risk factor for many cardiovascular diseases. This review discusses the psychobiological mechanisms that promote and maintain excessive dietary sodium intake. Of particular importance are experience-dependent processes including the sensitization of the neural systems underlying sodium appetite and the effects of sodium balance on hedonic state and mood. Accumulating evidence suggests that plasticity within the central nervous system as a result of experience with high salt intake, sodium depletion, or a chronic unresolved sodium appetite fosters enduring changes in sodium related appetitive and consummatory behaviors.
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Affiliation(s)
- Michael J Morris
- Department of Psychology, The University of Iowa, Iowa City, IA, 52242-1407, USA
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16
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17
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Geerling JC, Loewy AD. Sodium deprivation and salt intake activate separate neuronal subpopulations in the nucleus of the solitary tract and the parabrachial complex. J Comp Neurol 2007; 504:379-403. [PMID: 17663450 DOI: 10.1002/cne.21452] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Salt intake is an established response to sodium deficiency, but the brain circuits that regulate this behavior remain poorly understood. We studied the activation of neurons in the nucleus of the solitary tract (NTS) and their efferent target nuclei in the pontine parabrachial complex (PB) in rats during sodium deprivation and after salt intake. After 8-day dietary sodium deprivation, immunoreactivity for c-Fos (a neuronal activity marker) increased markedly within the aldosterone-sensitive neurons of the NTS, which express the enzyme 11-beta-hydroxysteroid dehydrogenase type 2 (HSD2). In the PB, c-Fos labeling increased specifically within two sites that relay signals from the HSD2 neurons to the forebrain--the pre-locus coeruleus and the innermost region of the external lateral parabrachial nucleus. Then, 1-2 hours after sodium-deprived rats ingested salt (a hypertonic 3% solution of NaCl), c-Fos immunoreactivity within the HSD2 neurons was virtually eliminated, despite a large increase in c-Fos activation in the surrounding NTS (including the A2 noradrenergic neurons) and area postrema. Also after salt intake, c-Fos activation increased within pontine nuclei that relay gustatory (caudal medial PB) and viscerosensory (rostral lateral PB) information from the NTS to the forebrain. Thus, sodium deficiency and salt intake stimulate separate subpopulations of neurons in the NTS, which then transmit this information to the forebrain via largely separate relay nuclei in the PB complex. These findings offer new perspectives on the roles of sensory information from the brainstem in the regulation of sodium appetite.
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Affiliation(s)
- Joel C Geerling
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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18
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Krause EG, Sakai RR. Richter and sodium appetite: from adrenalectomy to molecular biology. Appetite 2007; 49:353-67. [PMID: 17561308 PMCID: PMC2096615 DOI: 10.1016/j.appet.2007.01.015] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Revised: 01/24/2007] [Accepted: 01/25/2007] [Indexed: 11/24/2022]
Abstract
Nearly three-quarters of a century ago, Curt Richter removed the adrenal glands from rats and noted that the animal's vitality was dependent on its increased consumption of sodium chloride. In doing so, Richter revealed an innate behavioral mechanism that serves to maintain the hydromineral balance of an animal faced with sodium deficit. This experiment and others like it, led to the development of a field of research devoted to the investigation of salt appetite. The following is a discussion of how Richter's initial observations gave birth to an evolving field that incorporates multiple approaches to examine the drive to consume sodium.
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Affiliation(s)
- Eric G Krause
- Department of Psychiatry-North, University of Cincinnati Med CTR, GRI, Building 43/UC-E 212, Cincinnati, OH 45237, USA
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Zhang YL, Zhang HQ, Liu XY, Hua SN, Zhou LB, Yu J, Tan XH. Identification of human dopamine receptors agonists from Chinese herbs. Acta Pharmacol Sin 2007; 28:132-9. [PMID: 17184593 DOI: 10.1111/j.1745-7254.2007.00460.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
AIM To find human dopamine receptors, especially D1-like receptor specific agonists from Chinese herbs as potential antihypertension drug leads. METHODS Two D1-like receptor cell lines carrying a beta-lactamase reporter gene, and a D2 receptor cell line coexpressing a promiscuous G protein G15 were constructed using HEK293 cells. A natural compound library made from fractionated samples of herbal extracts was used for high-throughput screening (HTS) against one of the cell lines, HEK/D5R/CRE-blax. The interested hits were evaluated for their activities against various dopamine receptors. RESULTS Fourteen hits were identified from primary screening, of which 2 of the better hit samples, HD0522 and HD0059, were selected for further material and activity analysis, and to obtain 2 compounds that appeared as 2 single peaks in HPLC, HD0522H01 and HD0059H01. HD0059H01 could activate D1, D2, and D5 receptors, with EC(50 ) values of 2.28 microg/mL, 0.85 microg/mL, and 1.41 microg/mL, respectively. HD0522H01 could only activate D1R and D5R with EC(50 ) values of 2.95 microg/mL and 8.38 microg/mL. CONCLUSION We established cellbased assays for 3 different human dopamine receptors and identified specific agonists HD0522H01 and HD0059H01 through HTS. The specific agonist to D1-like receptors, HD0522H01, may become a new natural product-based drug lead for antihypertension treatment.
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MESH Headings
- Cell Cycle Proteins/genetics
- Cell Cycle Proteins/metabolism
- Cell Line
- DNA, Complementary/genetics
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Drug Evaluation, Preclinical/methods
- Drugs, Chinese Herbal/isolation & purification
- Drugs, Chinese Herbal/pharmacology
- Genes, Tumor Suppressor
- Humans
- Plants, Medicinal/chemistry
- Plasmids/genetics
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- Receptors, Dopamine D1/agonists
- Receptors, Dopamine D1/genetics
- Receptors, Dopamine D1/metabolism
- Receptors, Dopamine D2/agonists
- Receptors, Dopamine D2/genetics
- Receptors, Dopamine D2/metabolism
- Receptors, Dopamine D5/agonists
- Receptors, Dopamine D5/genetics
- Receptors, Dopamine D5/metabolism
- Transfection
- Tumor Suppressor Proteins/genetics
- Tumor Suppressor Proteins/metabolism
- beta-Lactamases/genetics
- beta-Lactamases/metabolism
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Affiliation(s)
- Yi-Lin Zhang
- Graduate School of the Chinese Academy of Sciences, Beijing 100039, China
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20
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Lucas LR, Grillo CA, McEwen BS. Salt appetite in sodium-depleted or sodium-replete conditions: possible role of opioid receptors. Neuroendocrinology 2007; 85:139-47. [PMID: 17483578 DOI: 10.1159/000102536] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2007] [Accepted: 02/22/2007] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS Acute sodium depletion by the combination of pharmacological natriuresis via furosemide administration and a sodium-deficient diet results in a strong induction of salt appetite in rats. Recent evidence suggests that acute furosemide decreases both dopamine uptake and striatal dopamine transporter density and increases enkephalin mRNA levels in the nucleus accumbens (Acb). Therefore, it has been hypothesized that the motivational/attentional circuit in the brain is activated in salt-appetitive rats. METHODS To determine which loci along the dopaminergic circuit are responsible for this behavior, 10-15 min before furosemide-treated adult male Sprague-Dawley rats were allowed 2-hour access to 2% salt solution (2-bottle choice), we pharmacologically blocked dopamine receptor subtype 1 (D1r) and subtype 2 (D2r) with SCH23390 or raclopride, respectively, and stimulated D1r with SKF81297 or D2r with quinpirole in the shell of the Acb (AcbSh). Furthermore, delta opioid receptors were blocked with naltrindole in the AcbSh or ventral tegmental area (VTA). RESULTS We found that microinjections (1 mug) of SCH23390, raclopride, SKF81297, quinpirole, or naltrindole into the AcbSh had no effect. However, infusion of naltrindole into the VTA attenuated salt intake, whereas [D-Ser(2),Leu(5),Thr(6)]-enkephalin had no effect. Additionally, in rats previously primed with furosemide to crave salt in a 'need-free' manner, salt intake was augmented in the VTA and reduced in the AcbSh after infusion of [D-Ser(2),Leu(5),Thr(6)]-enkephalin. CONCLUSION These data provide evidence that mesolimbic opioid systems are involved in the facilitation of salt-appetitive behavior.
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Affiliation(s)
- Louis R Lucas
- Department of Biology, Loyola University Chicago, Chicago, IL 60626, USA.
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21
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Voorhies AC, Bernstein IL. Induction and expression of salt appetite: effects on Fos expression in nucleus accumbens. Behav Brain Res 2006; 172:90-6. [PMID: 16712968 DOI: 10.1016/j.bbr.2006.04.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2005] [Revised: 04/12/2006] [Accepted: 04/17/2006] [Indexed: 11/21/2022]
Abstract
Sodium depletion is a strong natural motivator that creates a pronounced sodium appetite and has been shown to activate neural regions associated with fluid and sodium balance. However, it is not known whether sodium appetite affects the mesolimbic circuitry associated with reward motivation. The present studies examined expression of the immediate early gene Fos in the nucleus accumbens (NAc) as a marker of neuronal activation following the induction and expression of furosemide-induced sodium appetite. During sodium appetite expression, sham-drinking and normal drinking were used to dissociate effects of NaCl taste stimulation from the repletion that follows absorption of sodium. These studies revealed that the combination of NaCl taste stimulation and persistent sodium depletion experienced by sham-drinking animals dramatically activates the NAc, while neither induction nor expression of sodium appetite alone is sufficient to increase Fos expression in this region. Results are discussed in terms of current theories of reward motivation.
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Affiliation(s)
- Ann C Voorhies
- Department of Psychology, Guthrie Hall, University of Washington, P.O. Box 351525, Seattle, WA 98195, USA.
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22
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Clark JJ, Bernstein IL. A role for D2 but not D1 dopamine receptors in the cross-sensitization between amphetamine and salt appetite. Pharmacol Biochem Behav 2006; 83:277-84. [PMID: 16563477 DOI: 10.1016/j.pbb.2006.02.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2005] [Revised: 01/25/2006] [Accepted: 02/10/2006] [Indexed: 10/24/2022]
Abstract
A history of sodium depletions has been found to potentiate the psychomotor as well as the rewarding effects of amphetamine, an indirect dopamine agonist. The present experiments were conducted to further define the role of dopamine receptor subtypes in this cross-sensitization effect. Rats with a history of sodium depletions were found to display psychomotor sensitization to a D2 but not a D1 direct agonist. Cross-sensitization between salt appetite and amphetamine was found to be blocked by a D2 but not a D1 antagonist. Together, these results implicate D2 but not D1 receptor function in the cross-sensitization seen after sodium depletions.
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Roitman MF. Persistent hunger for sodium makes brain stimulation not so sweet: Theoretical comment on Morris et al. (2006). Behav Neurosci 2006; 120:744-7. [PMID: 16768628 DOI: 10.1037/0735-7044.120.3.744] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The rewarding value of a stimulus is not fixed but rather is subjective and can vary with motivational state. M. J. Morris, E. S. Na, A. J. Grippo, and A. K. Johnson (2006) report that generating a prolonged sodium appetite decreases the rewarding value of lateral hypothalamic brain stimulation and sucrose intake. The findings support the idea that a specific motivational state can have strong, nonspecific consequences for reward processing.
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Affiliation(s)
- Mitchell F Roitman
- Department of Psychology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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24
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Geerling JC, Loewy AD. Aldosterone-sensitive neurons in the nucleus of the solitary tract: Efferent projections. J Comp Neurol 2006; 497:223-50. [PMID: 16705681 DOI: 10.1002/cne.20993] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The nucleus of the solitary tract (NTS) contains a subpopulation of neurons that express the enzyme 11-beta-hydroxysteroid dehydrogenase type 2 (HSD2), which makes them uniquely sensitive to aldosterone. These neurons may drive sodium appetite, which is enhanced by aldosterone. Anterograde and retrograde neural tracing techniques were used to reveal the efferent projections of the HSD2 neurons in the rat. First, the anterograde tracer Phaseolus vulgaris leucoagglutinin was used to label axonal projections from the medial NTS. Then, NTS-innervated brain regions were injected with a retrograde tracer, cholera toxin beta subunit, to determine which sites are innervated by the HSD2 neurons. The HSD2 neurons project mainly to the ventrolateral bed nucleus of the stria terminalis (BSTvl), the pre-locus coeruleus (pre-LC), and the inner division of the external lateral parabrachial nucleus (PBel). They also send minor axonal projections to the midbrain ventral tegmental area, lateral and paraventricular hypothalamic nuclei, central nucleus of the amygdala, and periaqueductal gray matter. The HSD2 neurons do not innervate the ventrolateral medulla, a key brainstem autonomic site. Additionally, our tracing experiments confirmed that the BSTvl receives direct axonal projections from the neighboring A2 noradrenergic neurons in the NTS, and from the same pontine sites that receive major inputs from the HSD2 neurons (PBel and pre-LC). The efferent projections of the HSD2 neurons may provide new insights into the brain circuitry responsible for sodium appetite.
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Affiliation(s)
- Joel C Geerling
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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25
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Bek MJ, Wang X, Asico LD, Jones JE, Zheng S, Li X, Eisner GM, Grandy DK, Carey RM, Soares-da-Silva P, Jose PA. Angiotensin-II type 1 receptor-mediated hypertension in D4 dopamine receptor-deficient mice. Hypertension 2005; 47:288-95. [PMID: 16380537 DOI: 10.1161/01.hyp.0000198427.96225.36] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Dopamine receptors are important in systemic blood pressure regulation. D4 receptors are expressed in the kidney and brain, but their role in cardiovascular regulation is unknown. In pentobarbital-anesthetized mice, systolic and diastolic blood pressures were elevated in sixth-generation D4 receptor-deficient (D4(-/-)) mice and in tenth-generation D4(-/-) mice compared with D4 wild-type (D4(+/+)) littermates. The conscious blood pressures measured via a chronic arterial (femoral) catheter or telemetry (carotid) were also higher in D4(-/-) mice than in D4 littermates. Basal renal and plasma renin concentrations were similar in the 2 mouse strains. The protein expression of angiotensin II type 1 receptor was increased in homogenates of kidney (330+/-53%, n=5) and brain (272+/-69%, n=5) of D4(-/-) mice relative to D4(+/+) mice (kidney: 100+/-12%, n=5; brain: 100+/-32%, n=5). The expression of the receptor in renal membrane was also increased in D4(-/-) mice (289+/-28%, n=8) relative to D4(+/+) mice (100+/-14%, n=10). In contrast, the expression in the heart was similar in the 2 strains. Bolus intravenous injection of angiotensin II type 1 receptor antagonist losartan initially decreased mean arterial pressures to a similar degree in D4(-/-) and D4(+/+) littermates. However, the hypotensive effect of losartan dissipated after 10 minutes in D4(+/+) mice, whereas the effect persisted for >45 minutes in D4(-/-) mice. We conclude that the absence of the D(4) receptor increases blood pressure, possibly via increased angiotensin II type 1 receptor expression.
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Affiliation(s)
- Martin J Bek
- Department of Pediatrics, Georgetown University Medical Center, Washington, DC 20057, USA
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26
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Lucas LR, Grillo CA, McEwen BS. Involvement of mesolimbic structures in short-term sodium depletion: in situ hybridization and ligand-binding analyses. Neuroendocrinology 2003; 77:406-15. [PMID: 12845226 DOI: 10.1159/000071312] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2002] [Accepted: 02/24/2003] [Indexed: 11/19/2022]
Abstract
Acute treatment with the diuretic furosemide (Lasix) produces a reduction in plasma Na(+) and volume as well as increased thirst and salt appetite. The resulting hypovolemia stimulates the well-known counter-regulatory physiological response from the renin-angiotensin-aldosterone system. However, the neurochemical players underpinning the behavioral responses of thirst and salt appetite are less clear. Previously, we have reported that salt-replete deoxycorticosterone (DOCA) treatment activates mesolimbic structures associated with reward and goal-seeking behavior. The present study was designed to test whether the same brain regions are affected in a salt-depleted state. In experiment 1, two groups of adult male Sprague-Dawley (SD) rats were injected with Lasix (10 mg/rat, s.c.) and 18 h later were allowed access either to 2% NaCl solution ('Lasix+salt') or only to tap water ('Lasixnosalt') for 2 h. For comparison purposes, a third group received an isotonic saline injection instead of Lasix and was allowed access to the 2% salt solution (Vehicle). All groups were permitted 24 h access to tap water. We found no differences in dynorphin-mRNA levels in any striatal and accumbal regions among any of the treatment groups. However, as found previously in DOCA-treated rats, there were increased enkephalin (ENK)-mRNA and decreased dopamine transporter (DAT) binding levels throughout the striatum in Lasix+salt and decreased ENK-mRNA in Lasixnosalt rats versus Vehicle. In experiment 2, the involvement of the ENKergic and/or dopaminergic system was tested in rats divided into the same three groups described in experiment 1. However, before access to salt or water, the Lasix+salt and the vehicle groups were administered either a delta-opioid, naltrindole or a dopamine D(2) antagonist, raclopride. Only the naltrindole-treated rats showed a blunted intake of salt solution. Thus, these findings along with our neurochemical results suggest that mesolimbic enkephalin might impact salt intake through dopaminergic systems.
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Affiliation(s)
- Louis R Lucas
- Laboratory of Neuroendocrinology, The Rockefeller University, New York, NY 10021, USA.
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27
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Roitman MF, van Dijk G, Thiele TE, Bernstein IL. Dopamine mediation of the feeding response to violations of spatial and temporal expectancies. Behav Brain Res 2001; 122:193-9. [PMID: 11334649 DOI: 10.1016/s0166-4328(01)00189-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The present studies were aimed at further characterizing the role of DA in motivation. Rats, conditioned to expect food in one environment and no food in another, all received food on the test night. Those in the environment in which food was unexpected ate four times as much as those eating where food was expected. The overeating was eliminated by administration of the D2 antagonist raclopride. Another expectancy, timing of light offset in rats entrained to a fixed light--dark cycle, was violated by unexpectedly turning the lights off 1 h early. This provoked an elevation in food intake, which was also eliminated by the administration of raclopride. Feeding in two other situations not involving violation of expectancies (food deprivation; normal light offset) was unaffected by DA antagonism. These findings support the idea that DA signals errors in expectancy and that DA signaling is necessary for certain behavioral responses to unexpected events.
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Affiliation(s)
- M F Roitman
- Program in Neurobiology and Behavior, University of Washington, Box 351525, Guthrie Hall, Seattle, WA 98195, USA
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28
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Dwyer DM, Bennett CH, Mackintosh NJ. Evidence for inhibitory associations between the unique elements of two compound flavours. THE QUARTERLY JOURNAL OF EXPERIMENTAL PSYCHOLOGY. B, COMPARATIVE AND PHYSIOLOGICAL PSYCHOLOGY 2001; 54:97-107. [PMID: 11393938 DOI: 10.1080/713932748] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
In each of two experiments, rats were pre-exposed to two flavoured solutions, saline-lemon and sucrose-lemon. For group ALT, trials with one solution alternated with trials with the other. Group BLK received all trials with one solution in a block, before any trials with the other. An associative theory suggests that the alternating, but not the blocked, schedule would establish an inhibitory association between sucrose and saline. To provide a retardation test of this inhibition, some animals in each group were then given a single pairing of saline and sucrose, experienced sodium depletion, and were finally tested for their consumption of sucrose. Sodium depletion increased consumption of sucrose more in group BLK than in group ALT. In groups given no saline-sucrose pairing, sodium depletion had only a small effect on sucrose consumption, which was the same in both groups. After multiple pairings of saline and sucrose, sodium depletion had an equally large effect on sucrose consumption in both ALT and BLK groups. These results imply that alternating pre-exposure to two compound solutions does establish an inhibitory association between their unique elements, and thus provide support for an associative theory of perceptual learning.
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Affiliation(s)
- D M Dwyer
- University of Cambridge, Downing Street, Cambridge CB2 3EB, UK
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McCaughey SA, Scott TR. Rapid induction of sodium appetite modifies taste-evoked activity in the rat nucleus of the solitary tract. Am J Physiol Regul Integr Comp Physiol 2000; 279:R1121-31. [PMID: 10956274 DOI: 10.1152/ajpregu.2000.279.3.r1121] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sodium-deprived rats develop a salt appetite and show changes in gustatory responses to NaCl in the periphery and brain stem; salt-sensitive neurons respond less to hypertonic NaCl than do corresponding cells in replete controls. By administering DOCA and renin, we generated a need-free sodium appetite quickly enough to permit us to monitor the activity of individual neurons in the nucleus of the solitary tract before and after its creation, permitting a more powerful within-subjects design. Subjects received DOCA pretreatment followed by an intracerebroventricular infusion of renin. In animals that were tested behaviorally, this resulted in elevated intake of 0.5 M NaCl. In neural recordings, renin caused decreased responding to hypertonic NaCl across all neurons and in the salt-sensitive neurons that were most responsive to NaCl before infusion. Most sugar-sensitive cells, in contrast, gave increased phasic responses to NaCl. These results confirm that sodium appetite is accompanied by decreased responding to NaCl in salt-sensitive neurons, complemented by increased activity in sugar-sensitive cells, even when created rapidly and independently of need.
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Affiliation(s)
- S A McCaughey
- Monell Chemical Senses Center, Philadelphia, Pennsylvania 19104, USA.
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30
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Abstract
During the past decade, it has become evident that dopamine plays an important role in the regulation of fluid and electrolyte balance and blood pressure. Dopamine exerts its actions through two families of dopamine receptors, designated D1-like and D2-like, which are identical in the brain and in peripheral tissues. The two D1-like receptors--D1 and D5 receptors--expressed in mammals are linked to stimulation of adenylyl cyclase. The three D2-like receptors--D2, D3, and D4,--are linked to inhibition of adenylyl cyclase. Dopamine affects fluid and electrolyte balance by regulation of renal excretion of electrolytes and water through actions on renal hemodynamics and tubular epithelial transport and by modulation of the secretion and/or action of vasopressin, renin, aldosterone, catecholamines, and endothelin B receptors (ETB) receptors. It also affects fluid and sodium intake by way of "appetite" centers in the brain and alterations of gastrointestinal tract transport. The production of dopamine in neural and non-neural tissues and the presence of receptors in these tissues suggest that dopamine can act in an autocrine or paracrine fashion. This renal autocrine-paracrine function, which becomes most evident during extracellular fluid volume expansion, is lost in essential hypertension and in some animal models of genetic hypertension. This deficit may be caused by abnormalities in renal dopamine production and polymorphisms or abnormal post-translational modification and regulation of dopamine receptor subtypes.
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Affiliation(s)
- P A Jose
- Department of Pediatrics, Georgetown University Medical Center, 3800 Reservoir Road NW, Washington, DC 20007, USA
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31
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Lucas LR, Pompei P, McEwen BS. Correlates of deoxycorticosterone-induced salt appetite behavior and basal ganglia neurochemistry. Ann N Y Acad Sci 2000; 897:423-8. [PMID: 10676469 DOI: 10.1111/j.1749-6632.1999.tb07912.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- L R Lucas
- Laboratory of Neuroendocrinology, Rockefeller University, New York, New York 10021, USA
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32
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Roitman MF, Bernstein IL. Amiloride-sensitive sodium signals and salt appetite: multiple gustatory pathways. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:R1732-8. [PMID: 10362754 DOI: 10.1152/ajpregu.1999.276.6.r1732] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the rat, the ionic specificity of Na+ appetite is thought to rely on amiloride-sensitive Na+ signals conveyed by the chorda tympani (CT) nerve. We evaluated whether robust Na+ appetite relies exclusively on CT-mediated amiloride-sensitive Na+ signals. Amiloride dramatically reduced sham drinking of NaCl (41.9 +/- 9.0 vs. 6.9 +/- 3.7 ml, 0.1 M NaCl without vs. with 100 microM amiloride), which resulted in intake that was not different from intake of a non-Na+ salt solution (8.8 +/- 2.3 ml, 0.15 M KCl). In addition, intake of 0.1 M NaCl in CT-transected (CTX) rats was reduced (35.8 +/- 13.3 vs. 8.67 +/- 3.4 ml, sham-operated vs. CTX rats), but the addition of amiloride (100 microM) further reduced intake in CTX rats (0.5 +/- 0.29 ml). These data support the idea that amiloride-sensitive Na+ channels are the critical gustatory substrate for Na+ identification during Na+ appetite in the rat. However, the data indicate that these amiloride-sensitive signals are not conveyed exclusively by the CT nerve but by an additional afferent pathway.
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Affiliation(s)
- M F Roitman
- Program in Neurobiology and Behavior, University of Washington, Seattle, Washington 98195, USA.
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33
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Roitman MF, Patterson TA, Sakai RR, Bernstein IL, Figlewicz DP. Sodium depletion and aldosterone decrease dopamine transporter activity in nucleus accumbens but not striatum. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:R1339-45. [PMID: 10233025 DOI: 10.1152/ajpregu.1999.276.5.r1339] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Motivated behaviors, including sodium (Na) appetite, are correlated with increased dopamine (DA) transmission in the nucleus accumbens (NAc). DA transporter (DAT) modulation affects DA transmission and may play a role in motivated behaviors. In vivo Na depletion, which reliably induces Na appetite, was correlated with robust decreases in DA uptake via the DAT in the rat NAc with rotating disk electrode voltammetry [1,277 +/- 162 vs. 575 +/- 89 pmol. s-1. g-1; Vmax of transport for control vs. Na-depleted tissue]. Plasma aldosterone (Aldo) levels increase after in vivo Na depletion and contribute to Na appetite. Decreased DAT activity in the NAc was observed after in vitro Aldo treatment (428 +/- 28 vs. 300 +/- 25 pmol. s-1. g-1). Neither treatment affected DAT activity in the striatum. These results suggest that a direct action of Aldo is one possible mechanism by which Na depletion induces a reduction in DAT activity in the NAc. Reduced DAT activity may play a role in generating increased NAc DA transmission during Na appetite, which may underlie the motivating properties of Na for the Na-depleted rat.
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Affiliation(s)
- M F Roitman
- Program in Neurobiology and Behavior, University of Washington, Seattle, Washington 98195, USA.
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