RESUMO
The thyroid function was studied by means of a comparison between rats that drank daily less than 2 mEq of a NaCl solution (control) and rats that spontaneously drank daily above 4 mEq of this solution (0.25 M), which is considered aversive to rats. It was found that, in these rats, the protein-bound iodine (PBI-127) and the radioactive iodine uptake (I-131) were less than in the control rats, in spite of similar thyroid weight. It seems, therefore, that the rats that drank high levels of the aversive salt solution have hypothyroidism. This finding shows another link between the thyroid gland and NaCl intake. These data have implications in the design and interpretation of experiments in which NaCl intake is studied.
Assuntos
Ingestão de Líquidos/fisiologia , Hipotireoidismo/fisiopatologia , Cloreto de Sódio/administração & dosagem , Glândula Tireoide/fisiopatologia , Equilíbrio Hidroeletrolítico/fisiologia , Animais , Feminino , Ratos , Hormônios Tireóideos/fisiologiaRESUMO
1. The present study was undertaken to investigate the influence of the septal area on neural mechanisms involved in feeding behavior elicited by electrical stimulation of the lateral hypothalamic area of the rat. 2. Electrolytic damage to medial and lateral septal nuclei induced a significant increase (18.29 +/- 1.69 to 25.05 +/- 2.31 g, P less than 0.05, N = 14) in food intake elicited by hypothalamic stimulation. The threshold current for stimulus-induced eating decreased by 20% after septal lesion. 3. A significant decrease in food ingestion was observed after electrical stimulation of the septal nuclei, either preceding (27.47 +/- 1.57 to 19.30 +/- 2.06 g, P less than 0.05, N = 13) or simultaneous (26.20 +/- 1.60 to 12.10 +/- 2.40 g, P less than 0.05, N = 11) with hypothalamic stimulation. 4. The results indicate an inhibitory effect of the septum on the lateral hypothalamic area and also suggest that the functional state of the lateral hypothalamus, which is responsible for the feeding behavior, depends on the activity pattern of the septal area.
Assuntos
Comportamento Alimentar/fisiologia , Região Hipotalâmica Lateral/fisiologia , Núcleos Septais/fisiologia , Animais , Estimulação Elétrica/métodos , Masculino , Ratos , Ratos EndogâmicosRESUMO
The present study was undertaken to investigate the influence of the septal area on neural mechanisms involved in feeding behavior elicited by electrical stimulation of the lateral hypothalamic area of the rat. Electrolytic damage to medial and lateral septal nuclei induced a significant increase (18.29 + or - 1.69 to 25.05 + or - 2.31 g, P<0.05, N = 14) in food intake elicited by hypothalamic stimulation. The threshold current for stimulus-induced eating decreased by 20% after septal lesion. A significant decrease in food ingestion was observed after electrical stimulation of the septal nuclei, either preceding (27.47 + or - 1.57 to 19.30 + or - 2.06 g P <0.05, N = 13) or simultaneous (26.20 + or - 1.60 to 12.10 + or - 2.40 g, P<0.05, N = 11) with hypothalamic stimulation. The results indicate an inhibitory effect of the septum on the lateral hypothalamic area and also suggest that the functional state of the lateral hypothalamus, which is responsible for the feeding behavior, depends on the activity pattern of the septal area
Assuntos
Ratos , Animais , Masculino , Comportamento Alimentar/fisiologia , Hipotálamo/fisiologia , Núcleos Septais/fisiologia , Estimulação Elétrica/métodos , Ratos EndogâmicosRESUMO
By using the two-bottle, self-selection method it was found that an excess of thyroid hormone administration to rats increased water and sodium intake. Thyroidectomy changed the initial preference from water to sodium chloride. Oral treatment of the thyroidectomized rats with thyroid hormones brought salt ingestion back to normal levels and greatly augmented the water intake. Two-week treatment was followed by an increase in salt intake, which was characterized by large oscillations resembling the corresponding effects of adrenalectomy and treatment with deoxycorticosterone.
Assuntos
Comportamento de Ingestão de Líquido/efeitos dos fármacos , Cloreto de Sódio , Glândula Tireoide/fisiologia , Tiroxina/farmacologia , Tri-Iodotironina/farmacologia , Animais , Feminino , Ratos , Valores de Referência , TireoidectomiaRESUMO
To study the role played by neurotransmitters and their receptor mechanisms in the control of feeding behavior elicited by electrical stimulation, drugs that affect neurotransmission were injected via cannula electrodes into the lateral hypothalamic area. Pretreatment with noradrenaline (0.5 and 1.0 nmol) significantly increased the effect of hypothalamic stimulation on feeding, whereas injection of 1.0, 2.0 and 4.0 nmol of adrenaline or dopamine was ineffective. Phentolamine (40.0, 80.0 and 100.0 nmol) and propranolol (40.0, 80.0 and 120.0 nmol) induced a decrease in food intake, suggesting the involvement of both alpha and beta receptors in this mechanism. However, isoprenaline (20.0 nmol) also reduced food intake. Reduction of food intake by propranolol was probably related to the action of the local anesthetic. Alphamethyl-p-tyrosine (203.0 nmol), reserpine (32.8 nmol) and 6-hydroxydopamine (200.0 nmol) inhibited the feeding behavior elicited by electrical stimulation of the lateral hypothalamic area. These results suggest that electrical stimulation of the lateral hypothalamic area elicits feeding behavior by releasing noradrenaline. Alpha-adrenergic receptors seem to play a facilitatory role in feeding behavior.
Assuntos
Comportamento Alimentar , Hipotálamo/fisiologia , Norepinefrina/fisiologia , Simpatolíticos/farmacologia , Animais , Sítios de Ligação , Encéfalo/metabolismo , Estimulação Elétrica , Hipotálamo/efeitos dos fármacos , Isoproterenol/farmacologia , Masculino , Metiltirosinas/farmacologia , Norepinefrina/metabolismo , Fentolamina/farmacologia , Propranolol/farmacologia , Ratos , Ratos Endogâmicos , Reserpina/antagonistas & inibidores , Tirosina 3-Mono-Oxigenase/antagonistas & inibidores , alfa-MetiltirosinaRESUMO
Bipolar stainless steel electrodes or stainless steel cannulas were implanted stereotaxically into the lateral hypothalamus of rats. Drinking was elicited by electrical or chemical (carbachol or angiotensin II) stimulation of animals, which were offered water and solutions of sodium chloride, saccharin, acetic acid and quinine. During electrical stimulation, ingestion of water and of all the solutions increased significantly. The same rats ingested significantly more sodium chloride and saccharin solution after 23 h water deprivation and electrical stimulation of the lateral hypothalamus. Carbachol administered into the lateral hypothalamus induced ingestion of saccharin solution and water but not of sodium chloride. Angiotensin II injected into the lateral hypothalamus did not induce drinking in most of the rats and those which drank preferred sodium chloride, saccharin and water. Several of the rats which did not respond to angiotensin II injection into the lateral hypothalamus, 72 h after angiotensin II responded to injection of carbachol by drinking the saccharin solution. The results of electrical stimulation suggest that the lateral hypothalamus consists of neurons involved in the ingestion of primary taste solutions. Depending on the functional state of the organism, lateral hypothalamic stimulation modifies ingestion of other taste substances but not of salt, as indicated by water deprivation. Chemical stimulation indicates that the neurotransmitter responsible for salt intake is not cholinergic and that the cholinergic neurons evoke preference for sweet taste and water. It appears that angiotensin II is involved in salt intake, as well as in producing preference for sweet taste and water.
Assuntos
Angiotensina II/farmacologia , Carbacol/farmacologia , Comportamento de Ingestão de Líquido , Hipotálamo/fisiologia , Paladar , Animais , Estimulação Elétrica , Hipotálamo/efeitos dos fármacos , Masculino , Neurotransmissores/fisiologia , Ratos , Sacarina , Cloreto de Sódio , Técnicas Estereotáxicas , Privação de ÁguaAssuntos
Animais , Ratos , Antagonistas Adrenérgicos alfa , Antagonistas Adrenérgicos beta , Nicotina , Potássio , SódioRESUMO
Rats bearing lesions in the septal area (SA), or in the subfornical organ (SFO) or simultaneously in both regions were submitted to various thirst-eliciting procedures. The rats with hyperdipsia induced by lesion of the SA drank more water than either normal rats or SFO-lesioned animals under the same thirst-eliciting or angiotensin-liberating stimuli (polyethyleneglycol, isoproterenol, water deprivation and ligation of the inferior vena cava). The overdrinking elicited by SA lesions was blocked after SFO lesions. Neither hypovolemia, nor hypotension or water deprivation could elicit increased water intake in SFO-lesioned animals even after destruction of the SA. Animals with SFO lesions did not show increase of the water intake after cellular dehydration. The results obtained suggest that the SFO acts as the main structure in the regulation of water intake elicited by angiotensin with two opposite effects: one direct, facilitating water intake and the other indirect inhibiting the SA. The SA has an inhibitory effect on the SFO and on water intake.
Assuntos
Ingestão de Líquidos , Sistemas Neurossecretores/fisiologia , Núcleos Septais/fisiologia , Órgão Subfornical/fisiologia , Animais , Desidratação/induzido quimicamente , Ingestão de Líquidos/efeitos dos fármacos , Isoproterenol/farmacologia , Masculino , Polietilenoglicóis/farmacologia , Cloreto de Sódio/farmacologia , Sede/efeitos dos fármacos , Veia Cava Inferior/fisiologia , Privação de ÁguaRESUMO
Rats bearing lesions in the septal area (SA), or in the subfornical organ (SFO) or simultaneously in both regions were submitted to various thirst-eliciting procedures. The rats with hyperdipsia induced by lesion of the SA drank more water than either normal rats or SFO-lesioned animals under the same thirst-eliciting or angiotensin-liberating stimuli (polyethyleneglycol, isoproterenol, water deprivation and ligation of the inferior vena cava). The overdrinking elicited by SA lesions was blocked after SFO lesions. Neither hypovolemia, nor hypotension or water deprivation could elicit increased water intake in SFO-lesioned animals even after destruction of the SA. Animals with SFO lesions did not show increase of the water intake after cellular dehydration. The results obtained suggest that the SFO acts as the main structure in the regulation of water intake elicited by angiotensin with two opposite effects: one direct, facilitating water intake and the other indirect inhibiting the SA. The SA has an inhibitory effect on the SFO and on water intake.
RESUMO
Rats bearing lesions in the septal area (SA), or in the subfornical organ (SFO) or simultaneously in both regions were submitted to various thirst-eliciting procedures. The rats with hyperdipsia induced by lesion of the SA drank more water than either normal rats or SFO-lesioned animals under the same thirst-eliciting or angiotensin-liberating stimuli (polyethyleneglycol, isoproterenol, water deprivation and ligation of the inferior vena cava). The overdrinking elicited by SA lesions was blocked after SFO lesions. Neither hypovolemia, nor hypotension or water deprivation could elicit increased water intake in SFO-lesioned animals even after destruction of the SA. Animals with SFO lesions did not show increase of the water intake after cellular dehydration. The results obtained suggest that the SFO acts as the main structure in the regulation of water intake elicited by angiotensin with two opposite effects: one direct, facilitating water intake and the other indirect inhibiting the SA. The SA has an inhibitory effect on the SFO and on water intake.