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Clinical Journal of the American... May 2015Alterations in water homeostasis can disturb cell size and function. Although most cells can internally regulate cell volume in response to osmolar stress, neurons are... (Review)
Review
Alterations in water homeostasis can disturb cell size and function. Although most cells can internally regulate cell volume in response to osmolar stress, neurons are particularly at risk given a combination of complex cell function and space restriction within the calvarium. Thus, regulating water balance is fundamental to survival. Through specialized neuronal "osmoreceptors" that sense changes in plasma osmolality, vasopressin release and thirst are titrated in order to achieve water balance. Fine-tuning of water absorption occurs along the collecting duct, and depends on unique structural modifications of renal tubular epithelium that confer a wide range of water permeability. In this article, we review the mechanisms that ensure water homeostasis as well as the fundamentals of disorders of water balance.
Topics: Brain; Cell Size; Diabetes Insipidus; Homeostasis; Humans; Hyponatremia; Kidney Medulla; Kidney Tubules, Collecting; Osmotic Pressure; Sensory Receptor Cells; Thirst; Vasopressins; Water; Water-Electrolyte Balance
PubMed: 25078421
DOI: 10.2215/CJN.10741013 -
Cell Jan 2020The function of central appetite neurons is instructing animals to ingest specific nutrient factors that the body needs. Emerging evidence suggests that individual... (Review)
Review
The function of central appetite neurons is instructing animals to ingest specific nutrient factors that the body needs. Emerging evidence suggests that individual appetite circuits for major nutrients-water, sodium, and food-operate on unique driving and quenching mechanisms. This review focuses on two aspects of appetite regulation. First, we describe the temporal relationship between appetite neuron activity and consumption behaviors. Second, we summarize ingestion-related satiation signals that differentially quench individual appetite circuits. We further discuss how distinct appetite and satiation systems for each factor may contribute to nutrient homeostasis from the functional and evolutional perspectives.
Topics: Animals; Appetite; Appetite Regulation; Brain; Feeding Behavior; Homeostasis; Humans; Hunger; Nervous System Physiological Phenomena; Neurons; Satiation; Sodium; Thirst
PubMed: 31923398
DOI: 10.1016/j.cell.2019.11.040 -
Science (New York, N.Y.) Sep 2017Water deprivation produces a drive to seek and consume water. How neural activity creates this motivation remains poorly understood. We used activity-dependent genetic...
Water deprivation produces a drive to seek and consume water. How neural activity creates this motivation remains poorly understood. We used activity-dependent genetic labeling to characterize neurons activated by water deprivation in the hypothalamic median preoptic nucleus (MnPO). Single-cell transcriptional profiling revealed that dehydration-activated MnPO neurons consist of a single excitatory cell type. After optogenetic activation of these neurons, mice drank water and performed an operant lever-pressing task for water reward with rates that scaled with stimulation frequency. This stimulation was aversive, and instrumentally pausing stimulation could reinforce lever-pressing. Activity of these neurons gradually decreased over the course of an operant session. Thus, the activity of dehydration-activated MnPO neurons establishes a scalable, persistent, and aversive internal state that dynamically controls thirst-motivated behavior.
Topics: Animals; Cell Line; Dehydration; Drinking Behavior; Gene Expression Profiling; Mice; Motivation; Neurons; Optogenetics; Preoptic Area; Single-Cell Analysis; TNF Receptor-Associated Factor 2; Thirst
PubMed: 28912243
DOI: 10.1126/science.aan6747 -
Journal of the International Society of... Oct 2020Despite a substantial body of research, no clear best practice guidelines exist for the assessment of hydration in athletes. Body water is stored in and shifted between... (Review)
Review
BACKGROUND
Despite a substantial body of research, no clear best practice guidelines exist for the assessment of hydration in athletes. Body water is stored in and shifted between different sites throughout the body complicating hydration assessment. This review seeks to highlight the unique strengths and limitations of various hydration assessment methods described in the literature as well as providing best practice guidelines.
MAIN BODY
There is a plethora of methods that range in validity and reliability, including complicated and invasive methods (i.e. neutron activation analysis and stable isotope dilution), to moderately invasive blood, urine and salivary variables, progressing to non-invasive metrics such as tear osmolality, body mass, bioimpedance analysis, and sensation of thirst. Any single assessment of hydration status is problematic. Instead, the recommended approach is to use a combination, which have complementary strengths, which increase accuracy and validity. If methods such as salivary variables, urine colour, vital signs and sensation of thirst are utilised in isolation, great care must be taken due to their lack of sensitivity, reliability and/or accuracy. Detailed assessments such as neutron activation and stable isotope dilution analysis are highly accurate but expensive, with significant time delays due to data analysis providing little potential for immediate action. While alternative variables such as hormonal and electrolyte concentration, bioimpedance and tear osmolality require further research to determine their validity and reliability before inclusion into any test battery.
CONCLUSION
To improve best practice additional comprehensive research is required to further the scientific understanding of evaluating hydration status.
Topics: Absorptiometry, Photon; Blood Physiological Phenomena; Body Mass Index; Body Water; Dehydration; Drinking; Electric Impedance; Hematocrit; Hormones; Humans; Neutron Activation Analysis; Osmolar Concentration; Saliva; Serum; Sodium; Sports; Tears; Thirst; Urinalysis; Vital Signs
PubMed: 33126891
DOI: 10.1186/s12970-020-00381-6 -
Science (New York, N.Y.) Apr 2019Physiological needs produce motivational drives, such as thirst and hunger, that regulate behaviors essential to survival. Hypothalamic neurons sense these needs and...
Physiological needs produce motivational drives, such as thirst and hunger, that regulate behaviors essential to survival. Hypothalamic neurons sense these needs and must coordinate relevant brainwide neuronal activity to produce the appropriate behavior. We studied dynamics from ~24,000 neurons in 34 brain regions during thirst-motivated choice behavior in 21 mice as they consumed water and became sated. Water-predicting sensory cues elicited activity that rapidly spread throughout the brain of thirsty animals. These dynamics were gated by a brainwide mode of population activity that encoded motivational state. After satiation, focal optogenetic activation of hypothalamic thirst-sensing neurons returned global activity to the pre-satiation state. Thus, motivational states specify initial conditions that determine how a brainwide dynamical system transforms sensory input into behavioral output.
Topics: Animals; Choice Behavior; Female; Hypothalamus; Mice; Mice, Inbred C57BL; Neural Pathways; Neurons; Optogenetics; Sensory Receptor Cells; Single-Cell Analysis; Thirst
PubMed: 30948440
DOI: 10.1126/science.aav3932 -
Nature Nov 2023Animals perform flexible goal-directed behaviours to satisfy their basic physiological needs. However, little is known about how unitary behaviours are chosen under...
Animals perform flexible goal-directed behaviours to satisfy their basic physiological needs. However, little is known about how unitary behaviours are chosen under conflicting needs. Here we reveal principles by which the brain resolves such conflicts between needs across time. We developed an experimental paradigm in which a hungry and thirsty mouse is given free choices between equidistant food and water. We found that mice collect need-appropriate rewards by structuring their choices into persistent bouts with stochastic transitions. High-density electrophysiological recordings during this behaviour revealed distributed single neuron and neuronal population correlates of a persistent internal goal state guiding future choices of the mouse. We captured these phenomena with a mathematical model describing a global need state that noisily diffuses across a shifting energy landscape. Model simulations successfully predicted behavioural and neural data, including population neural dynamics before choice transitions and in response to optogenetic thirst stimulation. These results provide a general framework for resolving conflicts between needs across time, rooted in the emergent properties of need-dependent state persistence and noise-driven shifts between behavioural goals.
Topics: Animals; Mice; Brain; Choice Behavior; Food; Goals; Hunger; Neurons; Optogenetics; Reward; Stochastic Processes; Thirst; Time Factors; Water; Models, Neurological
PubMed: 37938783
DOI: 10.1038/s41586-023-06715-z -
Intensive Care Medicine Feb 2014Pain, dyspnea, and thirst are three of the most prevalent, intense, and distressing symptoms of intensive care unit (ICU) patients. In this report, the interdisciplinary... (Review)
Review
PURPOSE
Pain, dyspnea, and thirst are three of the most prevalent, intense, and distressing symptoms of intensive care unit (ICU) patients. In this report, the interdisciplinary Advisory Board of the Improving Palliative Care in the ICU (IPAL-ICU) Project brings together expertise in both critical care and palliative care along with current information to address challenges in assessment and management.
METHODS
We conducted a comprehensive review of literature focusing on intensive care and palliative care research related to palliation of pain, dyspnea, and thirst.
RESULTS
Evidence-based methods to assess pain are the enlarged 0-10 Numeric Rating Scale (NRS) for ICU patients able to self-report and the Critical Care Pain Observation Tool or Behavior Pain Scale for patients who cannot report symptoms verbally or non-verbally. The Respiratory Distress Observation Scale is the only known behavioral scale for assessment of dyspnea, and thirst is evaluated by patient self-report using an 0-10 NRS. Opioids remain the mainstay for pain management, and all available intravenous opioids, when titrated to similar pain intensity end points, are equally effective. Dyspnea is treated (with or without invasive or noninvasive mechanical ventilation) by optimizing the underlying etiological condition, patient positioning and, sometimes, supplemental oxygen. Several oral interventions are recommended to alleviate thirst. Systematized improvement efforts addressing symptom management and assessment can be implemented in ICUs.
CONCLUSIONS
Relief of symptom distress is a key component of critical care for all ICU patients, regardless of condition or prognosis. Evidence-based approaches for assessment and treatment together with well-designed work systems can help ensure comfort and related favorable outcomes for the critically ill.
Topics: Critical Care; Dyspnea; Humans; Intensive Care Units; Pain Management; Pain Measurement; Palliative Care; Quality Improvement; Thirst
PubMed: 24275901
DOI: 10.1007/s00134-013-3153-z -
The American Journal of Case Reports Dec 2021BACKGROUND Diabetes insipidus (DI) is a clinical syndrome characterized by polyuria and polydipsia that result from a deficiency of antidiuretic hormone (ADH), central...
BACKGROUND Diabetes insipidus (DI) is a clinical syndrome characterized by polyuria and polydipsia that result from a deficiency of antidiuretic hormone (ADH), central DI, or resistance to ADH, nephrogenic DI. In otherwise healthy patients with DI, normal thirst mechanism, and free access to water, the thirst system can maintain plasma osmolality in the near-normal range. However, in cases where DI presents with adipsia, cognitive impairment, or restricted access to water, true hypernatremia may occur, leading to severe morbidity and mortality. CASE REPORT We report a case of a 2-year-old boy who had global developmental delay and post-brain debulking surgery involving the hypothalamic region, which resulted in central DI and thirst center dysfunction. We describe the clinical presentation, the current understanding of adipsic DI, and a new practical approach for management. The main guidelines of treatment include (1) fixed desmopressin dosing that allows minimal urinary breakthroughs in-between the doses; (2) timely diaper weight-based replacement of water; (3) bodyweight-based fluid correction 2 times a day, and (4) providing the nutritional and water requirements in a way similar to any healthy child but at fixed time intervals. CONCLUSIONS This plan of management showed good effectiveness in controlling plasma sodium level and volume status of a child with adipsic DI without interfering with his average growth. This home treatment method is practical and readily available, provided that the family remains very adherent.
Topics: Child; Child, Preschool; Diabetes Insipidus; Diabetes Insipidus, Nephrogenic; Diabetes Insipidus, Neurogenic; Diabetes Mellitus; Humans; Hypernatremia; Male; Thirst
PubMed: 34898594
DOI: 10.12659/AJCR.934193 -
Intensive Care Medicine Sep 2014To test an intervention bundle for thirst intensity, thirst distress, and dry mouth, which are among the most pervasive, intense, distressful, unrecognized, and... (Randomized Controlled Trial)
Randomized Controlled Trial
PURPOSE
To test an intervention bundle for thirst intensity, thirst distress, and dry mouth, which are among the most pervasive, intense, distressful, unrecognized, and undertreated symptoms in ICU patients, but for which data-based interventions are lacking.
METHODS
This was a single-blinded randomized clinical trial in three ICUs in a tertiary medical center in urban California. A total of 252 cognitively intact patients reporting thirst intensity (TI) and/or thirst distress (TD) scores ≥3 on 0-10 numeric rating scales (NRS) were randomized to intervention or usual care groups. A research team nurse (RTN#1) obtained patients' pre-procedure TI and TD scores and reports of dry mouth. She then administered a thirst bundle to the intervention group: oral swab wipes, sterile ice-cold water sprays, and a lip moisturizer, or observed patients in the usual care group. RTN#2, blinded to group assignment, obtained post-procedure TI and TD scores. Up to six sessions per patient were conducted across 2 days.
RESULTS
Multilevel linear regression determined that the average decreases in TI and TD scores from pre-procedure to post-procedure were significantly greater in the intervention group (2.3 and 1.8 NRS points, respectively) versus the usual care group (0.6 and 0.4 points, respectively) (p < 0.05). The usual care group was 1.9 times more likely than the intervention group to report dry mouth for each additional session on day 1.
CONCLUSION
This simple, inexpensive thirst bundle significantly decreased ICU patients' thirst and dry mouth and can be considered a practice intervention for patients experiencing thirst.
Topics: Critical Care; Female; Humans; Intensive Care Units; Longitudinal Studies; Male; Middle Aged; Single-Blind Method; Thirst; Xerostomia
PubMed: 24894026
DOI: 10.1007/s00134-014-3339-z -
Physiological Reports Jun 2018Fluid satiation, or quenching of thirst, is a critical homeostatic signal to stop drinking; however, its underlying neurocircuitry is not well characterized.... (Review)
Review
Fluid satiation, or quenching of thirst, is a critical homeostatic signal to stop drinking; however, its underlying neurocircuitry is not well characterized. Cutting-edge genetically encoded tools and techniques are now enabling researchers to pinpoint discrete neuronal populations that control fluid satiation, revealing that hindbrain regions, such as the nucleus of the solitary tract, area postrema, and parabrachial nucleus, primarily inhibit fluid intake. By contrast, forebrain regions such as the lamina terminalis, primarily stimulate thirst and fluid intake. One intriguing aspect of fluid satiation is that thirst is quenched tens of minutes before water reaches the circulation, and the amount of water ingested is accurately calibrated to match physiological needs. This suggests that 'preabsorptive' inputs from the oropharyngeal regions, esophagus or upper gastrointestinal tract anticipate the amount of fluid required to restore fluid homeostasis, and provide rapid signals to terminate drinking once this amount has been consumed. It is likely that preabsorptive signals are carried via the vagal nerve to the hindbrain. In this review, we explore our current understanding of the fluid satiation neurocircuitry, its inputs and outputs, and its interconnections within the brain, with a focus on recent studies of the hindbrain, particularly the parabrachial nucleus.
Topics: Brain; Brain Mapping; Drinking; Homeostasis; Humans; Neural Pathways; Prosencephalon; Rhombencephalon; Satiation; Thirst
PubMed: 29932494
DOI: 10.14814/phy2.13744