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Activation of astrocytes after sensory stimulation has been reported to be involved in increased blood flow in the central nervous system. In the present study, using a chemogenetic method to induce astrocyte activation in mice without sensory stimulation, we found that astrocytic activation led to increased blood flow in the olfactory bulb, suggesting that astrocyte activation is sufficient for increasing blood flow in the olfactory bulb. The technique established here will be useful for studying the mechanisms underlying sensory input-dependent blood flow increases.
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Astrócitos , Bulbo Olfatório , Animais , Bulbo Olfatório/fisiologia , Bulbo Olfatório/irrigação sanguínea , Astrócitos/fisiologia , Camundongos Endogâmicos C57BL , Fluxo Sanguíneo Regional/fisiologia , Masculino , CamundongosRESUMO
Adult hippocampal neurogenesis is a lifelong process that involves the integration of newborn neurons into the hippocampal network, and plays a role in cognitive function and the modulation of mood-related behavior. Here, we sought to address the impact of chemogenetic activation of adult hippocampal progenitors on distinct stages of progenitor development, including quiescent stem cell activation, progenitor turnover, differentiation and morphological maturation. We find that hM3Dq-DREADD-mediated activation of nestin-positive adult hippocampal progenitors recruits quiescent stem cells, enhances progenitor proliferation, increases doublecortin-positive newborn neuron number, accompanied by an acceleration of differentiation and morphological maturation, associated with increased dendritic complexity. Behavioral analysis indicated anxiolytic behavioral responses in transgenic mice subjected to chemogenetic activation of adult hippocampal progenitors at timepoints when newborn neurons are predicted to integrate into the mature hippocampal network. Furthermore, we noted an enhanced fear memory extinction on a contextual fear memory learning task in transgenic mice subjected to chemogenetic activation of adult hippocampal progenitors. Our findings indicate that hM3Dq-DREAD-mediated chemogenetic activation of adult hippocampal progenitors impacts distinct aspects of hippocampal neurogenesis, associated with the regulation of anxiety-like behavior and fear memory extinction.
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The brain and immune system communicate through complex bidirectional pathways, but the specificity by which the brain perceives or even remembers alterations in immune homeostasis is still poorly understood. Recent data revealed that immune-related information under peripheral inflammatory conditions, termed as "immunengram", were represented in specific neuronal ensembles in the insular cortex (IC). Chemogenetic reactivation of these neuronal ensembles was sufficient to retrieve the inflammatory stages, indicating that the brain can store and retrieve specific immune responses. Against this background, the current approach was designed to investigate the ability of the IC to process states of immunosuppression pharmacologically induced by the mechanistic target of rapamycin (mTOR) inhibitor rapamycin. We here show that the IC perceives the initial state of immunosuppression, reflected by increased deep-brain electroencephalography (EEG) activity during acute immunosuppressive drug treatment. Following an experienced period of immunosuppression, though, diminished splenic cytokine production as formerly induced by rapamycin could not be reinstated by nonspecific chemogenetic activation or inhibition of the IC. These findings suggest that the information of a past, or experienced status of pharmacologically induced immunosuppression is not represented in the IC. Together, the present work extends the view of immune-to-brain communication during the states of peripheral immunosuppression and foster the prominent role of the IC for interoception.
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Imunossupressores , Córtex Insular , Sirolimo , Animais , Sirolimo/farmacologia , Córtex Insular/efeitos dos fármacos , Masculino , Imunossupressores/farmacologia , Eletroencefalografia , Terapia de Imunossupressão/métodos , Citocinas/metabolismo , Citocinas/imunologia , Camundongos , Tolerância Imunológica/efeitos dos fármacos , Tolerância Imunológica/fisiologia , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/imunologia , Córtex Cerebral/metabolismoRESUMO
Allostatic adaptations to a perceived threat are crucial for survival and may tap into mechanisms serving the homeostatic control of energy balance. We previously established that exposure to predator odor (PO) in rats significantly increases skeletal muscle thermogenesis and energy expenditure (EE). Evidence highlights steroidogenic factor 1 (SF1) cells within the central and dorsomedial ventromedial hypothalamus (c/dmVMH) as a modulator of both energy homeostasis and defensive behavior. However, the brain mechanism driving elevated EE and muscle thermogenesis during PO exposure has yet to be elucidated. To assess the ability of SF1 neurons of the c/dmVMH to induce muscle thermogenesis, we used the combined technology of chemogenetics, transgenic mice, temperature transponders, and indirect calorimetry. Here, we evaluate EE and muscle thermogenesis in SF1-Cre mice exposed to PO (ferret odor) compared to transgenic and viral controls. We detected significant increases in muscle temperature, EE, and oxygen consumption following the chemogenetic stimulation of SF1 cells. However, there were no detectable changes in muscle temperature in response to PO in either the presence or absence of chemogenetic stimulation. While the specific role of the VMH SF1 cells in PO-induced thermogenesis remains uncertain, these data establish a supporting role for SF1 neurons in the induction of muscle thermogenesis and EE similar to what is seen after predator threats.
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Metabolismo Energético , Camundongos Transgênicos , Neurônios , Fator Esteroidogênico 1 , Termogênese , Animais , Termogênese/efeitos dos fármacos , Camundongos , Fator Esteroidogênico 1/metabolismo , Fator Esteroidogênico 1/genética , Neurônios/metabolismo , Músculo Esquelético/metabolismo , Masculino , Núcleo Hipotalâmico Ventromedial/metabolismo , OdorantesRESUMO
Social behavior, defined as any mode of communication between conspecifics is regulated by a widespread network comprising multiple brain structures. The anterior cingulate cortex (ACC) serves as a hub region interconnected with several brain regions involved in social behavior. Because the ACC coordinates various behaviors, it is important to focus on a subpopulation of neurons that are potentially involved in social behavior to clarify the precise role of the ACC in social behavior. In this study, we aimed to analyze the roles of a social stimulus-responsive subpopulation of neurons in the ACC in social behavior in mice. We demonstrated that a subpopulation of neurons in the ACC was activated by social stimuli and that silencing the social stimulus-responsive subpopulation of neurons in the ACC significantly impaired social interaction without affecting locomotor activity or anxiety-like behavior. Our current findings highlight the importance of the social stimulus-responsive subpopulation of neurons in the ACC for social behavior and the association between ACC dysfunction and impaired social behavior, which sheds light on therapeutic interventions for psychiatric conditions.
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Giro do Cíngulo , Camundongos Endogâmicos C57BL , Neurônios , Comportamento Social , Animais , Giro do Cíngulo/fisiologia , Neurônios/fisiologia , Neurônios/metabolismo , Camundongos , Masculino , Ansiedade/fisiopatologia , Comportamento Animal/fisiologiaRESUMO
Despite the therapeutic potential of chemogenetics, the method lacks comprehensive preclinical validation, hindering its progression to human clinical trials. We aimed to validate a robust but simple in vivo efficacy assay in rats which could support chemogenetic drug discovery by providing a quick, simple and reliable animal model. Key methodological parameters such as adeno-associated virus (AAV) serotype, actuator drug, dose, and application routes were investigated by measuring the food-intake-reducing effect of chemogenetic inhibition of the lateral hypothalamus (LH) by hM4D(Gi) designer receptor stimulation. Subcutaneous deschloroclozapine in rats transfected with AAV9 resulted in a substantial reduction of food-intake, comparable to the efficacy of exenatide. We estimated that the effect of deschloroclozapine lasts 1-3 h post-administration. AAV5, oral administration of deschloroclozapine, and clozapine-N-oxide were also effective but with slightly less potency. The strongest effect on food-intake occurred within the first 30 min after re-feeding, suggesting this as the optimal experimental endpoint. This study demonstrates that general chemogenetic silencing of the LH can be utilized as an optimal, fast and reliable in vivo experimental model for conducting preclinical proof-of-concept studies in order to validate the in vivo effectiveness of novel chemogenetic treatments. We also hypothesize based on our results that universal LH silencing with existing and human translatable genetic neuroengineering techniques might be a viable strategy to affect food intake and influence obesity.
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Clozapina , Dependovirus , Ingestão de Alimentos , Região Hipotalâmica Lateral , Estudo de Prova de Conceito , Animais , Clozapina/análogos & derivados , Clozapina/farmacologia , Ratos , Ingestão de Alimentos/efeitos dos fármacos , Região Hipotalâmica Lateral/efeitos dos fármacos , Dependovirus/genética , Masculino , Exenatida/farmacologia , HumanosRESUMO
Introduction: Chemogenetic techniques, specifically the use of Designer Receptors Exclusively Activated by Designer Drugs (DREADDs), have become invaluable tools in neuroscience research. Yet, the understanding of how Gq- and Gicoupled DREADDs alter local field potential (LFP) oscillations in vivo remains incomplete. Methods: This study investigates the in vivo electrophysiological effects of DREADD actuation by deschloroclozapine, on spontaneous firing rate and LFP oscillations recorded from the anterior cingulate cortex in lightly anesthetized male rats. Results: Unexpectedly, in response to the administration of deschloroclozapine, we observed inhibitory effects with pan-neuronal hM3D(Gq) stimulation, and excitatory effects with pan-neuronal hM4D(Gi) stimulation in a significant portion of neurons. These results emphasize the need to account for indirect perturbation effects at the local neuronal network level in vivo, particularly when not all neurons express the chemogenetic receptors uniformly. In the current study, for instance, the majority of cells that were transduced with both hM3D(Gq) and hM4D(Gi) were GABAergic. Moreover, we found that panneuronal cortical chemogenetic modulation can profoundly alter oscillatory neuronal activity, presenting a potential research tool or therapeutic strategy in several neuropsychiatric models and diseases. Discussion: These findings help to optimize the use of chemogenetic techniques in neuroscience research and open new possibilities for novel therapeutic strategies.
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Cell therapy has proven to be a promising treatment for a range of neurological disorders, including Parkinson Disease, drug-resistant epilepsy, and stroke, by restoring function after brain damage. Nevertheless, evaluating the true effectiveness of these therapeutic interventions requires a deep understanding of the functional integration of grafted cells into existing neural networks. This review explores a powerful arsenal of molecular techniques revolutionizing our ability to unveil functional integration of grafted cells within the host brain. From precise manipulation of neuronal activity to pinpoint the functional contribution of transplanted cells by using opto- and chemo-genetics, to real-time monitoring of neuronal dynamics shedding light on functional connectivity within the reconstructed circuits by using genetically encoded (calcium) indicators in vivo. Finally, structural reconstruction and mapping communication pathways between grafted and host neurons can be achieved by monosynaptic tracing with viral vectors. The cutting-edge toolbox presented here holds immense promise for elucidating the impact of cell therapy on neural circuitry and guiding the development of more effective treatments for neurological disorders.
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According to previous studies, the median raphe region (MRR) is known to contribute significantly to social behavior. Besides serotonin, there have also been reports of a small population of dopaminergic neurons in this region. Dopamine is linked to reward and locomotion, but very little is known about its role in the MRR. To address that, we first confirmed the presence of dopaminergic cells in the MRR of mice (immunohistochemistry, RT-PCR), and then also in humans (RT-PCR) using healthy donor samples to prove translational relevance. Next, we used chemogenetic technology in mice containing the Cre enzyme under the promoter of the dopamine transporter. With the help of an adeno-associated virus, designer receptors exclusively activated by designer drugs (DREADDs) were expressed in the dopaminergic cells of the MRR to manipulate their activity. Four weeks later, we performed an extensive behavioral characterization 30 min after the injection of the artificial ligand (Clozapine-N-Oxide). Stimulation of the dopaminergic cells in the MRR decreased social interest without influencing aggression and with an increase in social discrimination. Additionally, inhibition of the same cells increased the friendly social behavior during social interaction test. No behavioral changes were detected in anxiety, memory or locomotion. All in all, dopaminergic cells were present in both the mouse and human samples from the MRR, and the manipulation of the dopaminergic neurons in the MRR elicited a specific social response.
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Clozapina/análogos & derivados , Neurônios Dopaminérgicos , Comportamento Social , Animais , Neurônios Dopaminérgicos/metabolismo , Masculino , Camundongos , Humanos , Clozapina/farmacologia , Núcleos da Rafe/metabolismo , Comportamento Animal , Dopamina/metabolismo , Camundongos Endogâmicos C57BLRESUMO
Neurodegenerative diseases are progressive disorders characterized by synaptic loss and neuronal death. Optogenetics combines optical and genetic methods to control the activity of specific cell types. The efficacy of this approach in neurodegenerative diseases has been investigated in many reviews, however, none of them tackled it systematically. Our study aimed to review systematically the findings of optogenetics and its potential applications in animal models of chronic neurodegenerative diseases and compare it with deep brain stimulation and designer receptors exclusively activated by designer drugs techniques. The search strategy was performed based on the PRISMA guidelines and the risk of bias was assessed following the Systematic Review Centre for Laboratory Animal Experimentation tool. A total of 247 articles were found, of which 53 were suitable for the qualitative analysis. Our data revealed that optogenetic manipulation of distinct neurons in the brain is efficient in rescuing memory impairment, alleviating neuroinflammation, and reducing plaque pathology in Alzheimer's disease. Similarly, this technique shows an advanced understanding of the contribution of various neurons involved in the basal ganglia pathways with Parkinson's disease motor symptoms and pathology. However, the optogenetic application using animal models of Huntington's disease, multiple sclerosis, and amyotrophic lateral sclerosis was limited. Optogenetics is a promising technique that enhanced our knowledge in the research of neurodegenerative diseases and addressed potential therapeutic solutions for managing these diseases' symptoms and delaying their progression. Nevertheless, advanced investigations should be considered to improve optogenetic tools' efficacy and safety to pave the way for their translatability to the clinic.
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Encéfalo , Doenças Neurodegenerativas , Optogenética , Optogenética/métodos , Animais , Doenças Neurodegenerativas/terapia , Doenças Neurodegenerativas/genética , Humanos , Encéfalo/metabolismo , Modelos Animais de Doenças , Neurônios/fisiologia , Neurônios/metabolismo , Estimulação Encefálica Profunda/métodosRESUMO
Neuroplasticity in the central nucleus of the amygdala (CeA) plays a key role in the modulation of pain and its aversive component. The dynorphin/kappa opioid receptor (KOR) system in the amygdala is critical for averse-affective behaviors in pain conditions, but its mechanisms are not well understood. Here, we used chemogenetic manipulations of amygdala KOR-expressing neurons to analyze the behavioral consequences in a chronic neuropathic pain model. For the chemogenetic inhibition or activation of KOR neurons in the CeA, a Cre-inducible viral vector encoding Gi-DREADD (hM4Di) or Gq-DREADD (hM3Dq) was injected stereotaxically into the right CeA of transgenic KOR-Cre mice. The chemogenetic inhibition of KOR neurons expressing hM4Di with a selective DREADD actuator (deschloroclozapine, DCZ) in sham control mice significantly decreased inhibitory transmission, resulting in a shift of inhibition/excitation balance to promote excitation and induced pain behaviors. The chemogenetic activation of KOR neurons expressing hM3Dq with DCZ in neuropathic mice significantly increased inhibitory transmission, decreased excitability, and decreased neuropathic pain behaviors. These data suggest that amygdala KOR neurons modulate pain behaviors by exerting an inhibitory tone on downstream CeA neurons. Therefore, activation of these interneurons or blockade of inhibitory KOR signaling in these neurons could restore control of amygdala output and mitigate pain.
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Tonsila do Cerebelo , Camundongos Transgênicos , Neuralgia , Neurônios , Receptores Opioides kappa , Animais , Receptores Opioides kappa/metabolismo , Receptores Opioides kappa/genética , Neuralgia/metabolismo , Neuralgia/fisiopatologia , Neurônios/metabolismo , Camundongos , Tonsila do Cerebelo/metabolismo , Comportamento Animal , Masculino , Clozapina/análogos & derivados , Clozapina/farmacologia , Núcleo Central da Amígdala/metabolismoRESUMO
Impaired diaphragm activation contributes to morbidity and mortality in many neurodegenerative diseases and neurologic injuries. We conducted experiments to determine if expression of an excitatory DREADD (designer receptors exclusively activation by designer drugs) in the mid-cervical spinal cord would enable respiratory-related activation of phrenic motoneurons to increase diaphragm activation. Wild type (C57/bl6) and ChAT-Cre mice received bilateral intraspinal (C4) injections of an adeno-associated virus (AAV) encoding the hM3D(Gq) excitatory DREADD. In wild type mice, this produced non-specific DREADD expression throughout the mid-cervical ventral horn. In ChAT-Cre mice, a Cre-dependent viral construct was used to drive DREADD expression in C4 ventral horn motoneurons, targeting the phrenic motoneuron pool. Diaphragm EMG was recorded during spontaneous breathing at 6-8 weeks post-AAV delivery. The selective DREADD ligand JHU37160 (J60) caused a bilateral, sustained (>1 hr) increase in inspiratory EMG bursting in both groups; the relative increase was greater in ChAT-Cre mice. Additional experiments in a ChAT-Cre rat model were conducted to determine if spinal DREADD activation could increase inspiratory tidal volume (VT) during spontaneous breathing without anesthesia. Three to four months after intraspinal (C4) injection of AAV driving Cre-dependent hM3D(Gq) expression, intravenous J60 resulted in a sustained (>30 min) increase in VT assessed using whole-body plethysmography. Subsequently, direct nerve recordings confirmed that J60 evoked a >50% increase in inspiratory phrenic output. The data show that mid-cervical spinal DREADD expression targeting the phrenic motoneuron pool enables ligand-induced, sustained increases in the neural drive to the diaphragm. Further development of this technology may enable application to clinical conditions associated with impaired diaphragm activation and hypoventilation.
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Spinal cord injury (SCI) is a devastating injury that causes permanent neurological dysfunction. To develop a new treatment strategy for SCI, a clinical trial of transplantation of human-induced pluripotent stem cell-derived neural precursor cells (NPCs) in patients in the subacute phase of SCI was recently initiated. The formation of synaptic connections with host neural tissues is one of the therapeutic mechanisms of cell transplantation, and this beneficial efficacy has been directly demonstrated using a chemogenetic tool. This research focuses on the establishment of cell therapy for chronic SCI, which is more challenging owing to cavity and scar formation. Thus, neurogenic NPC transplantation is more effective in forming functional synapses with the host neurons. Furthermore, combinatory rehabilitation therapy is useful to enhance the efficacy of this strategy, and a valid rehabilitative training program has been established for SCI animal models that received NPC transplantation in the chronic phase. Therefore, the use of regenerative medicine for chronic SCI is expected to increase.
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Hyperaldosteronism is often associated with inappropriate aldosterone production and aldosterone synthase (Cyp11b2) expression. Normally, Cyp11b2 expression is limited to the adrenal zona glomerulosa (ZG) and regulated by angiotensin II which signals through Gq protein-coupled receptors. As cells migrate inwards, they differentiate into 11ß-hydroxylase-expressing zona fasciculata (ZF) cells lacking Cyp11b2. The mechanism causing ZG-specific aldosterone biosynthesis is still unclear. We investigated the effect of chronic Gq signaling using transgenic mice with a clozapine N-oxide (CNO)-activated human M3 muscarinic receptor (DREADD) coupled to Gq (hM3Dq) that was expressed throughout the adrenal cortex. CNO raised circulating aldosterone in the presence of a high sodium diet with greater response seen in females compared to males. Immunohistochemistry and transcriptomics indicated disrupted zonal Cyp11b2 expression while Wnt signaling remained unchanged. Chronic Gq-DREADD signaling also induced an intra-adrenal RAAS in CNO-treated mice. Chronic Gq signaling disrupted adrenal cortex zonal aldosterone production associated with ZF expression of Cyp11b2.
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Córtex Suprarrenal , Hiperaldosteronismo , Masculino , Feminino , Humanos , Camundongos , Animais , Zona Fasciculada , Aldosterona/metabolismo , Córtex Suprarrenal/metabolismo , Zona Glomerulosa/metabolismo , Citocromo P-450 CYP11B2/genética , Via de Sinalização Wnt , Camundongos TransgênicosRESUMO
Previous work has demonstrated the importance of the prelimbic cortex (PL) in contextual control of operant behavior. However, the associated neural circuitry responsible for providing contextual information to the PL is not well understood. In Pavlovian fear conditioning the ventral hippocampus (vH) and its projection to the PL have been shown to be important in supporting the effects of context on learning. The present experiments used chemogenetic inhibition of the direct vH-PL projection or the vH to determine involvement in expression of context-specific operant behavior. Rats were injected with an inhibitory DREADD (hM4Di) or mCherry-only into the vH, and subsequently trained to perform a lever press response for a food pellet in a distinct context. The DREADD ligand clozapine-n-oxide (CNO) was then delivered directly into the PL (experiment 1) and then systemically (experiment 2) prior to tests of the response in the training context as well as an equally familiar but untrained context. vH (systemic CNO) but not vH-PL (intra-PL CNO) inhibition was found to attenuate operant responding in its acquisition context. A third experiment, using the same rats, showed that chemogenetic inhibition of vH also reduced Pavlovian contextual fear. The present results suggest that multisynapatic connections between the vH and PL may be responsible for integration of contextual information with operant behavior.
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The brain and peripheral organs communicate through hormones and neural connections. Proper communication is required to maintain normal whole-body energy homeostasis. In addition to endocrine system, from the perspective of neural connections for metabolic homeostasis, the role of the sympathetic nervous system has been extensively studied, but understanding of the parasympathetic nervous system is limited. The liver plays a central role in glucose and lipid metabolism. This study aimed to clarify the innervation of parasympathetic nervous system in the liver and its functional roles in metabolic homeostasis. The liver-specific parasympathetic nervous system innervation (PNS) was shown by tissue clearing, immunofluorescence and transgenic mice at the three-dimensional histological level. The parasympathetic efferent signals were manipulated using a chemogenetic technique and the activation of ChAT+ parasympathetic neurons in dorsal motor vagus (DMV) results in the increased blood glucose through the elevated hepatic gluconeogenic and lipogenic gene expression in the liver. Thus, our study showed the evidence of ChAT+ parasympathetic neurons in the liver and its role for hepatic parasympathetic nervous signaling in glucose homeostasis through the regulation of hepatic gene expression.
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Glicemia , Nervo Vago , Camundongos , Animais , Glicemia/metabolismo , Nervo Vago/fisiologia , Neurônios/metabolismo , Fígado/metabolismo , Glucose/metabolismo , Camundongos Transgênicos , Expressão GênicaRESUMO
Much research has been dedicated to understanding the psychological and neural bases of goal-directed action, yet the relationship between context and goal-directed action is not well understood. Here, we used excitotoxic lesions, chemogenetics, and circuit-specific manipulations to demonstrate the role of the ventral hippocampus (vHPC) in contextual learning that supports sensitivity to action-outcome contingencies, a hallmark of goal-directed action. We found that chemogenetic inhibition of the ventral, but not dorsal, hippocampus attenuated sensitivity to instrumental contingency degradation. We then tested the hypothesis that this deficit was due to an inability to discern the relative validity of the action compared with the context as a predictor of reward. Using latent inhibition and Pavlovian context conditioning, we confirm that degradation of action-outcome contingencies relies on intact context-outcome learning and show that this learning is dependent on vHPC. Finally, we show that chemogenetic inhibition of vHPC terminals in the medial prefrontal cortex also impairs both instrumental contingency degradation and context-outcome learning. These results implicate a hippocampo-cortical pathway in adapting to changes in instrumental contingencies and indicate that the psychological basis of this deficit is an inability to learn the predictive value of the context. Our findings contribute to a broader understanding of the neural bases of goal-directed action and its contextual regulation.
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Condicionamento Operante , Recompensa , Condicionamento Operante/fisiologia , Aprendizagem , Motivação , Condicionamento Clássico/fisiologia , Córtex Pré-Frontal/fisiologiaRESUMO
Parkinson's disease (PD) is a neurodegenerative disease showing uncontrollable motor symptoms that are primarily caused by the progressive loss of dopaminergic neurons in the brain. Currently no treatment exists to prevent PD progression. Therefore, discovery of new neuroprotective strategies still has great potential to benefit PD patients. A handful of studies show that activation of cAMP pathways is neuroprotective against PD progression. However, the neuroprotective role of this signaling cascade specifically in DA neurons has not been explored. In this study, fruit fly Drosophila melanogaster was used because of its sophisticated and powerful genetic approaches, especially with related to cAMP signaling pathway. We have investigated molecular mechanisms of neuroprotection in a fly larval model of PD by administering an environmental PD toxin rotenone. Increased cAMP signaling in the dunce mutant fly carrying defects in phosphodiesterase (PDE) gene, is neuroprotective against rotenone-induced locomotion deficits. Furthermore, the neuroprotective role of cAMP signaling specifically in DA neurons has been studied as it has not been explored. By using transgenic flies expressing designer receptors exclusively activated by designer drugs (DREADDs), we have shown that an increase of cAMP levels in DA neurons rescues rotenone-induced locomotion deficits. We also showed that this neuroprotection is mediated by activation of Gαs and PKA-C1 subunits. The results provide novel findings that expand our knowledge of neuroprotective mechanisms in DA neurons affecting PD progression, which could contribute to the development of new therapeutic treatments against PD. An important future study will explore downstream targets of cAMP-PKA signaling.
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Doenças Neurodegenerativas , Fármacos Neuroprotetores , Doença de Parkinson , Animais , Humanos , Doença de Parkinson/metabolismo , Drosophila/metabolismo , Neurônios Dopaminérgicos/metabolismo , Drosophila melanogaster/metabolismo , Rotenona , Doenças Neurodegenerativas/metabolismo , Larva , AMP Cíclico/metabolismo , Transdução de Sinais , Fármacos Neuroprotetores/metabolismo , Modelos Animais de DoençasRESUMO
Astrocyte-derived L-lactate was shown to confer beneficial effects on synaptic plasticity and cognitive functions. However, how astrocytic Gi signaling in the anterior cingulate cortex (ACC) modulates L-lactate levels and schema memory is not clear. Here, using chemogenetic approach and well-established behavioral paradigm, we demonstrate that astrocytic Gi pathway activation in the ACC causes significant impairments in flavor-place paired associates (PAs) learning, schema formation, and PA memory retrieval in rats. It also impairs new PA learning even if a prior associative schema exists. These impairments are mediated by decreased L-lactate in the ACC due to astrocytic Gi activation. Concurrent exogenous L-lactate administration bilaterally into the ACC rescues these impairments. Furthermore, we show that the impaired schema memory formation is associated with a decreased neuronal mitochondrial biogenesis caused by decreased L-lactate level in the ACC upon astrocytic Gi activation. Our study also reveals that L-lactate-mediated mitochondrial biogenesis is dependent on monocarboxylate transporter 2 (MCT2) and NMDA receptor activity - discovering a previously unrecognized signaling role of L-lactate. These findings expand our understanding of the role of astrocytes and L-lactate in the brain functions.
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Astrócitos , Giro do Cíngulo , Ratos , Animais , Giro do Cíngulo/fisiologia , Astrócitos/metabolismo , Biogênese de Organelas , Memória/fisiologia , Ácido Láctico/metabolismo , Transtornos da Memória/metabolismoRESUMO
Pharmacological stimulation of the vagus nerve has been shown to suppress inflammation and reduce blood pressure in a murine model of systemic lupus erythematosus (SLE) that is characterized by hypertension, inflammation, renal injury and dysautonomia. The present study aims to directly stimulate vagal nerves at the level of the dorsal motor nucleus of the vagus (DMV) using designer receptors exclusively activated by designer drugs (DREADDs) to determine if there is similar protection and confirm mechanism. Female NZBWF1/J (SLE) mice and NZW/LacJ mice (controls, labeled as NZW throughout) received bilateral microinjections of pAAV-hSyn-hM3D(Gq)-mCherry or control virus into the DMV at 31 weeks of age. After two weeks of recovery and viral transfection, the DREADD agonist clozapine-N-oxide (CNO; 3 mg/kg) was injected subcutaneously for an additional 14 days. At 35 weeks, mean arterial pressure (MAP; mmHg) was increased in SLE mice compared to NZW mice, but selective activation of DMV neurons did not significantly alter MAP in either group. SLE mice had higher indices of renal injury including albumin excretion rate (µg/day), glomerulosclerosis index, interstitial fibrosis, neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule-1 (KIM-1) compared to NZW mice. Selective DMV neuronal activation reduced albumin excretion rate, glomerulosclerosis, interstitial fibrosis, and NGAL in SLE mice but not NZW mice. Together, these data indicate that selective activation of neurons within the DMV by DREADD protects the kidney suggesting an important role of vagus-mediated pathways in the progression of renal injury in SLE.