RESUMO
Repeated exposure to propofol during early brain development is associated with anxiety disorders in adulthood, yet the mechanisms underlying propofol-induced susceptibility to anxiety disorders remain elusive. The lateral septum (LS), primarily composed of γ-aminobutyric acidergic (GABAergic) neurons, serves as a key brain region in the regulation of anxiety. However, it remains unclear whether LS GABAergic neurons are implicated in propofol-induced anxiety. Therefore, we conducted c-Fos immunostaining of whole-brain slices from mice exposed to propofol during early life. Our findings indicate that propofol exposure activates GABAergic neurons in the LS. Selective activation of LS GABAergic neurons resulted in increased anxiety-like behavior, while selective inhibition of these neurons reduced such behaviors. These results suggest that the LS is a critical brain region involved in propofol-induced anxiety. Furthermore, we investigated the molecular mechanism of propofol-induced anxiety in the LS. Microglia activation underlies the development of anxiety. Immunofluorescence staining and Western blot analysis of LS revealed activated microglia and significantly elevated levels of phospho-NF-κB p65 protein. Additionally, a decrease in the number of neuronal spines was observed. Our study highlights the crucial role of the LS in the development of anxiety-like behavior in adulthood following childhood propofol exposure, accompanied by the activation of inflammatory pathways.
Assuntos
Ansiedade , Comportamento Animal , Neurônios GABAérgicos , Microglia , Propofol , Propofol/farmacologia , Animais , Ansiedade/induzido quimicamente , Camundongos , Masculino , Neurônios GABAérgicos/efeitos dos fármacos , Neurônios GABAérgicos/metabolismo , Neurônios GABAérgicos/patologia , Comportamento Animal/efeitos dos fármacos , Microglia/efeitos dos fármacos , Microglia/metabolismo , Microglia/patologia , Proteínas Proto-Oncogênicas c-fos/metabolismo , Camundongos Endogâmicos C57BL , Fator de Transcrição RelA/metabolismo , Espinhas Dendríticas/efeitos dos fármacos , Espinhas Dendríticas/patologia , Espinhas Dendríticas/metabolismoRESUMO
The full mechanism of action of propofol, a commonly administered intravenous anesthetic drug in clinical practice, remains elusive. The focus of this study was the role of GABAergic neurons which are the main neuron group in the ventral pallidum (VP) closely associated with anesthetic effects in propofol anesthesia. The activity of VP GABAergic neurons following propofol anesthesia in Vgat-Cre mice was observed via detecting c-Fos immunoreactivity by immunofluorescence and western blotting. Subsequently, chemogenetic techniques were employed in Vgat-Cre mice to regulate the activity of VP GABAergic neurons. The role of VP GABAergic neurons in generating the effects of general anesthesia induced by intravenous propofol was further explored through behavioral tests of the righting reflex. The results revealed that c-Fos expression in VP GABAergic neurons in Vgat-Cre mice dramatically decreased after propofol injection. Further studies demonstrated that chemogenetic activation of VP GABAergic neurons during propofol anesthesia shortened the duration of anesthesia and promoted wakefulness. Conversely, the inhibition of VP GABAergic neurons extended the duration of anesthesia and facilitated the effects of anesthesia. The results obtained in this study suggested that regulating the activity of GABAergic neurons in the ventral pallidum altered the effect of propofol on general anesthesia.
Assuntos
Anestesia Geral , Anestésicos Intravenosos , Prosencéfalo Basal , Neurônios GABAérgicos , Propofol , Propofol/farmacologia , Neurônios GABAérgicos/efeitos dos fármacos , Neurônios GABAérgicos/metabolismo , Animais , Prosencéfalo Basal/efeitos dos fármacos , Anestésicos Intravenosos/farmacologia , Anestesia Geral/métodos , Camundongos , Masculino , Camundongos Transgênicos , Proteínas Proto-Oncogênicas c-fos/metabolismo , Reflexo de Endireitamento/efeitos dos fármacos , Reflexo de Endireitamento/fisiologia , Vigília/efeitos dos fármacos , Vigília/fisiologia , Camundongos Endogâmicos C57BL , Proteínas Vesiculares de Transporte de Aminoácidos InibidoresRESUMO
BACKGROUND: The thalamus system plays critical roles in the regulation of reversible unconsciousness induced by general anesthetics, especially the arousal stage of general anesthesia (GA). But the function of thalamus in GA-induced loss of consciousness (LOC) is little known. The thalamic reticular nucleus (TRN) is the only GABAergic neurons-composed nucleus in the thalamus, which is composed of parvalbumin (PV) and somatostatin (SST)-expressing GABAergic neurons. The anterior sector of TRN (aTRN) is indicated to participate in the induction of anesthesia, but the roles remain unclear. This study aimed to reveal the role of the aTRN in propofol and isoflurane anesthesia. METHODS: We first set up c-Fos straining to monitor the activity variation of aTRNPV and aTRNSST neurons during propofol and isoflurane anesthesia. Subsequently, optogenetic tools were utilized to activate aTRNPV and aTRNSST neurons to elucidate the roles of aTRNPV and aTRNSST neurons in propofol and isoflurane anesthesia. Electroencephalogram (EEG) recordings and behavioral tests were recorded and analyzed. Lastly, chemogenetic activation of the aTRNPV neurons was applied to confirm the function of the aTRN neurons in propofol and isoflurane anesthesia. RESULTS: c-Fos straining showed that both aTRNPV and aTRNSST neurons are activated during the LOC period of propofol and isoflurane anesthesia. Optogenetic activation of aTRNPV and aTRNSST neurons promoted isoflurane induction and delayed the recovery of consciousness (ROC) after propofol and isoflurane anesthesia, meanwhile chemogenetic activation of the aTRNPV neurons displayed the similar effects. Moreover, optogenetic and chemogenetic activation of the aTRN neurons resulted in the accumulated burst suppression ratio (BSR) during propofol and isoflurane GA, although they represented different effects on the power distribution of EEG frequency. CONCLUSION: Our findings reveal that the aTRN GABAergic neurons play a critical role in promoting the induction of propofol- and isoflurane-mediated GA.
Assuntos
Anestesia Geral , Estado de Consciência , Neurônios GABAérgicos , Isoflurano , Propofol , Propofol/farmacologia , Isoflurano/farmacologia , Animais , Neurônios GABAérgicos/efeitos dos fármacos , Neurônios GABAérgicos/fisiologia , Camundongos , Estado de Consciência/efeitos dos fármacos , Estado de Consciência/fisiologia , Masculino , Eletroencefalografia , Anestésicos Inalatórios/farmacologia , Núcleos Anteriores do Tálamo/efeitos dos fármacos , Núcleos Anteriores do Tálamo/fisiologia , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Anestésicos Intravenosos/farmacologia , Proteínas Proto-Oncogênicas c-fos/metabolismo , OptogenéticaRESUMO
Nicotinic acetylcholine receptors (nAChRs) regulate pain pathways with various outcomes depending on receptor subtypes, neuron types, and locations. But it remains unknown whether α4ß2 nAChRs abundantly expressed in the substantia nigra pars reticulata (SNr) have potential to mitigate hyperalgesia in pain states. We observed that injection of nAChR antagonists into the SNr reduced pain thresholds in naïve mice, whereas injection of nAChR agonists into the SNr relieved hyperalgesia in mice, subjected to capsaicin injection into the lower hind leg, spinal nerve injury, chronic constriction injury, or chronic nicotine exposure. The analgesic effects of nAChR agonists were mimicked by optogenetic stimulation of cholinergic inputs from the pedunculopontine nucleus (PPN) to the SNr, but attenuated upon downregulation of α4 nAChRs on SNr GABAergic neurons and injection of dihydro-ß-erythroidine into the SNr. Chronic nicotine-induced hyperalgesia depended on α4 nAChRs in SNr GABAergic neurons and was associated with the reduction of ACh release in the SNr. Either activation of α4 nAChRs in the SNr or optogenetic stimulation of the PPN-SNr cholinergic projection mitigated chronic nicotine-induced hyperalgesia. Interestingly, mechanical stimulation-induced ACh release was significantly attenuated in mice subjected to either capsaicin injection into the lower hind leg or SNI. These results suggest that α4 nAChRs on GABAergic neurons mediate a cholinergic analgesic circuit in the SNr, and these receptors may be effective therapeutic targets to relieve hyperalgesia in acute and chronic pain, and chronic nicotine exposure.
Assuntos
Neurônios GABAérgicos , Hiperalgesia , Camundongos Endogâmicos C57BL , Receptores Nicotínicos , Animais , Receptores Nicotínicos/metabolismo , Neurônios GABAérgicos/metabolismo , Neurônios GABAérgicos/efeitos dos fármacos , Neurônios GABAérgicos/fisiologia , Masculino , Hiperalgesia/metabolismo , Hiperalgesia/tratamento farmacológico , Camundongos , Parte Reticular da Substância Negra/metabolismo , Parte Reticular da Substância Negra/efeitos dos fármacos , Nicotina/farmacologia , Analgésicos/farmacologia , Agonistas Nicotínicos/farmacologia , Antagonistas Nicotínicos/farmacologia , Capsaicina/farmacologia , Acetilcolina/metabolismo , Optogenética , Limiar da Dor/efeitos dos fármacosRESUMO
Gaba-ergic neurons are a diverse cell class with extensive influence over cortical processing, but their role in experience-dependent plasticity is not completely understood. Here we addressed the role of cortical somatostatin- (SOM-INs) and vasoactive intestinal polypeptide- (VIP-INs) containing interneurons in a Pavlovian conditioning where stimulation of the vibrissae is used as a conditioned stimulus and tail shock as unconditioned one. This procedure induces a plastic change observed as an enlargement of the cortical functional representation of vibrissae activated during conditioning. Using layer-targeted, cell-selective DREADD transductions, we examined the involvement of SOM-INs and VIP-INs activity in learning-related plastic changes. Under optical recordings, we injected DREADD-expressing vectors into layer IV (L4) barrels or layer II/III (L2/3) areas corresponding to the activated vibrissae. The activity of the interneurons was modulated during all conditioning sessions, and functional 2-deoxyglucose (2DG) maps were obtained 24 h after the last session. In mice with L4 but not L2/3 SOM-INs suppressed during conditioning, the plastic change of whisker representation was absent. The behavioral effect of conditioning was disturbed. Both L4 SOM-INs excitation and L2/3 VIP-INs inhibition during conditioning did not affect the plasticity or the conditioned response. We found the activity of L4 SOM-INs is indispensable in the formation of learning-induced plastic change. We propose that L4 SOM-INs may provide disinhibition by blocking L4 parvalbumin interneurons, allowing a flow of information into upper cortical layers during learning.
Assuntos
Interneurônios/fisiologia , Aprendizagem , Inibição Neural , Plasticidade Neuronal , Córtex Somatossensorial/fisiologia , Animais , Neurônios GABAérgicos/efeitos dos fármacos , Neurônios GABAérgicos/metabolismo , Neurônios GABAérgicos/fisiologia , Interneurônios/efeitos dos fármacos , Interneurônios/metabolismo , Moduladores de Transporte de Membrana/farmacologia , Camundongos , Córtex Somatossensorial/citologia , Somatostatina/genética , Somatostatina/metabolismo , Vibrissas/inervação , Vibrissas/fisiologiaRESUMO
Neuroimmune signaling is increasingly identified as a critical component of various illnesses, including chronic pain, substance use disorder, and depression. However, the underlying neural mechanisms remain unclear. Proinflammatory cytokines, such as tumor necrosis factor-α (TNF-α), may play a role by modulating synaptic function and long-term plasticity. The midbrain structure periaqueductal gray (PAG) plays a well-established role in pain processing, and although TNF-α inhibitors have emerged as a therapeutic strategy for pain-related disorders, the impact of TNF-α on PAG neuronal activity has not been thoroughly characterized. Recent studies have identified subpopulations of ventrolateral PAG (vlPAG) with opposing effects on nociception, with dopamine (DA) neurons driving pain relief in contrast to GABA neurons. Therefore, we used slice physiology to examine the impact of TNF-α on neuronal activity of both these subpopulations. We focused on female mice since the PAG is a sexually dimorphic region and most studies use male subjects, limiting our understanding of mechanistic variations in females. We selectively targeted GABA and DA neurons using transgenic reporter lines. Following exposure to TNF-α, there was an increase in excitability of GABA neurons along with a reduction in glutamatergic synaptic transmission. In DA neurons, TNF-α exposure resulted in a robust decrease in excitability along with a modest reduction in glutamatergic synaptic transmission. Interestingly, TNF-α had no effect on inhibitory transmission onto DA neurons. Collectively, these data suggest that TNF-α differentially affects the function of GABA and DA neurons in female mice and enhances our understanding of how TNF-α-mediated signaling modulates vlPAG function.NEW & NOTEWORTHY This study describes the effects of TNF-α on two distinct subpopulations of neurons in the vlPAG. We show that TNF-α alters both neuronal excitability and glutamatergic synaptic transmission on GABA and dopamine neurons within the vlPAG of female mice. This provides critical new information on the role of TNF-α in the potential modulation of pain, since activation of vlPAG GABA neurons drives nociception, whereas activation of dopamine neurons drives analgesia.
Assuntos
Neurônios Dopaminérgicos/fisiologia , Neurônios GABAérgicos/fisiologia , Substância Cinzenta Periaquedutal/fisiologia , Transmissão Sináptica/fisiologia , Fator de Necrose Tumoral alfa/fisiologia , Animais , Neurônios Dopaminérgicos/efeitos dos fármacos , Feminino , Neurônios GABAérgicos/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Substância Cinzenta Periaquedutal/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos , Fator de Necrose Tumoral alfa/farmacologiaRESUMO
Phosphodiesterase 10A (PDE10A), the enzyme which catalyzes hydrolysis of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), is located almost exclusively in striatal γ-amino-butyric acid (GABA)ergic medium spiny neurons (MSNs). Since dopaminergic deficiency in Parkinson's disease (PD) leads to functional imbalance of striatal direct and indirect output pathways formed by MSNs, PDE10A seems to be of special interest as a potential therapeutic target in PD. The aim of the present study was to examine the influence of 7-{5,8-dimethyl-[1,2,4]triazolo[1,5-a]pyrazin-2-yl}-2-phenylimidazo[1,2-a]pyrimidine (CPL500036), a novel selective inhibitor of PDE10A, on sensorimotor deficits and therapeutic effects of L-3,4-dihydroxyphenylalanine (L-DOPA) in hemiparkinsonian rats. Animals were unilaterally lesioned with 6-hydroxydopamine, and their sensorimotor deficits were examined in the stepping, cylinder, vibrissae and catalepsy tests. CPL500036 (0.1 and 0.3 mg/kg) was administered either acutely or chronically (2 weeks), alone or in combination with L-DOPA/benserazide (6 mg/kg/6 mg/kg). Acute treatment with CPL500036 reversed the lesion-induced impairments of contralateral forelimb use in the stepping and cylinder tests but did not influence deficits in the vibrissae test and the lesion-induced catalepsy. Moreover, CPL500036 did not diminish the therapeutic effects produced by acute and chronic treatment with L-DOPA in these tests. The present study suggests a potential use of CPL500036 as a co-treatment to L-DOPA in PD therapy.
Assuntos
Antiparkinsonianos/uso terapêutico , Levodopa/uso terapêutico , Doença de Parkinson Secundária/tratamento farmacológico , Inibidores de Fosfodiesterase/uso terapêutico , Diester Fosfórico Hidrolases/metabolismo , Animais , Antiparkinsonianos/farmacologia , Modelos Animais de Doenças , Neurônios GABAérgicos/efeitos dos fármacos , Humanos , Levodopa/farmacologia , Masculino , Oxidopamina/administração & dosagem , Oxidopamina/toxicidade , Doença de Parkinson Secundária/induzido quimicamente , Doença de Parkinson Secundária/diagnóstico , Doença de Parkinson Secundária/patologia , Inibidores de Fosfodiesterase/farmacologia , Ratos , Índice de Gravidade de DoençaRESUMO
Somatostatin-expressing interneurons (SOM-INs) are a major subpopulation of GABAergic cells in CA1 hippocampus that receive excitation from pyramidal cells (PCs), and, in turn, provide feedback inhibition onto PC dendrites. Excitatory synapses onto SOM-INs show a Hebbian long-term potentiation (LTP) mediated by type 1a metabotropic glutamate receptors (mGluR1a) that is implicated in hippocampus-dependent learning. The neuropeptide somatostatin (SST) is also critical for hippocampal long-term synaptic plasticity, as well as learning and memory. SST effects on hippocampal PCs are well documented, but its actions on inhibitory interneurons remain largely undetermined. In the present work, we investigate the involvement of SST in long-term potentiation of CA1 SOM-IN excitatory synapses using pharmacological approaches targeting the somatostatinergic system and whole cell recordings in slices from transgenic mice expressing eYFP in SOM-INs. We report that application of exogenous SST14 induces long-term potentiation of excitatory postsynaptic potentials in SOM-INs via somatostatin type 1-5 receptors (SST1-5Rs) but does not affect synapses of PC or parvalbumin-expressing interneurons. Hebbian LTP in SOM-INs was prevented by inhibition of SSTRs and by depletion of SST by cysteamine treatment, suggesting a critical role of endogenous SST in LTP. LTP of SOM-IN excitatory synapses induced by SST14 was independent of NMDAR and mGluR1a, activity-dependent, and prevented by blocking GABAA receptor function. Our results indicate that endogenous SST may contribute to Hebbian LTP at excitatory synapses of SOM-INs by controlling GABAA inhibition, uncovering a novel role for SST in regulating long-term synaptic plasticity in somatostatinergic cells that may be important for hippocampus-dependent memory processes.
Assuntos
Região CA1 Hipocampal/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Neurônios GABAérgicos/efeitos dos fármacos , Interneurônios/efeitos dos fármacos , Potenciação de Longa Duração/efeitos dos fármacos , Somatostatina/fisiologia , Sinapses/efeitos dos fármacos , Animais , Proteínas de Bactérias , Cisteamina/farmacologia , Feminino , Antagonistas de Receptores de GABA-A/farmacologia , Neurônios GABAérgicos/metabolismo , Técnicas de Introdução de Genes , Genes Reporter , Humanos , Interneurônios/metabolismo , Proteínas Luminescentes , Masculino , Memória/fisiologia , Camundongos , Camundongos Transgênicos , Peptídeos Cíclicos/farmacologia , Receptores de Glutamato Metabotrópico/fisiologia , Receptores de N-Metil-D-Aspartato/fisiologia , Receptores de Somatostatina/efeitos dos fármacos , Receptores de Somatostatina/fisiologia , Somatostatina/farmacologia , Sinapses/fisiologiaRESUMO
The role of adenosine A2A receptor (A2AR) and striatal-enriched protein tyrosine phosphatase (STEP) interactions in the striatal-pallidal GABA neurons was recently discussed in relation to A2AR overexpression and cocaine-induced increases of brain adenosine levels. As to phosphorylation, combined activation of A2AR and metabotropic glutamate receptor 5 (mGluR5) in the striatal-pallidal GABA neurons appears necessary for phosphorylation of the GluA1 unit of the AMPA receptor to take place. Robert Yasuda (J Neurochem 152: 270-272, 2020) focused on finding a general mechanism by which STEP activation is enhanced by increased A2AR transmission in striatal-pallidal GABA neurons expressing A2AR and dopamine D2 receptor. In his Editorial, he summarized in a clear way the significant effects of A2AR activation on STEP in the dorsal striatal-pallidal GABA neurons which involves a rise of intracellular levels of calcium causing STEP activation through its dephosphorylation. However, the presence of the A2AR in an A2AR-fibroblast growth factor receptor 1 (FGFR1) heteroreceptor complex can be required in the dorsal striatal-pallidal GABA neurons for the STEP activation. Furthermore, Won et al. (Proc Natl Acad Sci USA 116: 8028-8037, 2019) found in mass spectrometry experiments that the STEP splice variant STEP61 can bind to mGluR5 and inactivate it. In addition, A2AR overexpression can lead to increased formation of A2AR-mGluR5 heterocomplexes in ventral striatal-pallidal GABA neurons. It involves enhanced facilitatory allosteric interactions leading to increased Gq-mediated mGluR5 signaling activating STEP. The involvement of both A2AR and STEP in the actions of cocaine on synaptic downregulation was also demonstrated. The enhancement of mGluR5 protomer activity by the A2AR protomer in A2AR-mGluR5 heterocomplexes in the nucleus accumbens shell appears to have a novel significant role in STEP mechanisms by both enhancing the activation of STEP and being a target for STEP61.
Assuntos
Neurônios GABAérgicos/fisiologia , Fosforilação/genética , Fosforilação/fisiologia , Células do Corno Posterior/fisiologia , Receptor A2A de Adenosina/metabolismo , Animais , Cocaína/farmacologia , Transtornos Relacionados ao Uso de Cocaína/genética , Transtornos Relacionados ao Uso de Cocaína/patologia , Neurônios GABAérgicos/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , Células do Corno Posterior/efeitos dos fármacos , Subunidades Proteicas/efeitos dos fármacos , Proteínas Tirosina Fosfatases/genética , Receptor A2A de Adenosina/genética , Receptor de Glutamato Metabotrópico 5/genéticaRESUMO
Exposure to steroid sex hormones such as 17ß-estradiol (estradiol) during early life potentially permanently masculinize neuron electrophysiological phenotype. In rodents, one crucial component of this developmental process occurs in males, with estradiol aromatized in the brain from testes-sourced testosterone. However, it is unknown whether most neuron electrophysiological phenotypes are altered by this early masculinization process, including medium spiny neurons (MSNs) of the rat caudate-putamen. MSNs are the predominant and primary output neurons of the caudate-putamen and exhibit increased intrinsic excitability in females compared to males. Here, we hypothesize that since perinatal estradiol exposure occurs in males, then a comparable exposure in females to estradiol or its receptor agonists would be sufficient to induce masculinization. To test this hypothesis, we injected perinatal female rats with estradiol or its receptor agonists and then later assessed MSN electrophysiology. Female and male rats on postnatal day 0 and 1 were systemically injected with either vehicle, estradiol, the estrogen receptor (ER)α agonist PPT, the ERß agonist DPN, or the G-protein-coupled receptor 1 (GPER-1) agonist G1. On postnatal days 19 ± 2, MSN electrophysiological properties were assessed using whole cell patch clamp recordings. Estradiol exposure abolished increased intrinsic excitability in female compared to male MSNs. Exposure to either an ERα or ERß agonist masculinized female MSN evoked action potential firing rate properties, whereas exposure to an ERß agonist masculinized female MSN inward rectification properties. Exposure to ER agonists minimally impacted male MSN electrophysiological properties. These findings indicate that perinatal estradiol exposure masculinizes MSN electrophysiological phenotype via activation of ERα and ERß.NEW & NOTEWORTHY This study is the first to demonstrate that estradiol and estrogen receptor α and ß stimulation during early development sexually differentiates the electrophysiological properties of caudate-putamen medium spiny neurons, the primary output neuron of the striatal regions. Overall, this evidence provides new insight into the neuroendocrine mechanism by which caudate-putamen neuron electrophysiology is sexually differentiated and demonstrates the powerful action of early hormone exposure upon individual neuron electrophysiology.
Assuntos
Núcleo Caudado/efeitos dos fármacos , Fenômenos Eletrofisiológicos/efeitos dos fármacos , Estradiol/farmacologia , Receptor alfa de Estrogênio/efeitos dos fármacos , Receptor beta de Estrogênio/efeitos dos fármacos , Estrogênios/farmacologia , Neurônios GABAérgicos/efeitos dos fármacos , Putamen/efeitos dos fármacos , Receptores Acoplados a Proteínas G/efeitos dos fármacos , Animais , Animais Recém-Nascidos , Estradiol/administração & dosagem , Receptor alfa de Estrogênio/agonistas , Receptor beta de Estrogênio/agonistas , Estrogênios/administração & dosagem , Feminino , Masculino , Técnicas de Patch-Clamp , Ratos , Ratos Sprague-Dawley , Caracteres SexuaisRESUMO
The amygdala plays a crucial role in anxiety-related behavior and various neuropsychiatric disorders. The offspring of dams, administered methylazoxymethanol acetate (MAM) intraperitoneally at gestational day 15, exhibit micrencephaly and anxiety-related behavior, such as hyperactivity in rearing and crossing behavior, alongside a distinct Fos expression profile in the basolateral (BLA) and central amygdala. However, the histochemical underpinnings of these changes remain to be elucidated. To determine the histochemical alterations in MAM-induced model rats, we performed Nissl staining, immunohistochemistry for parvalbumin (PV) or calbindin (Calb), and immunohistochemistry for PV in conjunction with in situ hybridization for glutamate decarboxylase (GAD). We compared immunoreactivity in the BLA between normal and MAM-induced model rats and observed a significant decrease in the number of PV-positive neurons in MAM-induced model rats; however, no significant differences in the number of Nissl- and Calb-positive neurons were observed. We did not detect any significant between-group differences with regards to the effects of environmental enrichment on the number of PV-positive neurons in the BLA. Double-labeling for GAD and PV revealed that many PV-positive neurons colocalized with digoxigenin-GAD65/67 signals. In addition, GAD/PV double-positive neurons and the total number of GAD-positive neurons in the BLA were lower in the MAM-induced model rats. These results indicate that histochemical alterations observed in the BLA of the MAM-induced model rats may attribute to an aberrant GABAergic inhibitory system.
Assuntos
Complexo Nuclear Basolateral da Amígdala/metabolismo , Neurônios GABAérgicos/metabolismo , Interneurônios/metabolismo , Acetato de Metilazoximetanol/análogos & derivados , Microcefalia/metabolismo , Parvalbuminas/metabolismo , Animais , Complexo Nuclear Basolateral da Amígdala/química , Complexo Nuclear Basolateral da Amígdala/efeitos dos fármacos , Carcinógenos/toxicidade , Feminino , Neurônios GABAérgicos/química , Neurônios GABAérgicos/efeitos dos fármacos , Interneurônios/química , Interneurônios/efeitos dos fármacos , Masculino , Acetato de Metilazoximetanol/toxicidade , Microcefalia/induzido quimicamente , Microcefalia/psicologia , Parvalbuminas/análise , Gravidez , Ratos , Ratos Sprague-DawleyRESUMO
BACKGROUND: Limonene, a common terpene found in citrus fruits, is assumed to reduce stress and mood disorders. Dopamine and γ-aminobutyric acid (GABA) have been reported to play an important role in modulating anxiety in different parts of the brain. HYPOTHESIS/PURPOSE: Herein, we report the anxiolytic activity of limonene. In addition, we identified a possible mechanism underlying the effect of limonene on DAergic and GABAergic neurotransmission. STUDY DESIGN: In this study, mice were injected with saline in the control group and limonene in the test group before behavioral analysis. We performed immunoblotting and high-performance liquid chromatography (HPLC) analysis after the behavioral study. RESULTS: The limonene treated group showed increased locomotor activity and open-arm preference in the elevated plus maze experiment. Limonene treatment increased the expression of both tyrosine hydroxylase and GAD-67 proteins and significantly upregulated dopamine levels in the striatum. Furthermore, tissue dopamine levels were increased in the striatum of mice following limonene treatment, and depolarization-induced GABA release was enhanced by limonene pre-treatment in PC-12 cells. Interestingly, limonene-induced anxiolytic activity and GABA release augmentation were blocked by an adenosine A2A receptor (A2AR) antagonist. CONCLUSION: Our results suggest that limonene inhibits anxiety-related behavior through A2A receptor-mediated regulation of DAergic and GABAergic neuronal activity.
Assuntos
Ansiolíticos/farmacologia , Corpo Estriado/efeitos dos fármacos , Limoneno/farmacologia , Receptor A2A de Adenosina/metabolismo , Animais , Ansiedade/tratamento farmacológico , Ansiedade/metabolismo , Comportamento Animal/efeitos dos fármacos , Corpo Estriado/metabolismo , Dopamina/metabolismo , Neurônios Dopaminérgicos/efeitos dos fármacos , Neurônios Dopaminérgicos/metabolismo , Neurônios GABAérgicos/efeitos dos fármacos , Neurônios GABAérgicos/metabolismo , Locomoção/efeitos dos fármacos , Masculino , Camundongos Endogâmicos C57BL , Ratos , Transmissão Sináptica/efeitos dos fármacos , Tirosina 3-Mono-Oxigenase/metabolismo , Ácido gama-Aminobutírico/metabolismoRESUMO
Fibroblast growth factor 9 (FGF9) has long been assumed to modulate multiple biological processes, yet very little is known about the impact of FGF9 on neurodevelopment. Herein, we found that loss of Fgf9 in olig1 progenitor cells induced epilepsy in mice, with pathological changes in the cortex. Then depleting Fgf9 in different neural populations revealed that epilepsy was associated with GABAergic neurons. Fgf9 CKO in GABAergic neuron (CKOVGAT) mice exhibited not only the most severe seizures, but also the most severe growth retardation and highest mortality. Fgf9 deletion in CKOVGAT mice caused neuronal apoptosis and decreased GABA expression, leading to a GABA/Glu imbalance and epilepsy. The adenylate cyclase/cyclic AMP and ERK signaling pathways were activated in this process. Recombinant FGF9 proteoliposomes could significantly decrease the number of seizures. Furthermore, the decrease of FGF9 was commonly observed in serum of epileptic patients, especially those with focal seizures. Thus, FGF9 plays essential roles in GABAergic neuron survival and epilepsy pathology, which could serve as a new target for the treatment of epilepsy.
Assuntos
Córtex Cerebral/metabolismo , Epilepsia/metabolismo , Fator 9 de Crescimento de Fibroblastos/deficiência , Neurônios GABAérgicos/metabolismo , Células-Tronco Neurais/metabolismo , Adenilil Ciclases/metabolismo , Adulto , Animais , Anticonvulsivantes/farmacologia , Apoptose , Estudos de Casos e Controles , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/patologia , Córtex Cerebral/fisiopatologia , AMP Cíclico/metabolismo , Modelos Animais de Doenças , Epilepsia/patologia , Epilepsia/fisiopatologia , Epilepsia/prevenção & controle , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Feminino , Fator 9 de Crescimento de Fibroblastos/sangue , Fator 9 de Crescimento de Fibroblastos/genética , Fator 9 de Crescimento de Fibroblastos/farmacologia , Neurônios GABAérgicos/efeitos dos fármacos , Neurônios GABAérgicos/patologia , Predisposição Genética para Doença , Humanos , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Pessoa de Meia-Idade , Células-Tronco Neurais/efeitos dos fármacos , Células-Tronco Neurais/patologia , Proteínas Recombinantes/farmacologia , Transdução de Sinais , Adulto JovemRESUMO
AIMS: Abundant evidence indicates that oestrogen (E2) plays a protective role against hypertension. Yet, the mechanism underlying the antihypertensive effect of E2 is poorly understood. In this study, we sought to determine the mechanism through which E2 inhibits salt-dependent hypertension. METHODS AND RESULTS: To this end, we performed a series of in vivo and in vitro experiments employing a rat model of hypertension that is produced by deoxycorticosterone acetate (DOCA)-salt treatment after uninephrectomy. We found that E2 prevented DOCA-salt treatment from inducing hypertension, raising plasma arginine-vasopressin (AVP) level, enhancing the depressor effect of the V1a receptor antagonist (Phenylac1,D-Tyr(Et)2,Lys6,Arg8,des-Gly9)-vasopressin, and converting GABAergic inhibition to excitation in hypothalamic magnocellular AVP neurons. Moreover, we obtained results indicating that the E2 modulation of the activity and/or expression of NKCC1 (Cl- importer) and KCC2 (Cl- extruder) underpins the effect of E2 on the transition of GABAergic transmission in AVP neurons. Lastly, we discovered that, in DOCA-salt-treated hypertensive ovariectomized rats, CLP290 (prodrug of the KCC2 activator CLP257, intraperitoneal injections) lowered blood pressure, and plasma AVP level and hyperpolarized GABA equilibrium potential to prevent GABAergic excitation from emerging in the AVP neurons of these animals. CONCLUSION: Based on these results, we conclude that E2 inhibits salt-dependent hypertension by suppressing GABAergic excitation to decrease the hormonal output of AVP neurons.
Assuntos
Anti-Hipertensivos/farmacologia , Arginina Vasopressina/metabolismo , Núcleo Basal de Meynert/efeitos dos fármacos , Pressão Sanguínea/efeitos dos fármacos , Estradiol/farmacologia , Neurônios GABAérgicos/efeitos dos fármacos , Hipertensão/prevenção & controle , Animais , Núcleo Basal de Meynert/metabolismo , Núcleo Basal de Meynert/fisiopatologia , Acetato de Desoxicorticosterona , Modelos Animais de Doenças , Feminino , Neurônios GABAérgicos/metabolismo , Hipertensão/induzido quimicamente , Hipertensão/metabolismo , Hipertensão/fisiopatologia , Masculino , Nefrectomia , Ovariectomia , Ratos Sprague-Dawley , Cloreto de Sódio na Dieta , Membro 2 da Família 12 de Carreador de Soluto/metabolismo , Simportadores/metabolismo , Vasoconstrição/efeitos dos fármacosRESUMO
Focal cortical dysplasia (FCD) is a major cause for drug-resistant epilepsies. The molecular and cellular mechanisms of epileptogenesis in FCD are still poorly understood. Some studies have suggested that deficiencies of γ-aminobutyric acid (GABA) system may play an important role in type II FCD, but it remains controversial. In order to examine whether and how GABAergic interneurons and synaptic function are affected, we generated a somatic mTOR hyperactivation-based mouse model of type II FCD by in utero electroporation, quantified densities of interneurons in the malformed cortices, and recorded miniature inhibitory postsynaptic currents in dysmorphic neurons. We detected 20-25% reduction of GABAergic interneurons within malformed cortices, independent of cortical regions and cell subtypes but proportionate to the decrease of global neuron counts. GABAergic synaptic transmission from interneurons to mTOR hyperactivated dysmorphic neurons was dramatically disrupted, outweighing the decrease of interneuron counts. Postnatal mTOR inhibition partially rescued these alterations of GABAergic system. We also quantified the expression of GABAA receptor, GABA transporter, and chloridion transporter encoding genes and found that their expression was relatively intact within the malformed cortices. Taken together, these results confirmed that GABAergic interneuron and synapse transmission are disturbed profoundly in an mTOR-dependent manner in type II FCD. Our study suggests that postsynaptic mechanisms independent of interneuron reduction or altered expression of GABA synapse genes might be accountable for the impaired GABAergic neurotransmission in type II FCD as well as other mTOR-related epilepsies.
Assuntos
Neurônios GABAérgicos/metabolismo , Interneurônios/metabolismo , Malformações do Desenvolvimento Cortical/patologia , Malformações do Desenvolvimento Cortical/fisiopatologia , Transmissão Sináptica , Serina-Treonina Quinases TOR/metabolismo , Animais , Animais Recém-Nascidos , Modelos Animais de Doenças , Neurônios GABAérgicos/efeitos dos fármacos , Perfilação da Expressão Gênica , Regulação da Expressão Gênica/efeitos dos fármacos , Potenciais Pós-Sinápticos Inibidores/efeitos dos fármacos , Interneurônios/efeitos dos fármacos , Malformações do Desenvolvimento Cortical/genética , Camundongos Transgênicos , Neocórtex/patologia , Sirolimo/farmacologia , Transmissão Sináptica/efeitos dos fármacosRESUMO
Reinforcement learning models postulate that neurons that release dopamine encode information about action and action outcome, and provide a teaching signal to striatal spiny projection neurons in the form of dopamine release1. Dopamine is thought to guide learning via dynamic and differential modulation of protein kinase A (PKA) in each class of spiny projection neuron2. However, the real-time relationship between dopamine and PKA in spiny projection neurons remains untested in behaving animals. Here we monitor the activity of dopamine-releasing neurons, extracellular levels of dopamine and net PKA activity in spiny projection neurons in the nucleus accumbens of mice during learning. We find positive and negative modulation of dopamine that evolves across training and is both necessary and sufficient to explain concurrent fluctuations in the PKA activity of spiny projection neurons. Modulations of PKA in spiny projection neurons that express type-1 and type-2 dopamine receptors are dichotomous, such that these neurons are selectively sensitive to increases and decreases, respectively, in dopamine that occur at different phases of learning. Thus, PKA-dependent pathways in each class of spiny projection neuron are asynchronously engaged by positive or negative dopamine signals during learning.
Assuntos
Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Dopamina/metabolismo , Aprendizagem , Animais , Proteínas Quinases Dependentes de AMP Cíclico/antagonistas & inibidores , Neurônios Dopaminérgicos/efeitos dos fármacos , Neurônios Dopaminérgicos/enzimologia , Neurônios Dopaminérgicos/metabolismo , Feminino , Fluorescência , Neurônios GABAérgicos/efeitos dos fármacos , Neurônios GABAérgicos/enzimologia , Neurônios GABAérgicos/metabolismo , Aprendizagem/efeitos dos fármacos , Masculino , Camundongos , Plasticidade Neuronal/efeitos dos fármacos , Núcleo Accumbens/citologia , Fotometria , Receptores Dopaminérgicos/classificação , Receptores Dopaminérgicos/metabolismoRESUMO
The antimalarial artemisinins have also been implicated in the regulation of various cellular pathways including immunomodulation of cancers and regulation of pancreatic cell signaling in mammals. Despite their widespread application, the cellular specificities and molecular mechanisms of target recognition by artemisinins remain poorly characterized. We recently demonstrated how these drugs modulate inhibitory postsynaptic signaling by direct binding to the postsynaptic scaffolding protein gephyrin. Here, we report the crystal structure of the central metabolic enzyme pyridoxal kinase (PDXK), which catalyzes the production of the active form of vitamin B6 (also known as pyridoxal 5'-phosphate [PLP]), in complex with artesunate at 2.4-Šresolution. Partially overlapping binding of artemisinins with the substrate pyridoxal inhibits PLP biosynthesis as demonstrated by kinetic measurements. Electrophysiological recordings from hippocampal slices and activity measurements of glutamic acid decarboxylase (GAD), a PLP-dependent enzyme synthesizing the neurotransmitter γ-aminobutyric acid (GABA), define how artemisinins also interfere presynaptically with GABAergic signaling. Our data provide a comprehensive picture of artemisinin-induced effects on inhibitory signaling in the brain.
Assuntos
Artemisininas/farmacologia , Regulação para Baixo , Inibição Neural/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Piridoxal Quinase/antagonistas & inibidores , Transmissão Sináptica/efeitos dos fármacos , Trifosfato de Adenosina/análogos & derivados , Trifosfato de Adenosina/metabolismo , Animais , Artemisininas/química , Sítios de Ligação , Regulação para Baixo/efeitos dos fármacos , Fenômenos Eletrofisiológicos/efeitos dos fármacos , Feminino , Neurônios GABAérgicos/efeitos dos fármacos , Neurônios GABAérgicos/metabolismo , Glutamato Descarboxilase/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Modelos Biológicos , Modelos Moleculares , Inibidores de Proteínas Quinases/química , Piridoxal Quinase/química , Piridoxal Quinase/metabolismo , Sinapses/efeitos dos fármacos , Sinapses/metabolismo , Ácido gama-Aminobutírico/biossínteseRESUMO
OBJECTIVE: Pharmacological inhibition of GABAergic synapses could represent a potent neuromodulation strategy to activate hippocampal neurons and increase neurotrophic factor gene expression, thus exerting a beneficial effect on post-stroke cognitive impairment (PSCI). The objective of this study was to assess the effects of low-level inhibition of GABAergic synapses on hippocampal gene expressions related to neuroplasticity using the middle cerebral artery occlusion surgery (MCAO) ischemic stroke rat model. METHODS: The animals were randomly assigned to three experimental groups-(1) a sham operated group (SHAM), (2) a control group (CON), and (3) a bicuculline group (BIC). MCAO was performed in the CON and BIC groups. A non-epileptic dose of bicuculline (0.25 mg/kg) was intraperitoneally administered every day for two weeks, starting three days after surgery, to the rats in the BIC group. The mRNA expression of brain-derived neurotrophic factor (BDNF), tropomyosin-related kinase B (TrkB), in relation to neurotrophic intracellular signal, p75, in relation to apoptosis, and synaptophysin (SYP) and PSD-95, synaptic markers, were assessed in the hippocampus ipsilateral to the ischemic site. RESULTS: MCAO increased the gene expression of TrkB. Furthermore, MCAO plus bicuculline administration increased the expression ratio of TrkB to p75 and SYP gene expression. CONCLUSION: Therefore, this study showed that administration of bicuculline after stroke beneficially modulated the expression of crucial genes for neuroplasticity, including BDNF receptors and SYP, in the ipsilateral hippocampus, suggesting that low-level inhibition of GABAergic synapses could lead to beneficial neuromodulation in the hippocampus after stroke.
Assuntos
Bicuculina/farmacologia , Antagonistas de Receptores de GABA-A/farmacologia , Neurônios GABAérgicos/efeitos dos fármacos , Hipocampo/efeitos dos fármacos , Infarto da Artéria Cerebral Média/tratamento farmacológico , Infarto da Artéria Cerebral Média/genética , Inibição Neural/efeitos dos fármacos , Plasticidade Neuronal/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos , Animais , Fator Neurotrófico Derivado do Encéfalo/genética , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Modelos Animais de Doenças , Proteína 4 Homóloga a Disks-Large/genética , Proteína 4 Homóloga a Disks-Large/metabolismo , Neurônios GABAérgicos/metabolismo , Neurônios GABAérgicos/patologia , Regulação da Expressão Gênica , Hipocampo/metabolismo , Hipocampo/patologia , Hipocampo/fisiopatologia , Infarto da Artéria Cerebral Média/metabolismo , Infarto da Artéria Cerebral Média/fisiopatologia , Masculino , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Ratos Sprague-Dawley , Receptor trkB/genética , Receptor trkB/metabolismo , Receptores de Fatores de Crescimento/genética , Receptores de Fatores de Crescimento/metabolismo , Sinaptofisina/genética , Sinaptofisina/metabolismoRESUMO
AIMS: Perioperative neurocognitive disorders (PND) are associated with cognitive impairment in the preoperative or postoperative period, and neuroinflammation is thought to be the most important mechanisms especially during the postoperative period. The GABAergic system is easily disrupted by neuroinflammation. This study investigated the impact of the GABAergic system on PND after anesthesia and surgery. METHODS: An animal model of laparotomy with inhalation anesthesia in 16-month-old mice was addressed. Effects of the GABAergic system were assessed using biochemical analysis. Pharmacological blocking of α5GABAA Rs or P38 mitogen-activated protein kinase (MAPK) were applied to investigate the effects of the GABAergic system. RESULTS: After laparotomy, the hippocampus-dependent memory and long-term potentiation were impaired, the levels of IL-6, IL-1ß and TNF-α up-regulated in the hippocampus, the concentration of GABA decreased, and the protein levels of the surface α5GABAA Rs up-regulated. Pharmacological blocking of α5GABAA Rs with L655,708 alleviated laparotomy induced cognitive deficits. Further studies found that the P38 MAPK signaling pathway was involved and pharmacological blocking with SB203,580 alleviated memory dysfunctions. CONCLUSIONS: Anesthesia and surgery caused neuroinflammation in the hippocampus, which consequently disrupted the GABAergic system, increased the expressions of surface α5GABAA Rs especially through the P38 MAPK signaling pathway, and eventually led to hippocampus-dependent memory dysfunctions.