1,720,987 research outputs found
Investigations of the role of the basolateral amygdala-nucleus accumbens circuit and endocannabinoid regulation of social interaction behavior in the Shank3B-/- model of autism spectrum disorder
No full textDeficits in social interaction (SI) are a core symptom of Autism Spectrum Disorders (ASD), however treatments for social deficits are notably lacking. Elucidating brain circuits and neuromodulatory signaling systems that regulate sociability could facilitate a deeper understanding of ASD pathophysiology and reveal novel treatments for ASD. Here we found that in vivo optogenetic activation of the basolateral amygdala-nucleus accumbens (BLA-NAc) glutamatergic circuit reduced SI and increased social avoidance in mice. Furthermore, we found that 2-arachidonoylglycerol (2-AG) endocannabinoid (eCB) signaling reduced BLA-NAc glutamatergic activity, and that pharmacological 2-AG augmentation via administration of JZL184 blocked SI deficits associated with in vivo BLA-NAc stimulation. Additionally, optogenetic inhibition of the BLA-NAc circuit significantly increased SI in the Shank3B-/-, an ASD model with substantial SI impairment, without affecting SI in wild-type mice. Finally, we demonstrated that JZL184 delivered systemically or directly to the NAc also normalized SI deficits in Shank3B-/- mice, while ex vivo JZL184 application corrected aberrant NAc excitatory and inhibitory neurotransmission and reduced BLA-NAc-elicited feedforward inhibition of NAc neurons in Shank3B-/- mice. These data reveal circuit-level and neuromodulatory mechanisms regulating social function relevant to ASD and suggest 2-AG augmentation could reduce social deficits via modulation of excitatory and inhibitory neurotransmission in the NAc
Elucidating circadian light entrainment and plasticity in the SCN at the molecular and network levels
No full textThe suprachiasmatic nucleus (SCN) of the hypothalamus serves as a central circadian oscillator that receives direct retinal light input and synchronizes (or entrains) endogenous daily rhythms in behavior and physiology to environmental light cycles. At the molecular level, nearly all mammalian cells have a circadian clock based on autoregulatory transcription-translation feedback loops of clock genes and their circadian rhythms are coordinated by the SCN. The work presented in this dissertation focuses on how the central SCN clock achieves light entrainment and expresses clock plasticity at the molecular and network levels. SCN clock gene rhythms under light entrainment change their waveforms from sinusoids to asymmetric shapes with accelerated synthetic phases following dawn and prolonged degradative phases following dusk. The SCN shows canonical forms of circadian clock plasticity at the fundamental level of core clock gene rhythms. The SCN has a particular spatial organization of phase resetting and after-effects on circadian period at the network levels: phase resetting is more pronounced in the ventrolateral region, while after-effects are greater in the dorsomedial region. Also, the molecular mechanisms of after-effects were examined, and it was uncovered that DNA methylation is involved in after-effects of photoperiods and that at the level of single clock-resetting cues the SCN clock involves DNA methylation to produce after-effects. Taken together, this work advances the understanding of SCN entrainment and plasticity to environmental lighting conditions
An ensemble recruited by α2a-adrenergic receptors is engaged in a stressor-specific manner in mice
No full textα2a-adrenergic receptor (α2a-AR) agonists are candidate substance use disorder therapeutics due to their ability to recruit noradrenergic autoreceptors to dampen stress system engagement. However, we recently found that postsynaptic α2a-ARs are required for stress-induced reinstatement of cocaine-conditioned behavior. Understanding the ensembles recruited by these postsynaptic receptors (heteroceptors) is necessary to understand noradrenergic circuit control. We utilized a variety of approaches in FosTRAP (Targeted Recombination in Active Populations) mice to define an ensemble of cells activated by the α2a-AR partial agonist guanfacine (“Guansembles”) in the bed nucleus of the stria terminalis (BST/BNST), a region key to stress-induced reinstatement of drug seeking. We define BNST “Guansembles” and show they differ from restraint stress-activated cells. Guanfacine produced inhibition of cAMP-dependent signaling in Guansembles, while chronic restraint stress increased cAMP-dependent signaling. Guanfacine both excited and inhibited aspects of Guansemble neuronal activity. Further, while some stressors produced overall reductions in Guansemble activity, active coping events during restraint stress and exposure to unexpected shocks were both associated with Guansemble recruitment. Using viral tracing, we define a BNST Guansemble afferent network that includes regions involved in the interplay of stress and homeostatic functions. Finally, we show that activation of Guansembles produces alterations in behavior on the elevated plus maze consistent with task-specific anxiety-like behavior. Overall, we define a population of BNST neurons recruited by α2a-AR signaling that opposes the behavioral action of canonical autoreceptor α2a-AR populations and which are differentially recruited by distinct stressors. Moreover, we demonstrate stressor-specific physiological responses in a specific neuronal population
Mechanisms Underlying Control of Wake-Promoting Dopamine Neurons by Norepinephrine and Alcohol
No full textAlcohol use disorder (AUD) and sleep disorders are commonly comorbid, where individuals with AUD frequently report insomnia, poor sleep quality and daytime sleepiness. The locus coeruleus (LC) promotes wakefulness via alpha-1 adrenergic receptor (α1AR) driven recruitment of dopamine (DA) neurons in the ventral periaqueductal gray (vPAGDA neurons). Understanding the effect of ethanol on the neuron-astrocyte interactions and norepinephrine (NE) release in the vPAG may better inform treatments for AUD sleep/wake dysfunction. Utilizing optical, electrical, and genetic approaches, we have identified a crucial role of vPAG astrocytic α1AR receptors in sustaining arousal through heightened excitability and activity of vPAGDA neurons mediated by local adenosine 2A (A2A) receptors. Furthermore, we found that chronic intermittent ethanol (CIE) exposure in mice increases sleep fragmentation, suggesting an increase in wakefulness. Additionally, acute and chronic ethanol in vivo increase baseline NE levels in the vPAG that persist through withdrawal and abstinence as measured with a fluorescence NE sensor (GRABNE2h) and fiber photometry. Acute ethanol ex vivo drives increases in vPAGDA neuron and vPAG astrocyte calcium activity via an α1AR and A2A independent mechanism. Thus, ethanol may be engaging the LC-vPAG arousal circuit via both a norepinephrine-dependent and an unidentified local direct mechanism to modulate wakefulness. In this dissertation I also present LIQ HD (Lick Instance Quantifier Home cage Device): an affordable, intuitive, and easy-to-build device that utilizes capacitive sensor technology to track two-bottle choice drinking behavior in up to 18 rodent home cages, or 36 single bottles, on a minute-to-minute timescale running off a single Arduino microcontroller
The Role of PKCd Cells and Expression in the Bed Nucleus of the Stria Terminalis in Stress Responses, Threat Detection, and Anxiety-Like Behaviors
No full textThe bed nucleus of the stria terminalis (BNST) is a critical mediator of stress responses and anxiety-like behaviors. Neurons expressing protein kinase C delta (BNST(PKCδ)) are an abundant but understudied subpopulation implicated in inhibiting feeding, but which have conflicting reports about their role in anxiety-like behaviors. We have previously shown that expression of PKCδ is dynamically regulated by stress. Here we first show that BNST(PKCδ) cells are recruited during bouts of active stress coping and receive input from the parabrachial nucleus. We then show that in vivo activation of this population is mildly aversive. This aversion was insensitive to prior restraint stress exposure. Further investigation revealed that unlike other BNST subpopulations, BNST(PKCδ) cells do not exhibit increased cfos expression following restraint stress. Ex vivo current clamp recordings also indicate they are resistant to firing. To elucidate their afferent control, we next used rabies tracing with whole brain imaging and channelrhodopsin-assisted circuit mapping, finding that BNST(PKCδ) cells receive abundant input from affective, arousal, and sensory regions including the basolateral amygdala (BLA), paraventricular thalamus (PVT), and central amygdala PKCδ-expressing cells (CeA(PKCδ)). Given these findings, we used in vivo optogenetics and fiber photometry to further examine BNST(PKCδ) cells in the context of stress and anxiety-like behavior. We found that BNST(PKCδ) cell activity is associated with increased anxiety-like behavior in the elevated plus maze, increases following footshock, and unlike other BNST subpopulations, doesn’t desensitize to repeated stress exposure. Taken together, we propose a model in which BNST(PKCδ) cells may serve as threat detectors, integrating exteroceptive and interoceptive information to inform stress coping behaviors
The role of neuronal ensembles in the nucleus accumbens in cocaine use disorder
No full textWhile significant effort has been made to understand the neural basis of addiction, it remains unclear how drugs of abuse alter the neural systems involved in motivated behavior to control drug taking and seeking. The goal of this dissertation was to understand how cocaine and associated stimuli are encoded in the brain and act to drive drug seeking. In a given brain region, only a small percentage of cells are activated to any stimulus - termed an “ensemble”. Here we aimed to determine if ensembles activated by cocaine in the nucleus accumbens (NAc) – a brain region central to reward encoding - could drive motivated behaviors. Using transgenic animals that allowed for the temporally specific tagging of ensembles in a transcriptional activity-dependent manner, we were able to record from, identify, and manipulate the neural ensembles that are selectively activated by cocaine experience. Repeated cocaine experience inhibited NAc neuronal activity, causing decreased ensemble size; simultaneously, this smaller population of neurons were more excitable and had fundamentally different physiological properties. Mice were motivated to optically reactivate all ensembles, including saline, acute cocaine, and repeated cocaine. However, lesioning of repeated cocaine ensemble attenuated cocaine-associated behaviors, such as locomotor sensitization and cocaine self-administration. Further, we show that there is a critical effect of sex on cue learning, that may be critical in governing how animals respond to drugs of abuse. Overall, we hypothesize that a history of cocaine alters the physiological properties of the ensemble neurons, refining them and causing them to play a key role in cocaine-related behaviors and reinforcement learning
Deciphering the Role of mGlu8 in Thalamocortical Circuitry: Insights from Conditional Knockout Strategies
No full textThis study investigates the function of the metabotropic glutamate receptor 8 (mGlu8) in the brain and its impact on behavior using mouse models with targeted genetic modifications. mGlu8 is a receptor involved in regulating brain activity and is a potential target for treating mental health disorders. We focused on its expression in the thalamic reticular nucleus (TRN), a brain region implicated in various psychiatric conditions. Through targeted genetic manipulations, we examined the effects of altering mGlu8 activity in specific cell types within the TRN. Our findings reveal that manipulating mGlu8 activity influences both excitatory neurotransmission and behaviors related to anxiety and movement control. These results shed light on the therapeutic potential of targeting mGlu8 and provide insights into its role in brain function
Role of Alpha2a-Adrenergic Heteroreceptors in Stress-Induced Reinstatement of Cocaine Associated Behaviors: Implications for the Pharmacological Treatment of Stress-Driven Relapse of Drug Use
No full textThe A2a-adrenergic receptor (A2a-AR) agonist guanfacine has been investigated as a potential treatment for substance use disorders. While decreasing stress-induced reinstatement of cocaine seeking in animal models and stress-induced craving in human studies, guanfacine has not been reported to decrease relapse rates. Although guanfacine engages A2a-AR autoreceptors, it also activates excitatory Gi-coupled heteroreceptors in the bed nucleus of the stria terminalis (BNST), a key brain region in driving stress-induced relapse. Thus, BNST A2a-AR heteroreceptor signaling might decrease the beneficial efficacy of guanfacine. The role of A2a-AR heteroreceptors and BNST Gi-GPCR signaling in stress-induced reinstatement of cocaine conditioned place preference (CPP) and the effects of low dose guanfacine on BNST activity and stress-induced reinstatement were examined. A genetic deletion strategy and the cocaine CPP procedure were used to first define the contributions of A2a-AR heteroreceptors to stress-induced reinstatement. Next, BNST Gi-coupled A2a-AR heteroreceptor signaling was mimicked using a Gi-coupled designer receptor exclusively activated by designer drug (Gi-DREADD) approach. Finally, the effects of low-dose guanfacine on BNST cFOS immunoreactivity and stress-induced reinstatement we investigated. We show that A2a-AR heteroreceptor deletion disrupts stress-induced reinstatement and that BNST Gi-DREADD activation is sufficient to induce reinstatement. Importantly, low-dose guanfacine does not increase BNST activity, but prevents stress-induced reinstatement. These findings demonstrate a role for A2a-AR heteroreceptors and BNST Gi-GPCR signaling in stress-induced reinstatement of cocaine CPP and provide insight into the impact of dose on the efficacy of guanfacine as a treatment for stress-induced relapse of cocaine use
Connectivity between the BNST and insula during abstinence from alcohol use disorder
No full textAlcohol use disorder (AUD) affects over 15 million Americans and remains exceptionally difficult to treat, with the majority of individuals relapsing within a year of initiating treatment. Much of this difficulty is thought to arise from the symptoms of anxiety and depression experienced by individuals with AUD during abstinence, as these symptoms are common triggers of relapse. Rodent work has identified a key pathway that regulates these abstinence-induced symptoms between the insula and the bed nucleus of the stria terminalis (BNST). Little is known, however, about the BNST-insula pathway in humans. The goal of this project is to 1) characterize a normative pattern of BNST-insula connectivity in humans; 2) identify differences in BNST-insula connectivity in abstinence; and 3) investigate the relationship between BNST-insula connectivity and anxiety and depressive symptoms during abstinence. Given known differences in connectivity and function between the anterior and posterior insula, this project evaluated both structural and resting state BNST connectivity with the anterior and posterior insula separately. To determine normative connectivity, BNST connectivity with anterior insula was compared to connectivity with the posterior insula in individuals without a psychiatric diagnosis. The anterior insula was shown to have greater structural and resting state BNST connectivity than the posterior insula. To investigate differences in BNST-insula connectivity during abstinence, 20 abstinent individuals with AUD and 20 controls completed structural and resting state scans and questionnaires capturing anxiety and depression symptoms. The results suggest a moderate effect of abstinence, where abstinent individuals did not show normative BNST-anterior insula resting state connectivity but had greater posterior insula structural connectivity with the BNST. In the abstinence group, depression symptoms were positively associated with BNST structural connectivity with both the anterior and posterior insula but not resting state connectivity. Anxiety symptoms in the abstinence group were not associated BNST structural or resting state connectivity with the anterior or posterior insula. These results provide evidence for normative BNST-insula connectivity in humans, which differs in abstinence, offering critical translational insights into the neural basis of abstinence and potential opportunities for treatment
Investigating the role of GluN2D-containing NMDARs in BNST excitatory signaling: Implications for regulating cell-specific synaptic function and the modulation of affective behaviors
No full textExcitatory signaling mediated by N-methyl-d-aspartate receptors (NMDARs) has been shown to regulate mood disorders. However, current treatments targeting NMDAR subtypes have shown limited success in treating patients, highlighting a need for alternative therapeutic targets. Here, we identify a role for GluN2D-containing NMDARs in modulating emotional behaviors and neural activity in the bed nucleus of the stria terminalis (BNST). Using a GluN2D knockout mouse line (GluN2D-/-), we assessed behavioral phenotypes across tasks modeling emotional behavior. We then used a combination of ex vivo electrophysiology and in vivo fiber photometry to assess changes in BNST plasticity, cell-specific physiology and cellular activity profiles. GluN2D-/- male mice exhibit evidence of exacerbated negative emotional behavior, and a deficit in BNST synaptic potentiation. We also found that GluN2D is functionally expressed on corticotropin-releasing factor (CRF) positive BNST cells implicated in driving negative emotional states, and recordings in mice of both sexes revealed increased excitatory and reduced inhibitory drive onto GluN2D-/- BNST-CRF cells ex vivo, and increased activity in vivo. Using a GluN2D conditional knockout line (GluN2Dflx/flx) to selectively delete the subunit from the BNST, we find that BNST-GluN2Dflx/flx male mice exhibit increased depressive-like behaviors, as well as altered NMDAR function and increased excitatory drive onto BNST-CRF neurons. Taken together, this study supports a role for GluN2D-NMDARs in regulating emotional behavior through their influence on excitatory signaling in a region-specific manner, and suggests that these NMDARs may serve as a novel target for selectively modulating glutamate signaling in stress-responsive structures and cell populations
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