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Nakagawa H, Ishiwata T. Effect of short- and long-term heat exposure on brain monoamines and emotional behavior in mice and rats. J Therm Biol 2021; 99:102923. [PMID: 34420602 DOI: 10.1016/j.jtherbio.2021.102923] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 03/26/2021] [Accepted: 03/27/2021] [Indexed: 10/21/2022]
Abstract
Heat exposure affects several physiological, neuronal, and emotional functions. Notably, monoaminergic neurotransmitters in the brain such as noradrenaline, dopamine, and serotonin, which regulate several basic physiological functions, such as thermoregulation, food intake, and energy balance, are affected by heat exposure and heat acclimation. Furthermore, cognition and emotional states are also affected by heat exposure and changes in brain monoamine levels. Short-term heat exposure has been reported to increase anxiety in some behavioral tests. In contrast, there is a possibility that long-term heat exposure decreases anxiety due to heat acclimation. These changes might be due to adaptation of the core body temperature and/or brain monoamine levels by heat exposure. In this review, we first outline the changes in brain monoamine levels and thereafter focus on changes in emotional behavior due to heat exposure and heat acclimation. Finally, we describe the relationships between emotional behavior and brain monoamine levels during heat acclimation.
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Affiliation(s)
- Hikaru Nakagawa
- Graduate School of Community & Human Services, Rikkyo University, 1-2-26 Kitano, Niiza, Saitama, 352-8558, Japan; Japan Society for the Promotion of Science, 5-3-1 Kojimachi, Chiyoda, Tokyo, 102-0083, Japan.
| | - Takayuki Ishiwata
- Graduate School of Community & Human Services, Rikkyo University, 1-2-26 Kitano, Niiza, Saitama, 352-8558, Japan
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2
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Nakagawa H, Matsunaga D, Ishiwata T. Effect of heat acclimation on anxiety-like behavior of rats in an open field. J Therm Biol 2020; 87:102458. [DOI: 10.1016/j.jtherbio.2019.102458] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 11/02/2019] [Accepted: 11/18/2019] [Indexed: 12/20/2022]
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Velasco ER, Florido A, Milad MR, Andero R. Sex differences in fear extinction. Neurosci Biobehav Rev 2019; 103:81-108. [PMID: 31129235 DOI: 10.1016/j.neubiorev.2019.05.020] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 03/08/2019] [Accepted: 05/19/2019] [Indexed: 12/18/2022]
Abstract
Despite the exponential increase in fear research during the last years, few studies have included female subjects in their design. The need to include females arises from the knowledge gap of mechanistic processes underlying the behavioral and neural differences observed in fear extinction. Moreover, the exact contribution of sex and hormones in relation to learning and behavior is still largely unknown. Insights from this field could be beneficial as fear-related disorders are twice as prevalent in women compared to men. Here, we review an up-to-date summary of animal and human studies in adulthood that report sex differences in fear extinction from a structural and functional approach. Furthermore, we describe how these factors could contribute to the observed sex differences in fear extinction during normal and pathological conditions.
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Affiliation(s)
- E R Velasco
- Institut de Neurociències, Universitat Autònoma de Barcelona, Spain
| | - A Florido
- Institut de Neurociències, Universitat Autònoma de Barcelona, Spain
| | - M R Milad
- Department of Psychiatry, University of Illinois at Chicago, USA
| | - R Andero
- Institut de Neurociències, Universitat Autònoma de Barcelona, Spain; CIBERSAM, Corporació Sanitaria Parc Taulí, Sabadell, Spain; Department of Psychobiology and Methodology of Health Sciences, Universitat Autònoma de Barcelona, Spain.
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Sase AS, Lombroso SI, Santhumayor BA, Wood RR, Lim CJ, Neve RL, Heller EA. Sex-Specific Regulation of Fear Memory by Targeted Epigenetic Editing of Cdk5. Biol Psychiatry 2019; 85:623-634. [PMID: 30661667 DOI: 10.1016/j.biopsych.2018.11.022] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 10/29/2018] [Accepted: 11/15/2018] [Indexed: 10/27/2022]
Abstract
BACKGROUND Sex differences in the expression and prevalence of trauma- and stress-related disorders have led to a growing interest in the sex-specific molecular and epigenetic mechanisms underlying these diseases. Cyclin-dependent kinase 5 (CDK5) is known to underlie both fear memory and stress behavior in male mice. Given our recent finding that targeted histone acetylation of Cdk5 regulates stress responsivity in male mice, we hypothesized that such a mechanism may be functionally relevant in female mice as well. METHODS We applied epigenetic editing of Cdk5 in the hippocampus and examined the regulation of fear memory retrieval in male and female mice. Viral expression of zinc finger proteins targeting histone acetylation to the Cdk5 promoter was paired with a quantification of learning and memory of contextual fear conditioning, expression of CDK5, and enrichment of histone modifications of the Cdk5 gene. RESULTS We found that male mice exhibit stronger long-term memory retrieval than do female mice, and this finding was associated with male-specific epigenetic activation of hippocampal Cdk5 expression. Sex differences in behavior and epigenetic regulation of Cdk5 occurred after long-term, but not short-term, fear memory retrieval. Finally, targeted histone acetylation of hippocampal Cdk5 promoter attenuated fear memory retrieval and increased tau phosphorylation in female but not male mice. CONCLUSIONS Epigenetic editing uncovered a female-specific role of Cdk5 activation in attenuating fear memory retrieval. This finding may be attributed to CDK5 mediated hyperphosphorylation of tau only in the female hippocampus. Sex-specific epigenetic regulation of Cdk5 may reflect differences in the effect of CDK5 on downstream target proteins that regulate memory.
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Affiliation(s)
- Ajinkya S Sase
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Sonia I Lombroso
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Brandon A Santhumayor
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Rozalyn R Wood
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Carissa J Lim
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Rachael L Neve
- Gene Delivery Technology Core, Massachusetts General Hospital, Boston, Massachusetts
| | - Elizabeth A Heller
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania; Penn Epigenetics Institute, University of Pennsylvania, Philadelphia, Pennsylvania.
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Hale MW, Lukkes JL, Dady KF, Kelly KJ, Paul ED, Smith DG, Heinze JD, Raison CL, Lowry CA. Interactions between whole-body heating and citalopram on body temperature, antidepressant-like behaviour, and neurochemistry in adolescent male rats. Behav Brain Res 2019; 359:428-439. [DOI: 10.1016/j.bbr.2018.11.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 10/26/2018] [Accepted: 11/19/2018] [Indexed: 10/27/2022]
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Conrad CD, Ortiz JB, Judd JM. Chronic stress and hippocampal dendritic complexity: Methodological and functional considerations. Physiol Behav 2016; 178:66-81. [PMID: 27887995 DOI: 10.1016/j.physbeh.2016.11.017] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 11/16/2016] [Accepted: 11/18/2016] [Indexed: 12/30/2022]
Abstract
The current understanding of how chronic stress impacts hippocampal dendritic arbor complexity and the subsequent relationship to hippocampal-dependent spatial memory is reviewed. A surge in reports investigating hippocampal dendritic morphology is occurring, but with wide variations in methodological detail being reported. Consequently, this review systematically outlines the basic neuroanatomy of relevant hippocampal features to help clarify how chronic stress or glucocorticoids impact hippocampal dendritic complexity and how these changes occur in parallel with spatial cognition. Chronic stress often leads to hippocampal CA3 apical dendritic retraction first with other hippocampal regions (CA3 basal dendrites, CA1, dentate gyrus, DG) showing dendritic retraction when chronic stress is sufficiently robust or long lasting. The stress-induced reduction in hippocampal CA3 apical dendritic arbor complexity often coincides with impaired hippocampal function, such as spatial learning and memory. Yet, when chronic stress ends and a post-stress recovery period ensues, the atrophied dendritic arbors and poor spatial abilities often improve. However, this process differs from a simple reversal of chronic stress-induced deficits. Recent reports suggest that this return to baseline-like functioning is uniquely different from non-stressed controls, emphasizing the need for further studies to enhance our understanding of how a history of stress subsequently alters an organism's spatial abilities. To provide a consistent framework for future studies, this review concludes with an outline for a quick and easy reference on points to consider when planning chronic stress studies with the goal of measuring hippocampal dendritic complexity and spatial ability.
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Affiliation(s)
- Cheryl D Conrad
- Department of Psychology, Arizona State University, Box 1104, Tempe, AZ 85287-1104, United States.
| | - J Bryce Ortiz
- Department of Psychology, Arizona State University, Box 1104, Tempe, AZ 85287-1104, United States
| | - Jessica M Judd
- Department of Psychology, Arizona State University, Box 1104, Tempe, AZ 85287-1104, United States
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Farrell MR, Gruene TM, Shansky RM. The influence of stress and gonadal hormones on neuronal structure and function. Horm Behav 2015; 76:118-24. [PMID: 25819727 PMCID: PMC4583315 DOI: 10.1016/j.yhbeh.2015.03.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 03/11/2015] [Accepted: 03/19/2015] [Indexed: 11/27/2022]
Abstract
This article is part of a Special Issue "SBN 2014". The brain is highly plastic, allowing us to adapt and respond to environmental and physiological challenges and experiences. In this review, we discuss the relationships among alterations in dendritic arborization, spine morphology, and behavior due to stress exposure, endogenous hormone fluctuation, or exogenous hormonal manipulation. Very few studies investigate structure-function associations directly in the same cohort of animals, and there are notable inconsistencies in evidence of structure-function relationships in the prefrontal cortex and hippocampus. Moreover, little work has been done to probe the causal relationship between dendritic morphology and neuronal excitability, leaving only speculation about the adaptive versus maladaptive nature of experience-dependent dendritic remodeling. We propose that future studies combine electrophysiology with a circuit-level approach to better understand how dendritic structure contributes to neuronal functional properties and behavioral outcomes.
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Affiliation(s)
| | - Tina M Gruene
- Department of Psychology, Northeastern University, USA
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Gruene TM, Roberts E, Thomas V, Ronzio A, Shansky RM. Sex-specific neuroanatomical correlates of fear expression in prefrontal-amygdala circuits. Biol Psychiatry 2015; 78:186-93. [PMID: 25579850 PMCID: PMC4449316 DOI: 10.1016/j.biopsych.2014.11.014] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 11/03/2014] [Accepted: 11/17/2014] [Indexed: 12/11/2022]
Abstract
BACKGROUND The neural projections from the infralimbic region of the prefrontal cortex to the amygdala are important for the maintenance of conditioned fear extinction. Neurons in this pathway exhibit a unique pattern of structural plasticity that is sex-dependent, but the relationship between the morphologic characteristics of these neurons and successful extinction in male and female subjects is unknown. METHODS Using classic cued fear conditioning and an extinction paradigm in large cohorts of male and female rats, we identified subpopulations of both sexes that exhibited high (HF) or low (LF) levels of freezing on an extinction retrieval test, representing failed or successful extinction maintenance, respectively. We combined retrograde tracing with fluorescent intracellular microinjections to perform three-dimensional reconstructions of infralimbic neurons that project to the basolateral amygdala in these groups. RESULTS The HF and LF male rats exhibited neuroanatomical distinctions that were not observed in HF or LF female rats. A retrospective analysis of behavior during fear conditioning and extinction revealed that despite no overall sex differences in freezing behavior, HF and LF phenotypes emerged in male rats during extinction and in female rats during fear conditioning, which does not involve infralimbic-basolateral amygdala neurons. CONCLUSIONS Our results suggest that the neural processes underlying successful or failed extinction maintenance may be sex-specific. These findings are relevant not only to future basic research on sex differences in fear conditioning and extinction but also to exposure-based clinical therapies, which are similar in premise to fear extinction and which are primarily used to treat disorders that are more common in women than in men.
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Shansky RM. Sex differences in PTSD resilience and susceptibility: Challenges for animal models of fear learning. Neurobiol Stress 2015; 1:60-65. [PMID: 25729759 PMCID: PMC4340080 DOI: 10.1016/j.ynstr.2014.09.005] [Citation(s) in RCA: 125] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 09/13/2014] [Accepted: 09/22/2014] [Indexed: 12/15/2022] Open
Abstract
PTSD occurs in only a small fraction of trauma-exposed individuals, but risk is twice as high in women as in men. The neurobiological basis for this discrepancy is not known, but the identification of biological determinants of resilience and susceptibility in each sex could lead to more targeted preventions and treatments. Animal models are a useful tool for dissecting the circuits and mechanisms that underlie the brain's response to stress, but the vast majority of this work has been developed and conducted in males. The limited work that does incorporate female animals is often inconsistent across labs and does not broadly reflect human populations in terms of female susceptibility to PTSD-like behaviors. In this review, we suggest that interpreting male vs. female comparisons in these models be approached carefully, since common behavioral outcome measures may in fact reflect distinct neural processes. Moreover, since the factors that determine resilience and susceptibility are likely at least in part distinct in men and women, models that take a within-sex approach to response variability may be more useful in identifying critical mechanisms for manipulation.
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Affiliation(s)
- Rebecca M. Shansky
- Department of Psychology, Northeastern University, 360 Huntington Ave, 125 NI, Boston, MA 02115, USA
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