RESUMO
The arginine vasopressin (AVP)-magnocellular neurosecretory system (AVPMNS) in the hypothalamus plays a critical role in homeostatic regulation as well as in allostatic motivational behaviors. However, it remains unclear whether adult neurogenesis exists in the AVPMNS. By using immunoreaction against AVP, neurophysin II, glial fibrillar acidic protein (GFAP), cell division marker (Ki67), migrating neuroblast markers (doublecortin, DCX), microglial marker (Ionized calcium binding adaptor molecule 1, Iba1), and 5'-bromo-2'-deoxyuridine (BrdU), we report morphological evidence that low-rate neurogenesis and migration occur in adult AVPMNS in the rat hypothalamus. Tangential AVP/GFAP migration routes and AVP/DCX neuronal chains as well as ascending AVP axonal scaffolds were observed. Chronic water deprivation significantly increased the BrdU+ nuclei within both the supraaoptic (SON) and paraventricular (PVN) nuclei. These findings raise new questions about AVPMNS's potential hormonal role for brain physiological adaptation across the lifespan, with possible involvement in coping with homeostatic adversities.
Assuntos
Movimento Celular , Proteína Duplacortina , Neurogênese , Neurônios , Animais , Ratos , Neurônios/metabolismo , Neurônios/citologia , Masculino , Núcleo Hipotalâmico Paraventricular/metabolismo , Núcleo Hipotalâmico Paraventricular/citologia , Hipotálamo/metabolismo , Hipotálamo/citologia , Arginina Vasopressina/metabolismoRESUMO
Neuropeptides are expressed in cell-specific patterns throughout mammalian brain. Neuropeptide gene expression has been useful for clustering neurons by phenotype, based on single-cell transcriptomics, and for defining specific functional circuits throughout the brain. How neuropeptides function as first messengers in inter-neuronal communication, in cooperation with classical small-molecule amine transmitters (SMATs) is a current topic of systems neurobiology. Questions include how neuropeptides and SMATs cooperate in neurotransmission at the molecular, cellular and circuit levels; whether neuropeptides and SMATs always co-exist in neurons; where neuropeptides and SMATs are stored in the neuron, released from the neuron and acting, and at which receptors, after release; and how neuropeptides affect 'classical' transmitter function, both directly upon co-release, and indirectly, via long-term regulation of gene transcription and neuronal plasticity. Here, we review an extensive body of data about the distribution of neuropeptides and their receptors, their actions after neuronal release, and their function based on pharmacological and genetic loss- and gain-of-function experiments, that addresses these questions, fundamental to understanding brain function, and development of neuropeptide-based, and potentially combinatorial peptide/SMAT-based, neurotherapeutics.
Assuntos
Aminas , Neuropeptídeos , Aminas/metabolismo , Animais , Mamíferos/metabolismo , Neurônios/metabolismo , Neuropeptídeos/genética , Neuropeptídeos/metabolismo , Transdução de Sinais , Transmissão SinápticaRESUMO
Homeostatic challenges may alter the drive for social interaction. The neural activity that prompts this motivation remains poorly understood. In the present study, we identify direct projections from the hypothalamic supraoptic nucleus to the cortico-amygdalar nucleus of the lateral olfactory tract (NLOT). Dual in situ hybridization with probes for pituitary adenylate cyclase-activating polypeptide (PACAP), as well as vesicular glutamate transporter (VGLUT)1, VGLUT2, V1a and V1b, revealed a population of vasopressin-receptive PACAPergic neurons in NLOT layer 2 (NLOT2). Water deprivation (48 h, WD48) increased sociability compared to euhydrated subjects, as assessed with the three-chamber social interaction test (3CST). Fos expression immunohistochemistry showed NLOT and its main efferent regions had further increases in rats subjected to WD48 + 3CST. These regions strongly expressed PAC1 mRNA. Microinjections of arginine vasopressin (AVP) into the NLOT produced similar changes in sociability to water deprivation, and these were reduced by co-injection of V1a or V1b antagonists along with AVP. We conclude that, during challenge to water homeostasis, there is a recruitment of a glutamatergic-multi-peptidergic cooperative circuit that promotes social behavior.
Assuntos
Neocórtex , Núcleo Supraóptico , Humanos , Ratos , Animais , Núcleo Supraóptico/metabolismo , Arginina Vasopressina/metabolismo , Bulbo Olfatório , Neocórtex/metabolismo , Ratos Wistar , Vasopressinas/metabolismo , Polipeptídeo Hipofisário Ativador de Adenilato Ciclase/metabolismo , Comportamento Social , Homeostase , Água/metabolismoRESUMO
Hypothalamic arginine vasopressin (AVP)-containing magnocellular neurosecretory neurons (AVPMNN) emit collaterals to synaptically innervate limbic regions influencing learning, motivational behaviour, and fear responses. Here, we characterize the dynamics of expression changes of two key determinants for synaptic strength, the postsynaptic density (PSD) proteins AMPAR subunit GluA1 and PSD scaffolding protein 95 (PSD95), in response to in vivo manipulations of AVPMNN neuronal activation state, or exposure to exogenous AVP ex vivo. Both long-term water deprivation in vivo, which powerfully upregulates AVPMNN metabolic activity, and exogenous AVP application ex vivo, in brain slices, significantly increased GluA1 and PSD95 expression as measured by western blotting, in brain regions reportedly receiving direct ascending innervations from AVPMNN (i.e., ventral hippocampus, amygdala and lateral habenula). By contrast, the visual cortex, a region not observed to receive AVPMNN projections, showed no such changes. Ex vivo application of V1a and V1b antagonists to ventral hippocampal slices ablated the AVP stimulated increase in postsynaptic protein expression measured by western blotting. Using a modified expansion microscopy technique, we were able to quantitatively assess the significant augmentation of PSD95 and GLUA1 densities in subcellular compartments in locus coeruleus tyrosine hydroxylase immunopositive fibres, adjacent to AVP axon terminals. Our data strongly suggest that the AVPMNN ascending system plays a role in the regulation of the excitability of targeted neuronal circuits through upregulation of key postsynaptic density proteins corresponding to excitatory synapses.
Assuntos
Sinapses , Tirosina 3-Mono-Oxigenase , Arginina Vasopressina/metabolismo , Hipocampo/metabolismo , Hipotálamo/metabolismo , Sinapses/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
Coronavirus disease 2019 (COVID-19) has become the most critical pandemic of the 21st Century and the most severe since the 1918 influenza pandemic. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infects the host by binding to angiotensin-converting enzyme 2 (ACE2). The role of ACE2 in the pathophysiology of coronavirus disease 2019 (COVID-19) is a topic of debate, with clinical and experimental evidence indicating a multifaceted relationship between ACE2 activity and disease severity. Here, we review the mechanisms by which the peptidergic substrates and products of ACE and ACE2 contribute to physiological and pathophysiological processes and hypothesise how down-regulation of ACE2 by SARS-CoV-2 cellular entry disrupts homeostasis. A better understanding of the endocrinology of the disease, in particular the neuroendocrinology of ACE2 during COVID-19, may contribute to the timely design of new therapeutic strategies, including the regulation of ACE2 itself by steroid hormones, to ameliorate the severity of COVID-19.
Assuntos
Enzima de Conversão de Angiotensina 2/metabolismo , Tratamento Farmacológico da COVID-19 , COVID-19/metabolismo , Estrogênios/uso terapêutico , Peptídeos/metabolismo , SARS-CoV-2/metabolismo , Humanos , Ligação ProteicaRESUMO
The neuropeptide PACAP, acting as a co-transmitter, increases neuronal excitability, which may enhance anxiety and arousal associated with threat conveyed by multiple sensory modalities. The distribution of neurons expressing PACAP and its receptor, PAC1, throughout the mouse nervous system was determined, in register with expression of glutamatergic and GABAergic neuronal markers, to develop a coherent chemoanatomical picture of PACAP role in brain motor responses to sensory input. A circuit role for PACAP was tested by observing Fos activation of brain neurons after olfactory threat cue in wild-type and PACAP knockout mice. Neuronal activation and behavioral response, were blunted in PACAP knock-out mice, accompanied by sharply downregulated vesicular transporter expression in both GABAergic and glutamatergic neurons expressing PACAP and its receptor. This report signals a new perspective on the role of neuropeptide signaling in supporting excitatory and inhibitory neurotransmission in the nervous system within functionally coherent polysynaptic circuits.
Assuntos
Neurônios GABAérgicos/metabolismo , Polipeptídeo Hipofisário Ativador de Adenilato Ciclase/genética , Transdução de Sinais , Animais , Feminino , Masculino , Camundongos , Polipeptídeo Hipofisário Ativador de Adenilato Ciclase/metabolismoRESUMO
Axon initial segments (AIS) of dentate granule cells in the hippocampus exhibit prominent spines (AISS) during early development that are associated with microglial contacts. In the present study, we investigated whether developmental changes in AISS could be modified by early-life stress (ELS), specifically neonatal maternal separation (MS), through stress hormones and microglial activation and examined the potential behavioural consequences. We examined AISS at postnatal day (PND)5, 15 and 50, using Golgi-Cox staining and anatomical analysis. Neurone-microglial interaction was assessed using antibodies against ankyrin-G, PSD-95 and Iba1, for AIS, AISS and microglia visualisation, respectively, in normally reared and neonatal maternally separated male and female rats. We observed a higher density of AISS in ELS rats at both PND15 and PND50 compared to controls. Effects were more pronounced in females than males. AIS-associated microglia in ELS rats showed a hyper-ramified morphology and less co-localisation with PSD-95 compared to controls at PND15. ELS-associated alteration in microglial morphology and synaptic pruning was mimicked by treatment of acute hippocampal slices of normally reared rats with vasopressin. ELS rats exhibited increased freezing behaviour during auditory fear memory testing, which was more pronounced in female subjects and corresponded with increased Fos expression in dorsal and ventral dentate granule cells. Thus, microglial synaptic pruning in dentate AIS of hippocampus is influenced by ELS, with demonstrable sex bias regarding its anatomical characteristics and subsequent fear-induced defensive behaviours.
Assuntos
Giro Denteado/fisiologia , Medo/psicologia , Microglia/fisiologia , Plasticidade Neuronal/fisiologia , Estresse Psicológico , Envelhecimento/psicologia , Animais , Animais Recém-Nascidos , Segmento Inicial do Axônio/fisiologia , Espinhas Dendríticas/fisiologia , Giro Denteado/citologia , Feminino , Masculino , Privação Materna , Microglia/citologia , Gravidez , Ratos , Ratos Wistar , Caracteres Sexuais , Estresse Psicológico/fisiopatologia , Estresse Psicológico/psicologiaRESUMO
We examined cell type-specific expression and distribution of rat brain angiotensin-converting enzyme 2 (ACE2), the receptor for SARS-CoV-2, in the rodent brain. ACE2 is ubiquitously present in brain vasculature, with the highest density of ACE2 expressing capillaries found in the olfactory bulb, the hypothalamic paraventricular, supraoptic, and mammillary nuclei, the midbrain substantia nigra and ventral tegmental area, and the hindbrain pontine nucleus, the pre-Bötzinger complex, and nucleus of tractus solitarius. ACE2 was expressed in astrocytes and astrocytic foot processes, pericytes and endothelial cells, key components of the blood-brain barrier. We found discrete neuronal groups immunopositive for ACE2 in brainstem respiratory rhythm generating centers, including the pontine nucleus, the parafascicular/retrotrapezoid nucleus, the parabrachial nucleus, the Bötzinger, and pre-Bötzinger complexes and the nucleus of tractus solitarius; in the arousal-related pontine reticular nucleus and gigantocellular reticular nuclei; in brainstem aminergic nuclei, including substantia nigra, ventral tegmental area, dorsal raphe, and locus coeruleus; in the epithalamic habenula, hypothalamic paraventricular and supramammillary nuclei; and in the hippocampus. Identification of ACE2-expressing neurons in rat brain within well-established functional circuits facilitates prediction of possible neurological manifestations of brain ACE2 dysregulation during and after COVID-19 infection.
Assuntos
Enzima de Conversão de Angiotensina 2/metabolismo , Encéfalo/metabolismo , COVID-19 , Doenças do Sistema Nervoso Central/metabolismo , Animais , Masculino , Ratos , Ratos Wistar , SARS-CoV-2RESUMO
The origin and functional significance of vasopressin (AVP)-containing fibres in limbic regions has been an ongoing subject of investigation for several years. We have previously identified AVP-magnocellular neurones of rat hypothalamus that provide glutamatergic projections to the hippocampus, amygdala, lateral habenula and locus coeruleus. However, we also reported AVP-immunopositive fibres in those regions that are thin and make Gray type II synapses, which are unlikely to be of magnocellular origin. Therefore, in the present study, we characterised AVP mRNA co-expression with expression of mRNAs marking glutamatergic (vesicular glutamate transporter [VGLUT]) and GABAergic (vesicular GABA transporter [VGAT]) neuronal traits in rat and mouse brain, using high-resolution in situ hybridisation methods, including a radio-ribonucleotide and RNAscope 2.5 HD duplex assay, with Slc17a7, Slc17a6, Slc32a1 and Avp probes corresponding to mRNAs of VGLUT1, VGLUT2, VGAT and AVP, respectively. We located 18 cell groups expressing Avp and identified their molecular signatures for VGLUT and VGAT mRNA expression. Avp cell groups of hypothalamus and midbrain are mainly VGLUT mRNA-expressing, whereas those in regions derived from cerebral nuclei are mainly VGAT mRNA-expressing, suggesting a functional segregation of glutamate/GABA co-transmission with AVP. A newly identified Slc17a7 and Slc17a6 (but not Slc32a1) expressing vasopressinergic cell group was found in layer II-III neurones of the central entorhinal cortex, which projects to the hippocampus. These data support the notion of a complex role for AVP with respect to modulating multiple central circuits controlling behaviour in specific ways depending on co-transmission with glutamate or GABA, potentially giving rise to a functional classification of AVPergic neurones in the central nervous system.
Assuntos
Ácido Glutâmico/metabolismo , Hipocampo/metabolismo , Neurônios/metabolismo , Proteínas Vesiculares de Transporte de Glutamato/metabolismo , Proteínas Vesiculares de Transporte de Aminoácidos Inibidores/metabolismo , Animais , Masculino , Mesencéfalo/metabolismo , Camundongos , Vias Neurais/metabolismo , Ratos , Ratos Wistar , Sinapses/metabolismoRESUMO
Recently, there has been a resurgence in regulatory peptide science as a result of three converging trends. The first is the increasing population of the drug pipeline with peptide-based therapeutics, mainly in, but not restricted to, incretin-like molecules for treatment of metabolic disorders such as diabetes. The second is the development of genetic and optogenetic tools enabling new insights into how peptides actually function within brain and peripheral circuits to accomplish homeostatic and allostatic regulation. The third is the explosion in defined structures of the G-protein coupled receptors to which most regulatory peptides bind and exert their actions. These trends have closely wedded basic systems biology to drug discovery and development, creating a "two-way street" on which translational advances travel from basic research to the clinic, and, equally importantly, "reverse-translational" information is gathered, about the molecular, cellular and circuit-level mechanisms of action of regulatory peptides, comprising information required for the fine-tuning of drug development through testing in animal models. This review focuses on a small group of 'influential' peptides, including oxytocin, vasopressin, pituitary adenylate cyclase-activating polypeptide, ghrelin, relaxin-3 and glucagon-like peptide-1, and how basic discoveries and their application to therapeutics have intertwined over the past decade.
Assuntos
Neuroendocrinologia , Biologia de Sistemas , Animais , Polipeptídeo Hipofisário Ativador de Adenilato CiclaseRESUMO
The locus coeruleus (LC)-norepinephrine (NE) system modulates a range of salient brain functions, including memory and response to stress. The LC-NE system is regulated by neurochemically diverse inputs, including a range of neuropeptides such as arginine-vasopressin (AVP). Whilst the origins of many of these LC inputs, their synaptic connectivity with LC neurons, and their contribution to LC-mediated brain functions, have been well characterized, this is not the case for the AVP-LC system. Therefore, our aims were to define the types of synapses formed by AVP+ fibers with LC neurons using immunohistochemistry together with confocal and transmission electron microscopy (TEM), the origins of such inputs, using retrograde tracers, and the plasticity of the LC AVP system in response to stress and spatial learning, using the maternal separation (MS) and Morris water maze (MWM) paradigms, respectively, in rat. Confocal microscopy revealed that AVP+ fibers contacting tyrosine hydroxylase (TH)+ LC neurons were also immunopositive for vesicular glutamate transporter 2, a marker of presynaptic glutamatergic axons. TEM confirmed that AVP+ axons formed Gray type I (asymmetric) synapses with TH+ dendrites thus confirming excitatory synaptic connections between these systems. Retrograde tracing revealed that these LC AVP+ fibers originate from hypothalamic vasopressinergic magnocellular neurosecretory neurons (AVPMNNs). MS induced a significant increase in the density of LC AVP+ fibers. Finally, AVPMNN circuit upregulation by water-deprivation improved MWM performance while increased Fos expression was found in LC and efferent regions such as hippocampus and prefrontal cortex, suggesting that AVPMMN projections to LC could integrate homeostatic responses modifying neuroplasticity.
RESUMO
Given the evidence that maternal hyperthyroidism (MH) compromises expression of neuronal cytoskeletal proteins in the late fetal brain by accelerated neuronal differentiation, we investigated possible consequences of MH for the emotional and cognitive functions of adult offspring during acute and subchronic stress coping. Experimental groups consisted of male rat offspring from mothers implanted with osmotic minipumps infusing either thyroxine (MH) or vehicle (Ctrl) during pregnancy. Body weight and T4 level were monitored during the first 3 postnatal months, and no differences were found with the controls. We analyzed hippocampal CA3 pyramidal neurons and dentate granular cell morphology during several postnatal stages and found increased dendritic arborization. On postnatal day 90 a modified subchronic mild stress (SCMS) protocol was applied to experimental subjects for 10 days. The Morris water maze was used before, during, and after application of the SCMS protocol to measure spatial learning. The tail suspension test (TST) and forced-swimming test (FST) were used to evaluate behavioral despair. The MH rats displayed normal locomotor activity and spatial memory prior to SCMS, but impaired spatial learning after acute and chronic stress. In both the FST and TST we found that MH rats spent significantly more time immobile than did controls. Serum corticosterone level was found to increase after 30 min of restraint stress, and corticotropin-releasing factor immunoreactivity was found to be increased in the central nucleus of the amygdala. Our results suggest that MH in rats leads to the offspring being more vulnerable to stress in adulthood.
Assuntos
Adaptação Psicológica/fisiologia , Hipertireoidismo/fisiopatologia , Neurônios/patologia , Complicações na Gravidez/fisiopatologia , Estresse Psicológico/fisiopatologia , Animais , Comportamento Animal/fisiologia , Corticosterona/sangue , Hormônio Liberador da Corticotropina/biossíntese , Ensaio de Imunoadsorção Enzimática , Feminino , Hipertireoidismo/patologia , Processamento de Imagem Assistida por Computador , Imuno-Histoquímica , Masculino , Aprendizagem em Labirinto/fisiologia , Gravidez , Complicações na Gravidez/patologia , Ratos , Ratos Wistar , Restrição Física/fisiologia , Natação/fisiologiaRESUMO
The locus coeruleus (LC) is a brainstem nucleus distinguished by its supply of noradrenaline throughout the central nervous system. Apart from modulating a range of brain functions, such as arousal, cognition and the stress response, LC neuronal excitability also corresponds to the activity of various peripheral systems, such as pelvic viscera and the cardiovascular system. Neurochemically diverse inputs set the tone for LC neuronal activity, which in turn modulates these adaptive physiological and behavioral responses essential for survival. One such LC afferent system which is poorly understood contains the neurohormone arginine-vasopressin (AVP). Here we provide the first demonstration of the molecular and functional characteristics of the LC-AVP system, by characterizing its receptor-specific modulation of identified LC neurons and plasticity in response to stress. High resolution confocal microscopy revealed that immunoreactivity for the AVP receptor 1b (V1b) was located on plasma membranes of noradrenergic and non-noradrenergic LC neurons. In contrast, immunoreactivity for the V1a receptor was exclusively located on LC noradrenergic neurons. No specific signal, either at the mRNA or protein level, was detected for the V2 receptor in the LC. Clusters immunoreactive for V1a-b were located in proximity to profiles immunoreactive for GABAergic and glutamatergic synaptic marker proteins. AVP immunopositive varicosities were also located adjacent to labeling for such synaptic markers. Whole-cell patch clamp electrophysiology revealed that the pharmacological activation of V1b receptors significantly increased the spontaneous activity of 45% (9/20) of recorded noradrenergic neurons, with the remaining 55% (11/20) of cells exhibiting a significant decrease in their basal firing patterns. Blockade of V1a and V1b receptors on their own significantly altered LC neuronal excitability in a similar heterogeneous manner, demonstrating that endogenous AVP sets the basal LC neuronal firing rates. Finally, exposing animals to acute stress increased V1b, but not V1a receptor expression, whilst decreasing AVP immunoreactivity. This study reveals the AVP-V1a-b system as a considerable component of the LC molecular architecture and regulator of LC activity. Since AVP primarily functions as a regulator of homeostasis, the data suggest a novel pathway by modulating the functioning of a brain region that is integral to mediating adaptive responses.
RESUMO
The lateral habenula (LHb) has a key role in integrating a variety of neural circuits associated with reward and aversive behaviors. There is limited information about how the different cell types and neuronal circuits within the LHb coordinate physiological and motivational states. Here, we report a cell type in the medial division of the LHb (LHbM) in male rats that is distinguished by: (1) a molecular signature for GABAergic neurotransmission (Slc32a1/VGAT) and estrogen receptor (Esr1/ERα) expression, at both mRNA and protein levels, as well as the mRNA for vesicular glutamate transporter Slc17a6/VGLUT2, which we term the GABAergic estrogen-receptive neuron (GERN); (2) its axonal projection patterns, identified by in vivo juxtacellular labeling, to both local LHb and to midbrain modulatory systems; and (3) its somatic expression of receptors for vasopressin, serotonin and dopamine, and mRNA for orexin receptor 2. This cell type is anatomically located to receive afferents from midbrain reward (dopamine and serotonin) and hypothalamic water and energy homeostasis (vasopressin and orexin) circuits. These afferents shared the expression of estrogen synthase (aromatase) and VGLUT2, both in their somata and axon terminals. We demonstrate dynamic changes in LHbM VGAT+ cell density, dependent upon gonadal functional status, that closely correlate with motivational behavior in response to predator and forced swim stressors. The findings suggest that the homeostasis and reward-related glutamatergic convergent projecting pathways to LHbMC employ a localized neurosteroid signaling mechanism via axonal expression of aromatase, to act as a switch for GERN excitation/inhibition output prevalence, influencing depressive or motivated behavior.
Assuntos
Comportamento Animal/fisiologia , Estrogênios/metabolismo , Neurônios GABAérgicos/fisiologia , Hormônios Esteroides Gonadais/metabolismo , Habenula/fisiologia , Homeostase/fisiologia , Hipotálamo/fisiologia , Mesencéfalo/fisiologia , Motivação/fisiologia , Transdução de Sinais/fisiologia , Proteína Vesicular 2 de Transporte de Glutamato/metabolismo , Proteínas Vesiculares de Transporte de Aminoácidos Inibidores/metabolismo , Animais , Neurônios GABAérgicos/metabolismo , Habenula/metabolismo , Hipotálamo/metabolismo , Masculino , Mesencéfalo/metabolismo , Ratos , Ratos WistarRESUMO
Water-homeostasis is a fundamental physiological process for terrestrial life. In vertebrates, thirst drives water intake, but the neuronal circuits that connect the physiology of water regulation with emotional context are poorly understood. Vasopressin (VP) is a prominent messenger in this circuit, as well as L-glutamate. We have investigated the role of a VP circuit and interaction between thirst and motivational behaviors evoked by life-threatening stimuli in rats. We demonstrate a direct pathway from hypothalamic paraventricular VP-expressing, glutamatergic magnocellular neurons to the medial division of lateral habenula (LHbM), a region containing GABAergic neurons. In vivo recording and juxtacellular labeling revealed that GABAergic neurons in the LHbM had locally branching axons, and received VP-positive axon terminal contacts on their dendrites. Water deprivation significantly reduced freezing and immobility behaviors evoked by innate fear and behavioral despair, respectively, accompanied by decreased Fos expression in the lateral habenula. Our results reveal a novel VP-expressing hypothalamus to the LHbM circuit that is likely to evoke GABA-mediated inhibition in the LHbM, which promotes escape behavior during stress coping.
Assuntos
Ácido Glutâmico/metabolismo , Habenula/fisiologia , Transdução de Sinais/fisiologia , Estresse Psicológico/fisiopatologia , Sede/fisiologia , Vasopressinas/metabolismo , Animais , Gatos , Colchicina/farmacologia , Modelos Animais de Doenças , Medo/psicologia , Glutamato Descarboxilase/metabolismo , Habenula/citologia , Habenula/efeitos dos fármacos , Habenula/ultraestrutura , Masculino , Neurônios/efeitos dos fármacos , Neurônios/ultraestrutura , Proteínas Oncogênicas v-fos/metabolismo , Núcleo Hipotalâmico Paraventricular/citologia , Núcleo Hipotalâmico Paraventricular/ultraestrutura , Ratos , Ratos Wistar , Transdução de Sinais/efeitos dos fármacos , Estresse Psicológico/patologia , Sinapses/metabolismo , Sede/efeitos dos fármacos , Moduladores de Tubulina/farmacologia , Privação de Água/fisiologia , Ácido gama-Aminobutírico/metabolismoRESUMO
The arginine-vasopressin (AVP)-containing hypothalamic magnocellular neurosecretory neurons (VPMNNs) are known for their role in hydro-electrolytic balance control via their projections to the neurohypophysis. Recently, projections from these same neurons to hippocampus, habenula and other brain regions in which vasopressin infusion modulates contingent social and emotionally-affected behaviors, have been reported. Here, we present evidence that VPMNN collaterals also project to the amygdaloid complex, and establish synaptic connections with neurons in central amygdala (CeA). The density of AVP innervation in amygdala was substantially increased in adult rats that had experienced neonatal maternal separation (MS), consistent with our previous observations that MS enhances VPMNN number in the paraventricular (PVN) and supraoptic (SON) nuclei of the hypothalamus. In the CeA, V1a AVP receptor mRNA was only observed in GABAergic neurons, demonstrated by complete co-localization of V1a transcripts in neurons expressing Gad1 and Gad2 transcripts in CeA using the RNAscope method. V1b and V2 receptor mRNAs were not detected, using the same method. Water-deprivation (WD) for 24 h, which increased the metabolic activity of VPMNNs, also increased anxiety-like behavior measured using the elevated plus maze (EPM) test, and this effect was mimicked by bilateral microinfusion of AVP into the CeA. Anxious behavior induced by either WD or AVP infusion was reversed by CeA infusion of V1a antagonist. VPMNNs are thus a newly discovered source of CeA inhibitory circuit modulation, through which both early-life and adult stress coping signals are conveyed from the hypothalamus to the amygdala.
Assuntos
Antagonistas dos Receptores de Hormônios Antidiuréticos/farmacologia , Ansiedade/metabolismo , Arginina Vasopressina/metabolismo , Núcleo Central da Amígdala , Glutamato Descarboxilase/metabolismo , Hipotálamo , Neurônios , Receptores de Vasopressinas/metabolismo , Animais , Antagonistas dos Receptores de Hormônios Antidiuréticos/administração & dosagem , Ansiedade/induzido quimicamente , Comportamento Animal , Núcleo Central da Amígdala/citologia , Núcleo Central da Amígdala/metabolismo , Modelos Animais de Doenças , Neurônios GABAérgicos/citologia , Neurônios GABAérgicos/metabolismo , Hipotálamo/citologia , Hipotálamo/metabolismo , Masculino , Privação Materna , Neurônios/citologia , Neurônios/metabolismo , Núcleo Hipotalâmico Paraventricular/citologia , Núcleo Hipotalâmico Paraventricular/metabolismo , Ratos Wistar , Núcleo Supraóptico/citologia , Núcleo Supraóptico/metabolismo , Privação de ÁguaRESUMO
Morbid obesity has been shown to increase the risk to develop hepatic steatosis, also referred to as non-alcoholic fatty liver disease (NAFLD). Emerging evidence suggests that the severity of NAFLD may associate with increased serum levels of inflammatory markers as well as decreased concentration of mediators with anti-inflammatory actions, such as tumor necrosis factor alpha (TNF-α) and interleukin (IL) 10, respectively. We thus examined the serum levels of TNF-α and IL-10 in 102 morbidly obese women and men (body mass index > 40 kg/m(2)), exhibiting different grades of NAFLD. Blood glucose, glycated hemoglobin, insulin, the homeostatic model assessment of insulin resistance (HOMA-IR), total cholesterol, triglycerides, high- and low-density lipoproteins, parameters of liver function, TNF-α, and IL-10 were measured in each subject. The stage of NAFLD was estimated by abdominal ultrasound imaging. In comparison with morbidly obese subjects without steatosis, morbidly obese patients with NAFLD showed increased age (39.23 ± 9.80 years), HOMA-IR (6.74 ± 1.62), total cholesterol (219.7 ± 9.58 mg/dl), aspartate aminotransferase (36.25 ± 3.24 UI/l), gamma-glutamyl transpeptidase (37.12 ± 3.41 UI/l), and TNF-α (37.41 ± 1.72 pg/ml) as well as decreased serum levels of IL-10 (61.05 ± 2.43 pg/ml). Interestingly, the systemic levels of TNF-α increased, while IL-10 decreased in accordance with the severity of NAFLD, which supports a role for systemic inflammatory mediators in promoting steatosis progression. Further clinical prospective studies need to be addressed to elucidate the role of TNF-α and IL-10 in the development of NAFLD while also establishing their clinical utility in the assessment of morbidly obese patients at higher risk to develop severe steatosis.
Assuntos
Interleucina-10/sangue , Hepatopatia Gordurosa não Alcoólica/patologia , Obesidade Mórbida/complicações , Soro/química , Fator de Necrose Tumoral alfa/sangue , Adolescente , Adulto , Idoso , Feminino , Humanos , Fígado/diagnóstico por imagem , Testes de Função Hepática , Masculino , Pessoa de Meia-Idade , Índice de Gravidade de Doença , Ultrassonografia , Adulto JovemRESUMO
Conventional neuroanatomical, immunohistochemical techniques, and electrophysiological recording, as well as in vitro labeling methods may fail to detect long range extra-neurohypophyseal-projecting axons from vasopressin (AVP)-containing magnocellular neurons (magnocells) in the hypothalamic paraventricular nucleus (PVN). Here, we used in vivo extracellular recording, juxtacellular labeling, post-hoc anatomo-immunohistochemical analysis and camera lucida reconstruction to address this question. We demonstrate that all well-labeled AVP immunopositive neurons inside the PVN possess main axons joining the tract of Greving and multi-axon-like processes, as well as axonal collaterals branching very near to the somata, which project to extra-neurohypophyseal regions. The detected regions in this study include the medial and lateral preoptical area, suprachiasmatic nucleus (SCN), lateral habenula (LHb), medial and central amygdala and the conducting systems, such as stria medullaris, the fornix and the internal capsule. Expression of vesicular glutamate transporter 2 was observed in axon-collaterals. These results, in congruency with several previous reports in the literature, provided unequivocal evidence that AVP magnocells have an uncommon feature of possessing multiple axon-like processes emanating from somata or proximal dendrites. Furthermore, the long-range non-neurohypophyseal projections are more common than an "occasional" phenomenon as previously thought.
RESUMO
Pilocarpine model for temporal lobe epilepsy has shown aberrant neurogenesis, but mainly restricted to the dentate gyrus (DG). Herein, by using a modified protocol, combining pilocarpine with ipratropium bromide, we unexpectedly observed a heretofore-unrecognized distinct cellular population expressing the neuroprogenitor marker doublecortin (DCX) on post insult days (PID) 10, 14 and 18, mainly located in the temporal segment of the hippocampal fissure (hf). Some of these DCX+ cells possessed high morphological complexity and seemed to disperse toward the CA fields. Next, we injected bromodeoxyuridine (BrdU) in early (PID 2-4) and delayed (PID 5-7) fashions and killed the rats 7-35 days later for immunohistochemical and anatomical analysis. Massive increase of BrdU labeling was found in the delayed group and the neural stem cell-specific marker nestin was highly expressed in the same narrow band on PID7, so was glial fibrillary acidic protein (GFAP). Using double labeling with BrdU and a mature neuron marker NeuN, we found discrete but clear BrdU+/NeuN+ double labeled cells in the Cornu Ammonis (CA) pyramidal cell layer on PID35. Based on immunohistochemical and anatomical observations, as well as time-course analysis of BrdU, nestin, GFAP, DCX and NeuN expressions in this population of cells located in/near hf, we wish to suggest that this structure harbors neurogenic niches, in addition of the possible dispersion of neuroprogenitors from subgranular niches to CA fields also revealed by this study. Our results support the few previous reports demonstrating hippocampal CA field neurogenesis in adult rats. Mechanistic basis of the phenomenon is discussed.
Assuntos
Hipocampo/citologia , Agonistas Muscarínicos/toxicidade , Células-Tronco Neurais/citologia , Neurogênese/fisiologia , Pilocarpina/toxicidade , Nicho de Células-Tronco , Animais , Proteína Duplacortina , Imuno-Histoquímica , Masculino , Ratos , Ratos WistarRESUMO
L-Dopa is the major symptomatic therapy for Parkinson's disease, which commonly occurs in elderly patients. However, the effects of chronic use on mood and cognition in old subjects remain elusive. In order to compare the effects of a chronic pulsatile L-Dopa treatment on emotional and cognitive functions in young (3 months) and old (18 months) intact rats, an L-Dopa/carbidopa treatment was administered every 12 h over 4 weeks. Rats were assessed for behavioural despair (repeated forced swimming test, RFST), anhedonia (sucrose preference test, SPT) and spatial learning (Morris water maze, MWM) in the late phase of treatment (T). Neuronal expression of Fos in the hippocampus at the early and late phases of T, as well as after MWM was studied. The density and ratio of dopamine D5r, D3r and D2r receptors were also evaluated in the hippocampus using immunohistochemistry and confocal microscopy. Young rats showed similar patterns during behavioural tests, whereas aged treated rats showed increased immobility counts in RFST, diminished sucrose liquid intake in SPT, and spatial learning impairment during MWM. Fos expression was significantly blunted in the aged treated group after MWM. The density of D5r, D3r and D2r was increased in both aged groups. The treatment reduced the ratio of D5r/D3r and D5r/D2r in both groups. Moreover, aged treated subjects had significant lower values of D5r/D3r and higher values of D5r/D2r when compared with young treated subjects. These results indicate that chronic L-Dopa treatment in itself could trigger emotional and cognitive dysfunctions in elderly subjects through dopamine receptor dysregulation.