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1.
Am J Physiol Regul Integr Comp Physiol ; 322(3): R161-R169, 2022 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-35018823

RESUMO

Arginine vasopressin (AVP) is produced in the paraventricular (PVN) and supraoptic nuclei (SON). Peripheral AVP, which is secreted from the posterior pituitary, is produced in the magnocellular division of the PVN (mPVN) and SON. In addition, AVP is produced in the parvocellular division of the PVN (pPVN), where corticotrophin-releasing factor (CRF) is synthesized. These peptides synergistically modulate the hypothalamic-pituitary-adrenal (HPA) axis. Previous studies have revealed that the HPA axis was activated by hypovolemia. However, the detailed dynamics of AVP in the pPVN under hypovolemic state has not been elucidated. Here, we evaluated the effects of hypovolemia and hyperosmolality on the hypothalamus, using AVP-enhanced green fluorescent protein (eGFP) transgenic rats. Polyethylene glycol (PEG) or 3% hypertonic saline (HTN) was intraperitoneally administered to develop hypovolemia or hyperosmolality. AVP-eGFP intensity was robustly upregulated at 3 and 6 h after intraperitoneal administration of PEG or HTN in the mPVN. While in the pPVN, eGFP intensity was significantly increased at 6 h after intraperitoneal administration of PEG with significant induction of Fos-immunoreactive (-ir) neurons. Consistently, eGFP mRNA, AVP hnRNA, and CRF mRNA in the pPVN and plasma AVP and corticosterone were significantly increased at 6 h after intraperitoneal administration of PEG. The results suggest that AVP and CRF syntheses in the pPVN were activated by hypovolemia, resulting in the activation of the HPA axis.


Assuntos
Arginina Vasopressina/genética , Proteínas de Fluorescência Verde/genética , Sistema Hipotálamo-Hipofisário/metabolismo , Hipovolemia/metabolismo , Núcleo Hipotalâmico Paraventricular/metabolismo , Animais , Corticosterona/sangue , Hormônio Liberador da Corticotropina/genética , Hormônio Liberador da Corticotropina/metabolismo , Modelos Animais de Doenças , Genes Reporter , Proteínas de Fluorescência Verde/biossíntese , Sistema Hipotálamo-Hipofisário/fisiopatologia , Hipovolemia/genética , Hipovolemia/fisiopatologia , Injeções Intraperitoneais , Masculino , Núcleo Hipotalâmico Paraventricular/fisiopatologia , Polietilenoglicóis/administração & dosagem , Proteínas Proto-Oncogênicas c-fos/metabolismo , Ratos Transgênicos , Ratos Wistar , Solução Salina Hipertônica/administração & dosagem , Núcleo Supraóptico/metabolismo , Núcleo Supraóptico/fisiopatologia , Fatores de Tempo , Regulação para Cima
2.
Cell Physiol Biochem ; 55(S1): 119-134, 2021 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-33711228

RESUMO

BACKGROUND/AIMS: Arginine vasopressin (AVP) neurons play an important role for sensing a change in the plasma osmolarity and thereby responding with regulated AVP secretion in order to maintain the body fluid homeostasis. The osmo-sensing processes in magnocellular neurosecretory cells (MNCs) including AVP and oxytocin (OXT) neurons of the hypothalamus were reported to be coupled to sustained osmotic shrinkage or swelling without exhibiting discernible cell volume regulation. Since increasing evidence has shown some important differences in properties between AVP and OXT neurons, osmotic volume responses are to be reexamined with distinguishing these cell types from each other. We previously reported that AVP neurons identified by transgenic expression of enhanced green fluorescence protein (eGFP) possess the ability of regulatory volume decrease (RVD) after hypoosmotic cell swelling. Thus, in the present study, we examined the ability of regulatory volume increase (RVI) after hyperosmotic cell shrinkage in AVP neurons. METHODS: Here, we used eGFP-identified AVP neurons acutely dissociated from AVP-eGFP transgenic rats. We performed single-cell size measurements, cytosolic RT-PCR analysis, AVP secretion measurements, and patch-clamp studies. RESULTS: The AVP neurons were found to respond to a hyperosmotic challenge with physiological cell shrinkage caused by massive secretion of AVP, called a secretory volume decrease (SVD), superimposed onto physical osmotic cell shrinkage, and also to exhibit the ability of RVI coping with osmotic and secretory cell shrinkage. Furthermore, our pharmacological and molecular examinations indicated that AVP secretion and its associated SVD event are triggered by activation of T-type Ca2+ channels, and the RVI event is attained by parallel operation of Na+/H+ exchanger and Cl-/HCO3- anion exchanger. CONCLUSION: Thus, it is concluded that AVP neurons respond to hyperosmotic stimulation with the regulatory volume increase and the secretory volume increase by activating ion transporters and Ca2+ channels, respectively.


Assuntos
Cálcio/metabolismo , Neurônios/metabolismo , Ocitocina/metabolismo , Vasopressinas/metabolismo , Animais , Canais de Cálcio/metabolismo , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Humanos , Reação em Cadeia da Polimerase em Tempo Real
3.
Nutr Neurosci ; 24(9): 688-696, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31581905

RESUMO

Objectives: Dried bonito dashi, a traditional Japanese fish broth made from dried bonito tuna, enhances food palatability due to its specific umami flavor characteristics. However, the pattern of brain activation following dashi ingestion has not been previously investigated.Methods: We mapped activation sites of the rat brain after intragastric loads of dried bonito dashi by measuring neuronal levels of the Fos protein, a functional marker of neuronal activation.Results: Compared to intragastric saline, intragastric dashi administration produced enhanced Fos expression in four forebrain regions: the medial preoptic area, subfornical organ, habenular nucleus, and central nucleus of the amygdala. Interestingly, the medial preoptic area was found to be the only feeding-related hypothalamic area responsive to dashi administration. Moreover, dashi had no effect in the nucleus accumbens and ventral tegmental area, two connected sites known to be activated by highly palatable sugars and fats. In the hindbrain, dashi administration produced enhanced Fos expression in both visceral sensory (caudal nucleus of the solitary tract, dorsal part of the lateral parabrachial nucleus, and area postrema) and autonomic (rostral ventrolateral medulla, and caudal ventrolateral medulla) sites.Discussion: The results demonstrate the activation of discrete forebrain and hindbrain regions following intragastric loads of dried bonito dashi. Our data suggest that the gut-brain axis is the principal mediator of the postingestive effects associated with the ingestion of dashi.


Assuntos
Eixo Encéfalo-Intestino/fisiologia , Encéfalo/fisiologia , Produtos Pesqueiros , Proteínas Proto-Oncogênicas c-fos/análise , Atum , Animais , Química Encefálica , Alimentos em Conserva , Expressão Gênica , Masculino , Prosencéfalo/fisiologia , Proteínas Proto-Oncogênicas c-fos/genética , Ratos , Ratos Sprague-Dawley , Rombencéfalo/fisiologia , Soluções/administração & dosagem
4.
Mol Pain ; 16: 1744806920943334, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32686583

RESUMO

The neurohypophysial hormone oxytocin (OXT) is synthesized in the hypothalamic paraventricular and supraoptic nuclei. Recently, some studies have considered OXT to be important in sensory modulation and that the OXT protein is upregulated by acute and chronic nociception. However, the mechanism by which OXT is upregulated in neurons is unknown. In this study, we examined the resting membrane potentials and excitatory postsynaptic currents in OXT-ergic neurons in the paraventricular nucleus in adjuvant arthritis rat model, a model of chronic inflammation, using whole-cell patch-clamping. Transgenic rats expressing OXT and monomeric red fluorescent protein 1 (mRFP1) fusion protein to visualize the OXT-ergic neurons were used, and the OXT-mRFP1 transgenic rat model of adjuvant arthritis was developed by injection of heat-killed Mycobacterium butyricum. Furthermore, the feedback system of synthesized OXT was also examined using the OXT receptor antagonist L-368,899. We found that the resting membrane potentials and frequency of miniature excitatory postsynaptic currents and spontaneous excitatory postsynaptic currents in OXT-monomeric red fluorescent protein 1 neurons in the paraventricular nucleus were significantly increased in adjuvant arthritis rats. Furthermore, L-368,899 dose-dependently increased the frequency of miniature excitatory postsynaptic currents and spontaneous excitatory postsynaptic currents in OXT-ergic neurons. Following bath application of the GABAA receptor antagonist picrotoxin and the cannabinoid receptor 1 antagonist AM 251, L-368,899 still increased the frequency of miniature excitatory postsynaptic currents. However, following bath application of the nitric oxide synthase inhibitor Nω-Nitro-L-arginine methyl ester hydrochloride, L-368,899 did not alter the miniature excitatory postsynaptic current frequency. Thus, it is suggested that OXT-ergic neuron activity is upregulated via an increase in glutamate release, and that the upregulated OXT neurons have a feedback system with released endogenous OXT. It is possible that nitric oxide, but not GABA, may contribute to the feedback system of OXT neurons in chronic inflammation.


Assuntos
Artrite Experimental/metabolismo , Retroalimentação , Glutamatos/metabolismo , Hipotálamo/metabolismo , Neurônios/metabolismo , Ocitocina/metabolismo , Terminações Pré-Sinápticas/metabolismo , Transmissão Sináptica , Animais , Canfanos/farmacologia , Modelos Animais de Doenças , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Proteínas Luminescentes/metabolismo , Masculino , Modelos Biológicos , NG-Nitroarginina Metil Éster/farmacologia , Neurônios/efeitos dos fármacos , Núcleo Hipotalâmico Paraventricular/efeitos dos fármacos , Núcleo Hipotalâmico Paraventricular/metabolismo , Técnicas de Patch-Clamp , Picrotoxina/farmacologia , Piperazinas/farmacologia , Piperidinas/farmacologia , Terminações Pré-Sinápticas/efeitos dos fármacos , Pirazóis/farmacologia , Ratos Transgênicos , Ratos Wistar , Receptores de Ocitocina/antagonistas & inibidores , Receptores de Ocitocina/metabolismo , Transmissão Sináptica/efeitos dos fármacos , Proteína Vermelha Fluorescente
5.
Cell Tissue Res ; 375(1): 311-327, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30338378

RESUMO

Rats have been widely used as one of the most common laboratory animals for biological research, because their physiology, pathology, and behavioral characteristics are highly similar to humans. Recent developments in rat genetic modification techniques have now led to further their utility for a broad range of research questions, including the ability to specifically label individual neurones, and even manipulate neuronal function in rats. We have succeeded in generating several transgenic rat lines that enable visualization of specific neurones due to their expression of fluorescently-tagged oxytocin, vasopressin, and c-fos protein. Furthermore, we have been able to generate novel transgenic rat lines in which we can activate vasopressin neurones using optogenetic and chemogenetic techniques. In this review, we will summarize the techniques of genetic modification for labeling and manipulating the specific neurones. Successful examples of generating transgenic rat lines in our lab and usefulness of these rats will also be introduced. These transgenic rat lines enable the interrogation of neuronal function and physiology in a way that was not possible in the past, providing novel insights into neuronal mechanisms both in vivo and ex vivo.


Assuntos
Técnicas Genéticas , Neurônios/metabolismo , Ocitocina/genética , Vasopressinas/genética , Vírus/metabolismo , Animais , Optogenética , Ratos Transgênicos
6.
Biosci Biotechnol Biochem ; 83(2): 202-211, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30392457

RESUMO

Oxytocin is produced by neurons in the paraventricular nucleus (PVN) and the supraoptic nucleus in the hypothalamus. Various ion channels are considered to regulate the excitability of oxytocin neurons and its secretion. A-type currents of voltage-gated potassium channels (Kv channels), generated by Kv4.2/4.3 channels, are known to be involved in the regulation of neuron excitability. However, it is unclear whether the Kv4.2/4.3 channels participate in the regulation of excitability in PVN oxytocin neurons. Here, we investigated the contribution of the Kv4.2/4.3 channels to PVN oxytocin neuron excitability. By using transgenic rat brain slices with the oxytocin-monomeric red fluorescent protein 1 fusion transgene, we examined the excitability of oxytocin neurons by electrophysiological technique. In some oxytocin neurons, the application of Kv4.2/4.3 channel blocker increased firing frequency and membrane potential with extended action potential half-width. Our present study indicates the contribution of Kv4.2/4.3 channels to PVN oxytocin neuron excitability regulation. Abbreviation: PVN, paraventricular nucleus; Oxt-mRFP1, Oxt-monometric red fluorescent protein 1; PaTx-1, Phrixotoxin-1; TEA, Tetraethylammonium Chloride; TTX, tetrodotoxin; aCSF, artificial cerebrospinal fluid;PBS, phosphate buffered saline 3v, third ventricle.


Assuntos
Ativação do Canal Iônico , Neurônios/fisiologia , Ocitocina/metabolismo , Núcleo Hipotalâmico Paraventricular/metabolismo , Canais de Potássio Shal/metabolismo , Potenciais de Ação/efeitos dos fármacos , Animais , Feminino , Imuno-Histoquímica , Proteínas Luminescentes/genética , Masculino , Potenciais da Membrana/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Núcleo Hipotalâmico Paraventricular/citologia , Bloqueadores dos Canais de Potássio/farmacologia , Ratos Transgênicos , Ratos Wistar , Canais de Potássio Shal/antagonistas & inibidores , Venenos de Aranha/farmacologia , Proteína Vermelha Fluorescente
7.
Am J Physiol Endocrinol Metab ; 315(4): E478-E488, 2018 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-28174180

RESUMO

Light synchronizes the body's circadian rhythms by modulating the master clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus. In modern lifestyles that run counter to normal circadian rhythms, the extended and/or irregular light exposure impairs circadian rhythms and, consequently, promotes feeding and metabolic disorders. However, the neuronal pathway through which light is coupled to feeding behavior is less elucidated. The present study employed the light exposure during the dark phase of the day in rats and observed its effect on neuronal activity and feeding behavior. Light exposure acutely suppressed food intake and elevated c-Fos expression in the AVP neurons of SCN and the oxytocin (Oxt) neurons of paraventricular nucleus (PVN) in the hypothalamus. The light-induced suppression of food intake was abolished by blockade of the Oxt receptor in the brain. Retrograde tracer analysis demonstrated the projection of SCN AVP neurons to the PVN. Furthermore, intracerebroventricular injection of AVP suppressed food intake and increased c-Fos in PVN Oxt neurons. Intra-PVN injection of AVP exerted a stronger anorexigenic effect than intracerebroventriclar injection. AVP also induced intracellular Ca2+ signaling and increased firing frequency in Oxt neurons in PVN slices. These results reveal the novel neurocircuit from SCN AVP to PVN Oxt that relays light reception to inhibition of feeding behavior. This light-induced neurocircuit may serve as a pathway for forming the circadian feeding rhythm and linking irregular light exposure to arrhythmic feeding and, consequently, obesity and metabolic diseases.


Assuntos
Arginina Vasopressina/metabolismo , Comportamento Alimentar/fisiologia , Luz , Ocitocina/metabolismo , Núcleo Hipotalâmico Paraventricular/metabolismo , Núcleo Supraquiasmático/metabolismo , Animais , Arginina Vasopressina/farmacologia , Arginina Vasopressina/fisiologia , Sinalização do Cálcio/efeitos dos fármacos , Sinalização do Cálcio/fisiologia , Ritmo Circadiano/fisiologia , Comportamento Alimentar/efeitos dos fármacos , Hipotálamo/metabolismo , Hipotálamo/fisiologia , Inibição Psicológica , Masculino , Vias Neurais , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Ocitocina/fisiologia , Núcleo Hipotalâmico Paraventricular/fisiologia , Proteínas Proto-Oncogênicas c-fos/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-fos/metabolismo , Ratos , Ratos Wistar , Receptores de Ocitocina , Núcleo Supraquiasmático/fisiologia
8.
J Pharmacol Sci ; 137(1): 67-75, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29716811

RESUMO

Oxytocin (OT) is a 9-amine neuropeptide that plays an essential role in mammalian labor, lactation, maternal bonding, and social affiliation. OT has been reported to exert an analgesic effect in both humans and animals, and the results of certain animal experiments have shown that the analgesic effect of OT is partially blocked by opioid receptor antagonists. To investigate the relationship between OT and µ opioid receptor (MOR), we evaluated how OT affects MOR in vitro by performing an electrical impedance-based receptor biosensor assay (CellKey™ assay), an intracellular cAMP assay, and a competitive receptor-binding analysis by using cells stably expressing human MOR and OT receptor. In both the CellKey™ assay and the intracellular cAMP assay, OT alone exerted no direct agonistic effect on human MOR, but treatment with 10-6 M OT markedly enhanced the MOR signaling induced by 10-6 M endomorphin-1, ß-endorphin, morphine, fentanyl, and DAMGO. Moreover, in the competitive receptor-binding assay, 10-6 M OT did not alter the affinity of endomorphin-1 or morphine for MOR. These results suggest that OT could function as a positive allosteric modulator that regulates the efficacy of MOR signaling, and thus OT might represent a previously unrecognized candidate analgesic agent.


Assuntos
Regulação Alostérica/efeitos dos fármacos , Neuropeptídeos/farmacologia , Ocitocina/farmacologia , Receptores Opioides mu/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Analgésicos , Animais , AMP Cíclico/metabolismo , Células HEK293 , Humanos , Ocitocina/fisiologia , Receptores Opioides mu/fisiologia , Estimulação Química
9.
Gen Comp Endocrinol ; 258: 15-32, 2018 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-29155265

RESUMO

It is now accepted that vasopressin, through V1A/V1B receptors, centrally regulates cognitive functions such as memory, affiliation, stress, fear and depression. However, the respective roles of these receptor isoforms and their contribution to stress-related pathologies remain uncertain. The development of new therapeutic treatments requires a precise knowledge of the distribution of these receptors within the brain, which has been so far hampered by the lack of selective V1B markers. In the present study, we have determined the pharmacological properties of three new potent rat V1B fluorescent ligands and demonstrated that they constitute valuable tools for simultaneous visualization and activation of native V1B receptors in living rat brain tissue. Thus, d[Leu4,Lys-Alexa 647)8]VP (analogue 3), the compound with the best affinity-selectivity/fluorescence ratio for the V1B receptor emerged as the most promising. The rat brain regions most concerned by stress such as hippocampus, olfactory bulbs, cortex and amygdala display the highest V1B fluorescent labelling with analogue 3. In the hippocampus CA2, V1B receptors are located on glutamatergic, not GABAergic neurones, and are absent from astrocytes. Using AVP-EGFP rats, we demonstrate the presence of V1B autoreceptors on AVP-secreting neurones not only in the hypothalamus, but also sparsely in the hippocampus. Finally, using both electrophysiology and visualization of ERK phosphorylation, we show analogue 3-induced activation of the V1B receptor in situ. This will help to analyse expression and functionality of V1B receptors in the brain and contribute to further explore the AVPergic circuitry in normal and pathological conditions.


Assuntos
Encéfalo/anatomia & histologia , Encéfalo/metabolismo , Corantes Fluorescentes/metabolismo , Receptores de Vasopressinas/metabolismo , Animais , Arginina Vasopressina/metabolismo , Astrócitos/metabolismo , Células CHO , Cricetinae , Cricetulus , Células HEK293 , Humanos , Hipotálamo/metabolismo , Ligantes , Masculino , Neuroanatomia , Neurônios/metabolismo , Hipófise/citologia , Ratos Sprague-Dawley , Receptores de GABA/metabolismo , Coloração e Rotulagem , Vasopressinas/metabolismo
10.
J Physiol ; 595(17): 5857-5874, 2017 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-28714095

RESUMO

KEY POINTS: A growing body of evidence suggests that epithelial Na+ channels (ENaCs) in the brain play a significant role in the regulation of blood pressure; however, the brain structures that mediate the effect are not well understood. Because vasopressin (VP) neurons play a pivotal role in coordinating neuroendocrine and autonomic responses to maintain cardiovascular homeostasis, a basic understanding of the regulation and activity of ENaC in VP neurons is of great interest. We show that high dietary salt intake caused an increase in the expression and activity of ENaC which resulted in the steady state depolarization of VP neurons. The results help us understand one of the mechanisms underlying how dietary salt intake affects the activity of VP neurons via ENaC activity. ABSTRACT: All three epithelial Na+ channel (ENaC) subunits (α, ß and γ) are located in vasopressin (VP) magnocellular neurons in the hypothalamic supraoptic (SON) and paraventricular nuclei. Our previous study demonstrated that ENaC mediates a Na+ leak current that affects the steady state membrane potential in VP neurons. In the present study, we evaluated the effect of dietary salt intake on ENaC regulation and activity in VP neurons. High dietary salt intake for 7 days caused an increase in expression of ß- and γENaC subunits in the SON and the translocation of αENaC immunoreactivity towards the plasma membrane. Patch clamp experiments on hypothalamic slices showed that the mean amplitude of the putative ENaC currents was significantly greater in VP neurons from animals that were fed a high salt diet compared with controls. The enhanced ENaC current contributed to the more depolarized basal membrane potential observed in VP neurons in the high salt diet group. These findings indicate that high dietary NaCl intake enhances the expression and activity of ENaCs, which augments synaptic drive by depolarizing the basal membrane potential close to the action potential threshold during hormonal demand. However, ENaCs appear to have only a minor role in the regulation of the firing activity of VP neurons in the absence of synaptic inputs as neither the mean intraburst frequency, burst duration, nor interspike interval variability of phasic bursting activity was affected. Moreover, ENaC activity did not affect the initiation, sustention, or termination of the phasic bursting generated in an intrinsic manner without synaptic inputs.


Assuntos
Canais Epiteliais de Sódio/fisiologia , Neurônios/efeitos dos fármacos , Sódio na Dieta/farmacologia , Núcleo Supraóptico/efeitos dos fármacos , Amilorida/análogos & derivados , Amilorida/farmacologia , Animais , Bloqueadores do Canal de Sódio Epitelial/farmacologia , Canais Epiteliais de Sódio/genética , Masculino , Potenciais da Membrana/efeitos dos fármacos , Neurônios/fisiologia , Subunidades Proteicas/genética , Subunidades Proteicas/fisiologia , RNA Mensageiro/metabolismo , Ratos Wistar , Núcleo Supraóptico/fisiologia , Vasopressinas/fisiologia
11.
Biochem Biophys Res Commun ; 485(2): 409-413, 2017 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-28213131

RESUMO

Neuroendocrine regulatory peptide (NERP)-2 is derived from a distinct region of VGF, a neurosecretory protein originally identified as a product of a nerve growth factor-responsive gene in rat PC12 cells. Colocalization of NERP-2 with orexin-A in the lateral hypothalamus increases orexin-A-induced feeding and energy expenditure in both rats and mice. Orexigenic and anorectic peptides in the hypothalamus modulate gastric function. In this study, we investigated the effect of NERP-2 on gastric function in rats. Intracerebroventricular administration of NERP-2 to rats increased gastric acid secretion and gastric emptying, whereas peripheral administration did not affect gastric function. NERP-2-induced gastric acid secretion and gastric emptying were blocked by an orexin 1 receptor antagonist, SB334867. NERP-2 also induced Fos expression in the lateral hypothalamus and the dorsomotor nucleus of the vagus X, which are key sites in the central nervous system for regulation of gastric function. Atropine, a blocker of vagal efferent signal transduction, completely blocked NERP-2-induced gastric acid secretion. These results demonstrate that central administration of NERP-2 activates the orexin pathway, resulting in elevated gastric acid secretion and gastric emptying.


Assuntos
Ácido Gástrico/metabolismo , Esvaziamento Gástrico/efeitos dos fármacos , Proteínas do Tecido Nervoso/farmacologia , Receptores de Orexina/metabolismo , Transdução de Sinais/efeitos dos fármacos , Animais , Atropina/farmacologia , Benzoxazóis/farmacologia , Injeções Intraventriculares , Masculino , Naftiridinas , Proteínas do Tecido Nervoso/administração & dosagem , Parassimpatolíticos/farmacologia , Ratos Sprague-Dawley , Ratos Transgênicos , Ratos Wistar , Ureia/análogos & derivados , Ureia/farmacologia , Nervo Vago/efeitos dos fármacos , Nervo Vago/fisiologia
12.
Biochem Biophys Res Commun ; 490(3): 794-799, 2017 08 26.
Artigo em Inglês | MEDLINE | ID: mdl-28645611

RESUMO

Cisplatin, known as an anticancer drug, has been widely used; however, diverse disadvantageous side effects, including appetite loss, afflict patients. Nesfatin-1/NucB2, discovered as an anorexic neuropeptide, is broadly expressed in the central nervous system (CNS) and peripheral organ. In the present study, we examined the effects of intraperitoneally (i.p.) administered cisplatin on central nesfatin-1/NucB2. Saline, as control, or cisplatin (6 mg/kg dissolved in saline) was i.p. administered in adult male Wistar rats (180-220 g). Cumulative food intake was remarkably suppressed for at least 24 h and body weight was significantly smaller at 24 h after i.p. administration of cisplatin compared to control group. At 90 min after i.p. administration, they were perfused, followed by carrying out double-immunohistochemistry for Fos and nesfatin-1/NucB2. The percentage of nesfatin-1/NucB2 immunoreactive neurons expressing Fos was marked increased in the hypothalamus and brainstem after i.p. administration of cisplatin. Intracerebroventricularlly administered nesfatin-1/NucB2-antisense resulted in a significant attenuation of decreased food intake for 2 h after i.p. administration of cisplatin compared to nesfatin-1/NucB2-missense treated group. These results suggest that i.p. administration of cisplatin activated, at least in part, nesfatin-1/NucB2 neuron in the CNS and may exert anorexigenic effects in rats.


Assuntos
Anorexia/induzido quimicamente , Antineoplásicos/efeitos adversos , Proteínas de Ligação ao Cálcio/metabolismo , Cisplatino/efeitos adversos , Proteínas de Ligação a DNA/metabolismo , Ingestão de Alimentos/efeitos dos fármacos , Proteínas do Tecido Nervoso/metabolismo , Neurônios/efeitos dos fármacos , Aumento de Peso/efeitos dos fármacos , Animais , Anorexia/metabolismo , Anorexia/patologia , Antineoplásicos/administração & dosagem , Proteínas de Ligação ao Cálcio/análise , Cisplatino/administração & dosagem , Proteínas de Ligação a DNA/análise , Injeções Intraperitoneais , Masculino , Proteínas do Tecido Nervoso/análise , Neurônios/metabolismo , Neurônios/patologia , Nucleobindinas , Ratos , Ratos Wistar
13.
Histochem Cell Biol ; 148(3): 289-298, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28550404

RESUMO

We have newly developed a system that allows monitoring of the intensity of fluorescent signals from deep brains of rats transgenically modified to express enhanced green fluorescent protein (eGFP) via an optical fiber. One terminal of the optical fiber was connected to a blue semiconductor laser oscillator/green fluorescence detector. The other terminal was inserted into the vicinity of the eGFP-expressing neurons. Since the optical fiber was vulnerable to twisting stresses caused by animal movement, we also developed a cage in which the floor automatically turns, in response to the turning of the rat's head. This relieved the twisting stress on the optical fiber. The system then enabled real-time monitoring of fluorescence in awake and unrestrained rats over many hours. Using this system, we could continuously monitor eGFP-expression in arginine vasopressin-eGFP transgenic rats. Moreover, we observed an increase of eGFP-expression in the paraventricular nucleus under salt-loading conditions. We then performed in vivo imaging of eGFP-expressing GnRH neurons in the hypothalamus, via a bundle consisting of 3000 thin optical fibers. With the combination of the optical fiber bundle connection to the fluorescence microscope, and the special cage system, we were able to capture and retain images of eGFP-expressing neurons from free-moving rats. We believe that our newly developed method for monitoring and imaging eGFP-expression in deep brain neurons will be useful for analysis of neuronal functions in awake and unrestrained animals for long durations.


Assuntos
Encéfalo/citologia , Lasers , Neurônios/fisiologia , Animais , Proteínas de Fluorescência Verde/análise , Proteínas de Fluorescência Verde/biossíntese , Masculino , Microscopia de Fluorescência/instrumentação , Neurônios/citologia , Ratos , Ratos Transgênicos , Ratos Wistar , Fatores de Tempo
14.
J UOEH ; 38(4): 325-334, 2016.
Artigo em Japonês | MEDLINE | ID: mdl-27980316

RESUMO

Oxytocin (OXT), which is a well-known neurohypophysial hormone that is synthesized in the paraventricular (PVN) and supraoptic nuclei (SON) of the hypothalamus, is secreted from the posterior pituitary (PP) into the systemic circulation, where it plays an essential role in reproduction, especially during and after childbirth. Many recent studies have shown that OXT contributes to the modulation of several functions, such as social recognition, trust building, anti-nociception, anti-inflammation, stress relief and suppression of feeding. However, little is known about the neuronal networks responsible for OXT effects. Endogenious OXT has two regulations: the 1st regulation is humoral regulation, in which OXT is delivered to target organs from PP via the bloodstream; the 2nd regulation is nerve regulations, in which OXT from parvocellular neurosecretory neurons in the PVN directly project to the central nerve system (CNS). OXT binding sites, as well as OXT receptor expression, are located in various regions of the CNS, including the dorsal horn of spinal cord in rats, where it plays an important role in nociception. We examined the response to acute and chronic nociception/-inflammation in rat models using OXT-monomeric red fluorescent protein 1 (mRFP1) transgenic rats. We used formalin test as acute nociceptive/-inflammatory rat models and adjuvant arthritis as chronic nociceptive/-inflammatory rat models. We studied the effects of acute and chronic nociception/-inflammation on OXT-mRFP1 expression in the hypothalamus, posterior pituitary and spinal cord, and examined the role that OXT plays in acute and chronic nociceptive responses in rats. This review focuses on pain modulation and anti-inflammation by OXT according to previous clinical and animal research.


Assuntos
Inflamação/tratamento farmacológico , Ocitocina/uso terapêutico , Manejo da Dor , Dor , Animais , Encéfalo/efeitos dos fármacos , Modelos Animais de Doenças , Humanos
15.
Nature ; 462(7272): 505-9, 2009 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-19940926

RESUMO

Receptor-activator of NF-kappaB ligand (TNFSF11, also known as RANKL, OPGL, TRANCE and ODF) and its tumour necrosis factor (TNF)-family receptor RANK are essential regulators of bone remodelling, lymph node organogenesis and formation of a lactating mammary gland. RANKL and RANK are also expressed in the central nervous system. However, the functional relevance of RANKL/RANK in the brain was entirely unknown. Here we report that RANKL and RANK have an essential role in the brain. In both mice and rats, central RANKL injections trigger severe fever. Using tissue-specific Nestin-Cre and GFAP-Cre rank(floxed) deleter mice, the function of RANK in the fever response was genetically mapped to astrocytes. Importantly, Nestin-Cre and GFAP-Cre rank(floxed) deleter mice are resistant to lipopolysaccharide-induced fever as well as fever in response to the key inflammatory cytokines IL-1beta and TNFalpha. Mechanistically, RANKL activates brain regions involved in thermoregulation and induces fever via the COX2-PGE(2)/EP3R pathway. Moreover, female Nestin-Cre and GFAP-Cre rank(floxed) mice exhibit increased basal body temperatures, suggesting that RANKL and RANK control thermoregulation during normal female physiology. We also show that two children with RANK mutations exhibit impaired fever during pneumonia. These data identify an entirely novel and unexpected function for the key osteoclast differentiation factors RANKL/RANK in female thermoregulation and the central fever response in inflammation.


Assuntos
Regulação da Temperatura Corporal/efeitos dos fármacos , Regulação da Temperatura Corporal/fisiologia , Febre/induzido quimicamente , Febre/metabolismo , Ligante RANK/farmacologia , Receptor Ativador de Fator Nuclear kappa-B/metabolismo , Caracteres Sexuais , Animais , Astrócitos/efeitos dos fármacos , Astrócitos/metabolismo , Criança , Dinoprostona/metabolismo , Feminino , Febre/complicações , Perfilação da Expressão Gênica , Humanos , Injeções Intraventriculares , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pneumonia/complicações , Pneumonia/metabolismo , Ligante RANK/administração & dosagem , Ligante RANK/antagonistas & inibidores , Ligante RANK/metabolismo , Ratos , Ratos Wistar , Receptor Ativador de Fator Nuclear kappa-B/genética , Receptores de Prostaglandina E/metabolismo , Receptores de Prostaglandina E Subtipo EP3
16.
Proc Natl Acad Sci U S A ; 109(8): 3030-4, 2012 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-22323586

RESUMO

The present study demonstrates a key role for the oxysterol receptor liver X receptor ß (LXRß) in the etiology of diabetes insipidus (DI). Given free access to water, LXRß(-/-) but not LXRα(-/-) mice exhibited polyuria (abnormal daily excretion of highly diluted urine) and polydipsia (increased water intake), both features of diabetes insipidus. LXRß(-/-) mice responded to 24-h dehydration with a decreased urine volume and increased urine osmolality. To determine whether the DI was of central or nephrogenic origin, we examined the responsiveness of the kidney to arginine vasopressin (AVP). An i.p. injection of AVP to LXRß(-/-) mice revealed a partial kidney response: There was no effect on urine volume, but there was a significant increase of urine osmolality, suggesting that DI may be caused by a defect in central production of AVP. In the brain of WT mice LXRß was expressed in the nuclei of magnocellular neurons in the supraoptic and paraventricular nuclei of the hypothalamus. In LXRß(-/-) mice the expression of AVP was markedly decreased in the magnocellular neurons as well as in urine collected over a 24-h period. The persistent high urine volume after AVP administration was traced to a reduction in aquaporin-1 expression in the kidney of LXRß(-/-) mice. The LXR agonist (GW3965) in WT mice elicited an increase in urine osmolality, suggesting that LXRß is a key receptor in controlling water balance with targets in both the brain and kidney, and it could be a therapeutic target in disorders of water balance.


Assuntos
Aquaporina 1/metabolismo , Diabetes Insípido Neurogênico/metabolismo , Rim/metabolismo , Receptores Nucleares Órfãos/deficiência , Animais , Arginina Vasopressina/administração & dosagem , Arginina Vasopressina/farmacologia , Arginina Vasopressina/urina , Benzoatos/administração & dosagem , Benzoatos/farmacologia , Benzilaminas/administração & dosagem , Benzilaminas/farmacologia , Água Corporal , Desidratação/sangue , Desidratação/complicações , Desidratação/fisiopatologia , Desidratação/urina , Diabetes Insípido Neurogênico/complicações , Diabetes Insípido Neurogênico/patologia , Diabetes Insípido Neurogênico/fisiopatologia , Feminino , Rim/patologia , Rim/fisiopatologia , Receptores X do Fígado , Camundongos , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Receptores Nucleares Órfãos/metabolismo , Concentração Osmolar , Núcleo Hipotalâmico Paraventricular/efeitos dos fármacos , Núcleo Hipotalâmico Paraventricular/metabolismo , Núcleo Hipotalâmico Paraventricular/patologia , Núcleo Hipotalâmico Paraventricular/fisiopatologia , Polidipsia/sangue , Polidipsia/complicações , Polidipsia/fisiopatologia , Polidipsia/urina , Poliúria/sangue , Poliúria/complicações , Poliúria/fisiopatologia , Poliúria/urina , Núcleo Supraóptico/efeitos dos fármacos , Núcleo Supraóptico/metabolismo , Núcleo Supraóptico/patologia , Núcleo Supraóptico/fisiopatologia , Equilíbrio Hidroeletrolítico/fisiologia
17.
Am J Physiol Endocrinol Metab ; 306(4): E373-87, 2014 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-24347053

RESUMO

Cancer cachexia (CC), a syndrome characterized by anorexia and body weight loss due to low fat-free mass levels, including reduced musculature, markedly worsens patient quality of life. Although stomach cancer patients have the highest incidence of cachexia, few experimental models for the study of stomach CC have been established. Herein, we developed stomach CC animal models using nude rats subcutaneously implanted with two novel cell lines, i.e., MKN45c185, established from the human stomach cancer cell line MKN-45, and 85As2, derived from peritoneal dissemination of orthotopically implanted MKN45c185 cells in mice. Both CC models showed marked weight loss, anorexia, reduced musculature and muscle strength, increased inflammatory markers, and low plasma albumin levels; however, CC developed earlier and was more severe in rats implanted with 85As2 than in those implanted with MKN45cl85. Moreover, human leukemia inhibitory factor (LIF), a known cachectic factor, and hypothalamic orexigenic peptide mRNA levels increased in the models, whereas hypothalamic anorexigenic peptide mRNA levels decreased. Surgical removal of the tumor not only abolished cachexia symptoms but also reduced plasma LIF levels to below detectable limits. Importantly, oral administration of rikkunshito, a traditional Japanese medicine, substantially ameliorated CC-related anorexia and body composition changes. In summary, our novel peritoneal dissemination-derived 85As2 rat model developed severe cachexia, possibly caused by LIF from cancer cells, that was ameliorated by rikkunshito. This model should provide a useful tool for further study into the mechanisms and treatment of stomach CC.


Assuntos
Caquexia/etiologia , Linhagem Celular Tumoral/transplante , Modelos Animais de Doenças , Neoplasias Gástricas/complicações , Proteína Relacionada com Agouti/genética , Proteína Relacionada com Agouti/metabolismo , Animais , Caquexia/tratamento farmacológico , Caquexia/metabolismo , Hormônio Liberador da Corticotropina/genética , Hormônio Liberador da Corticotropina/metabolismo , Citocinas/sangue , Medicamentos de Ervas Chinesas/uso terapêutico , Humanos , Hormônios Hipotalâmicos/genética , Hormônios Hipotalâmicos/metabolismo , Hipotálamo/metabolismo , Fator Inibidor de Leucemia/genética , Fator Inibidor de Leucemia/metabolismo , Masculino , Melaninas/genética , Melaninas/metabolismo , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Neuropeptídeo Y/genética , Neuropeptídeo Y/metabolismo , Consumo de Oxigênio , Hormônios Hipofisários/genética , Hormônios Hipofisários/metabolismo , Pró-Opiomelanocortina/genética , Pró-Opiomelanocortina/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Nus , Neoplasias Gástricas/tratamento farmacológico , Neoplasias Gástricas/metabolismo
18.
Am J Physiol Regul Integr Comp Physiol ; 307(2): R225-36, 2014 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-24829503

RESUMO

Nesfatin-1/NucB2, an anorexigenic molecule, is expressed mainly in the hypothalamus, particularly in the supraoptic nucleus (SON) and the paraventricular nucleus (PVN). Nesfatin-1/NucB2 is also expressed in the subfornical organ (SFO). Because the SON and PVN are involved in body fluid regulation, nesfatin-1/NucB2 may be involved in dehydration-induced anorexia. To clarify the effects of endogenous nesfatin-1/NucB2, we studied changes in nesfatin-1/NucB2 mRNA levels in the SFO, SON, and PVN in adult male Wistar rats after exposure to osmotic stimuli by using in situ hybridization histochemistry. Significant increases in nesfatin-1/NucB2 mRNA levels, ∼2- to 3-fold compared with control, were observed in the SFO, SON, and PVN following water deprivation for 48 h, consumption of 2% NaCl hypertonic saline in drinking water for 5 days, and polyethylene glycol-induced hypovolemia. In addition, nesfatin-1/NucB2 expression was increased in response to water deprivation in a time-dependent manner. These changes in nesfatin-1/NucB2 mRNA expression were positively correlated with plasma sodium concentration, plasma osmolality, and total protein levels in all of the examined nuclei. Immunohistochemistry for nesfatin-1/NucB2 revealed that nesfatin-1/NucB2 protein levels were also increased after 48 h of dehydration and attenuated by 24 h of rehydration. Moreover, intracerebroventricular administration of nesfatin-1/NucB2-neutralizing antibody after 48 h of water deprivation resulted in a significant increase in food intake compared with administration of vehicle alone. These results suggested that nesfatin-1/NucB2 is a crucial peptide in dehydration-induced anorexia.


Assuntos
Anorexia/etiologia , Proteínas de Ligação ao Cálcio/metabolismo , Proteínas de Ligação a DNA/metabolismo , Desidratação/fisiopatologia , Proteínas do Tecido Nervoso/metabolismo , Núcleo Hipotalâmico Paraventricular/metabolismo , Núcleo Supraóptico/metabolismo , Animais , Anorexia/metabolismo , Desidratação/complicações , Ingestão de Alimentos/fisiologia , Masculino , Nucleobindinas , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Sódio/sangue , Privação de Água/fisiologia
19.
Peptides ; 179: 171263, 2024 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-38897354

RESUMO

Oxytocin (OXT) was discovered in 1906 as a substance that promotes the pregnancy and childbirth. It affects uterine contraction and lactation. Furthermore, as one of its physiological properties, it exerts analgesic effects. The living body has an ascending pathway that transmits pain stimuli from the periphery to the center and a descending pathway that regulates the dorsal horn neurons from the upper center downward. OXT is involved in the pain-inhibitory descending pathway and generally assumed to exert analgesic effects. In this article, we describe the pain-suppressive effects of OXT, among its many physiological effects.

20.
J Neurosci ; 32(2): 572-82, 2012 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-22238092

RESUMO

Neuronal excitability in the adult brain is controlled by a balance between synaptic excitation and inhibition mediated by glutamate and GABA, respectively. While generally inhibitory in the adult brain, GABA(A) receptor activation is excitatory under certain conditions in which the GABA reversal potential is shifted positive due to intracellular Cl(-) accumulation, such as during early postnatal development and brain injury. However, the conditions under which GABA is excitatory are generally either transitory or pathological. Here, we reveal GABAergic synaptic inputs to be uniformly excitatory in vasopressin (VP)-secreting magnocellular neurons in the adult hypothalamus under normal conditions. The GABA reversal potential (E(GABA)) was positive to resting potential and spike threshold in VP neurons, but not in oxytocin (OT)-secreting neurons. The VP neurons lacked expression of the K(+)-Cl(-) cotransporter 2 (KCC2), the predominant Cl(-) exporter in the adult brain. The E(GABA) was unaffected by inhibition of KCC2 in VP neurons, but was shifted positive in OT neurons, which express KCC2. Alternatively, inhibition of the Na(+)-K(+)-Cl(-) cotransporter 1 (NKCC1), a Cl(-) importer expressed in most cell types mainly during postnatal development, caused a negative shift in E(GABA) in VP neurons, but had no effect on GABA currents in OT neurons. GABA(A) receptor blockade caused a decrease in the firing rate of VP neurons, but an increase in firing in OT neurons. Our findings demonstrate that GABA is excitatory in adult VP neurons, suggesting that the classical excitation/inhibition paradigm of synaptic glutamate and GABA control of neuronal excitability does not apply to VP neurons.


Assuntos
Potenciais Pós-Sinápticos Excitadores/fisiologia , Células Neuroendócrinas/fisiologia , Núcleo Hipotalâmico Paraventricular/fisiologia , Núcleo Supraóptico/fisiologia , Vasopressinas/fisiologia , Ácido gama-Aminobutírico/fisiologia , Envelhecimento/fisiologia , Animais , Neurônios GABAérgicos/fisiologia , Masculino , Núcleo Hipotalâmico Paraventricular/citologia , Ratos , Ratos Transgênicos , Ratos Wistar , Núcleo Supraóptico/citologia
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