Basolateral Amygdala Neurons Research Articles

Acute stress activates basolateral amygdala neurons expressing corticotropin-releasing hormone receptor type 1 (CRHR1): Topographical distribution and projection-specific activation in male and female rats

Acute stress activates basolateral amygdala neurons expressing corticotropin-releasing hormone receptor type 1 (CRHR1): Topographical distribution and projection-specific activation in male and female rats

Posterior Basolateral Amygdala is a Critical Amygdaloid Area for Temporal Lobe Epilepsy.

The amygdaloid complex consists of multiple nuclei and is a key node in controlling temporal lobe epilepsy (TLE) in both human and animal model studies. However, the specific nucleus in the amygdaloid complex and the neural circuitry governing seizures remain unknown. Here, it is discovered that activation of glutamatergic neurons in the posterior basolateral amygdala (pBLA) induces severe seizures and even mortality. The pBLA glutamatergic neurons project collateral connections to multiple brain regions, including the insular cortex (IC), bed nucleus of the stria terminalis (BNST), and central amygdala (CeA). Stimulation of pBLA-targeted IC neurons triggers seizures, whereas ablation of IC neurons suppresses seizures induced by activating pBLA glutamatergic neurons. GABAergic neurons in the BNST and CeA establish feedback inhibition on pBLA glutamatergic neurons. Deleting GABAergic neurons in the BNST or CeA leads to sporadic seizures, highlighting their role in balancing pBLA activity. Furthermore, pBLA neurons receive glutamatergic inputs from the ventral hippocampal CA1 (vCA1). Ablation of pBLA glutamatergic neurons mitigates both acute and chronic seizures in the intrahippocampal kainic acid-induced mouse model of TLE. Together, these findings identify the pBLA as a pivotal nucleus in the amygdaloid complex for regulating epileptic seizures in TLE.

Neuronal excitation-inhibition imbalance in the basolateral amygdala is involved in propofol-mediated enhancement of fear memory

Posttraumatic stress disorder (PTSD) is associated with glutamatergic neuron hyperactivation in the basolateral amygdala (BLA) brain area, while GABAergic interneurons in the BLA modulate glutamatergic neuron excitability. Studies have shown that propofol exerts its effects through potentiation of the inhibitory neurotransmitter γ-aminobutyric acid. The neuronal mechanism by which propofol anesthesia modulates fear memory is currently unknown. Here, we used optogenetics and chemogenetics to suppress glutamatergic neurons or activate GABAergic interneurons in the BLA to assess alterations in neuronal excitation-inhibition balance and investigate fear memory. The excitability of glutamatergic neurons in the BLA was significantly reduced by the suppression of glutamatergic neurons or activation of GABAergic interneurons, while propofol-mediated enhancement of fear memory was attenuated. We suggest that propofol anesthesia could reduce the excitability of GABAergic neurons through activation of GABAA receptors, subsequently increasing the excitability of glutamatergic neurons in the mice BLA; the effect of propofol on enhancing mice fear memory might be mediated by strengthening glutamatergic neuronal excitability and decreasing the excitability of GABAergic neurons in the BLA; neuronal excitation-inhibition imbalance in the BLA might be important in mediating the enhancement of fear memory induced by propofol.

Emerging many-to-one weighted mapping in hippocampus-amygdala network underlies memory formation

Memories are crucial for daily life, yet the network-level organizing principles governing neural representations of experiences remain unknown. Employing dual-site in vivo recording in freely behaving male mice, here we show that hippocampal dorsal CA1 (dCA1) and basolateral amygdala (BLA) utilize distinct coding strategies for novel experiences. A small assembly of BLA neurons emerged active during memory acquisition and persisted through consolidation, whereas most dCA1 neurons were engaged in both processes. Machine learning decoding revealed that dCA1 population spikes predicted BLA assembly firing rate, suggesting that most dCA1 neurons concurrently index an episodic event by rapidly establishing weighted communication with a specific BLA assembly – a process we term “many-to-one weighted mapping.” We also found that dCA1 reactivations preceded BLA assembly activity preferably during elongated and enlarged dCA1 ripples. Using a closed-loop strategy, we demonstrated that suppressing BLA activity after large dCA1 ripples impaired memory. These findings highlight a many-to-one weighted mapping mechanism underlying both the acquisition and consolidation of new memories.

Basolateral amygdala parvalbumin and cholecystokinin-expressing GABAergic neurons modulate depressive and anxiety-like behaviors.

The basolateral amygdala (BLA) is increasingly recognized as a key regulator of depression and anxiety-like behaviors. However, the specific contribution of individual BLA neurons to these behaviors remains poorly understood. Building on our previous study, which demonstrated increased activity in glutamatergic BLA neurons in response to aversive stimuli and that enhancing inhibition in the BLA can alleviate depressive-like behaviors, we investigated the role of individual BLA GABAergic neurons (BLAGABA) in depressive and anxiety-like phenotypes. To address this question, we employed a comprehensive array of techniques, including c-fos staining, fiber photometry recording, optogenetic and chemogenetic manipulation, and behavior analysis. Our findings indicate that BLAGABA neurons show decreased activity during tail suspension and after chronic social defeat stress (CSDS) during social interaction. High-frequency activation of BLAGABA neurons attenuated depressive and anxiety-like behaviors, while low-frequency activation had no effect. Fiber photometry recordings revealed increased activity in BLA GABAergic neurons expressing somatostatin (SST), parvalbumin (PV), and cholecystokinin (CCK) during footshock aversive stimuli. Moreover, we found increased activity in PV and SST neurons and decreased activity in CCK-GABA neurons in the BLA during tail suspension stress. However, after CSDS, BLAPV neurons displayed decreased activity, while SST and CCK neurons showed no changes during the social interaction test. Behavioral analysis demonstrated that chemogenetic inhibition of PV and CCK-GABA neurons induced depressive and anxiety-like behaviors. whereas SST neuron inhibition had no effect. Conversely, chemogenetic activation of BLAPV neurons alleviated depressive behaviors, and activation of BLACCK-GABA neurons alleviated at least partly both depressive and anxiety-like behaviors. This study provides compelling evidence that BLAPV neurons play a critical role in regulating depressive-like behaviors, and that BLACCK-GABA neurons are involved, at least in part, in modulating both depressive-like and anxiety-like behaviors in mice.

Orbitofrontal Cortex Mediates Sustained Basolateral Amygdala Encoding of Cued Reward-Seeking States.

Basolateral amygdala (BLA) neurons are engaged by emotionally salient stimuli. An area of increasing interest is how BLA dynamics relate to evolving reward-seeking behavior, especially under situations of uncertainty or ambiguity. Here, we recorded the activity of individual BLA neurons in male rats across the acquisition and extinction of conditioned reward seeking. We assessed ongoing neural dynamics in a task where long reward cue presentations preceded an unpredictable, variably time reward delivery. We found that, with training, BLA neurons discriminated the CS+ and CS- cues with sustained cue-evoked activity that correlated with behavior and terminated only after reward receipt. BLA neurons were bidirectionally modulated, with a majority showing prolonged inhibition during cued reward seeking. Strikingly, population-level analyses revealed that neurons showing cue-evoked inhibitions and those showing excitations similarly represented the CS+ and behavioral state. This sustained population code rapidly extinguished in parallel with conditioned behavior. We next assessed the contribution of the orbitofrontal cortex (OFC), a major reciprocal partner to the BLA. Inactivation of the OFC while simultaneously recording in the BLA revealed a blunting of sustained cue-evoked activity in the BLA that accompanied reduced reward seeking. Optogenetic disruption of BLA activity and OFC terminals in the BLA also reduced reward seeking. Our data indicate that the BLA represents reward-seeking states via sustained, bidirectional cue-driven neural encoding. This code is regulated by cortical input and is important for the maintenance of vigilant reward-seeking behavior.

Opioid drug seeking after early-life adversity: a role for delta opioid receptors

Opioid use disorder (OUD) is associated with a history of early-life adversity (ELA), an association that is particularly strong in women. In a rodent model, we previously found that ELA enhances risk for opioid addiction selectively in females, but the mechanisms for this effect are unclear. Here, we show that ELA robustly alters cFos responses to opioid drugs in females’ nucleus accumbens (NAc) and basolateral amygdala (BLA), but not elsewhere. We further identify delta opioid receptors (DOR), which mature in the first week of life and thus later than kappa or mu opioid receptors, as a potential mediator of ELA's impacts on reward circuit functions. Accordingly, DOR mRNA in NAc was persistently reduced in adult females with ELA history. Moreover, pharmacological stimulation of NAc DORs increased opioid demand in control females (recapitulating the ELA phenotype), while blocking DORs in ELA females conversely reduced high-effort drug consumption, simulating the control rearing phenotype. These findings support a role for NAc DORs in mediating ELA-induced opioid vulnerability. In contrast, BLA neurons expressing DOR protein do not overlap heroin- responsive cells in ELA rats, arguing against a direct relationship of BLA DORs to heroin's addiction-relevant actions in the brain. Together, these results suggest a novel and selective role for NAc DORs in contributing to enduring, ELA-provoked vulnerability to OUD.

Activation of NPY Receptors in the BLA Inhibits Projections to the Bed Nucleus of the Stria Terminalis and Buffers Stress-Induced Decreases in Social Interaction in Male Rats.

Neuropeptide Y (NPY) increases resilience and buffers behavioral stress responses in male rats in part through decreasing the excitability of principal output neurons in the basolateral amygdala (BLA). Intra-BLA administration of NPY acutely increases social interaction (SI) through activation of either Y1 or Y5 receptors, whereas repeated NPY (rpNPY) injections (once daily for 5 d) produce persistent increases in SI through Y5 receptor-mediated neuroplasticity in the BLA. In this series of studies, we characterized the neural circuits from the BLA that underlie these behavioral responses to NPY. Using neuronal tract tracing, NPY Y1 and Y5 receptor immunoreactivity was identified on subpopulations of BLA neurons projecting to the bed nucleus of the stria terminalis (BNST) and the central nucleus of the amygdala (CeA). Inhibition of BLA→BNST, but not BLA→CeA, neurons using projection-restricted, cre-driven designer receptors exclusively activated by designer drug-Gi expression increased SI and prevented stress-induced decreases in SI produced by a 30 min restraint stress. This behavioral profile was similar to that seen after both acute and rpNPY injections into the BLA. Intracellular recordings of BLA→BNST neurons demonstrated NPY-mediated inhibition via suppression of H currents, as seen previously. Repeated intra-BLA injections of NPY, which are associated with the induction of BLA neuroplasticity, decreased the activity of BLA→BNST neurons and decreased their dendritic complexity. These results demonstrate that NPY modulates the activity of BNST-projecting BLA neurons, suggesting that this pathway contributes to the stress-buffering actions of NPY and provides a novel substrate for the proresilient effects of NPY.

Periaqueductal gray activates antipredatory neural responses in the amygdala of foraging rats.

Pavlovian fear conditioning research suggests that the interaction between the dorsal periaqueductal gray (dPAG) and basolateral amygdala (BLA) acts as a prediction error mechanism in the formation of associative fear memories. However, their roles in responding to naturalistic predatory threats, characterized by less explicit cues and the absence of reiterative trial-and-error learning events, remain unexplored. In this study, we conducted single-unit recordings in rats during an 'approach food-avoid predator' task, focusing on the responsiveness of dPAG and BLA neurons to a rapidly approaching robot predator. Optogenetic stimulation of the dPAG triggered fleeing behaviors and increased BLA activity in naive rats. Notably, BLA neurons activated by dPAG stimulation displayed immediate responses to the robot, demonstrating heightened synchronous activity compared to BLA neurons that did not respond to dPAG stimulation. Additionally, the use of anterograde and retrograde tracer injections into the dPAG and BLA, respectively, coupled with c-Fos activation in response to predatory threats, indicates that the midline thalamus may play an intermediary role in innate antipredatory-defensive functioning.

Periaqueductal gray activates antipredatory neural responses in the amygdala of foraging rats

Pavlovian fear conditioning research suggests that the interaction between the dorsal periaqueductal gray (dPAG) and basolateral amygdala (BLA) acts as a prediction error mechanism in the formation of associative fear memories. However, their roles in responding to naturalistic predatory threats, characterized by less explicit cues and the absence of reiterative trial-and-error learning events, remain unexplored. In this study, we conducted single-unit recordings in rats during an ‘approach food-avoid predator’ task, focusing on the responsiveness of dPAG and BLA neurons to a rapidly approaching robot predator. Optogenetic stimulation of the dPAG triggered fleeing behaviors and increased BLA activity in naive rats. Notably, BLA neurons activated by dPAG stimulation displayed immediate responses to the robot, demonstrating heightened synchronous activity compared to BLA neurons that did not respond to dPAG stimulation. Additionally, the use of anterograde and retrograde tracer injections into the dPAG and BLA, respectively, coupled with c-Fos activation in response to predatory threats, indicates that the midline thalamus may play an intermediary role in innate antipredatory-defensive functioning.

Identification of a stress-responsive subregion of the basolateral amygdala in male rats.

The basolateral amygdala (BLA) is reliably activated by psychological stress and hyperactive in conditions of pathological stress or trauma; however, subsets of BLA neurons are also readily activated by rewarding stimuli and can suppress fear and avoidance behaviours. The BLA is highly heterogeneous anatomically, exhibiting continuous molecular and connectivity gradients throughout the entire structure. A critical gap remains in understanding the anatomical specificity of amygdala subregions, circuits, and cell types explicitly activated by acute stress and how they are dynamically activated throughout stimulus exposure. Using a combination of topographical mapping for the activity-responsive protein FOS and fiber photometry to measure calcium transients in real-time, we sought to characterize the spatial and temporal patterns of BLA activation in response to a range of novel stressors (shock, swim, restraint, predator odour) and non-aversive, but novel stimuli (crackers, citral odour). We report four main findings: (1) the BLA exhibits clear spatial activation gradients in response to novel stimuli throughout the medial-lateral and dorsal-ventral axes, with aversive stimuli strongly biasing activation towards medial aspects of the BLA; (2) novel stimuli elicit distinct temporal activation patterns, with stressful stimuli exhibiting particularly enhanced or prolonged temporal activation patterns; (3) changes in BLA activity are associated with changes in behavioural state; and (4) norepinephrine enhances stress-induced activation of BLA neurons via the ß-noradrenergic receptor. Moving forward, it will be imperative to combine our understanding of activation gradients with molecular and circuit-specificity.

Deep brain stimulation of the Tbr1-deficient mouse model of autism spectrum disorder at the basolateral amygdala alters amygdalar connectivity, whole-brain synchronization, and social behaviors.

Autism spectrum disorders (ASDs) are considered neural dysconnectivity syndromes. To better understand ASD and uncover potential treatments, it is imperative to know and dissect the connectivity deficits under conditions of autism. Here, we apply a whole-brain immunostaining and quantification platform to demonstrate impaired structural and functional connectivity and aberrant whole-brain synchronization in a Tbr1+/- autism mouse model. We express a channelrhodopsin variant oChIEF fused with Citrine at the basolateral amygdala (BLA) to outline the axonal projections of BLA neurons. By activating the BLA under blue light theta-burst stimulation (TBS), we then evaluate the effect of BLA activation on C-FOS expression at a whole brain level to represent neural activity. We show that Tbr1 haploinsufficiency almost completely disrupts contralateral BLA axonal projections and results in mistargeting in both ipsilateral and contralateral hemispheres, thereby globally altering BLA functional connectivity. Based on correlated C-FOS expression among brain regions, we further show that Tbr1 deficiency severely disrupts whole-brain synchronization in the absence of salient stimulation. Tbr1+/- and wild-type (WT) mice exhibit opposing responses to TBS-induced amygdalar activation, reducing synchronization in WT mice but enhancing it in Tbr1+/- mice. Whole-brain modular organization and intermodule connectivity are also affected by Tbr1 deficiency and amygdalar activation. Following BLA activation by TBS, the synchronizations of the whole brain and the default mode network, a specific subnetwork highly relevant to ASD, are enhanced in Tbr1+/- mice, implying a potential ameliorating effect of amygdalar stimulation on brain function. Indeed, TBS-mediated BLA activation increases nose-to-nose social interactions of Tbr1+/- mice, strengthening evidence for the role of amygdalar connectivity in social behaviors. Our high-resolution analytical platform reveals the inter- and intrahemispheric connectopathies arising from ASD. Our study emphasizes the defective synchronization at a whole-brain scale caused by Tbr1 deficiency and implies a potential beneficial effect of deep brain stimulation at the amygdala for TBR1-linked autism.

Emotional vocalizations alter behaviors and neurochemical release into the amygdala

The basolateral amygdala (BLA), a brain center of emotional expression, contributes to acoustic communication by first interpreting the meaning of social sounds in the context of the listener’s internal state, then organizing the appropriate behavioral responses. We propose that modulatory neurochemicals such as acetylcholine (ACh) and dopamine (DA) provide internal-state signals to the BLA while an animal listens to social vocalizations. We tested this in a vocal playback experiment utilizing highly affective vocal sequences associated with either mating or restraint, then sampled and analyzed fluids within the BLA for a broad range of neurochemicals and observed behavioral responses of adult male and female mice. In male mice, playback of restraint vocalizations increased ACh release and usually decreased DA release, while playback of mating sequences evoked the opposite neurochemical release patterns. In non-estrus female mice, patterns of ACh and DA release with mating playback were similar to males. Estrus females, however, showed increased ACh, associated with vigilance, as well as increased DA, associated with reward-seeking. Experimental groups that showed increased ACh release also showed the largest increases in an aversive behavior. These neurochemical release patterns and several behavioral responses depended on a single prior experience with the mating and restraint behaviors. Our results support a model in which ACh and DA provide contextual information to sound analyzing BLA neurons that modulate their output to downstream brain regions controlling behavioral responses to social vocalizations.

Emotional vocalizations alter behaviors and neurochemical release into the amygdala.

The basolateral amygdala (BLA), a brain center of emotional expression, contributes to acoustic communication by first interpreting the meaning of social sounds in the context of the listener's internal state, then organizing the appropriate behavioral responses. We propose that modulatory neurochemicals such as acetylcholine (ACh) and dopamine (DA) provide internal-state signals to the BLA while an animal listens to social vocalizations. We tested this in a vocal playback experiment utilizing highly affective vocal sequences associated with either mating or restraint, then sampled and analyzed fluids within the BLA for a broad range of neurochemicals and observed behavioral responses of adult male and female mice. In male mice, playback of restraint vocalizations increased ACh release and usually decreased DA release, while playback of mating sequences evoked the opposite neurochemical release patterns. In non-estrus female mice, patterns of ACh and DA release with mating playback were similar to males. Estrus females, however, showed increased ACh, associated with vigilance, as well as increased DA, associated with reward-seeking. Experimental groups that showed increased ACh release also showed the largest increases in an aversive behavior. These neurochemical release patterns and several behavioral responses depended on a single prior experience with the mating and restraint behaviors. Our results support a model in which ACh and DA provide contextual information to sound analyzing BLA neurons that modulate their output to downstream brain regions controlling behavioral responses to social vocalizations.

Comparative basolateral amygdala connectomics reveals dissociable single-neuron projection patterns to frontal cortex in macaques and mice

Basolateral amygdala (BLA) is a key hub for affect in the brain,1,2,3 and dysfunction within this area contributes to a host of psychiatric disorders.4,5 BLA is extensively and reciprocally interconnected with frontal cortex,6,7,8,9 and some aspects of its function are evolutionarily conserved across rodents, anthropoid primates, and humans.10 Neuron density in BLA is substantially lower in primates compared to murine rodents,11 and frontal cortex (FC) is dramatically expanded in primates, particularly the more anterior granular and dysgranular areas.12,13,14 Yet, how these anatomical differences influence the projection patterns of single BLA neurons to frontal cortex across rodents and primates is unknown. Using a barcoded connectomic approach, we assessed the single BLA neuron connections to frontal cortex in mice and macaques. We found that BLA neurons are more likely to project to multiple distinct parts of FC in mice than in macaques. Further, while single BLA neuron projections to nucleus accumbens were similarly organized in mice and macaques, BLA-FC connections differed substantially. Notably, BLA connections to subcallosal anterior cingulate cortex (scACC) in macaques were least likely to branch to other medial frontal cortex areas compared to perigenual ACC (pgACC). This pattern of connections was reversed in the mouse homologues of these areas, infralimbic and prelimbic cortex (IL and PL), mirroring functional differences between rodents and non-human primates. Taken together, these results indicate that BLA connections to FC are not linearly scaled from mice to macaques and instead the organization of single-neuron BLA connections is distinct between these species.

Periaqueductal gray activates antipredatory neural responses in the amygdala of foraging rats.

Pavlovian fear conditioning research suggests that the interaction between the dorsal periaqueductal gray (dPAG) and basolateral amygdala (BLA) acts as a prediction error mechanism in the formation of associative fear memories. However, their roles in responding to naturalistic predatory threats, characterized by less explicit cues and the absence of reiterative trial-and-error learning events, remain unexplored. In this study, we conducted single-unit recordings in rats during an 'approach food-avoid predator' task, focusing on the responsiveness of dPAG and BLA neurons to a rapidly approaching robot predator. Optogenetic stimulation of the dPAG triggered fleeing behaviors and increased BLA activity in naive rats. Notably, BLA neurons activated by dPAG stimulation displayed immediate responses to the robot, demonstrating heightened synchronous activity compared to BLA neurons that did not respond to dPAG stimulation. Additionally, the use of anterograde and retrograde tracer injections into the dPAG and BLA, respectively, coupled with c-Fos activation in response to predatory threats, indicates that the midline thalamus may play an intermediary role in innate antipredatory defensive functioning.

EphB2 activation in neural stem cells in the basolateral amygdala facilitates neurogenesis and enhances long-term memory

Many brain diseases lead to a reduction in the number of functional neurons and it would be of value to be able to increase the number of neurons in the affected brain areas. In this study, we examined whether we can promote neural stem cells to produce mature neurons and whether an increase in the mature neurons can affect cognitive performance. We detected that the EphB2 receptor is localized in immature basolateral amygdala (BLA) neurons. We therefore aimed to increase the level of EphB2 activity in neural stem cells (NSCs) in the BLA and examine the effects on the production of mature neurons and cognition. Toward that end, we utilized a photoactivatable EphB2 construct (optoEphB2) to increase EphB2 forward signaling in NSCs in the BLA. We revealed that the activation of optoEphB2 in NSCs in the BLA increased the level of immature and mature neurons in the BLA. We further found that activation of optoEphB2 in BLA NSCs enhanced auditory, but not contextual, long-term fear memory formation. Impairing EphB2 forward signaling did not affect the level of immature and mature neurons in the BLA. This study provides evidence that NSCs can be promoted to produce mature neurons by activating EphB2 to enhance specific brain functions.

Bidirectional modulation of negative emotional states by parallel genetically-distinct basolateral amygdala pathways to ventral striatum subregions.

Distinct basolateral amygdala (BLA) cell populations influence emotional responses in manners thought important for anxiety and anxiety disorders. The BLA contains numerous cell types which can broadcast information into structures that may elicit changes in emotional states and behaviors. BLA excitatory neurons can be divided into two main classes, one of which expresses Ppp1r1b (encoding protein phosphatase 1 regulatory inhibitor subunit 1B) which is downstream of the genes encoding the D1 and D2 dopamine receptors (drd1 and drd2 respectively). The role of drd1+ or drd2+ BLA neurons in learned and unlearned emotional responses is unknown. Here, we identified that the drd1+ and drd2+ BLA neuron populations form two parallel pathways for communication with the ventral striatum. These neurons arise from the basal nucleus of the BLA, innervate the entire space of the ventral striatum, and are capable of exciting ventral striatum neurons. Further, through three separate behavioral assays, we found that the drd1+ and drd2+ parallel pathways bidirectionally influence both learned and unlearned emotional states when they are activated or suppressed, and do so depending upon where they synapse in the ventral striatum - with unique contributions of drd1+ and drd2+ circuitry on negative emotional states. Overall, these results contribute to a model whereby parallel, genetically-distinct BLA to ventral striatum circuits inform emotional states in a projection-specific manner.

Dimethyl fumarate ameliorates chronic stress-induced anxiety-like behaviors by decreasing neuroinflammation and neuronal activity in the amygdala

BackgroundChronic stress-induced neuroinflammation plays a pivotal role in the development and exacerbation of mental disorders, such as anxiety and depression. Dimethyl Fumarate (DMF), an effective therapeutic agent approved for the treatment of multiple sclerosis, has been widely reported to display anti-inflammatory and anti-oxidative effects. However, the impact of DMF on chronic stress-induced anxiety disorders and the exact underlying mechanisms remain largely unknown. MethodsWe established a mouse model of chronic social defeat stress (CSDS). DMF was administered orally 1 h before daily stress session for 10 days in CSDS + DMF group. qRT-PCR and western blotting were used to analyze mRNA and protein expression of NLRP3, Caspase-1 and IL-1β. Immunofluorescence staining was carried out to detect the expression of Iba 1 and c-fos positive cells as well as morphological change of Iba 1+ microglia. Whole-cell patch-clamp recording was applied to evaluate synaptic transmission and intrinsic excitability of neurons. ResultsDMF treatment significantly alleviated CSDS-induced anxiety-like behaviors in mice. Mechanistically, DMF treatment prevented CSDS-induced neuroinflammation by inhibiting the activation of microglia and NLRP3/Caspase-1/IL-1β signaling pathway in basolateral amygdala (BLA), a brain region important for emotional processing. Furthermore, DMF treatment effectively reversed the CSDS-caused disruption of excitatory and inhibitory synaptic transmission balance, as well as the increased intrinsic excitability of BLA neurons. ConclusionsOur findings provide new evidence that DMF may exert anxiolytic effect by preventing CSDS-induced activation of NLRP3/Caspase-1/IL-1β signaling pathway and alleviating hyperactivity of BLA neurons.

Synergism between two BLA-to-BNST pathways for appropriate expression of anxiety-like behaviors in male mice

Understanding how distinct functional circuits are coordinated to fine-tune mood and behavior is of fundamental importance. Here, we observe that within the dense projections from basolateral amygdala (BLA) to bed nucleus of stria terminalis (BNST), there are two functionally opposing pathways orchestrated to enable contextually appropriate expression of anxiety-like behaviors in male mice. Specifically, the anterior BLA neurons predominantly innervate the anterodorsal BNST (adBNST), while their posterior counterparts send massive fibers to oval BNST (ovBNST) with moderate to adBNST. Optogenetic activation of the anterior and posterior BLA inputs oppositely regulated the activity of adBNST neurons and anxiety-like behaviors, via disengaging and engaging the inhibitory ovBNST-to-adBNST microcircuit, respectively. Importantly, the two pathways exhibited synchronized but opposite responses to both anxiolytic and anxiogenic stimuli, partially due to their mutual inhibition within BLA and the different inputs they receive. These findings reveal synergistic interactions between two BLA-to-BNST pathways for appropriate anxiety expression with ongoing environmental demands.