Intra-BLA alteration of interneurons’ modulation of activity in rats, reveals a dissociation between effects on anxiety symptoms and extinction learning
{"title":"Intra-BLA alteration of interneurons’ modulation of activity in rats, reveals a dissociation between effects on anxiety symptoms and extinction learning","authors":"","doi":"10.1016/j.ynstr.2024.100681","DOIUrl":null,"url":null,"abstract":"<div><div>The basolateral amygdala (BLA) is a dynamic brain region involved in emotional experiences and subject to long-term plasticity. The BLA also modulates activity, plasticity, and related behaviors associated with other brain regions, including the mPFC and hippocampus. Accordingly, intra-BLA plasticity can be expected to alter both BLA-dependent behaviors and behaviors mediated by other brain regions. Lasting intra-BLA plasticity may be considered a form of metaplasticity, since it will affect subsequent plasticity and response to challenges later on. Activity within the BLA is tightly modulated by GABAergic interneurons, and thus inducing lasting alteration of GABAergic modulation of principal neurons may have an impactful metaplastic effect on BLA functioning. Previously, we demonstrated that intra-BLA knockdown (KD) of neurofascin (NF) reduced GABAergic synapses exclusively at the axon initial segment (AIS). Here, by reducing the expression of the tyrosine kinase receptor ephrin A7 (EphA7), we selectively impaired the modulatory function of a different subpopulation of interneurons, specifically targeting the soma and proximal dendrites of principal neurons. This perturbation induced an expected reduction in the spontaneous inhibitory synaptic input and an increase in the excitatory spontaneous synaptic activity, most probably due to the reduction of inhibitory tone. Moreover, this increased synaptic activity was followed by a reduction in intrinsic excitability. While intra-BLA NF-KD resulted in impaired extinction learning, without increased symptoms of anxiety, intra-BLA reduction of EphA7 expression resulted in increased symptoms of anxiety, as measured in the elevated plus maze, but without affecting fear conditioning or extinction learning. These results confirm the role of the BLA and intra-BLA metaplasticity in stress-induced increased anxiety symptoms and in impaired fear extinction learning but reveals a difference in intra-BLA mechanisms involved. The results also confirm the contribution of GABAergic interneurons to these effects but indicate selective roles for different subpopulations of intra-BLA interneurons.</div></div>","PeriodicalId":19125,"journal":{"name":"Neurobiology of Stress","volume":null,"pages":null},"PeriodicalIF":4.3000,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Neurobiology of Stress","FirstCategoryId":"3","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2352289524000778","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"NEUROSCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
The basolateral amygdala (BLA) is a dynamic brain region involved in emotional experiences and subject to long-term plasticity. The BLA also modulates activity, plasticity, and related behaviors associated with other brain regions, including the mPFC and hippocampus. Accordingly, intra-BLA plasticity can be expected to alter both BLA-dependent behaviors and behaviors mediated by other brain regions. Lasting intra-BLA plasticity may be considered a form of metaplasticity, since it will affect subsequent plasticity and response to challenges later on. Activity within the BLA is tightly modulated by GABAergic interneurons, and thus inducing lasting alteration of GABAergic modulation of principal neurons may have an impactful metaplastic effect on BLA functioning. Previously, we demonstrated that intra-BLA knockdown (KD) of neurofascin (NF) reduced GABAergic synapses exclusively at the axon initial segment (AIS). Here, by reducing the expression of the tyrosine kinase receptor ephrin A7 (EphA7), we selectively impaired the modulatory function of a different subpopulation of interneurons, specifically targeting the soma and proximal dendrites of principal neurons. This perturbation induced an expected reduction in the spontaneous inhibitory synaptic input and an increase in the excitatory spontaneous synaptic activity, most probably due to the reduction of inhibitory tone. Moreover, this increased synaptic activity was followed by a reduction in intrinsic excitability. While intra-BLA NF-KD resulted in impaired extinction learning, without increased symptoms of anxiety, intra-BLA reduction of EphA7 expression resulted in increased symptoms of anxiety, as measured in the elevated plus maze, but without affecting fear conditioning or extinction learning. These results confirm the role of the BLA and intra-BLA metaplasticity in stress-induced increased anxiety symptoms and in impaired fear extinction learning but reveals a difference in intra-BLA mechanisms involved. The results also confirm the contribution of GABAergic interneurons to these effects but indicate selective roles for different subpopulations of intra-BLA interneurons.
期刊介绍:
Neurobiology of Stress is a multidisciplinary journal for the publication of original research and review articles on basic, translational and clinical research into stress and related disorders. It will focus on the impact of stress on the brain from cellular to behavioral functions and stress-related neuropsychiatric disorders (such as depression, trauma and anxiety). The translation of basic research findings into real-world applications will be a key aim of the journal.
Basic, translational and clinical research on the following topics as they relate to stress will be covered:
Molecular substrates and cell signaling,
Genetics and epigenetics,
Stress circuitry,
Structural and physiological plasticity,
Developmental Aspects,
Laboratory models of stress,
Neuroinflammation and pathology,
Memory and Cognition,
Motivational Processes,
Fear and Anxiety,
Stress-related neuropsychiatric disorders (including depression, PTSD, substance abuse),
Neuropsychopharmacology.