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Premachandran H, Wilkin J, Arruda-Carvalho M. Minimizing Variability in Developmental Fear Studies in Mice: Toward Improved Replicability in the Field. Curr Protoc 2024; 4:e1040. [PMID: 38713136 DOI: 10.1002/cpz1.1040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
In rodents, the first weeks of postnatal life feature remarkable changes in fear memory acquisition, retention, extinction, and discrimination. Early development is also marked by profound changes in brain circuits underlying fear memory processing, with heightened sensitivity to environmental influences and stress, providing a powerful model to study the intersection between brain structure, function, and the impacts of stress. Nevertheless, difficulties related to breeding and housing young rodents, preweaning manipulations, and potential increased variability within that population pose considerable challenges to developmental fear research. Here we discuss several factors that may promote variability in studies examining fear conditioning in young rodents and provide recommendations to increase replicability. We focus primarily on experimental conditions, design, and analysis of rodent fear data, with an emphasis on mouse studies. The convergence of anatomical, synaptic, physiological, and behavioral changes during early life may increase variability, but careful practice and transparency in reporting may improve rigor and consensus in the field. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC.
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Affiliation(s)
- Hanista Premachandran
- Department of Psychology, University of Toronto Scarborough, Toronto, Ontario, Canada
- These authors contributed equally to this work
| | - Jennifer Wilkin
- Department of Psychology, University of Toronto Scarborough, Toronto, Ontario, Canada
- These authors contributed equally to this work
| | - Maithe Arruda-Carvalho
- Department of Psychology, University of Toronto Scarborough, Toronto, Ontario, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
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Ketlyn Lazzarim M, Luiza Paiva Krepel G, Zolet D, Fantin Sardi N, José Polato Gomes H, Jacson Martynhak B. Social buffering reduces fear expression in Wistar rats when tested in pairs, but not when retested alone. Neurobiol Learn Mem 2023:107798. [PMID: 37422207 DOI: 10.1016/j.nlm.2023.107798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 06/30/2023] [Accepted: 07/06/2023] [Indexed: 07/10/2023]
Abstract
Social buffering is a phenomenon in which the stress response of an individual can be reduced by the presence of another individual. However, little is known about the effect of social buffering on aversive after memory extinction, especially when animals are tested alone afterwards. The aim of this study was to verify the social buffering effect in rats during the extinction session of the contextual fear conditioning model and the fear response when animals are tested alone in the following day. Animals were divided into subjects and associates, with the subjects undergoing the fear conditioning protocol and the associates paired with the subjects during the fear extinction session. Across five different experiments, we tested moderate and high intensity contextual fear conditioning protocols, as well four variations of pairs: (i) two conditioned subjects, (ii) a conditioned subject and a non-conditioned associate, (iii) a conditioned subject and an associate who observed the conditioning of the partner and (iv) two conditioned subjects, with one treated with diazepam. The social buffering effect was found efficient to reduce the fear memory expression during the fear extinction session. In the moderate intensity protocol, the reduction in freezing time occurred only in subjects accompanied by non-conditioned associates and observer associates. In the high intensity protocol, the social buffering effect occurred in subjects accompanied by either conditioned or non-conditioned associates, although the effect was more evident in the presence of non-conditioned subjects. Treatment of the conditioned associates with diazepam did not improve the social buffering effect. Moreover, social buffering effects were not correlated with self-grooming or prosocial behaviors, which indicates that the presence of another animal might decrease freezing by promotion of exploratory activity. Finally, the social buffering effect was not observed in the extinction test, either because the extinction was too effective in the moderate intensity protocol or because the extinction was equally ineffective in the high intensity protocol. Our results suggest that social buffering does not improve fear extinction consolidation.
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Affiliation(s)
| | | | - Daniela Zolet
- Pontifícia Universidade Católica do Paraná, Curitiba, Parana, Brazil
| | - Natalia Fantin Sardi
- Department of Physiology, Federal University of Parana, Curitiba, Parana, Brazil
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Shin S, Lee S. The impact of environmental factors during maternal separation on the behaviors of adolescent C57BL/6 mice. Front Mol Neurosci 2023; 16:1147951. [PMID: 37293540 PMCID: PMC10244624 DOI: 10.3389/fnmol.2023.1147951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 05/03/2023] [Indexed: 06/10/2023] Open
Abstract
Neonatal maternal separation is a widely used method to construct an early-life stress model in rodents. In this method, pups are separated from their mothers for several hours every day during the first 2 weeks of life, which results in adverse early-life events. It is a known fact that maternal separation can exert a significant impact on the behavior and psychological health, such as anxiety and depression, in adolescent offspring. However, environmental conditions during maternal separation can differ such as the presence of other animals or by placing pups in a different dam. To investigate the differential effects of various conditions of maternal separation on the behavior of adolescent mice, we created the following groups: (1) iMS group: pups were moved to an isolated room with no other adult mice in a nearby cage, (2) eDam group: the pups randomly exchanged their dams, (3) OF group: pups were shifted to another cage with the bedding material containing maternal odor (olfactory stimulation), and (4) MS group: pups were shifted to another vivarium. From postnatal day (PND) 2-20 (i.e., 19 consecutive days), pups were separated from the dam daily for 4 h and exposed to various environments (MS, iMS, eDam, and OF) or were left undisturbed [control (CON) group]. A series of behavioral assessments were conducted to evaluate locomotion, anxiety, recognition, learning, and memory in adolescent offspring. The results showed that neonatal maternal separation led to impaired recognition memory, motor coordination, and motor skill learning across all groups. However, the iMS group exhibited anxiety-like behavior in the elevated plus maze test and enhanced the extinction of fear memory in the auditory fear conditioning test. The OF and eDam groups displayed partially recovered short-term working memory in the Y-maze test but exhibited opposite exploratory behaviors. The OF group spent more time in the center, while the eDam group spent less time. These findings demonstrated that exposure to different environmental conditions during maternal separation causes behavioral alterations in adolescent offspring, providing a potential explanation for the variation in behavioral phenotypes observed in the early-life stress models.
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On making (and turning adaptive to) maladaptive aversive memories in laboratory rodents. Neurosci Biobehav Rev 2023; 147:105101. [PMID: 36804263 DOI: 10.1016/j.neubiorev.2023.105101] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 02/03/2023] [Accepted: 02/14/2023] [Indexed: 02/18/2023]
Abstract
Fear conditioning and avoidance tasks usually elicit adaptive aversive memories. Traumatic memories are more intense, generalized, inflexible, and resistant to attenuation via extinction- and reconsolidation-based strategies. Inducing and assessing these dysfunctional, maladaptive features in the laboratory are crucial to interrogating posttraumatic stress disorder's neurobiology and exploring innovative treatments. Here we analyze over 350 studies addressing this question in adult rats and mice. There is a growing interest in modeling several qualitative and quantitative memory changes by exposing already stressed animals to freezing- and avoidance-related tests or using a relatively high aversive training magnitude. Other options combine aversive/fearful tasks with post-acquisition or post-retrieval administration of one or more drugs provoking neurochemical or epigenetic alterations reported in the trauma aftermath. It is potentially instructive to integrate these procedures and incorporate the measurement of autonomic and endocrine parameters. Factors to consider when defining the organismic and procedural variables, partially neglected aspects (sex-dependent differences and recent vs. remote data comparison) and suggestions for future research (identifying reliable individual risk and treatment-response predictors) are discussed.
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Price ME, McCool BA. Structural, functional, and behavioral significance of sex and gonadal hormones in the basolateral amygdala: A review of preclinical literature. Alcohol 2022; 98:25-41. [PMID: 34371120 DOI: 10.1016/j.alcohol.2021.08.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 07/12/2021] [Accepted: 08/03/2021] [Indexed: 12/16/2022]
Abstract
The basolateral amygdala (BLA) is intimately involved in the development of neuropsychiatric disorders such as anxiety and alcohol use disorder (AUD). These disorders have clear sex biases, with women more likely to develop an anxiety disorder and men more likely to develop AUD. Preclinical models have largely confirmed these sex-specific vulnerabilities and emphasize the effects of sex hormones on behaviors influenced by the BLA. This review will discuss sex differences in BLA-related behaviors and highlight potential mechanisms mediated by altered BLA structure and function, including the composition of GABAergic interneuron subpopulations, glutamatergic pyramidal neuron morphology, glutamate/GABA neurotransmission, and neuromodulators. Further, sex hormones differentially organize dimorphic circuits during sensitive developmental periods (organizational effects) and initiate more transient effects throughout adulthood (activational effects). Current literature indicates that estradiol and allopregnanolone, a neuroactive progestogen, generally reduce BLA-related behaviors through a variety of mechanisms, including activation of estrogen receptors or facilitation of GABAA-mediated inhibition, respectively. This enhanced GABAergic inhibition may protect BLA pyramidal neurons from the excitability associated with anxiety and alcohol withdrawal. Understanding sex differences and the effects of sex hormones on BLA structure and function may help explain sex-specific vulnerabilities in BLA-related behaviors and ultimately improve treatments for anxiety and AUD.
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Meyer HC, Sangha S, Radley JJ, LaLumiere RT, Baratta MV. Environmental certainty influences the neural systems regulating responses to threat and stress. Neurosci Biobehav Rev 2021; 131:1037-1055. [PMID: 34673111 PMCID: PMC8642312 DOI: 10.1016/j.neubiorev.2021.10.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 09/29/2021] [Accepted: 10/01/2021] [Indexed: 10/20/2022]
Abstract
Flexible calibration of threat responding in accordance with the environment is an adaptive process that allows an animal to avoid harm while also maintaining engagement of other goal-directed actions. This calibration process, referred to as threat response regulation, requires an animal to calculate the probability that a given encounter will result in a threat so they can respond accordingly. Here we review the neural correlates of two highly studied forms of threat response suppression: extinction and safety conditioning. We focus on how relative levels of certainty or uncertainty in the surrounding environment alter the acquisition and application of these processes. We also discuss evidence indicating altered threat response regulation following stress exposure, including enhanced fear conditioning, and disrupted extinction and safety conditioning. To conclude, we discuss research using an animal model of coping that examines the impact of stressor controllability on threat responding, highlighting the potential for previous experiences with control, or other forms of coping, to protect against the effects of future adversity.
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Affiliation(s)
- Heidi C Meyer
- Department of Psychological and Brain Sciences, Boston University, Boston, MA, 02215, USA.
| | - Susan Sangha
- Department of Psychological Sciences, Purdue University, West Lafayette, IN, 47907, USA.
| | - Jason J Radley
- Department of Psychological and Brain Sciences, University of Iowa, Iowa City, IA, 52242, USA.
| | - Ryan T LaLumiere
- Department of Psychological and Brain Sciences, University of Iowa, Iowa City, IA, 52242, USA.
| | - Michael V Baratta
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, 80301, USA.
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Bisby MA, Stylianakis AA, Baker KD, Richardson R. Fear extinction learning and retention during adolescence in rats and mice: A systematic review. Neurosci Biobehav Rev 2021; 131:1264-1274. [PMID: 34740753 DOI: 10.1016/j.neubiorev.2021.10.044] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 10/20/2021] [Accepted: 10/29/2021] [Indexed: 10/19/2022]
Abstract
Despite exposure-based treatments being recommended for anxiety disorders, these treatments are ineffective for over half of all adolescents who receive them. The limited efficacy of exposure during adolescence may be driven by a deficit in extinction. Although indications of diminished extinction learning during adolescence were first reported over 10 years ago, these findings have yet to be reviewed and compared. This review (k = 34) found a stark inter-species difference in extinction performance: studies of adolescent mice reported deficits in extinction learning and retention of both cued and context fear. In contrast, studies of adolescent rats only reported poor extinction retention specific to cued fear. Adolescent mice and rats appeared to have only one behavioral outcome in common, being poor extinction retention of cued fear. These findings suggest that different behavioral phenotypes are present across rodent species in adolescence and highlight that preclinical work in rats and mice is not interchangeable. Further investigation of these differences offers the opportunity to better understand the etiology, maintenance, and treatment of fear-based disorders.
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Affiliation(s)
- Madelyne A Bisby
- School of Psychology, UNSW Sydney, Sydney, 2052, NSW, Australia; eCentreClinic, School of Psychological Sciences, Faculty of Medicine and Health, Macquarie University, Sydney, 2109, NSW, Australia.
| | | | - Kathryn D Baker
- School of Psychology, UNSW Sydney, Sydney, 2052, NSW, Australia
| | - Rick Richardson
- School of Psychology, UNSW Sydney, Sydney, 2052, NSW, Australia
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Paradoxical changes in mood-related behaviors on continuous social isolation after weaning. Exp Brain Res 2021; 239:2537-2550. [PMID: 34143240 PMCID: PMC8354913 DOI: 10.1007/s00221-021-06149-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 06/04/2021] [Indexed: 12/18/2022]
Abstract
Continuous social isolation (SI) from an early developmental stage may have different effects in youth and adulthood. Moreover, SI is reported to impair neuronal plasticity. In this study, we used post-weaning rats to compare the impact of continuous SI on depressive-like, anxiety-related, and fear-related behaviors and neuronal plasticity in puberty and adulthood. Furthermore, we assessed the effect of lithium on behavioral changes and neuronal plasticity. Continuous SI after weaning induced depressive-like behaviors in puberty; however, in adulthood, depressive-like and anxiety-related behaviors did not increase, but—paradoxically—decreased in comparison with the controls. The decreased expression of neuronal plasticity-related proteins in the hippocampus in puberty was more prominent in the prefrontal cortex and hippocampus in adulthood. In contrast, SI after weaning tended to decrease fear-related behaviors in puberty, a decrease which was more prominent in adulthood with increased neuronal plasticity-related protein expression in the amygdala. Lithium administration over the last 14 days of the SI-induced period removed the behavioral and expression changes of neuronal plasticity-related proteins observed in puberty and adulthood. Our findings suggest that the extension of the duration of SI from an early developmental stage does not simply worsen depressive-like behaviors; rather, it induces a behavior linked to neuronal plasticity damage. Lithium may improve behavioral changes in puberty and adulthood by reversing damage to neuronal plasticity. The mechanisms underlying the depressive-like and anxiety-related behaviors may differ from those underlying fear-related behaviors.
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Maturation of amygdala inputs regulate shifts in social and fear behaviors: A substrate for developmental effects of stress. Neurosci Biobehav Rev 2021; 125:11-25. [PMID: 33581221 DOI: 10.1016/j.neubiorev.2021.01.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 01/26/2021] [Accepted: 01/26/2021] [Indexed: 11/21/2022]
Abstract
Stress can negatively impact brain function and behaviors across the lifespan. However, stressors during adolescence have particularly harmful effects on brain maturation, and on fear and social behaviors that extend beyond adolescence. Throughout development, social behaviors are refined and the ability to suppress fear increases, both of which are dependent on amygdala activity. We review rodent literature focusing on developmental changes in social and fear behaviors, cortico-amygdala circuits underlying these changes, and how this circuitry is altered by stress. We first describe changes in fear and social behaviors from adolescence to adulthood and parallel developmental changes in cortico-amygdala circuitry. We propose a framework in which maturation of cortical inputs to the amygdala promote changes in social drive and fear regulation, and the particularly damaging effects of stress during adolescence may occur through lasting changes in this circuit. This framework may explain why anxiety and social pathologies commonly co-occur, adolescents are especially vulnerable to stressors impacting social and fear behaviors, and predisposed towards psychiatric disorders related to abnormal cortico-amygdala circuits.
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Prefrontal α7nAChR Signaling Differentially Modulates Afferent Drive and Trace Fear Conditioning Behavior in Adolescent and Adult Rats. J Neurosci 2021; 41:1908-1916. [PMID: 33478990 DOI: 10.1523/jneurosci.1941-20.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 11/29/2020] [Accepted: 12/23/2020] [Indexed: 01/22/2023] Open
Abstract
Increased level of kynurenic acid is thought to contribute to the development of cognitive deficits in schizophrenia through an α7nAChR-mediated mechanism in the prefrontal cortex (PFC). However, it remains unclear to what extent disruption of PFC α7nAChR signaling impacts afferent transmission and its modulation of behavior. Using male rats, we found that PFC infusion of methyllycaconitine (MLA; α7nAChR antagonist) shifts ventral hippocampal-induced local field potential (LFP) suppression to LFP facilitation, an effect only observed in adults. Hippocampal stimulation can also elicit a GluN2B-mediated LFP potentiation (when PFC GABAAR is blocked) that is insensitive to MLA. Conversely, PFC infusion of MLA diminished the gain of amygdalar transmission, which is already enabled by postnatal day (P)30. Behaviorally, the impact of prefrontal MLA on trace fear-conditioning and extinction was also age related. While freezing behavior during conditioning was reduced by MLA only in adults, it elicited opposite effects in adolescent and adult rats during extinction as revealed by the level of reduced and increased freezing response, respectively. We next asked whether the late-adolescent onset of α7nAChR modulation of hippocampal inputs contributes to the age-dependent effect of MLA during extinction. Data revealed that the increased freezing behavior elicited by MLA in adult rats could be driven by a dysregulation of the GluN2B transmission in the PFC. Collectively, these results indicate that distinct neural circuits are recruited during the extinction of trace fear memory in adolescents and adults, likely because of the late-adolescent maturation of the ventral hippocampal-PFC functional connectivity and its modulation by α7nAChR signaling.SIGNIFICANCE STATEMENT Abnormal elevation of the astrocyte-derived metabolite kynurenic acid in the prefrontal cortex (PFC) is thought to impair cognitive functions in schizophrenia through an α7nAChR-mediated mechanism. Here, we found that prefrontal α7nAChR signaling is recruited to control the gain of hippocampal and amygdalar afferent transmission in an input-specific, age-related manner during the adolescent transition to adulthood. Behaviorally, prefrontal α7nAChR modulation of trace fear memory was also age-related, likely because of the late-adolescent maturation of the ventral hippocampal pathway and its recruitment of PFC GABAergic transmission enabled by local α7nAChR signaling. Collectively, these results reveal that distinct α7nAChR-sensitive neural circuits contribute to regulate behavior responses in adolescents and adults, particularly those requiring proper integration of hippocampal and amygdalar inputs by the PFC.
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Drzewiecki CM, Juraska JM. The structural reorganization of the prefrontal cortex during adolescence as a framework for vulnerability to the environment. Pharmacol Biochem Behav 2020; 199:173044. [DOI: 10.1016/j.pbb.2020.173044] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 09/04/2020] [Accepted: 09/30/2020] [Indexed: 11/26/2022]
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Xu Z, Lu W, Miao Y, Li H, Xie X, Zhang F. mRNA profiling reveals the potential mechanism of TIPE2 in attenuating cognitive deficits in APP/PS1 mice. Int Immunopharmacol 2020; 87:106792. [DOI: 10.1016/j.intimp.2020.106792] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 06/17/2020] [Accepted: 07/06/2020] [Indexed: 01/08/2023]
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Downregulation of parvalbumin expression in the prefrontal cortex during adolescence causes enduring prefrontal disinhibition in adulthood. Neuropsychopharmacology 2020; 45:1527-1535. [PMID: 32403119 PMCID: PMC7360578 DOI: 10.1038/s41386-020-0709-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 05/04/2020] [Accepted: 05/08/2020] [Indexed: 01/10/2023]
Abstract
The expression of the calcium binding protein parvalbumin (PV) has been observed in several cortical regions during development in a temporal pattern consistent with increased afferent-dependent activity. In the prefrontal cortex (PFC), PV expression appears last and continues to substantially increase throughout adolescence, yet the significance of this increase remains unclear. Because of the expression of PV in fast-spiking GABAergic interneurons, we hypothesized that PV upregulation during adolescence is necessary to sustain the increase in GABAergic activity observed in the PFC during this period. To test this hypothesis, we utilized an RNAi strategy to directly downregulate PV levels in the PFC during adolescence and examined its impact on prefrontal GABAergic function, plasticity, and associated behaviors during adulthood. The data indicate that a mere 25% reduction of adult PV levels in the PFC was sufficient to reduce local GABAergic transmission onto pyramidal neurons, disrupt prefrontal excitatory-inhibitory balance, and alter processing of afferent information from the ventral hippocampus. Accordingly, these animals displayed an impairment in the level of extinction learning of a trace fear conditioning response, a behavioral paradigm that requires intact PFC-ventral hippocampus connectivity. These results indicate the PV upregulation observed in the PFC during adolescence is necessary for refinement of prefrontal GABAergic function, the absence of which results in immature afferent processing and a hypofunctional state. Importantly, these results suggest there is a critical window of plasticity during which PV upregulation supports the acquisition of mature GABAergic phenotype necessary to sustain adult PFC functions.
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MK-801 Exposure during Adolescence Elicits Enduring Disruption of Prefrontal E-I Balance and Its Control of Fear Extinction Behavior. J Neurosci 2020; 40:4881-4887. [PMID: 32430298 DOI: 10.1523/jneurosci.0581-20.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 05/05/2020] [Accepted: 05/11/2020] [Indexed: 01/04/2023] Open
Abstract
Understanding how disruption of prefrontal cortex (PFC) maturation during adolescence is crucial to reveal which neural processes could contribute to the onset of psychiatric disorders that display frontal cortical deficits. Of particular interest is the gain of GABAergic function in the PFC during adolescence and its susceptibility to the impact of transient blockade of NMDA receptor function. Here we assessed whether exposure to MK-801 during adolescence in male rats triggers a state of excitatory-inhibitory imbalance in the PFC that limits its functional capacity to regulate behavior in adulthood. Recordings from PFC brain slices revealed that MK-801 exposure during adolescence preferentially reduces the presynaptic functionality of GABAergic activity over that of excitatory synapses. As a result, an imbalance of excitatory-inhibitory synaptic activity emerges in the PFC that correlates linearly with the GABAergic deficit. Notably, the data also suggest that the diminished prefrontal GABAergic function could arise from a deficit in the recruitment of fast-spiking interneurons by excitatory inputs during adolescence. At the behavioral level, MK-801 exposure during adolescence did not disrupt the acquisition of trace fear conditioning, but markedly increased the level of freezing response during extinction testing. Infusion of the GABAA receptor-positive allosteric modulator Indiplon into the PFC before extinction testing reduced the level of freezing response in MK-801-treated rats to control levels. Collectively, the results indicate NMDA receptor signaling during adolescence enables the gain of prefrontal GABAergic function, which is required for maintaining proper excitatory-inhibitory balance in the PFC and its control of behavioral responses.SIGNIFICANCE STATEMENT A developmental disruption of prefrontal cortex maturation has been implicated in the pathophysiology of cognitive deficits in psychiatric disorders. Of particular interest is the susceptibility of the local GABAergic circuit to the impact of transient disruption of NMDA receptors. Here we found that NMDA receptor signaling is critical to enable the gain of prefrontal GABAergic transmission during adolescence for maintaining proper levels of excitatory-inhibitory balance in the PFC and its control of behavior.
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Ferrara NC, Mrackova E, Loh MK, Padival M, Rosenkranz JA. Fear Learning Enhances Prefrontal Cortical Suppression of Auditory Thalamic Inputs to the Amygdala in Adults, but Not Adolescents. Int J Mol Sci 2020; 21:ijms21083008. [PMID: 32344598 PMCID: PMC7215292 DOI: 10.3390/ijms21083008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 04/21/2020] [Accepted: 04/22/2020] [Indexed: 12/19/2022] Open
Abstract
Adolescence is characterized by increased susceptibility to the development of fear- and anxiety-related disorders. Adolescents also show elevated fear responding and aversive learning that is resistant to behavioral interventions, which may be related to alterations in the circuitry supporting fear learning. These features are linked to ongoing adolescent development of medial prefrontal cortical (PFC) inputs to the basolateral amygdala (BLA) that regulate neural activity and contribute to the refinement of fear responses. Here, we tested the hypothesis that the extent of PFC inhibition of the BLA following fear learning is greater in adults than in adolescents, using anesthetized in vivo recordings to measure local field potentials (LFPs) evoked by stimulation of PFC or auditory thalamic (MgN) inputs to BLA. We found that BLA LFPs evoked by stimulation of MgN inputs were enhanced in adults following fear conditioning. Fear conditioning also led to reduced summation of BLA LFPs evoked in response to PFC train stimulation, and increased the capacity of PFC inhibition of MgN inputs in adults. These data suggest that fear conditioning recruits additional inhibitory capacity by PFC inputs to BLA in adults, but that this capacity is weaker in adolescents. These results provide insight into how the development of PFC inputs may relate to age differences in memory retention and persistence following aversive learning.
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Affiliation(s)
- Nicole C. Ferrara
- Department of Foundational Sciences and Humanities, Discipline of Cellular and Molecular Pharmacology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA; (E.M.); (M.K.L.); (M.P.); (J.A.R.)
- Center for Neurobiology of Stress Resilience and Psychiatric Disorders, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
- Correspondence:
| | - Eliska Mrackova
- Department of Foundational Sciences and Humanities, Discipline of Cellular and Molecular Pharmacology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA; (E.M.); (M.K.L.); (M.P.); (J.A.R.)
- Center for Neurobiology of Stress Resilience and Psychiatric Disorders, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
| | - Maxine K. Loh
- Department of Foundational Sciences and Humanities, Discipline of Cellular and Molecular Pharmacology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA; (E.M.); (M.K.L.); (M.P.); (J.A.R.)
- Center for Neurobiology of Stress Resilience and Psychiatric Disorders, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
| | - Mallika Padival
- Department of Foundational Sciences and Humanities, Discipline of Cellular and Molecular Pharmacology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA; (E.M.); (M.K.L.); (M.P.); (J.A.R.)
- Center for Neurobiology of Stress Resilience and Psychiatric Disorders, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
| | - J. Amiel Rosenkranz
- Department of Foundational Sciences and Humanities, Discipline of Cellular and Molecular Pharmacology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA; (E.M.); (M.K.L.); (M.P.); (J.A.R.)
- Center for Neurobiology of Stress Resilience and Psychiatric Disorders, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
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Blume SR, Padival M, Urban JH, Rosenkranz JA. Disruptive effects of repeated stress on basolateral amygdala neurons and fear behavior across the estrous cycle in rats. Sci Rep 2019; 9:12292. [PMID: 31444385 PMCID: PMC6707149 DOI: 10.1038/s41598-019-48683-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 08/08/2019] [Indexed: 02/02/2023] Open
Abstract
Stress is a precipitating factor in depression and anxiety disorders. Patients with these disorders often show amygdala abnormalities. The basolateral amygdala (BLA) is integral in mood and emotion, and is sensitive to stress. While much is known about effects of stress on BLA neuron activity and morphology in males, less is known in females. We tested whether repeated stress exerts distinct effects on BLA in vivo neuronal activity and morphology of Golgi-stained BLA neurons [lateral (LAT) and basal (BA) nuclei] in adult female rats. Repeated restraint stress increased BLA neuronal firing and caused hypertrophy of BLA neurons in males, while it decreased LAT and BA neuronal firing and caused hypotrophy of neurons in the LAT of females. BLA neuronal activity and function, such as fear conditioning, shifts across the estrous cycle. Repeated stress disrupted this pattern of BLA activity and fear expression over the estrous cycle. The disruptive effects of stress on the pattern of BLA function across estrous may produce behavior that is non-optimal for a specific phase of the estrous cycle. The contrasting effects of stress may contribute to sex differences in the effects of stress on mood and psychiatric disorders.
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Affiliation(s)
- Shannon R Blume
- Discipline of Cellular and Molecular Pharmacology, The Chicago Medical School, Rosalind Franklin University, North Chicago, IL, 60064, USA
- AbbVie, Inc., 1 North Waukegan Road, North Chicago, IL, 60064, USA
| | - Mallika Padival
- Discipline of Cellular and Molecular Pharmacology, The Chicago Medical School, Rosalind Franklin University, North Chicago, IL, 60064, USA
- Center for Neurobiology of Stress Resilience and Psychiatric Disorders, The Chicago Medical School, Rosalind Franklin University, North Chicago, IL, 60064, USA
| | - Janice H Urban
- Discipline of Physiology and Biophysics, The Chicago Medical School, Rosalind Franklin University, North Chicago, IL, 60064, USA
- Center for Neurobiology of Stress Resilience and Psychiatric Disorders, The Chicago Medical School, Rosalind Franklin University, North Chicago, IL, 60064, USA
| | - J Amiel Rosenkranz
- Discipline of Cellular and Molecular Pharmacology, The Chicago Medical School, Rosalind Franklin University, North Chicago, IL, 60064, USA.
- Center for Neurobiology of Stress Resilience and Psychiatric Disorders, The Chicago Medical School, Rosalind Franklin University, North Chicago, IL, 60064, USA.
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17
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Miao Y, Wang N, Shao W, Xu Z, Yang Z, Wang L, Ju C, Zhang R, Zhang F. Overexpression of TIPE2, a Negative Regulator of Innate and Adaptive Immunity, Attenuates Cognitive Deficits in APP/PS1 Mice. J Neuroimmune Pharmacol 2019; 14:519-529. [DOI: 10.1007/s11481-019-09861-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 06/30/2019] [Indexed: 12/29/2022]
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18
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Kruse MS, Vadillo MJ, Miguelez Fernández AMM, Rey M, Zanutto BS, Coirini H. Sucrose exposure in juvenile rats produces long-term changes in fear memory and anxiety-like behavior. Psychoneuroendocrinology 2019; 104:300-307. [PMID: 30928734 DOI: 10.1016/j.psyneuen.2019.03.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 03/12/2019] [Accepted: 03/19/2019] [Indexed: 12/31/2022]
Abstract
Sugar consumption has increased dramatically in our society, a phenomenon that is primarily associated with obesity and diabetes appearance. However, whether this overconsumption of sugar has an impact on the developing CNS remains unknown. This study investigated the long-term effects of unlimited access to sucrose using the two-bottle choice paradigm and the juvenile and adult effects were compared. Male Sprague Dawley rats had free access to water containing 10% sucrose and water during youth (PD 25-50) or adulthood (PD 75-100). Rats in the sucrose group, privileged to take sugary solution over the water. No weight differences were observed between the sucrose groups and their age-matched water controls. After treatment all animals drank only water for another 25 days. Frustration, measured as the amount of water drank after the sucrose period, was higher in young-exposed animals compared to adults. In addition, rats that consumed sucrose during youth travelled less the central zones of an open field. Sucrose consumption during youth also affected fear behavior as animals exhibited impaired extinction of fear memory compared to control, indicating that prefrontal and hippocampal function is impaired. In contrast, rats exposed to sucrose during adulthood did not behave significantly different from control on either task. The calretinin and parvalbumin GABAergic interneurons go through extensive remodeling during youth in the medial prefrontal cortex and the ventral hippocampus. Here, we found that rats exposed to sucrose during youth presented an increased expression of calretinin-immunoreactivity in the medial prefrontal cortex, but not in the ventral hippocampus, indicating that early sucrose consumption produces enduring effects on the GABA system. Altogether these results indicate that sugar overconsumption at early stages of life induces long-term effects on behaviors related to fear and anxiety in adulthood.
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Affiliation(s)
- María Sol Kruse
- Laboratorio de Neurobiología, Instituto de Biología y Medicina Experimental-CONICET, Vuelta de Obligado 2490, C1428ADN, Buenos Aires, Argentina.
| | - Martín Javier Vadillo
- Laboratorio de Neurobiología, Instituto de Biología y Medicina Experimental-CONICET, Vuelta de Obligado 2490, C1428ADN, Buenos Aires, Argentina
| | | | - Mariana Rey
- Laboratorio de Neurobiología, Instituto de Biología y Medicina Experimental-CONICET, Vuelta de Obligado 2490, C1428ADN, Buenos Aires, Argentina
| | - Bonifacio Silvano Zanutto
- Laboratorio de Biología del Comportamiento, Instituto de Biología y Medicina Experimental-CONICET, Vuelta de Obligado 2490, C1428ADN, Buenos Aires, Argentina
| | - Héctor Coirini
- Laboratorio de Neurobiología, Instituto de Biología y Medicina Experimental-CONICET, Vuelta de Obligado 2490, C1428ADN, Buenos Aires, Argentina; Depto. de Bioquímica Humana, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, C1121ABG, Buenos Aires, Argentina
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19
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Cardenas A, Blanca M, Dimitrov E. Persistent pain intensifies recall of consolidated fear memories. Neurobiol Stress 2019; 10:100163. [PMID: 31193505 PMCID: PMC6535623 DOI: 10.1016/j.ynstr.2019.100163] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 04/04/2019] [Accepted: 04/04/2019] [Indexed: 12/04/2022] Open
Abstract
Ensembles of principal neurons in the basolateral amygdala (BLA) generate the initial engrams for fear memories, while projections from the BLA to the medial prefrontal cortex (mPFC) are essential for the encoding, transfer and storage of remote fear memories. We tested the effects of chronic pain on remote fear memories in mice. Male mice underwent classic fear conditioning by pairing a single tone (conditional stimulus, CS) with a single electric foot shock (unconditional stimulus, US). Sciatic nerve constriction was used to induce neuropathic pain at various time points before or after the fear conditioning. The mice with sciatic nerve cuffs implanted 48 h after the fear conditioning showed an increased freezing response to CS when compared to mice without cuffs or when compared to mice in which the nerve cuffing was performed 48 h before the fear conditioning. The enhancing effect of pain on consolidated fear memory was further tested and mice in which the nerve cuffing was performed 14 days after the fear conditioning also showed an increased fear response when tested 56 days later. We used immunostaining to detect morphological changes in the BLA that could suggest a mechanism for the observed increase in fear response. We found an increased number of calbindin/parvalbumin positive neurons in the BLA and increased perisomatic density of GAD65 on projection neurons that connect BLA to mPFC in mice with nerve cuffs. Despite the strong increase of c-Fos expression in BLA and mPFC that was induced by fear recall, neither the BLA to mPFC nor the mPFC to BLA projection neurons were activated in mice with nerve cuffs. Furthermore, non-injured mice had an increased fear response when BLA to mPFC projections were inhibited by a chemogenetic method. In conclusion, this study provides evidence that persistent pain has a significant impact on consolidated fear memories. Very likely the underlying mechanism for this phenomenon is increased inhibitory input onto the BLA to mPFC projection neurons, possibly from neurons with induced parvalbumin expression. Conceivably, the increased fear response to consolidated fear memory is a harbinger for the later development of anxiety and depression symptoms associated with chronic pain.
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Affiliation(s)
- Andrea Cardenas
- Department of Physiology and Biophysics, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, USA
| | - Michelle Blanca
- Department of Physiology and Biophysics, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, USA
| | - Eugene Dimitrov
- Department of Physiology and Biophysics, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, USA
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20
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Zimmermann KS, Richardson R, Baker KD. Maturational Changes in Prefrontal and Amygdala Circuits in Adolescence: Implications for Understanding Fear Inhibition during a Vulnerable Period of Development. Brain Sci 2019; 9:E65. [PMID: 30889864 PMCID: PMC6468701 DOI: 10.3390/brainsci9030065] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 03/13/2019] [Accepted: 03/14/2019] [Indexed: 12/24/2022] Open
Abstract
Anxiety disorders that develop in adolescence represent a significant burden and are particularly challenging to treat, due in no small part to the high occurrence of relapse in this age group following exposure therapy. This pattern of persistent fear is preserved across species; relative to those younger and older, adolescents consistently show poorer extinction, a key process underpinning exposure therapy. This suggests that the neural processes underlying fear extinction are temporarily but profoundly compromised during adolescence. The formation, retrieval, and modification of fear- and extinction-associated memories are regulated by a forebrain network consisting of the prefrontal cortex (PFC), the amygdala, and the hippocampus. These regions undergo robust maturational changes in early life, with unique alterations in structure and function occurring throughout adolescence. In this review, we focus primarily on two of these regions-the PFC and the amygdala-and discuss how changes in plasticity, synaptic transmission, inhibition/excitation, and connectivity (including modulation by hippocampal afferents to the PFC) may contribute to transient deficits in extinction retention. We end with a brief consideration of how exposure to stress during this adolescent window of vulnerability can permanently disrupt neurodevelopment, leading to lasting impairments in pathways of emotional regulation.
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Affiliation(s)
- Kelsey S Zimmermann
- School of Psychology, University of New South Wales (UNSW), Sydney, NSW 2052, Australia.
| | - Rick Richardson
- School of Psychology, University of New South Wales (UNSW), Sydney, NSW 2052, Australia.
| | - Kathryn D Baker
- School of Psychology, University of New South Wales (UNSW), Sydney, NSW 2052, Australia.
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21
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Rahman MM, Shukla A, Chattarji S. Extinction recall of fear memories formed before stress is not affected despite higher theta activity in the amygdala. eLife 2018; 7:35450. [PMID: 30102149 PMCID: PMC6125126 DOI: 10.7554/elife.35450] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Accepted: 08/08/2018] [Indexed: 11/13/2022] Open
Abstract
Stress is known to exert its detrimental effects not only by enhancing fear, but also by impairing its extinction. However, in earlier studies stress exposure preceded both processes. Thus, compared to unstressed animals, stressed animals had to extinguish fear memories that were strengthened by prior exposure to stress. Here, we dissociate the two processes to examine if stress specifically impairs the acquisition and recall of fear extinction. Strikingly, when fear memories were formed before stress exposure, thereby allowing animals to initiate extinction from comparable levels of fear, recall of fear extinction was unaffected. Despite this, we observed a persistent increase in theta activity in the BLA. Theta activity in the mPFC, by contrast, was normal. Stress also disrupted mPFC-BLA theta-frequency synchrony and directional coupling. Thus, in the absence of the fear-enhancing effects of stress, the expression of fear during and after extinction reflects normal regulation of theta activity in the mPFC, not theta hyperactivity in the amygdala.
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Affiliation(s)
| | | | - Sumantra Chattarji
- National Centre for Biological Sciences, Bangalore, India.,Centre for Brain Development and Repair, Institute for Stem Cell Biology and Regenerative Medicine, Bangalore, India.,Centre for Integrative Physiology, Deanery of Biomedical Sciences, University of Edinburgh, Edinburgh, United Kingdom
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22
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Morozov A, Ito W. Social modulation of fear: Facilitation vs buffering. GENES BRAIN AND BEHAVIOR 2018; 18:e12491. [PMID: 29896766 DOI: 10.1111/gbb.12491] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 05/29/2018] [Accepted: 06/11/2018] [Indexed: 12/23/2022]
Abstract
Social behaviors largely constitute mutual exchanges of social cues and the responses to them. The adaptive response also requires proper interpretation of the current context. In fear behaviors, social signals have bidirectional effects-some cues elicit or enhance fear whereas other suppress or buffer it. Studies on the social facilitation and social buffering of fear provide evidence of competition between social cues of opposing meanings. Co-expression of opposing cues by the same animal may explain the contradicting outcomes from the interaction between naive and frightened conspecifics, which reflect the fine balance between fear facilitation and buffering. The neuronal mechanisms that determine that balance provide an exciting target for future studies to probe the brain circuits underlying social modulation of emotional behaviors.
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Affiliation(s)
- Alexei Morozov
- Virginia Tech Carilion Research Institute, Roanoke, Virginia.,School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg, Virginia.,Department of Psychiatry and Behavioral Medicine, Virginia Tech Carilion School of Medicine, Roanoke, Virginia
| | - Wataru Ito
- Virginia Tech Carilion Research Institute, Roanoke, Virginia
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23
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Lo Iacono L, Carola V. The impact of adolescent stress experiences on neurobiological development. Semin Cell Dev Biol 2018; 77:93-103. [DOI: 10.1016/j.semcdb.2017.09.040] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 09/18/2017] [Accepted: 09/29/2017] [Indexed: 01/23/2023]
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24
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McDonnell-Dowling K, Miczek KA. Alcohol, psychomotor-stimulants and behaviour: methodological considerations in preclinical models of early-life stress. Psychopharmacology (Berl) 2018; 235:909-933. [PMID: 29511806 DOI: 10.1007/s00213-018-4852-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 02/06/2018] [Indexed: 12/14/2022]
Abstract
BACKGROUND In order to assess the risk associated with early-life stress, there has been an increase in the amount of preclinical studies investigating early-life stress. There are many challenges associated with investigating early-life stress in animal models and ensuring that such models are appropriate and clinically relevant. OBJECTIVES The purpose of this review is to highlight the methodological considerations in the design of preclinical studies investigating the effects of early-life stress on alcohol and psychomotor-stimulant intake and behaviour. METHODS The protocols employed for exploring early-life stress were investigated and summarised. Experimental variables include animals, stress models, and endpoints employed. RESULTS The findings in this paper suggest that there is little consistency among these studies and so the interpretation of these results may not be as clinically relevant as previously thought. CONCLUSION The standardisation of these simple stress procedures means that results will be more comparable between studies and that results generated will give us a more robust understanding of what can and may be happening in the human and veterinary clinic.
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Affiliation(s)
| | - Klaus A Miczek
- Department of Psychology, Tufts University, 530 Boston Avenue, Medford, MA, 02155, USA
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25
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Li L, Feng X, Zhou Z, Zhang H, Shi Q, Lei Z, Shen P, Yang Q, Zhao B, Chen S, Li L, Zhang Y, Wen P, Lu Z, Li X, Xu F, Wang L. Stress Accelerates Defensive Responses to Looming in Mice and Involves a Locus Coeruleus-Superior Colliculus Projection. Curr Biol 2018; 28:859-871.e5. [DOI: 10.1016/j.cub.2018.02.005] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 12/13/2017] [Accepted: 02/02/2018] [Indexed: 02/07/2023]
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26
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da Silva DDC, Tavares MG, do Nascimento CKB, Lira EC, dos Santos ÂA, Maia LMSDS, Batista-de-Oliveira Hornsby M. Can coconut oil and treadmill exercise during the critical period of brain development ameliorate stress-related effects on anxiety-like behavior and episodic-like memory in young rats? Food Funct 2018. [DOI: 10.1039/c7fo01516j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Virgin coconut oil (CO) and treadmill exercise have been reported to improve memory performance in young rats.
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Affiliation(s)
| | | | | | - Eduardo Carvalho Lira
- Department of Physiology & Pharmacology
- CB – Federal University of Pernambuco
- Recife
- Brazil
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27
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Daws SE, Joseph NF, Jamieson S, King ML, Chévere-Torres I, Fuentes I, Shumyatsky GP, Brantley AF, Rumbaugh G, Miller CA. Susceptibility and Resilience to Posttraumatic Stress Disorder-like Behaviors in Inbred Mice. Biol Psychiatry 2017; 82:924-933. [PMID: 28778658 PMCID: PMC5683920 DOI: 10.1016/j.biopsych.2017.06.030] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 05/15/2017] [Accepted: 06/13/2017] [Indexed: 11/23/2022]
Abstract
BACKGROUND The limited neurobiological understanding of posttraumatic stress disorder (PTSD) has been partially attributed to the need for improved animal models. Stress-enhanced fear learning (SEFL) in rodents recapitulates many PTSD-associated behaviors, including stress-susceptible and stress-resilient subgroups in outbred rats. Identification of subgroups requires additional behavioral phenotyping, a confound to mechanistic studies. METHODS We employed a SEFL paradigm in inbred male and female C57BL/6 mice that combines acute stress with fear conditioning to precipitate traumatic-like memories. Extinction and long-term retention of extinction were examined after SEFL. Further characterization of SEFL effects on male mice was performed with additional behavioral tests, determination of regional activation by Fos immunofluorescence, and RNA sequencing of the basolateral amygdala. RESULTS Stressed animals displayed persistently elevated freezing during extinction. While more uniform in females, SEFL produced male subgroups with differential susceptibility that were identified without posttraining phenotyping. Additional phenotyping of male mice revealed PTSD-associated behaviors, including extinction-resistant fear memory, hyperarousal, generalization, and dysregulated corticosterone in stress-susceptible male mice. Altered Fos activation was also seen in the infralimbic cortex and basolateral amygdala of stress-susceptible male mice after remote memory retrieval. Key behavioral outcomes, including susceptibility, were replicated by two independent laboratories. RNA sequencing of the basolateral amygdala revealed transcriptional divergence between the male subgroups, including genes with reported polymorphic association to patients with PTSD. CONCLUSIONS This SEFL model provides a tool for development of PTSD therapeutics that is compatible with the growing number of mouse-specific resources. Furthermore, use of an inbred strain allows for investigation into epigenetic mechanisms that are expected to critically regulate susceptibility and resilience.
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Affiliation(s)
- Stephanie E Daws
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, Florida; Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida
| | - Nadine F Joseph
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, Florida; Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida
| | - Sarah Jamieson
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, Florida; Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida
| | - Michelle L King
- Behavioral Core, The Scripps Research Institute, Jupiter, Florida
| | | | - Illeana Fuentes
- Department of Genetics, Rutgers University, Piscataway, New Jersey
| | | | | | - Gavin Rumbaugh
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida
| | - Courtney A Miller
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, Florida; Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida.
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28
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Barbayannis G, Franco D, Wong S, Galdamez J, Romeo RD, Bauer EP. Differential effects of stress on fear learning and activation of the amygdala in pre-adolescent and adult male rats. Neuroscience 2017; 360:210-219. [PMID: 28768158 PMCID: PMC5973547 DOI: 10.1016/j.neuroscience.2017.07.058] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 06/21/2017] [Accepted: 07/21/2017] [Indexed: 10/19/2022]
Abstract
Adolescence is accompanied by the maturation of several stress-responsive areas of the brain including the amygdala, a key region for the acquisition and expression of conditioned fear. These changes may contribute to the development of stress-related disorders in adolescence, such as anxiety and depression, and increase the susceptibility to these psychopathologies later in life. Here, we assessed the effects of acute restraint stress on fear learning and amygdala activation in pre-adolescent and adult male rats. Pre-adolescents exposed to stress prior to fear conditioning showed greater resistance to the extinction of fear memories than adults. At the cellular level, the combination of stress and fear conditioning resulted in a greater number of FOS-positive cells in the basolateral nucleus of the amygdala (BLA) than fear conditioning alone, and this increase was greater in pre-adolescents than in adults. Despite age-dependent differences, we found no changes in glucocorticoid receptor (GR) levels in the amygdala of either pre-adolescent or adult males. Overall, our data indicate that stress prior to fear conditioning leads to extinction-resistant fear responses in pre-adolescent animals, and that the BLA may be one neural locus mediating these age-dependent effects of stress on fear learning.
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Affiliation(s)
- Georgia Barbayannis
- Departments of Biology and Psychology and Neuroscience and Behavior Program, Barnard College of Columbia University, 3009 Broadway, New York, NY 10027, United States
| | - Daly Franco
- Departments of Biology and Psychology and Neuroscience and Behavior Program, Barnard College of Columbia University, 3009 Broadway, New York, NY 10027, United States
| | - Solange Wong
- Departments of Biology and Psychology and Neuroscience and Behavior Program, Barnard College of Columbia University, 3009 Broadway, New York, NY 10027, United States
| | - Josselyn Galdamez
- Departments of Biology and Psychology and Neuroscience and Behavior Program, Barnard College of Columbia University, 3009 Broadway, New York, NY 10027, United States
| | - Russell D Romeo
- Departments of Biology and Psychology and Neuroscience and Behavior Program, Barnard College of Columbia University, 3009 Broadway, New York, NY 10027, United States
| | - Elizabeth P Bauer
- Departments of Biology and Psychology and Neuroscience and Behavior Program, Barnard College of Columbia University, 3009 Broadway, New York, NY 10027, United States.
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29
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Sex- and Estrus-Dependent Differences in Rat Basolateral Amygdala. J Neurosci 2017; 37:10567-10586. [PMID: 28954870 DOI: 10.1523/jneurosci.0758-17.2017] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 09/18/2017] [Accepted: 09/19/2017] [Indexed: 01/24/2023] Open
Abstract
Depression and anxiety are diagnosed almost twice as often in women, and the symptomology differs in men and women and is sensitive to sex hormones. The basolateral amygdala (BLA) contributes to emotion-related behaviors that differ between males and females and across the reproductive cycle. This hints at sex- or estrus-dependent features of BLA function, about which very little is known. The purpose of this study was to test whether there are sex differences or estrous cyclicity in rat BLA physiology and to determine their mechanistic correlates. We found substantial sex differences in the activity of neurons in lateral nuclei (LAT) and basal nuclei (BA) of the BLA that were associated with greater excitatory synaptic input in females. We also found strong differences in the activity of LAT and BA neurons across the estrous cycle. These differences were associated with a shift in the inhibition-excitation balance such that LAT had relatively greater inhibition during proestrus which paralleled more rapid cued fear extinction. In contrast, BA had relatively greater inhibition during diestrus that paralleled more rapid contextual fear extinction. These results are the first to demonstrate sex differences in BLA neuronal activity and the impact of estrous cyclicity on these measures. The shift between LAT and BA predominance across the estrous cycle provides a simple construct for understanding the effects of the estrous cycle on BLA-dependent behaviors. These results provide a novel framework to understand the cyclicity of emotional memory and highlight the importance of considering ovarian cycle when studying the BLA of females.SIGNIFICANCE STATEMENT There are differences in emotional responses and many psychiatric symptoms between males and females. This may point to sex differences in limbic brain regions. Here we demonstrate sex differences in neuronal activity in one key limbic region, the basolateral amygdala (BLA), whose activity fluctuates across the estrous cycle due to a shift in the balance of inhibition and excitation across two BLA regions, the lateral and basal nuclei. By uncovering this push-pull shift between lateral and basal nuclei, these results help to explain disparate findings about the effects of biological sex and estrous cyclicity on emotion and provide a framework for understanding fluctuations in emotional memory and psychiatric symptoms.
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30
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Predictable Chronic Mild Stress during Adolescence Promotes Fear Memory Extinction in Adulthood. Sci Rep 2017; 7:7857. [PMID: 28798340 PMCID: PMC5552791 DOI: 10.1038/s41598-017-08017-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 07/03/2017] [Indexed: 01/16/2023] Open
Abstract
Early-life stress in adolescence has a long-lasting influence on brain function in adulthood, and it is mostly recognized as a predisposing factor for mental illnesses, such as anxiety and posttraumatic stress disorder. Previous studies also indicated that adolescent predictable chronic mild stress (PCMS) in early life promotes resilience to depression- and anxiety-like behaviors in adulthood. However, the role of PCMS in associated memory process is still unclear. In the present study, we found that adolescent PCMS facilitated extinction and inhibited fear response in reinstatement and spontaneous recovery tests in adult rats, and this effect was still present 1 week later. PCMS in adolescence increased the activity of brain-derived neurotrophic factor (BDNF)-extracellular signal-regulated kinase 1/2 (ERK1/2) signaling in infralimbic cortex (IL) but not prelimbic cortex in adulthood. Intra-IL infusion of BDNF antibody and the ERK1/2 inhibitor U0126 reversed PCMS-induced enhancement of fear extinction. Moreover, we found that PCMS decreased DNA methylation of the Bdnf gene at exons IV and VI and elevated the mRNA levels of Bdnf in the IL. Our findings indicate that adolescent PCMS exposure promotes fear memory extinction in adulthood, which reevaluates the traditional notion of adolescent stress.
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31
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Schayek R, Maroun M. Dissociation in the effects of stress and D1 receptors activation on basolateral amygdalar LTP in juvenile and adult animals. Neuropharmacology 2017; 113:511-518. [DOI: 10.1016/j.neuropharm.2016.11.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 10/28/2016] [Accepted: 11/02/2016] [Indexed: 01/08/2023]
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32
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Effects of Repeated Stress on Age-Dependent GABAergic Regulation of the Lateral Nucleus of the Amygdala. Neuropsychopharmacology 2016; 41:2309-23. [PMID: 26924679 PMCID: PMC4946062 DOI: 10.1038/npp.2016.33] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 01/25/2016] [Accepted: 02/03/2016] [Indexed: 12/17/2022]
Abstract
The adolescent age is associated with lability of mood and emotion. The onset of depression and anxiety disorders peaks during adolescence and there are differences in symptomology during adolescence. This points to differences in the adolescent neural circuitry that underlies mood and emotion, such as the amygdala. The human adolescent amygdala is more responsive to evocative stimuli, hinting to less local inhibitory regulation of the amygdala, but this has not been explored in adolescents. The amygdala, including the lateral nucleus (LAT) of the basolateral amygdala complex, is sensitive to stress. The amygdala undergoes maturational processes during adolescence, and therefore may be more vulnerable to harmful effects of stress during this time period. However, little is known about the effects of stress on the LAT during adolescence. GABAergic inhibition is a key regulator of LAT activity. Therefore, the purpose of this study was to test whether there are differences in the local GABAergic regulation of the rat adolescent LAT, and differences in its sensitivity to repeated stress. We found that LAT projection neurons are subjected to weaker GABAergic inhibition during adolescence. Repeated stress reduced in vivo endogenous and exogenous GABAergic inhibition of LAT projection neurons in adolescent rats. Furthermore, repeated stress decreased measures of presynaptic GABA function and interneuron activity in adolescent rats. In contrast, repeated stress enhanced glutamatergic drive of LAT projection neurons in adult rats. These results demonstrate age differences in GABAergic regulation of the LAT, and age differences in the mechanism for the effects of repeated stress on LAT neuron activity. These findings provide a substrate for increased mood lability in adolescents, and provide a substrate by which adolescent repeated stress can induce distinct behavioral outcomes and psychiatric symptoms.
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Baker KD, Bisby MA, Richardson R. Impaired fear extinction in adolescent rodents: Behavioural and neural analyses. Neurosci Biobehav Rev 2016; 70:59-73. [PMID: 27235077 DOI: 10.1016/j.neubiorev.2016.05.019] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 05/06/2016] [Accepted: 05/21/2016] [Indexed: 01/01/2023]
Abstract
Despite adolescence being a developmental window of vulnerability, up until very recently there were surprisingly few studies on fear extinction during this period. Here we summarise the recent work in this area, focusing on the unique behavioural and neural characteristics of fear extinction in adolescent rodents, and humans where relevant. A prominent hypothesis posits that anxiety disorders peak during late childhood/adolescence due to the non-linear maturation of the fear inhibition neural circuitry. We discuss evidence that impaired extinction retention in adolescence is due to subregions of the medial prefrontal cortex and amygdala mediating fear inhibition being underactive while other subregions that mediate fear expression are overactive. We also review work on various interventions and surprising circumstances which enhance fear extinction in adolescence. This latter work revealed that the neural correlates of extinction in adolescence are different to that in younger and older animals even when extinction retention is not impaired. This growing body of work highlights that adolescence is a unique period of development for fear inhibition.
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Affiliation(s)
- Kathryn D Baker
- School of Psychology, UNSW Australia, Sydney, NSW 2052, Australia.
| | - Madelyne A Bisby
- School of Psychology, UNSW Australia, Sydney, NSW 2052, Australia
| | - Rick Richardson
- School of Psychology, UNSW Australia, Sydney, NSW 2052, Australia
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Hoffman KL. New dimensions in the use of rodent behavioral tests for novel drug discovery and development. Expert Opin Drug Discov 2016; 11:343-53. [DOI: 10.1517/17460441.2016.1153624] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Maren S, Holmes A. Stress and Fear Extinction. Neuropsychopharmacology 2016; 41:58-79. [PMID: 26105142 PMCID: PMC4677122 DOI: 10.1038/npp.2015.180] [Citation(s) in RCA: 238] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Revised: 06/03/2015] [Accepted: 06/17/2015] [Indexed: 12/11/2022]
Abstract
Stress has a critical role in the development and expression of many psychiatric disorders, and is a defining feature of posttraumatic stress disorder (PTSD). Stress also limits the efficacy of behavioral therapies aimed at limiting pathological fear, such as exposure therapy. Here we examine emerging evidence that stress impairs recovery from trauma by impairing fear extinction, a form of learning thought to underlie the suppression of trauma-related fear memories. We describe the major structural and functional abnormalities in brain regions that are particularly vulnerable to stress, including the amygdala, prefrontal cortex, and hippocampus, which may underlie stress-induced impairments in extinction. We also discuss some of the stress-induced neurochemical and molecular alterations in these brain regions that are associated with extinction deficits, and the potential for targeting these changes to prevent or reverse impaired extinction. A better understanding of the neurobiological basis of stress effects on extinction promises to yield novel approaches to improving therapeutic outcomes for PTSD and other anxiety and trauma-related disorders.
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Affiliation(s)
- Stephen Maren
- Department of Psychology, Institute of Neuroscience, Texas A&M University, College Station, TX, USA
| | - Andrew Holmes
- National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, USA
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Duan Y, Zhou S, Ma J, Yin P, Cao X. Forebrain NR2B overexpression enhancing fear acquisition and long-term potentiation in the lateral amygdala. Eur J Neurosci 2015; 42:2214-23. [PMID: 26118841 DOI: 10.1111/ejn.13008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 06/09/2015] [Accepted: 06/23/2015] [Indexed: 11/29/2022]
Abstract
N-methyl-d-aspartic acid (NMDA) receptor-dependent long-term potentiation (LTP) at the thalamus-lateral amygdala (T-LA) synapses is the basis for acquisition of auditory fear memory. However, the role of the NMDA receptor NR2B subunit in synaptic plasticity at T-LA synapses remains speculative. In the present study, using transgenic mice with forebrain-specific overexpression of the NR2B subunit, we have observed that forebrain NR2B overexpression results in enhanced LTP but does not alter long-term depression (LTD) at the T-LA synapses in transgenic mice. To elucidate the cellular mechanisms underlying enhanced LTP at T-LA synapses in these transgenic mice, AMPA and NMDA receptor-mediated postsynaptic currents have been measured. The data show a marked increasing in the amplitude and decay time of NMDA receptor-mediated currents in these transgenic mice. Consistent with enhanced LTP at T-LA synapses, NR2B-transgenic mice exhibit better performance in the acquisition of auditory fear memory than wild-type littermates. Our results demonstrate that up-regulation of NR2B expression facilitates acquisition of auditory cued fear memory and enhances LTP at T-LA synapses.
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Affiliation(s)
- Yanhong Duan
- Key Laboratory of Brain Functional Genomics, Ministry of Education, Shanghai Key Laboratory of Brain Functional Genomics, School of Life Sciences, East China Normal University, 3663 N. Zhongshan Rd., Shanghai, 200062, China
| | - Siqi Zhou
- Key Laboratory of Brain Functional Genomics, Ministry of Education, Shanghai Key Laboratory of Brain Functional Genomics, School of Life Sciences, East China Normal University, 3663 N. Zhongshan Rd., Shanghai, 200062, China
| | - Jing Ma
- Key Laboratory of Brain Functional Genomics, Ministry of Education, Shanghai Key Laboratory of Brain Functional Genomics, School of Life Sciences, East China Normal University, 3663 N. Zhongshan Rd., Shanghai, 200062, China
| | - Pengcheng Yin
- Key Laboratory of Brain Functional Genomics, Ministry of Education, Shanghai Key Laboratory of Brain Functional Genomics, School of Life Sciences, East China Normal University, 3663 N. Zhongshan Rd., Shanghai, 200062, China
| | - Xiaohua Cao
- Key Laboratory of Brain Functional Genomics, Ministry of Education, Shanghai Key Laboratory of Brain Functional Genomics, School of Life Sciences, East China Normal University, 3663 N. Zhongshan Rd., Shanghai, 200062, China
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Wilson MA, Grillo CA, Fadel JR, Reagan LP. Stress as a one-armed bandit: Differential effects of stress paradigms on the morphology, neurochemistry and behavior in the rodent amygdala. Neurobiol Stress 2015; 1:195-208. [PMID: 26844236 PMCID: PMC4721288 DOI: 10.1016/j.ynstr.2015.06.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 06/04/2015] [Accepted: 06/05/2015] [Indexed: 12/12/2022] Open
Abstract
Neuroplasticity may be defined as the ability of the central nervous system (CNS) to respond to changes in the internal and external environment and it is well established that some stimuli have the ability to facilitate or impair neuroplasticity depending on the pre-existing milieu. A classic example of a stimulus that can both facilitate and impair neuroplasticity is stress. Indeed, the ability of CNS to respond to acute stress is often dependent upon the prior stress history of the individual. While responses to acute stress are often viewed as adaptive in nature, stress reactivity in subjects with prior chronic stress experiences are often linked to neuropsychiatric disorders, including major depressive disorder, post-traumatic stress disorder (PTSD) and anxiety. In rodent studies, chronic stress exposure produces structural and functional alterations in the hippocampus and medial prefrontal cortex that are consistent across different types of stress paradigms. Conversely, the amygdala appears to exhibit differential structural and functional responses to stress that are dependent on a variety of factors, including the type of stressor performed and the duration of the stress paradigm. This is most evident in output measures including morphological analysis of amygdala neurons, measurement of glutamatergic tone in amygdalar subdivisions and the analysis of amygdala-centric behaviors. Accordingly, this review will provide an overview of the effects of stress on the structural and functional plasticity of the rodent amygdala, especially in relation to the differential effects of repeated or chronic stress paradigms on dendritic architecture, neurochemistry of the glutamatergic system and behavior.
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Affiliation(s)
- Marlene A. Wilson
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA
- WJB Dorn Veterans Affairs Medical Center, Columbia, SC, USA
| | - Claudia A. Grillo
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA
| | - Jim R. Fadel
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA
| | - Lawrence P. Reagan
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA
- WJB Dorn Veterans Affairs Medical Center, Columbia, SC, USA
- Corresponding author. Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, 6439 Garners Ferry Road, D40, Columbia, SC 29208, USA.
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Padival MA, Blume SR, Vantrease JE, Rosenkranz JA. Qualitatively different effect of repeated stress during adolescence on principal neuron morphology across lateral and basal nuclei of the rat amygdala. Neuroscience 2015; 291:128-45. [PMID: 25701125 DOI: 10.1016/j.neuroscience.2015.02.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 01/21/2015] [Accepted: 02/07/2015] [Indexed: 01/04/2023]
Abstract
Repeated stress can elicit symptoms of depression and anxiety. The amygdala is a significant contributor to the expression of emotion and the basolateral amygdala (BLA) is a major target for the effects of stress on emotion. The adolescent time period may be particularly susceptible to the effects of stress on emotion. While repeated stress has been demonstrated to modify the morphology of BLA neurons in adult rats, little is known about its effects on BLA neurons during adolescence. This study tests the effects of repeated stress during adolescence on BLA neuronal morphology, and whether these are similar to the effects of stress during adulthood. The BLA includes the basal (BA) and lateral (LAT) nuclei, which are differentially responsive to stress in adults. Therefore, effects of stress during adolescence were compared between the BA and LAT nuclei. Morphological features of reconstructed BLA neurons were examined using Golgi-Cox-stained tissue from control or repeated restraint stress-exposed rats. We found subtle dendritic growth coupled with loss of spines after repeated stress during adolescence. The magnitude and dendritic location of these differences varied between the BA and LAT nuclei in strong contrast to the stress-induced increases in spine number seen in adults. These results demonstrate that repeated stress during adolescence has markedly different effects on BLA neuronal morphology, and the extent of these changes is BLA nucleus-dependent. Moreover, altered neuroanatomy was associated with age-dependent effects of repeated stress on generalization of fear, and may point to the necessity for different approaches to target stress-induced changes in adolescents.
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Affiliation(s)
- M A Padival
- Department of Cellular and Molecular Pharmacology, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, United States
| | - S R Blume
- Department of Cellular and Molecular Pharmacology, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, United States
| | - J E Vantrease
- Department of Cellular and Molecular Pharmacology, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, United States
| | - J A Rosenkranz
- Department of Cellular and Molecular Pharmacology, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, United States.
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Distinct effects of repeated restraint stress on basolateral amygdala neuronal membrane properties in resilient adolescent and adult rats. Neuropsychopharmacology 2014; 39:2114-30. [PMID: 24619244 PMCID: PMC4104329 DOI: 10.1038/npp.2014.60] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 02/24/2014] [Accepted: 02/27/2014] [Indexed: 12/30/2022]
Abstract
Severe and repeated stress has damaging effects on health, including initiation of depression and anxiety. Stress that occurs during development has long-lasting and particularly damaging effects on emotion. The basolateral amygdala (BLA) plays a key role in many affective behaviors, and repeated stress causes different forms of BLA hyperactivity in adolescent and adult rats. However, the mechanism is not known. Furthermore, not every individual is susceptible to the negative consequences of stress. Differences in the effects of stress on the BLA might contribute to determine whether an individual will be vulnerable or resilient to the effects of stress on emotion. The purpose of this study is to test the cellular underpinnings for age dependency of BLA hyperactivity after stress, and whether protective changes occur in resilient individuals. To test this, the effects of repeated stress on membrane excitability and other membrane properties of BLA principal neurons were compared between adult and adolescent rats, and between vulnerable and resilient rats, using in vitro whole-cell recordings. Vulnerability was defined by adrenal gland weight, and verified by body weight gain after repeated restraint stress, and fecal pellet production during repeated restraint sessions. We found that repeated stress increased the excitability of BLA neurons, but in a manner that depended on age and BLA subnucleus. Furthermore, stress resilience was associated with an opposite pattern of change, with increased slow afterhyperpolarization (AHP) potential, whereas vulnerability was associated with decreased medium AHP. The opposite outcomes in these two populations were further distinguished by differences of anxiety-like behavior in the elevated plus maze that were correlated with BLA neuronal excitability and AHP. These results demonstrate a substrate for BLA hyperactivity after repeated stress, with distinct membrane properties to target, as well as age-dependent factors that contribute to resilience to the effects of stress.
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Bukalo O, Pinard CR, Holmes A. Mechanisms to medicines: elucidating neural and molecular substrates of fear extinction to identify novel treatments for anxiety disorders. Br J Pharmacol 2014; 171:4690-718. [PMID: 24835117 DOI: 10.1111/bph.12779] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 04/28/2014] [Accepted: 05/04/2014] [Indexed: 12/11/2022] Open
Abstract
The burden of anxiety disorders is growing, but the efficacy of available anxiolytic treatments remains inadequate. Cognitive behavioural therapy for anxiety disorders focuses on identifying and modifying maladaptive patterns of thinking and behaving, and has a testable analogue in rodents in the form of fear extinction. A large preclinical literature has amassed in recent years describing the neural and molecular basis of fear extinction in rodents. In this review, we discuss how this work is being harnessed to foster translational research on anxiety disorders and facilitate the search for new anxiolytic treatments. We begin by summarizing the anatomical and functional connectivity of a medial prefrontal cortex (mPFC)-amygdala circuit that subserves fear extinction, including new insights from optogenetics. We then cover some of the approaches that have been taken to model impaired fear extinction and associated impairments with mPFC-amygdala dysfunction. The principal goal of the review is to evaluate evidence that various neurotransmitter and neuromodulator systems mediate fear extinction by modulating the mPFC-amygdala circuitry. To that end, we describe studies that have tested how fear extinction is impaired or facilitated by pharmacological manipulations of dopamine, noradrenaline, 5-HT, GABA, glutamate, neuropeptides, endocannabinoids and various other systems, which either directly target the mPFC-amygdala circuit, or produce behavioural effects that are coincident with functional changes in the circuit. We conclude that there are good grounds to be optimistic that the progress in defining the molecular substrates of mPFC-amygdala circuit function can be effectively leveraged to identify plausible candidates for extinction-promoting therapies for anxiety disorders.
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Affiliation(s)
- Olena Bukalo
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA
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Mouse social stress induces increased fear conditioning, helplessness and fatigue to physical challenge together with markers of altered immune and dopamine function. Neuropharmacology 2014; 85:328-41. [PMID: 24907589 DOI: 10.1016/j.neuropharm.2014.05.039] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 05/24/2014] [Accepted: 05/26/2014] [Indexed: 12/24/2022]
Abstract
In neuropsychiatry, animal studies demonstrating causal effects of environmental manipulations relevant to human aetiology on behaviours relevant to human psychopathologies are valuable. Such valid models can improve understanding of aetio-pathophysiology and preclinical discovery and development of new treatments. In depression, specific uncontrollable stressful life events are major aetiological factors, and subsequent generalized increases in fearfulness, helplessness and fatigue are core symptoms or features. Here we exposed adult male C57BL/6 mice to 15-day psychosocial stress with loss of social control but minimal physical wounding. One cohort was assessed in a 3-day test paradigm of motor activity, fear conditioning and 2-way avoid-escape behaviour on days 16-18, and a second cohort was assessed in a treadmill fatigue paradigm on days 19 and 29, followed by the 3-day paradigm on days 30-32. All tests used a physical aversive stimulus, namely mild, brief electroshocks. Socially stressed mice displayed decreased motor activity, increased fear acquisition, decreased 2-way avoid-escape responding (increased helplessness) and increased fatigue. They also displayed increased plasma TNF and spleen hypertrophy, and adrenal hypertrophy without hyper-corticoidism. In a third cohort, psychosocial stress effects on brain gene expression were assessed using next generation sequencing. Gene expression was altered in pathways of inflammation and G-protein coupled receptors in prefrontal cortex and amygdala; in the latter, expression of genes important in dopamine function were de-regulated including down-regulated Drd2, Adora2a and Darpp-32. This model can be applied to identify targets for treating psychopathologies such as helplessness or fatigue, and to screen compounds/biologics developed to act at these targets.
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Heat exposure in female rats elicits abnormal fear expression and cellular changes in prefrontal cortex and hippocampus. Neurobiol Learn Mem 2014; 115:38-42. [PMID: 24859751 DOI: 10.1016/j.nlm.2014.05.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 05/10/2014] [Accepted: 05/13/2014] [Indexed: 12/11/2022]
Abstract
Despite a twofold higher prevalence of fear-related disorders in women, the neurobiological factors that modulate and drive fear expression are rarely studied in female animals. Fear conditioning and extinction are useful tools for dissecting these mechanisms, and here we tested the effects of environmental manipulations - four days of exposure to 31°C temperatures in the animal housing facility - on fear learning and memory exclusively in female rats. We found that heat exposure disrupted freezing to tone during fear conditioning, and elicited enhanced freezing during extinction and extinction retrieval. We also performed immunohistochemistry for c-fos expression in the infralimbic (IL) and prelimbic (PL) regions of the prefrontal cortex during extinction retrieval, and found that heat exposure induced a switch from IL-dominated activity to PL-dominated activity. Finally, morphological analysis of spines in hippocampal CA3 neurons revealed an increase in spine head diameter in heat-exposed animals, which may partly underlie the persistent freezing observed in these animals. Together, our data show that heat exposure can induce changes at behavioral, physiological, and structural levels, and add to a woefully lacking body of literature on fear processes in female animals.
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A window of vulnerability: impaired fear extinction in adolescence. Neurobiol Learn Mem 2013; 113:90-100. [PMID: 24513634 DOI: 10.1016/j.nlm.2013.10.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 09/21/2013] [Accepted: 10/17/2013] [Indexed: 01/06/2023]
Abstract
There have been significant advances made towards understanding the processes mediating extinction of learned fear. However, despite being of clear theoretical and clinical significance, very few studies have examined fear extinction in adolescence, which is often described as a developmental window of vulnerability to psychological disorders. This paper reviews the relatively small body of research examining fear extinction in adolescence. A prominent finding of this work is that adolescents, both humans and rodents, exhibit a marked impairment in extinction relative to both younger (e.g., juvenile) and older (e.g., adult) groups. We then review some potential mechanisms that could produce the striking extinction deficit observed in adolescence. For example, one neurobiological candidate mechanism for impaired extinction in adolescence involves changes in the functional connectivity within the fear extinction circuit, particularly between prefrontal cortical regions and the amygdala. In addition, we review research on emotion regulation and attention processes that suggests that developmental changes in attention bias to threatening cues may be a cognitive mechanism that mediates age-related differences in extinction learning. We also examine how a differential reaction to chronic stress in adolescence impacts upon extinction retention during adolescence as well as in later life. Finally, we consider the findings of several studies illustrating promising approaches that overcome the typically-observed extinction impairments in adolescent rodents and that could be translated to human adolescents.
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Changes in the brain expression of alpha-2 subunits of the GABA-A receptor after chronic restraint stress in low- and high-anxiety rats. Behav Brain Res 2013; 253:337-45. [PMID: 23916758 DOI: 10.1016/j.bbr.2013.07.042] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 07/19/2013] [Accepted: 07/23/2013] [Indexed: 01/02/2023]
Abstract
This study assessed the mechanisms underlying the behavioral differences between high- (HR) and low-anxiety (LR) rats selected for their behavior in the contextual fear test (i.e., the duration of the freezing response was used as a discriminating variable). Rats were subjected to chronic restraint stress (21 days, 3h daily). We found that in the HR group, chronic restraint stress decreased rat activity in the Porsolt test and reduced the concentration of corticosterone in the prefrontal cortex. The behavioral changes were accompanied by a lower expression of alpha-2 GABA-A receptor subunits in the secondary motor cortex (M2 area) and in the dentate gyrus of the hippocampus (DG) compared to LR restraint animals. Moreover, restraint stress increased the density of alpha-2 GABA-A subunits in the basolateral amygdala (BLA) in HR rats and decreased the expression of these subunits in the DG and M2 areas compared to the HR control group. The present results suggest that, in HR rats exposed to chronic restraint stress, the function of hippocampal and cortical GABAergic neurotransmission is attenuated and that this effect could have important influences on the functioning of the hypothalamic-pituitary-adrenal axis and on depressive symptoms.
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Scherf KS, Smyth JM, Delgado MR. The amygdala: an agent of change in adolescent neural networks. Horm Behav 2013; 64:298-313. [PMID: 23756154 PMCID: PMC3781589 DOI: 10.1016/j.yhbeh.2013.05.011] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Revised: 05/03/2013] [Accepted: 05/28/2013] [Indexed: 01/15/2023]
Abstract
This article is part of a Special Issue "Puberty and Adolescence". A unique component of adolescent development is the need to master new developmental tasks in which peer interactions become primary (for the purposes of becoming autonomous from parents, forming intimate friendships, and romantic/sexual partnerships). Previously, it has been suggested that the ability to master these tasks requires an important re-organization in the relation between perceptual, motivational, affective, and cognitive systems in a very general and broad way that is fundamentally influenced by the infusion of sex hormones during pubertal development (Scherf et al., 2012). Herein, we extend this argument to suggest that the amygdala, which is vastly connected with cortical and subcortical regions and contains sex hormone receptors, may lie at the heart of this re-organization. We propose that during adolescent development there is a shift in the attribution of relevance to existing stimuli and contexts that is mediated by the amygdala (e.g., heightened relevance of peer faces, reduced relevance of physical distance from parents). As a result, amygdala inputs to existing stable neural networks are re-weighted (increased or decreased), which destabilizes the functional interactions among regions within these networks and allows for a critical restructuring of the network functional organization. This process of network re-organization enables processing of qualitatively new kinds of social information and the emergence of novel behaviors that support mastery of adolescent-specific developmental tasks.
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Affiliation(s)
- K. Suzanne Scherf
- Dept. of Psychology, Center for Brain, Behavior & Cognition, and Social Science Research Institute, Penn State University
| | - Joshua M. Smyth
- Dept. of Biobehavioral Health and Social Science Research Institute, Penn State University
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