Tiago Chaves - Academia.edu (original) (raw)
Papers by Tiago Chaves
International Journal of Molecular Sciences, 2022
Glutamate is the most abundant excitatory amino acid in the central nervous system. Neurons using... more Glutamate is the most abundant excitatory amino acid in the central nervous system. Neurons using glutamate as a neurotransmitter can be characterised by vesicular glutamate transporters (VGLUTs). Among the three subtypes, VGLUT3 is unique, co-localising with other “classical” neurotransmitters, such as the inhibitory GABA. Glutamate, manipulated by VGLUT3, can modulate the packaging as well as the release of other neurotransmitters and serve as a retrograde signal through its release from the somata and dendrites. Its contribution to sensory processes (including seeing, hearing, and mechanosensation) is well characterised. However, its involvement in learning and memory can only be assumed based on its prominent hippocampal presence. Although VGLUT3-expressing neurons are detectable in the hippocampus, most of the hippocampal VGLUT3 positivity can be found on nerve terminals, presumably coming from the median raphe. This hippocampal glutamatergic network plays a pivotal role in sev...
Life Sciences, 2021
Gamma-aminobutyric acid (GABA) is a well-known inhibitory neurotransmitter implicated in numerous... more Gamma-aminobutyric acid (GABA) is a well-known inhibitory neurotransmitter implicated in numerous physiological and pathological behaviors including social interest. Dysregulation of the median raphe region (MRR), a main serotoninergic nucleus, is also characterized by increased social problems. As the majority of MRR cells are GABAergic, we aimed to reveal the social role of these cells. Chemogenetic techniques were used in vesicular GABA transporter Cre mice and with the help of adeno-associated virus vectors artificial receptors (DREADDs, stimulatory, inhibitory or control, containing only a fluorophore) were expressed in MRR GABAergic cells confirmed by immunohistochemistry. Four weeks after viral injection a behavioral test battery (sociability; social interaction; resident-intruder) was conducted. The artificial ligand (clozapine-N-oxide, 1 mg/10 ml/kg) was administrated 30 min before the tests. As possible confounding factors, locomotion (open field/OF), anxiety-like behavior (elevated plus maze/EPM), and short-term memory (Y-maze) were also evaluated. Stimulation of the GABAergic cells in MRR had no effect on locomotion or working and social memory; however, it increased social interest during sociability and social interaction but not in resident-intruder tests. Accordingly, c-Fos elevation in MRR-GABAergic cells was detected after sociability, but not resident-intruder tests. In the EPM test, the inhibitory group entered into the open arms later, suggesting an anxiogenic-like tendency. We confirmed the role of MRR-GABAergic cells in promoting social interest. However, different subpopulations (e.g. long vs short projecting, various neuropeptide containing) might have divergent roles, which might remain hidden and requires further studies.
International Journal of Molecular Sciences, 2021
Stress adaptation is of utmost importance for the maintenance of homeostasis and, therefore, of l... more Stress adaptation is of utmost importance for the maintenance of homeostasis and, therefore, of life itself. The prevalence of stress-related disorders is increasing, emphasizing the importance of exploratory research on stress adaptation. Two major regulatory pathways exist: the hypothalamic–pituitary–adrenocortical axis and the sympathetic adrenomedullary axis. They act in unison, ensured by the enormous bidirectional connection between their centers, the paraventricular nucleus of the hypothalamus (PVN), and the brainstem monoaminergic cell groups, respectively. PVN and especially their corticotropin-releasing hormone (CRH) producing neurons are considered to be the centrum of stress regulation. However, the brainstem seems to be equally important. Therefore, we aimed to summarize the present knowledge on the role of classical neurotransmitters of the brainstem (GABA, glutamate as well as serotonin, noradrenaline, adrenaline, and dopamine) in stress adaptation. Neuropeptides, inc...
Integrative Physiology, 2021
The hypothalamic-pituitary-adrenocortical axis is one of the main components of stress adaptation... more The hypothalamic-pituitary-adrenocortical axis is one of the main components of stress adaptation. Corticotropin-releasing hormone (CRH) coming from the nucleus paraventricularis hypothalami (PVN) is the canonical central regulator of the axis. This CRH acts on the CRH-R1 receptors of the pituitary, and, through adrenocorticotropin, stimulates glucocorticoid release from the adrenal cortex. However, it may be synthetized in other parts of the brain as well, and may act both on CRH-R1 and CRH-R2 receptors. These areas form the central CRH network. Many of them are also stress reactive and participate in physical and psychological stress response. The central nucleus of the amygdala and bed nucleus of stria terminalis are two areas best known for their role in emotions, while hippocampus is mostly involved in glucocorticoid feedback as well as memory formation, all heavily connected to stress adaptation. Among others, the brainstem raphe nuclei get dense CRHergic innervation that, through CRH-R1 receptors, may influence the serotoninergic tone of the brain. Both stress and serotonin are strongly implicated in depression, therefore, it is not surprising that CRH-R1 antagonists were developed as therapeutic tools that extensively act on the brain CRH system. Our review suggests a general role of brain CRH network in stress adaptation which is not restricted to PVN.
Anais do IX Simpósio em Sistemas Computacionais de Alto Desempenho (WSCAD 2008), 2008
Redes tolerantes a atrasos e desconexões (DTNs) são uma classe de redes que apresentam frequentes... more Redes tolerantes a atrasos e desconexões (DTNs) são uma classe de redes que apresentam frequentes partições e longos atrasos. Redes com estas características possuem uma variedade de aplicações como comunicações entre dispositivos com restrições de energia, comunicações rurais, submarinas e interplanetárias. Neste trabalho, nós propomos dois algoritmos distribuídos para roteamento em redes DTN previsíveis, que consideram o menor número de saltos e o tempo de chegada mais cedo ao destino. Eles produzem como saída uma tabela de roteamento para cada nó da rede. Durante a fase de construção da tabela, são realizadas críticas nos intervalos de tempo dos enlaces adjacentes visando minimizar a quantidade de mensagens e bits enviados na rede. Os algoritmos foram avaliados experimentalmente para verificar a redução do número de mensagens trocadas na versão com crítica quando comparada à versão que não realiza crítica nos intervalos. Os resultados mostraram que a crítica reduz significativame...
International Journal of Molecular Sciences, 2022
Glutamate is the most abundant excitatory amino acid in the central nervous system. Neurons using... more Glutamate is the most abundant excitatory amino acid in the central nervous system. Neurons using glutamate as a neurotransmitter can be characterised by vesicular glutamate transporters (VGLUTs). Among the three subtypes, VGLUT3 is unique, co-localising with other “classical” neurotransmitters, such as the inhibitory GABA. Glutamate, manipulated by VGLUT3, can modulate the packaging as well as the release of other neurotransmitters and serve as a retrograde signal through its release from the somata and dendrites. Its contribution to sensory processes (including seeing, hearing, and mechanosensation) is well characterised. However, its involvement in learning and memory can only be assumed based on its prominent hippocampal presence. Although VGLUT3-expressing neurons are detectable in the hippocampus, most of the hippocampal VGLUT3 positivity can be found on nerve terminals, presumably coming from the median raphe. This hippocampal glutamatergic network plays a pivotal role in sev...
Life Sciences, 2021
Gamma-aminobutyric acid (GABA) is a well-known inhibitory neurotransmitter implicated in numerous... more Gamma-aminobutyric acid (GABA) is a well-known inhibitory neurotransmitter implicated in numerous physiological and pathological behaviors including social interest. Dysregulation of the median raphe region (MRR), a main serotoninergic nucleus, is also characterized by increased social problems. As the majority of MRR cells are GABAergic, we aimed to reveal the social role of these cells. Chemogenetic techniques were used in vesicular GABA transporter Cre mice and with the help of adeno-associated virus vectors artificial receptors (DREADDs, stimulatory, inhibitory or control, containing only a fluorophore) were expressed in MRR GABAergic cells confirmed by immunohistochemistry. Four weeks after viral injection a behavioral test battery (sociability; social interaction; resident-intruder) was conducted. The artificial ligand (clozapine-N-oxide, 1 mg/10 ml/kg) was administrated 30 min before the tests. As possible confounding factors, locomotion (open field/OF), anxiety-like behavior (elevated plus maze/EPM), and short-term memory (Y-maze) were also evaluated. Stimulation of the GABAergic cells in MRR had no effect on locomotion or working and social memory; however, it increased social interest during sociability and social interaction but not in resident-intruder tests. Accordingly, c-Fos elevation in MRR-GABAergic cells was detected after sociability, but not resident-intruder tests. In the EPM test, the inhibitory group entered into the open arms later, suggesting an anxiogenic-like tendency. We confirmed the role of MRR-GABAergic cells in promoting social interest. However, different subpopulations (e.g. long vs short projecting, various neuropeptide containing) might have divergent roles, which might remain hidden and requires further studies.
International Journal of Molecular Sciences, 2021
Stress adaptation is of utmost importance for the maintenance of homeostasis and, therefore, of l... more Stress adaptation is of utmost importance for the maintenance of homeostasis and, therefore, of life itself. The prevalence of stress-related disorders is increasing, emphasizing the importance of exploratory research on stress adaptation. Two major regulatory pathways exist: the hypothalamic–pituitary–adrenocortical axis and the sympathetic adrenomedullary axis. They act in unison, ensured by the enormous bidirectional connection between their centers, the paraventricular nucleus of the hypothalamus (PVN), and the brainstem monoaminergic cell groups, respectively. PVN and especially their corticotropin-releasing hormone (CRH) producing neurons are considered to be the centrum of stress regulation. However, the brainstem seems to be equally important. Therefore, we aimed to summarize the present knowledge on the role of classical neurotransmitters of the brainstem (GABA, glutamate as well as serotonin, noradrenaline, adrenaline, and dopamine) in stress adaptation. Neuropeptides, inc...
Integrative Physiology, 2021
The hypothalamic-pituitary-adrenocortical axis is one of the main components of stress adaptation... more The hypothalamic-pituitary-adrenocortical axis is one of the main components of stress adaptation. Corticotropin-releasing hormone (CRH) coming from the nucleus paraventricularis hypothalami (PVN) is the canonical central regulator of the axis. This CRH acts on the CRH-R1 receptors of the pituitary, and, through adrenocorticotropin, stimulates glucocorticoid release from the adrenal cortex. However, it may be synthetized in other parts of the brain as well, and may act both on CRH-R1 and CRH-R2 receptors. These areas form the central CRH network. Many of them are also stress reactive and participate in physical and psychological stress response. The central nucleus of the amygdala and bed nucleus of stria terminalis are two areas best known for their role in emotions, while hippocampus is mostly involved in glucocorticoid feedback as well as memory formation, all heavily connected to stress adaptation. Among others, the brainstem raphe nuclei get dense CRHergic innervation that, through CRH-R1 receptors, may influence the serotoninergic tone of the brain. Both stress and serotonin are strongly implicated in depression, therefore, it is not surprising that CRH-R1 antagonists were developed as therapeutic tools that extensively act on the brain CRH system. Our review suggests a general role of brain CRH network in stress adaptation which is not restricted to PVN.
Anais do IX Simpósio em Sistemas Computacionais de Alto Desempenho (WSCAD 2008), 2008
Redes tolerantes a atrasos e desconexões (DTNs) são uma classe de redes que apresentam frequentes... more Redes tolerantes a atrasos e desconexões (DTNs) são uma classe de redes que apresentam frequentes partições e longos atrasos. Redes com estas características possuem uma variedade de aplicações como comunicações entre dispositivos com restrições de energia, comunicações rurais, submarinas e interplanetárias. Neste trabalho, nós propomos dois algoritmos distribuídos para roteamento em redes DTN previsíveis, que consideram o menor número de saltos e o tempo de chegada mais cedo ao destino. Eles produzem como saída uma tabela de roteamento para cada nó da rede. Durante a fase de construção da tabela, são realizadas críticas nos intervalos de tempo dos enlaces adjacentes visando minimizar a quantidade de mensagens e bits enviados na rede. Os algoritmos foram avaliados experimentalmente para verificar a redução do número de mensagens trocadas na versão com crítica quando comparada à versão que não realiza crítica nos intervalos. Os resultados mostraram que a crítica reduz significativame...