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1.
Cell ; 180(1): 25-32, 2020 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-31923398

RESUMO

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.


Assuntos
Apetite/fisiologia , Fome/fisiologia , Sede/fisiologia , Animais , Regulação do Apetite/fisiologia , Encéfalo/fisiologia , Comportamento Alimentar/fisiologia , Homeostase/fisiologia , Humanos , Fenômenos Fisiológicos do Sistema Nervoso , Neurônios/fisiologia , Saciação/fisiologia , Sódio/metabolismo
2.
Neuron ; 105(6): 1094-1111.e10, 2020 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-31955944

RESUMO

Interoception, the sense of internal bodily signals, is essential for physiological homeostasis, cognition, and emotions. While human insular cortex (InsCtx) is implicated in interoception, the cellular and circuit mechanisms remain unclear. We imaged mouse InsCtx neurons during two physiological deficiency states: hunger and thirst. InsCtx ongoing activity patterns reliably tracked the gradual return to homeostasis but not changes in behavior. Accordingly, while artificial induction of hunger or thirst in sated mice via activation of specific hypothalamic neurons (AgRP or SFOGLUT) restored cue-evoked food- or water-seeking, InsCtx ongoing activity continued to reflect physiological satiety. During natural hunger or thirst, food or water cues rapidly and transiently shifted InsCtx population activity to the future satiety-related pattern. During artificial hunger or thirst, food or water cues further shifted activity beyond the current satiety-related pattern. Together with circuit-mapping experiments, these findings suggest that InsCtx integrates visceral-sensory signals of current physiological state with hypothalamus-gated amygdala inputs that signal upcoming ingestion of food or water to compute a prediction of future physiological state.


Assuntos
Córtex Cerebral/fisiologia , Fome/fisiologia , Interocepção/fisiologia , Sede/fisiologia , Proteína Relacionada com Agouti/metabolismo , Animais , Clozapina/análogos & derivados , Clozapina/farmacologia , Sinais (Psicologia) , Feminino , Hipotálamo/fisiologia , Masculino , Camundongos , Camundongos Transgênicos , Vias Neurais/fisiologia , Imagem Óptica , Optogenética , Órgão Subfornical/fisiologia
3.
Nutrients ; 11(11)2019 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-31703247

RESUMO

The purpose of this study was to examine the perception of thirst as a marker of hydration status following prolonged exercise in the heat. Twelve men (mean ± SD; age, 23 ± 4 y; body mass, 81.4 ± 9.9 kg; height, 182 ± 9 cm; body fat, 14.3% ± 4.7%) completed two 180 min bouts of exercise on a motorized treadmill in a hot environment (35.2 ± 0.6 °C; RH, 30.0 ± 5.4%), followed by a 60 min recovery period. Participants completed a euhydrated (EUH) and hypohydrated (HYPO) trial. During recovery, participants were randomly assigned to either fluid replacement (EUHFL and HYPOFL; 10 min ad libitum consumption) or no fluid replacement (EUHNF and HYPONF). Thirst was measured using both a nine-point scale and separate visual analog scales. The percent of body mass loss (%BML) was significantly greater immediately post exercise in HYPO (HYPOFL, 3.0% ± 1.2%; HYPONF, 2.6% ± 0.6%) compared to EUH (EUHFL, 0.2% ± 0.7%; EUHNF, 0.6% ± 0.5%) trials (p < 0.001). Following recovery, there were no differences in %BML between HYPOFL and HYPONF (p > 0.05) or between EUHFL and EUHNF (p > 0.05). Beginning at minute 5 during the recovery period, thirst perception was significantly greater in HYPONF than EUHFL, EUHNF, and HYPOFL (p < 0.05). A 10 min, ad libitum consumption of fluid post exercise when hypohydrated (%BML > 2%), negated differences in perception of thirst between euhydrated and hypohydrated trials. These results represent a limitation in the utility of thirst in guiding hydration practices.


Assuntos
Desidratação , Exercício Físico/fisiologia , Sede/fisiologia , Adulto , Biomarcadores , Desidratação/diagnóstico , Desidratação/fisiopatologia , Hidratação , Temperatura Alta , Humanos , Adulto Jovem
4.
Nat Neurosci ; 22(12): 2029-2039, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31659341

RESUMO

Motivational states modulate how animals value sensory stimuli and engage in goal-directed behaviors. The motivational states of thirst and hunger are represented in the brain by shared and unique neuromodulatory systems. However, it is unclear how such systems interact to coordinate the expression of appropriate state-specific behavior. We show that the activity of two brain neurons expressing leucokinin neuropeptide is elevated in thirsty and hungry flies, and that leucokinin release is necessary for state-dependent expression of water- and sugar-seeking memories. Leucokinin inhibits two types of mushroom-body-innervating dopaminergic neurons (DANs) to promote thirst-specific water memory expression, whereas it activates other mushroom-body-innervating DANs to facilitate hunger-dependent sugar memory expression. Selection of hunger- or thirst-appropriate memory emerges from competition between leucokinin and other neuromodulatory hunger signals at the level of the DANs. Therefore, coordinated modulation of the dopaminergic system allows flies to prioritize the expression of the relevant state-dependent motivated behavior.


Assuntos
Neurônios Dopaminérgicos/fisiologia , Drosophila , Fome/fisiologia , Memória/fisiologia , Neuropeptídeos/fisiologia , Sede/fisiologia , Animais , Animais Endogâmicos , Comportamento Animal/fisiologia , Sinais (Psicologia) , Feminino , Privação de Alimentos/fisiologia , Masculino , Corpos Pedunculados/fisiologia , Inibição Neural/fisiologia , Neurônios/metabolismo , Neuropeptídeos/metabolismo , Água , Privação de Água/fisiologia
5.
BMJ Case Rep ; 12(9)2019 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-31494590

RESUMO

A 40-year-old Caucasian man developed excessive thirst and polyuria particularly at night over the preceding 6 months. He had been taking lithium for 16 years for the treatment of bipolar affective disorder. Investigations revealed subnormal maximum urinary concentrating ability after 8 hours of water deprivation and only a borderline response of urine osmolality to exogenous desmopressin given by intramuscular injection. A plasma copeptin concentration was elevated at 23 pmol/L. These results were consistent with partial nephrogenic diabetes insipidus. He was encouraged to increase his water intake as dictated by his thirst. In addition, he received amiloride with some improvement in his symptoms. Clinicians should be aware of the risk of nephrogenic diabetes insipidus with long-term lithium use and seek confirmation by a supervised water deprivation test augmented with a baseline plasma copeptin. If increased water intake is insufficient to control symptoms, amiloride may be considered.


Assuntos
Amilorida/uso terapêutico , Antidepressivos/uso terapêutico , Transtorno Bipolar/tratamento farmacológico , Diabetes Insípido Nefrogênico/tratamento farmacológico , Capacidade de Concentração Renal/efeitos dos fármacos , Lítio/uso terapêutico , Sede/fisiologia , Adulto , Antidepressivos/efeitos adversos , Transtorno Bipolar/fisiopatologia , Diabetes Insípido Nefrogênico/induzido quimicamente , Diabetes Insípido Nefrogênico/fisiopatologia , Humanos , Lítio/efeitos adversos , Masculino , Concentração Osmolar , Poliúria , Resultado do Tratamento , Privação de Água
6.
Med Hypotheses ; 129: 109225, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31371074

RESUMO

The multitude of terms associated with love has given rise to a false perception of love. In this paper, only maternal and romantic love are considered. Love is usually regarded as a feeling, motivation, addiction, passion, and, above all, an emotion. This confusion has consequences in the lives of human beings, leading not only to divorces, suicides, femicides but possibly also to a number of mental illnesses and suffering. Therefore, it is crucial to first clarify what is meant by emotion, motivation and love. This work aims to finally place love within the category of physiological motivations, such as hunger, thirst, sleep, or sex, on the basis that love is also essential for human survival, especially in childhood. Love is presented from an evolutionary perspective. Some other similarities between love and other physiological motivations are pointed out, such as its importance for appropriate human development, both its ontogeny and its permanence, and the long-lasting consequences of abuse and neglect. There are summarized reasons that account for this, such as the fact that physiological motivations are essential for survival and that love is an essential motivation for the survival of human offspring. Other reasons are that minimum changes in the quantity and quality of love alters development, that there can be a variety of neurophysiological and behavioural states within a motivation, and that motivations (also love) appear and change throughout development. Also, motivations and love sometimes may lead to an addictive behaviour. Finally, it is recognized that once physiological motivations (and love) appear, they become permanent. In a third section, some potential social, cultural, clinical and scientific consequences of the proposed consideration of love as a motivation are discussed. Accordingly, love's recognition as a motivation in the clinical field would imply a better understanding of its disorders and its inclusion in classifications manuals such as The Diagnostic and Statistical Manual of Mental Disorders (DSM), or in the International Classification of Diseases (ICD). Considering love as a motivation rather than an emotion could also impact the results of scientific research (an example is included). A comprehensive understanding of these questions could potentially allow for a new therapeutic approach in the treatment of mental illness, while offering an all-inclusive evolutionary explanation of cultural phenomena such as the origin and diffusion of both language and art. Love should be understood as a physiological motivation, like hunger, sleep or sex, and not as an emotion as it is commonly considered.


Assuntos
Fome/fisiologia , Amor , Motivação , Comportamento Sexual , Sono/fisiologia , Sede/fisiologia , Características Culturais , Emoções/fisiologia , Humanos , Modelos Biológicos , Modelos Teóricos , Relações Mãe-Filho , Percepção , Comportamento Social
7.
Science ; 364(6437): 253, 2019 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-30948440

RESUMO

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.


Assuntos
Comportamento de Escolha/fisiologia , Hipotálamo/citologia , Hipotálamo/fisiologia , Vias Neurais/fisiologia , Sede/fisiologia , Animais , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/fisiologia , Optogenética , Células Receptoras Sensoriais/fisiologia , Análise de Célula Única
8.
Nature ; 568(7750): 98-102, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30918408

RESUMO

Satiation is the process by which eating and drinking reduce appetite. For thirst, oropharyngeal cues have a critical role in driving satiation by reporting to the brain the volume of fluid that has been ingested1-12. By contrast, the mechanisms that relay the osmolarity of ingested fluids remain poorly understood. Here we show that the water and salt content of the gastrointestinal tract are precisely measured and then rapidly communicated to the brain to control drinking behaviour in mice. We demonstrate that this osmosensory signal is necessary and sufficient for satiation during normal drinking, involves the vagus nerve and is transmitted to key forebrain neurons that control thirst and vasopressin secretion. Using microendoscopic imaging, we show that individual neurons compute homeostatic need by integrating this gastrointestinal osmosensory information with oropharyngeal and blood-borne signals. These findings reveal how the fluid homeostasis system monitors the osmolarity of ingested fluids to dynamically control drinking behaviour.


Assuntos
Encéfalo/fisiologia , Ingestão de Líquidos/fisiologia , Trato Gastrointestinal/fisiologia , Neurônios/fisiologia , Saciação/fisiologia , Sede/fisiologia , Animais , Encéfalo/citologia , Feminino , Neurônios GABAérgicos/metabolismo , Trato Gastrointestinal/inervação , Glutamatos/metabolismo , Masculino , Camundongos , Orofaringe/inervação , Orofaringe/fisiologia , Concentração Osmolar , Prosencéfalo/metabolismo , Nervo Vago/fisiologia , Vasopressinas/metabolismo
9.
Annu Rev Physiol ; 81: 359-373, 2019 02 10.
Artigo em Inglês | MEDLINE | ID: mdl-30742785

RESUMO

Recent experiments using optogenetic tools facilitate the identification and functional analysis of thirst neurons and vasopressin-producing neurons. Four major advances provide a detailed anatomy and physiology of thirst, taste for water, and arginine-vasopressin (AVP) release: ( a) Thirst and AVP release are regulated by the classical homeostatic, interosensory plasma osmolality negative feedback as well as by novel, exterosensory, anticipatory signals. These anticipatory signals for thirst and vasopressin release concentrate on the same homeostatic neurons and circumventricular organs that monitor the composition of blood. ( b) Acid-sensing taste receptor cells (TRCs) expressing otopetrin 1 on type III presynaptic TRCs on the tongue, which were previously suggested as the sour taste sensors, also mediate taste responses to water. ( c) Dehydration is aversive, and median preoptic nucleus (MnPO) neuron activity is proportional to the intensity of this aversive state. ( d) MnPOGLP1R neurons serve as a central detector that discriminates fluid ingestion from solid ingestion, which promotes acute satiation of thirst through the subfornical organ and other downstream targets.


Assuntos
Sede/fisiologia , Vasopressinas/fisiologia , Animais , Homeostase/fisiologia , Humanos , Neurônios/fisiologia , Equilíbrio Hidroeletrolítico/fisiologia
10.
N Engl J Med ; 380(5): 459-471, 2019 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-30699320

RESUMO

Well-being requires the maintenance of energy stores, water, and sodium within permissive zones. The brain, as ringleader, orchestrates their homeostatic control. It senses disturbances, decides what needs to be done next, and then restores balance by altering physiological processes and ingestive drives (i.e., hunger, thirst, and salt appetite). But how the brain orchestrates this control has been unknown until recently ­ largely because we have lacked the ability to elucidate and then probe the underlying neuronal "wiring diagrams." This has changed with the advent of new, transformative neuroscientific tools. When targeted to specific neurons, these tools make it possible to selectively map a neuron's connections, measure its responses to various homeostatic challenges, and experimentally manipulate its activity. This review examines these approaches and then highlights how they are advancing, and in some cases profoundly changing, our understanding of energy, water, and salt homeostasis and the linked ingestive drives.


Assuntos
Encéfalo/fisiologia , Impulso (Psicologia) , Homeostase/fisiologia , Fome/fisiologia , Neurônios/fisiologia , Sede/fisiologia , Animais , Encéfalo/anatomia & histologia , Expressão Gênica , Humanos , Natriurese/fisiologia , Neurônios/citologia , Cloreto de Sódio
11.
Front Horm Res ; 52: 8-23, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-32097945

RESUMO

In the evolutionary process, the successful adaptation of living organisms initially to an aqueous and thereafter to an arid terrestrial environment posed radically different challenges to the maintenance of water balance. Whereas the former required defense against water excess, the latter called for water conservation. To meet such challenges, the mammalian nephron evolved mechanisms for increasing both water excretion by diluting and water conservation by concentrating the urine. This chapter reviews the process whereby the osmosensors control thirst and the secretion of the antidiuretic hormone (vasopressin) to allow for either urinary dilution or concentration and thereby delicately maintain tonicity of body fluids within a very narrow range. Central to this process is the now well-defined cellular pathway whereby vasopressin renders the collecting duct, water permeable. Disorders of vasopressin secretion and action result in disturbances of body fluids tonicity, which are clinically recognized as abnormalities in reduced plasma sodium concentration or hyponatremia.


Assuntos
Água Corporal/metabolismo , Homeostase/fisiologia , Hiponatremia/metabolismo , Sede/fisiologia , Urina/fisiologia , Vasopressinas/metabolismo , Animais , Humanos
12.
PLoS One ; 13(9): e0204066, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30212542

RESUMO

Head-fixed behavioral tasks can provide important insights into cognitive processes in rodents. Despite the widespread use of this experimental approach, there is only limited knowledge of how differences in task parameters, such as motivational incentives, affect overall task performance. Here, we provide a detailed methodological description of the setup and procedures for training mice efficiently on a two-choice lick left/lick right visual discrimination task. We characterize the effects of two distinct restriction regimens, i.e. food and water restriction, on animal wellbeing, activity patterns, task acquisition, and performance. While we observed reduced behavioral activity during the period of food and water restriction, the average animal discomfort scores remained in the 'sub-threshold' and 'mild' categories throughout the experiment, irrespective of the restriction regimen. We found that the type of restriction significantly influenced specific aspects of task acquisition and engagement, i.e. the number of sessions until the learning criterion was reached and the number of trials performed per session, but it did not affect maximum learning curve performance. These results indicate that the choice of restriction paradigm does not strongly affect animal wellbeing, but it can have a significant effect on how mice perform in a task.


Assuntos
Comportamento Animal/fisiologia , Comportamento de Escolha/fisiologia , Aprendizagem por Discriminação/fisiologia , Privação de Alimentos/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Sede/fisiologia , Bem-Estar do Animal , Animais , Condicionamento Operante/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Restrição Física/instrumentação , Restrição Física/métodos
13.
PLoS One ; 13(8): e0202793, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30148889

RESUMO

BACKGROUND: Glassware design may affect drinking behaviour for alcoholic beverages, with glass shape and size influencing drinking speed and amount consumed. Uncertainty remains both about the extent to which these effects are restricted to alcohol and the underlying mechanisms. The primary aim of the current study was to examine the effect of differently shaped glasses on time taken to drink a soft drink. The secondary aim was to develop hypotheses about mechanisms concerning micro-drinking behaviours and perceptual effects. METHOD: In a single-session experiment, 162 participants were randomised to receive 330ml of carbonated apple juice in a glass that was either inward-sloped, straight-sided, or outward-sloped. The primary outcome measure was total drinking time. Secondary outcome measures included micro-drinking behaviours (sip size, sip duration, interval duration), and perceptual measures (midpoint bias, drink enjoyment). RESULTS: Participants drank 21.4% faster from the outward-sloped glass than from the straight-sided glass [95%CI: 0.2%,38.0%] in adjusted models. They were also 18.2% faster from the inward-sloped glass than the straight-sided glass, but this did not reach statistical significance with wide confidence intervals also consistent with slower drinking [95%CI: -3.8%,35.6%]. Larger sips were associated with faster drinking times (Pearson's r(162) = -.45, p < .001). The direction of effects suggested sips were larger from the outward-sloped and inward-sloped glasses, compared to the straight-sided glass (15.1%, 95%CI: -4.3%,38.0%; 19.4%, 95%CI: -0.5%,43.6%, respectively). There were no significant differences between glasses in mean sip or interval duration. Bias in midpoint estimation was greater for the outward-sloped glass (12.9ml, 95%CI: 6.6ml,19.2ml) than for the straight-sided glass, although the degree of bias was not associated with total drinking time (Pearson's r(162) = 0.01, p = .87). DISCUSSION: Individuals drank a soft drink more quickly from an outward-sloped glass, relative to a straight-sided glass. Micro-drinking behaviours, such as sip size, are promising candidates for underlying mechanisms.


Assuntos
Bebidas Gaseificadas , Ingestão de Líquidos/fisiologia , Vidro/análise , Adulto , Feminino , Humanos , Masculino , Fatores Sexuais , Temperatura , Sede/fisiologia , Adulto Jovem
14.
PLoS Genet ; 14(8): e1007618, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-30138334

RESUMO

Animals need to continuously adjust their water metabolism to the internal and external conditions. Homeostasis of body fluids thus requires tight regulation of water intake and excretion, and a balance between ingestion of water and solid food. Here, we investigated how these processes are coordinated in Drosophila melanogaster. We identified the first thirst-promoting and anti-diuretic hormone of Drosophila, encoded by the gene Ion transport peptide (ITP). This endocrine regulator belongs to the CHH (crustacean hyperglycemic hormone) family of peptide hormones. Using genetic gain- and loss-of-function experiments, we show that ITP signaling acts analogous to the human vasopressin and renin-angiotensin systems; expression of ITP is elevated by dehydration of the fly, and the peptide increases thirst while repressing excretion, promoting thus conservation of water resources. ITP responds to both osmotic and desiccation stress, and dysregulation of ITP signaling compromises the fly's ability to cope with these stressors. In addition to the regulation of thirst and excretion, ITP also suppresses food intake. Altogether, our work identifies ITP as an important endocrine regulator of thirst and excretion, which integrates water homeostasis with feeding of Drosophila.


Assuntos
Proteínas de Drosophila/fisiologia , Drosophila melanogaster/genética , Homeostase , Neuropeptídeos/fisiologia , Sede/fisiologia , Animais , Proteínas de Drosophila/genética , Feminino , Trato Gastrointestinal/fisiologia , Regulação da Expressão Gênica , Fome , Masculino , Neuropeptídeos/genética , Transdução de Sinais , Estresse Fisiológico , Água
15.
Physiol Behav ; 194: 233-238, 2018 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-29885324

RESUMO

There is general consensus that drinking water facilitates certain cognitive processes. However, it is not yet known what mechanism underlies the effect of drinking on performance and these may be different for different cognitive processes. We sought to elucidate the mechanisms involved by establishing at what stage of the drinking process cognitive performance is influenced. We examined the effect of mouth rinsing and mouth drying on subjective thirst and mood, visual attention and short term memory in children. Data are reported from 24 children aged 9- to 10-years. Children's performance was assessed in three conditions - mouth drying, mouth rinsing and a control (no intervention). In each condition they were assessed twice - at baseline, before intervention, and 20 min later at test. Mouth rinsing improved visual attention performance, but not short term memory, mood or subjective thirst. The effects of mouth drying were more equivocal. The selective nature of the results is consistent with suggestions that different domains of cognition are influenced by different mechanisms.


Assuntos
Atenção , Água Potável , Memória de Curto Prazo , Boca , Afeto/fisiologia , Atenção/fisiologia , Criança , Ingestão de Líquidos/fisiologia , Água Potável/administração & dosagem , Feminino , Humanos , Masculino , Memória de Curto Prazo/fisiologia , Boca/fisiologia , Sede/fisiologia , Percepção Visual/fisiologia
16.
Physiol Rep ; 6(12): e13744, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29932494

RESUMO

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.


Assuntos
Encéfalo/fisiologia , Saciação/fisiologia , Sede/fisiologia , Mapeamento Encefálico/métodos , Ingestão de Líquidos/fisiologia , Homeostase/fisiologia , Humanos , Vias Neurais/fisiologia , Prosencéfalo/fisiologia , Rombencéfalo/fisiologia
17.
Ann Nutr Metab ; 72 Suppl 2: 3-7, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29925072

RESUMO

Recent experiments using optogenetic tools allow the identification and functional analysis of thirst neurons and vasopressin producing neurons. Two major advances provide a detailed anatomy of taste for water and arginine-vasopressin (AVP) release: (1) thirst and AVP release are regulated not only by the classical homeostatic, intero-sensory plasma osmolality negative feedback, but also by novel, extero-sensory, anticipatory signals. These anticipatory signals for thirst and vasopressin release converge on the same homeostatic neurons of circumventricular organs that monitor the composition of the blood; (2) acid-sensing taste receptor cells (which express polycystic kidney disease 2-like 1 protein) on the tongue that were previously suggested as the sour taste sensors also mediate taste responses to water. The tongue has a taste for water. The median preoptic nucleus (MnPO) of the hypothalamus could integrate multiple thirst-generating stimuli including cardiopulmonary signals, osmolality, angiotensin II, oropharyngeal and gastric signals, the latter possibly representing anticipatory signals. Dehydration is aversive and MnPO neuron activity is proportional to the intensity of this aversive state.


Assuntos
Arginina Vasopressina/fisiologia , Hipotálamo/fisiologia , Neurônios/fisiologia , Sede/fisiologia , Animais , Desidratação , Ingestão de Líquidos/fisiologia , Ingestão de Alimentos/fisiologia , Homeostase , Humanos , Paladar
18.
Neuroscience ; 383: 170-177, 2018 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-29704610

RESUMO

Recent studies investigating neural correlates of human thirst have identified various subcortical and telencephalic brain areas. The experience of thirst represents a homeostatic emotion and a state that slowly evolves over time. Therefore, the present study aims at systematically examining cerebral perfusion during the parametric progression of thirst. We measured subjective thirst ratings, serum parameters and cerebral blood flow in 20 healthy subjects across four different thirst stages: intense thirst, moderate thirst, subjective satiation and physiological satiation. Imaging data revealed dehydration-related perfusion differences in previously identified brain areas, such as the anterior cingulate cortex, the middle temporal gyrus and the insular cortex. However, significant differences across all four thirst stages (including the moderate thirst level), were exclusively found in the posterior insular cortex. The subjective thirst ratings over the different thirst stages, however, were associated with perfusion differences in the right anterior insula. These findings add to our understanding of the insular cortex as a key player in human thirst - both on the level of physiological dehydration and the level of the subjective thirst experience.


Assuntos
Córtex Cerebral/fisiologia , Circulação Cerebrovascular/fisiologia , Emoções , Sede/fisiologia , Adulto , Córtex Cerebral/irrigação sanguínea , Humanos , Processamento de Imagem Assistida por Computador , Imagem por Ressonância Magnética , Masculino , Adulto Jovem
19.
Nature ; 555(7695): 204-209, 2018 03 08.
Artigo em Inglês | MEDLINE | ID: mdl-29489747

RESUMO

Neural circuits for appetites are regulated by both homeostatic perturbations and ingestive behaviour. However, the circuit organization that integrates these internal and external stimuli is unclear. Here we show in mice that excitatory neural populations in the lamina terminalis form a hierarchical circuit architecture to regulate thirst. Among them, nitric oxide synthase-expressing neurons in the median preoptic nucleus (MnPO) are essential for the integration of signals from the thirst-driving neurons of the subfornical organ (SFO). Conversely, a distinct inhibitory circuit, involving MnPO GABAergic neurons that express glucagon-like peptide 1 receptor (GLP1R), is activated immediately upon drinking and monosynaptically inhibits SFO thirst neurons. These responses are induced by the ingestion of fluids but not solids, and are time-locked to the onset and offset of drinking. Furthermore, loss-of-function manipulations of GLP1R-expressing MnPO neurons lead to a polydipsic, overdrinking phenotype. These neurons therefore facilitate rapid satiety of thirst by monitoring real-time fluid ingestion. Our study reveals dynamic thirst circuits that integrate the homeostatic-instinctive requirement for fluids and the consequent drinking behaviour to maintain internal water balance.


Assuntos
Ingestão de Líquidos/fisiologia , Vias Neurais , Área Pré-Óptica/citologia , Área Pré-Óptica/fisiologia , Órgão Subfornical/citologia , Órgão Subfornical/fisiologia , Sede/fisiologia , Animais , Apetite/fisiologia , Feminino , Neurônios GABAérgicos/metabolismo , Receptor do Peptídeo Semelhante ao Glucagon 1/metabolismo , Homeostase , Instinto , Masculino , Camundongos , Óxido Nítrico Sintase/metabolismo , Resposta de Saciedade/fisiologia , Equilíbrio Hidroeletrolítico
20.
J Nutr Health Aging ; 22(3): 335-340, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29484346

RESUMO

OBJECTIVES: Water is an essential nutrient for thermoregulation, metabolism, cognition, and overall physiological homeostatic function. However, aging adults display a blunted thirst mechanism and subsequently have an increased risk for dehydration or hyponatremia. Fluid consumption behaviors are modifiable and the importance of practicing adequate drinking behaviors for aging adults is amplified during exercise. Identification of aging adult's hydration beliefs and how they attain hydration advice could provide valuable information into ways to promote better drinking habits to reduce fluid imbalances. Thus, this investigation evaluated the knowledge, beliefs and behaviors of middle-aged cyclists (MA) that were associated with hydration status and drinking behavior, before and during a 164-km mass-participation event (ambient temperature, 33.3±2.8ºC(mean±SD)). DESIGN: This cross-sectional field study retrospectively grouped participants by their second urine specific gravity (Usg) measurement of the event morning prior to a mass participation cycling event. Usg was assessed via handheld refractometer. SETTING: The Hotter N' Hell Hundred 164-km cycling event in Wichita Falls, Texas during the month of August. PARTICIPANTS: 36 male recreational cyclists (age, 53±9 y(mean±SD)). MEASUREMENTS: Participants were grouped according their urine specific gravity as either slightly hyperhydrated (SH; n=12, Usg≤1.014), euhydrated (EUH; n=12, Usg, 1.015-1.020), or slightly dehydrated (SD; n=12, Usg≥1.021). Exercise histories and questionnaires were recorded 24-48 h prior to the cycling event. RESULTS: Regardless of pre-event hydration status, all groups experienced a similar body mass loss during the 164-km event and finished with statistically similar exercise times; also, drinking behavior within all groups was influenced by multiple factors. The primary factors associated with MA cyclist drinking behavior were trial and error/personal history and thirst; further, the majority of cyclists (≥65%) in SH, EUH, and SD believed that dehydration affects performance negatively. The least important factors included rehydration recommendations from scientific and sports medicine organizations, plus information from sports drink manufacturers. CONCLUSION: Considering the complexity of the present findings and the physiological changes that accompany aging such as delayed thirst perception, we recommend that MA cyclists formulate an individualized drinking plan that is based on observations during exercise.


Assuntos
Ciclismo/estatística & dados numéricos , Comportamento de Ingestão de Líquido , Exercício Físico/fisiologia , Sede/fisiologia , Índice de Massa Corporal , Estudos Transversais , Desidratação , Ingestão de Líquidos , Temperatura Alta , Humanos , Hiponatremia/prevenção & controle , Masculino , Pessoa de Meia-Idade , Estado Nutricional , Estudos Retrospectivos , Inquéritos e Questionários , Água
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