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Gouws JM, Sherrington A, Zheng S, Kim JS, Iremonger KJ. Regulation of corticotropin-releasing hormone neuronal network activity by noradrenergic stress signals. J Physiol 2022; 600:4347-4359. [PMID: 36040213 PMCID: PMC9825848 DOI: 10.1113/jp283328] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 08/26/2022] [Indexed: 01/11/2023] Open
Abstract
Noradrenaline is a neurotransmitter released in response to homeostatic challenge and activates the hypothalamic-pituitary-adrenal axis via stimulation of corticotropin-releasing hormone (CRH) neurons. Here we investigated the mechanism through which noradrenaline regulates activity within the CRH neuronal network. Using a combination of in vitro GCaMP6f Ca2+ imaging and electrophysiology, we show that noradrenaline induces a robust increase in excitability in a proportion of CRH neurons with many neurons displaying a bursting mode of activity. Noradrenaline-induced activation required α1 -adrenoceptors and L-type voltage-gated Ca2+ channels, but not GABA/glutamate synaptic transmission or sodium action potentials. Exposure of mice to elevated corticosterone levels was able to suppress noradrenaline-induced activation. These results provide further insight into the mechanisms by which noradrenaline regulates CRH neural network activity and hence stress responses. KEY POINTS: GCaMP6f Ca2+ imaging and on-cell patch-clamp recordings reveal that corticotropin-releasing hormone neurons are activated by noradrenaline with many neurons displaying a bursting mode of activity. Noradrenaline-induced activation requires α1 -adrenoceptors. Noradrenaline-induced Ca2+ elevations persist after blocking GABAA , AMPA, NMDA receptors and voltage-gated Na+ channels. Noradrenaline-induced Ca2+ elevations require L-type voltage-gated Ca2+ channels. Corticosterone suppresses noradrenaline-induced excitation.
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Affiliation(s)
- Julia M. Gouws
- Centre for Neuroendocrinology, Department of Physiology, School of Biomedical SciencesUniversity of OtagoDunedinOtagoNew Zealand
| | - Aidan Sherrington
- Centre for Neuroendocrinology, Department of Physiology, School of Biomedical SciencesUniversity of OtagoDunedinOtagoNew Zealand
| | - Shaojie Zheng
- Centre for Neuroendocrinology, Department of Physiology, School of Biomedical SciencesUniversity of OtagoDunedinOtagoNew Zealand
| | - Joon S. Kim
- Centre for Neuroendocrinology, Department of Physiology, School of Biomedical SciencesUniversity of OtagoDunedinOtagoNew Zealand
| | - Karl J. Iremonger
- Centre for Neuroendocrinology, Department of Physiology, School of Biomedical SciencesUniversity of OtagoDunedinOtagoNew Zealand
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Chronic corticosterone exposure impairs emotional regulation and cognitive function through disturbing neural oscillations in mice. Behav Brain Res 2022; 434:114030. [DOI: 10.1016/j.bbr.2022.114030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 05/17/2022] [Accepted: 07/27/2022] [Indexed: 11/23/2022]
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Ichiyama A, Mestern S, Benigno GB, Scott KE, Allman BL, Muller L, Inoue W. State-dependent activity dynamics of hypothalamic stress effector neurons. eLife 2022; 11:76832. [PMID: 35770968 PMCID: PMC9278954 DOI: 10.7554/elife.76832] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 06/17/2022] [Indexed: 11/30/2022] Open
Abstract
The stress response necessitates an immediate boost in vital physiological functions from their homeostatic operation to an elevated emergency response. However, the neural mechanisms underlying this state-dependent change remain largely unknown. Using a combination of in vivo and ex vivo electrophysiology with computational modeling, we report that corticotropin releasing hormone (CRH) neurons in the paraventricular nucleus of the hypothalamus (PVN), the effector neurons of hormonal stress response, rapidly transition between distinct activity states through recurrent inhibition. Specifically, in vivo optrode recording shows that under non-stress conditions, CRHPVN neurons often fire with rhythmic brief bursts (RB), which, somewhat counterintuitively, constrains firing rate due to long (~2 s) interburst intervals. Stressful stimuli rapidly switch RB to continuous single spiking (SS), permitting a large increase in firing rate. A spiking network model shows that recurrent inhibition can control this activity-state switch, and more broadly the gain of spiking responses to excitatory inputs. In biological CRHPVN neurons ex vivo, the injection of whole-cell currents derived from our computational model recreates the in vivo-like switch between RB and SS, providing direct evidence that physiologically relevant network inputs enable state-dependent computation in single neurons. Together, we present a novel mechanism for state-dependent activity dynamics in CRHPVN neurons.
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Plasticity of intrinsic excitability across the estrous cycle in hypothalamic CRH neurons. Sci Rep 2021; 11:16700. [PMID: 34404890 PMCID: PMC8371084 DOI: 10.1038/s41598-021-96341-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 08/02/2021] [Indexed: 02/07/2023] Open
Abstract
Stress responses are highly plastic and vary across physiological states. The female estrous cycle is associated with a number of physiological changes including changes in stress responses, however, the mechanisms driving these changes are poorly understood. Corticotropin-releasing hormone (CRH) neurons are the primary neural population controlling the hypothalamic-pituitary-adrenal (HPA) axis and stress-evoked corticosterone secretion. Here we show that CRH neuron intrinsic excitability is regulated over the estrous cycle with a peak in proestrus and a nadir in estrus. Fast inactivating voltage-gated potassium channel (IA) currents showed the opposite relationship, with current density being lowest in proestrus compared to other cycle stages. Blocking IA currents equalized excitability across cycle stages revealing a role for IA in mediating plasticity in stress circuit function over the female estrous cycle.
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Wang Y, Hu P, Shan Q, Huang C, Huang Z, Chen P, Li A, Gong H, Zhou JN. Single-cell morphological characterization of CRH neurons throughout the whole mouse brain. BMC Biol 2021; 19:47. [PMID: 33722214 PMCID: PMC7962243 DOI: 10.1186/s12915-021-00973-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 02/01/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Corticotropin-releasing hormone (CRH) is an important neuromodulator that is widely distributed in the brain and plays a key role in mediating stress responses and autonomic functions. While the distribution pattern of fluorescently labeled CRH-expressing neurons has been studied in different transgenic mouse lines, a full appreciation of the broad diversity of this population and local neural connectivity can only come from integration of single-cell morphological information as a defining feature. However, the morphologies of single CRH neurons and the local circuits formed by these neurons have not been acquired at brain-wide and dendritic-scale levels. RESULTS We screened the EYFP-expressing CRH-IRES-Cre;Ai32 mouse line to reveal the morphologies of individual CRH neurons throughout the whole mouse brain by using a fluorescence micro-optical sectioning tomography (fMOST) system. Diverse dendritic morphologies and projection fibers of CRH neurons were found in various brain regions. Follow-up reconstructions showed that hypothalamic CRH neurons had the smallest somatic volumes and simplest dendritic branches and that CRH neurons in several brain regions shared a common bipolar morphology. Further investigations of local CRH neurons in the medial prefrontal cortex unveiled somatic depth-dependent morphologies of CRH neurons that exhibited three types of mutual connections: basal dendrites (upper layer) with apical dendrites (layer 3); dendritic-somatic connections (in layer 2/3); and dendritic-dendritic connections (in layer 4). Moreover, hypothalamic CRH neurons were classified into two types according to their somatic locations and characteristics of dendritic varicosities. Rostral-projecting CRH neurons in the anterior parvicellular area had fewer and smaller dendritic varicosities, whereas CRH neurons in the periventricular area had more and larger varicosities that were present within dendrites projecting to the third ventricle. Arborization-dependent dendritic spines of CRH neurons were detected, among which the most sophisticated types were found in the amygdala and the simplest types were found in the hypothalamus. CONCLUSIONS By using the CRH-IRES-Cre;Ai32 mouse line and fMOST imaging, we obtained region-specific morphological distributions of CRH neurons at the dendrite level in the whole mouse brain. Taken together, our findings provide comprehensive brain-wide morphological information of stress-related CRH neurons and may facilitate further studies of the CRH neuronal system.
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Affiliation(s)
- Yu Wang
- Chinese Academy of Science Key Laboratory of Brain Function and Diseases, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
| | - Pu Hu
- Chinese Academy of Science Key Laboratory of Brain Function and Diseases, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
| | - Qinghong Shan
- Chinese Academy of Science Key Laboratory of Brain Function and Diseases, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
| | - Chuan Huang
- Chinese Academy of Science Key Laboratory of Brain Function and Diseases, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
| | - Zhaohuan Huang
- Chinese Academy of Science Key Laboratory of Brain Function and Diseases, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
| | - Peng Chen
- Chinese Academy of Science Key Laboratory of Brain Function and Diseases, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
| | - Anan Li
- Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China.,Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Hui Gong
- Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China. .,Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Huazhong University of Science and Technology, Wuhan, 430074, China.
| | - Jiang-Ning Zhou
- Chinese Academy of Science Key Laboratory of Brain Function and Diseases, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China. .,Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China.
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Corticosterone Attenuates Reward-Seeking Behavior and Increases Anxiety via D2 Receptor Signaling in Ventral Tegmental Area Dopamine Neurons. J Neurosci 2021; 41:1566-1581. [PMID: 33372063 PMCID: PMC7896015 DOI: 10.1523/jneurosci.2533-20.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 12/08/2020] [Accepted: 12/14/2020] [Indexed: 01/13/2023] Open
Abstract
Corticosteroids (CORT) have been widely used in anti-inflammatory medication. Chronic CORT treatment can cause mesocorticolimbic system dysfunctions, which are known to play a key role for the development of psychiatric disorders. The VTA is a critical site in the mesocorticolimbic pathway and is responsible for motivation and reward-seeking behaviors. However, the mechanism by which chronic CORT alters VTA dopamine neuronal activity is largely unknown. We treated periadolescent male mice with vehicle, 1 d, or 7 d CORT in the drinking water, examined behavioral impacts with light/dark box, elevated plus maze, operant chamber, and open field tests, measured the effects of CORT on VTA dopamine neuronal activity using patch-clamp electrophysiology and dopamine concentration using fast-scan cyclic voltammetry, and tested the effects of dopamine D2 receptor (D2R) blockade by intra-VTA infusion of a D2R antagonist. CORT treatment induced anxiety-like behavior as well as decreased food-seeking behaviors. We show that chronic CORT treatment decreased excitability and excitatory synaptic transmission onto VTA dopamine neurons. Furthermore, chronic CORT increased somatodendritic dopamine concentration. The D2R antagonist sulpiride restored decreased excitatory transmission and excitability of VTA dopamine neurons. Furthermore, sulpiride decreased anxiety-like behavior and rescued food-seeking behavior in mice with chronic CORT exposure. Together, 7 d CORT treatment induces anxiety-like behavior and impairs food-seeking in a mildly aversive environment. D2R signaling in the VTA might be a potential target to ameliorate chronic CORT-induced anxiety and reward-seeking deficits. SIGNIFICANCE STATEMENT With widespread anti-inflammatory effects throughout the body, corticosteroids (CORT) have been used in a variety of therapeutic conditions. However, long-term CORT treatment causes cognitive impairments and neuropsychiatric disorders. The impact of chronic CORT on the mesolimbic system has not been elucidated. Here, we demonstrate that 7 d CORT treatment increases anxiety-like behavior and attenuates food-seeking behavior in a mildly aversive environment. By elevating local dopamine concentration in the VTA, a region important for driving motivated behavior, CORT treatment suppresses excitability and synaptic transmission onto VTA dopamine neurons. Intriguingly, blockade of D2 receptor signaling in the VTA restores neuronal excitability and food-seeking and alleviates anxiety-like behaviors. Our findings provide a potential therapeutic target for CORT-induced reward deficits.
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Matovic S, Ichiyama A, Igarashi H, Salter EW, Sunstrum JK, Wang XF, Henry M, Kuebler ES, Vernoux N, Martinez-Trujillo J, Tremblay ME, Inoue W. Neuronal hypertrophy dampens neuronal intrinsic excitability and stress responsiveness during chronic stress. J Physiol 2020; 598:2757-2773. [PMID: 32347541 DOI: 10.1113/jp279666] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 04/17/2020] [Indexed: 01/16/2023] Open
Abstract
KEY POINTS The hypothalamic-pituitary-adrenal (HPA) axis habituates to repeated stress exposure. We studied hypothalamic corticotropin-releasing hormone (CRH) neurons that form the apex of the HPA axis in a mouse model of stress habituation using repeated restraint. The intrinsic excitability of CRH neurons decreased after repeated stress in a time course that coincided with the development of HPA axis habituation. This intrinsic excitability plasticity co-developed with an expansion of surface membrane area, which increased a passive electric load and dampened membrane depolarization in response to the influx of positive charge. We report a novel structure-function relationship for intrinsic excitability plasticity as a neural correlate for HPA axis habituation. ABSTRACT Encountering a stressor immediately activates the hypothalamic-pituitary-adrenal (HPA) axis, but this stereotypic stress response also undergoes experience-dependent adaptation. Despite the biological and clinical importance, how the brain adjusts stress responsiveness in the long term remains poorly understood. We studied hypothalamic corticotropin-releasing hormone neurons that form the apex of the HPA axis in a mouse model of stress habituation using repeated restraint. Using patch-clamp electrophysiology in acute slices, we found that the intrinsic excitability of these neurons substantially decreased after daily repeated stress in a time course that coincided with their loss of stress responsiveness in vivo. This intrinsic excitability plasticity co-developed with an expansion of surface membrane area, which increased a passive electric load, and dampened membrane depolarization in response to the influx of positive charge. Multiphoton imaging and electron microscopy revealed that repeated stress augmented ruffling of the plasma membrane, suggesting an ultrastructural plasticity that may efficiently accommodate the membrane area expansion. Overall, we report a novel structure-function relationship for intrinsic excitability plasticity as a neural correlate for adaptation of the neuroendocrine stress response.
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Affiliation(s)
- Sara Matovic
- Robarts Research Institute, University of Western Ontario.,Neuroscience Program, University of Western Ontario
| | - Aoi Ichiyama
- Neuroscience Program, University of Western Ontario
| | | | - Eric W Salter
- Robarts Research Institute, University of Western Ontario.,Current address: University of Toronto
| | | | - Xue Fan Wang
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario
| | - Mathilde Henry
- Axe Neurosciences, CRCHU de Quebec-Université Laval.,Current address: INRAE, Univ. Bordeaux, Bordeaux INP, Nutrineuro, UMR 1286, Bordeaux, F-33000, France
| | - Eric S Kuebler
- Robarts Research Institute, University of Western Ontario
| | | | - Julio Martinez-Trujillo
- Robarts Research Institute, University of Western Ontario.,Neuroscience Program, University of Western Ontario.,Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario
| | - Marie-Eve Tremblay
- Axe Neurosciences, CRCHU de Quebec-Université Laval.,Département de médecine moléculaire, Université Laval.,Division of Medical Sciences, University of Victoria
| | - Wataru Inoue
- Robarts Research Institute, University of Western Ontario.,Neuroscience Program, University of Western Ontario.,Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario
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Focke CMB, Iremonger KJ. Rhythmicity matters: Circadian and ultradian patterns of HPA axis activity. Mol Cell Endocrinol 2020; 501:110652. [PMID: 31738971 DOI: 10.1016/j.mce.2019.110652] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 10/29/2019] [Accepted: 11/11/2019] [Indexed: 12/15/2022]
Abstract
Oscillations are a fundamental feature of neural and endocrine systems. The hypothalamic-pituitary-adrenal (HPA) axis dynamically controls corticosteroid secretion in basal conditions and in response to stress. Across the 24-h day, HPA axis activity oscillates with both an ultradian and circadian rhythm. These rhythms have been shown to be important for regulating metabolism, inflammation, mood, cognition and stress responsiveness. Here we will discuss the neural and endocrine mechanisms driving these rhythms, the physiological importance of these rhythms and health consequences when they are disrupted.
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Affiliation(s)
- Caroline M B Focke
- Centre for Neuroendocrinology, Department of Physiology, University of Otago, Dunedin, New Zealand
| | - Karl J Iremonger
- Centre for Neuroendocrinology, Department of Physiology, University of Otago, Dunedin, New Zealand.
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Stress experience and hormone feedback tune distinct components of hypothalamic CRH neuron activity. Nat Commun 2019; 10:5696. [PMID: 31836701 PMCID: PMC6911111 DOI: 10.1038/s41467-019-13639-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 11/11/2019] [Indexed: 11/09/2022] Open
Abstract
Stress leaves a lasting impression on an organism and reshapes future responses. However, the influence of past experience and stress hormones on the activity of neural stress circuits remains unclear. Hypothalamic corticotropin-releasing hormone (CRH) neurons orchestrate behavioral and endocrine responses to stress and are themselves highly sensitive to corticosteroid (CORT) stress hormones. Here, using in vivo optical recordings, we find that CRH neurons are rapidly activated in response to stress. CRH neuron activity robustly habituates to repeated presentations of the same, but not novel stressors. CORT feedback has little effect on CRH neuron responses to acute stress, or on habituation to repeated stressors. Rather, CORT preferentially inhibits tonic CRH neuron activity in the absence of stress stimuli. These findings reveal how stress experience and stress hormones modulate distinct components of CRH neuronal activity to mediate stress-induced adaptations. Stress activates corticotropin-releasing hormone (CRH) neurons in the hypothalamus, but how their activity is regulated during and after stress is unclear. Here, the authors show that stress habituation and corticosteroid feedback tune different components of CRH neuron activity.
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Kim JS, Iremonger KJ. Temporally Tuned Corticosteroid Feedback Regulation of the Stress Axis. Trends Endocrinol Metab 2019; 30:783-792. [PMID: 31699237 DOI: 10.1016/j.tem.2019.07.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 05/23/2019] [Accepted: 07/08/2019] [Indexed: 01/28/2023]
Abstract
Activity of the hypothalamic-pituitary-adrenal (HPA) axis is tuned by corticosteroid feedback. Corticosteroids regulate cellular function via genomic and nongenomic mechanisms, which operate over diverse time scales. This review summarizes recent advances in our understanding of how corticosteroid feedback regulates hypothalamic stress neuron function and output through synaptic plasticity, changes in intrinsic excitability, and modulation of neuropeptide production. The temporal kinetics of corticosteroid actions in the brain versus the pituitary have important implications for how organisms respond to stress. Furthermore, we will discuss, some of the technical limitations and missing links in the field, and the potential implications these may have on our interpretations of corticosteroid negative feedback experiments.
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Affiliation(s)
- Joon S Kim
- Centre for Neuroendocrinology, Department of Physiology, University of Otago, Dunedin, New Zealand
| | - Karl J Iremonger
- Centre for Neuroendocrinology, Department of Physiology, University of Otago, Dunedin, New Zealand.
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