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Abstract
The central noradrenergic system comprises multiple brainstem nuclei whose cells synthesize and release the catecholamine transmitter norepinephrine (NE). The largest of these nuclei is the pontine locus coeruleus (LC), which innervates the vast majority of the forebrain. NE interacts with a number of pre- and postsynaptically expressed G protein-coupled receptors to affect a wide array of functions, including sensory signal processing, waking and arousal, stress responsiveness, mood, attention, and memory. Given the myriad functions ascribed to the locus coeruleus-noradrenergic (LC-NE) system, it is unsurprising that it is implicated in many disease states, including various mood, cognitive, neuropsychiatric, and neurodegenerative diseases. The LC-NE system is also notably sexually dimorphic with regard to its morphologic and anatomical features as well as how it responds to the peptide transmitter corticotropin releasing hormone (CRH), a major mediator of the central stress response. The sex-biased morphology and signaling that is observed in the LC could then be considered a potential contributor to the differential prevalence of various diseases between men and women. This chapter summarizes the primary differences between the male and female LC, based primarily on preclinical observations and how these disparities may relate to differential diagnoses of several diseases between men and women.
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Affiliation(s)
- Neal Joshi
- Department of Cell Biology and Neuroscience, Rowan University School of Osteopathic Medicine, Stratford, NJ, United States
| | - Daniel Chandler
- Department of Cell Biology and Neuroscience, Rowan University School of Osteopathic Medicine, Stratford, NJ, United States.
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Role of orexin type-1 receptors in paragiganto-coerulear modulation of opioid withdrawal and tolerance: A site specific focus. Neuropharmacology 2017; 126:25-37. [DOI: 10.1016/j.neuropharm.2017.08.024] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Revised: 08/13/2017] [Accepted: 08/16/2017] [Indexed: 11/21/2022]
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Valentino RJ, Bangasser DA. Sex-biased cellular signaling: molecular basis for sex differences in neuropsychiatric diseases. DIALOGUES IN CLINICAL NEUROSCIENCE 2017. [PMID: 28179810 PMCID: PMC5286724 DOI: 10.31887/dcns.2016.18.4/rvalentino] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The recognition that there are fundamental biological sex differences that extend beyond those that define sexual behavior and reproductive function has inspired the drive toward inclusion of both sexes in research design. This is supported by an underlying clinical rationale that studying both sexes is necessary to elucidate pathophysiology and develop treatments for the entire population. However, at a more basic level, sex differences, like genetic differences, can be exploited to better understand biology. Here, we discuss how sex differences at the molecular level of cell signaling and protein trafficking are amplified to create a state of vulnerability that under the right conditions can result in symptoms of neuropsychiatry disease. Although this dialogue focuses on the specific example of corticotropin-releasing factor, the potential for analogous sex differences in signaling and/or trafficking of receptors for other neuromodulators has broad biological and therapeutic implications.
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Affiliation(s)
- Rita J Valentino
- Department of Anesthesiology and Critical Care Medicine, The Children's Hospital of Philadelphia and University of Pennsylvania, USA
| | - Debra A Bangasser
- Department of Psychology and Neuroscience Program, Temple University, USA
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Sex differences in the locus coeruleus-norepinephrine system and its regulation by stress. Brain Res 2015; 1641:177-88. [PMID: 26607253 DOI: 10.1016/j.brainres.2015.11.021] [Citation(s) in RCA: 152] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 10/27/2015] [Accepted: 11/12/2015] [Indexed: 12/26/2022]
Abstract
Women are more likely than men to suffer from post-traumatic stress disorder (PTSD) and major depression. In addition to their sex bias, these disorders share stress as an etiological factor and hyperarousal as a symptom. Thus, sex differences in brain arousal systems and their regulation by stress could help explain increased vulnerability to these disorders in women. Here we review preclinical studies that have identified sex differences in the locus coeruleus (LC)-norepinephrine (NE) arousal system. First, we detail how structural sex differences in the LC can bias females towards increased arousal in response to emotional events. Second, we highlight studies demonstrating that estrogen can increase NE in LC target regions by enhancing the capacity for NE synthesis, while reducing NE degradation, potentially increasing arousal in females. Third, we review data revealing how sex differences in the stress receptor, corticotropin releasing factor 1 (CRF1), can increase LC neuronal sensitivity to CRF in females compared to males. This effect could translate into hyperarousal in women under conditions of CRF hypersecretion that occur in PTSD and depression. The implications of these sex differences for the treatment of stress-related psychiatric disorders are discussed. Moreover, the value of using information regarding biological sex differences to aid in the development of novel pharmacotherapies to better treat men and women with PTSD and depression is also highlighted. This article is part of a Special Issue entitled SI: Noradrenergic System.
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Chapman CR, Bradshaw DH, Donaldson GW, Jacobson RC, Nakamura Y. Central noradrenergic mechanisms and the acute stress response during painful stimulation. J Psychopharmacol 2014; 28:1135-42. [PMID: 25122041 DOI: 10.1177/0269881114543718] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Events that threaten tissue integrity including noxious stimulation activate central noradrenergic circuits, particularly locus coeruleus and its projections. Recent advances in theory hold that an adaptive, defensive shift in brain activity takes place in response to threat. In principle, this shift may accentuate the autonomic and central biomarkers of the perception of painful events and the experience of pain itself. We have examined the effects of an alpha-2 agonist on pupil dilation responses, skin conductance responses, near field somatosensory evoked potentials and pain reports in normal volunteers undergoing repeated trials of painful fingertip stimulation delivered at low, medium and high intensities. In a double-blinded study, 114 healthy male and female volunteers underwent repeated noxious stimulation under baseline, placebo and active drug conditions where the active drug was the alpha-2 agonist tizanidine 4 mg. In contrast to baseline and placebo conditions, tizanidine 4 mg significantly reduced the magnitudes of the mean pupil dilation response, the mean skin conductance response, the mean near field somatosensory evoked potential peak-to-peak amplitude and the mean pain intensity rating. Stimulus intensity significantly altered all three biomarkers and the pain report in a graded fashion. There were no sex differences. These findings support the hypotheses that painful events activate central noradrenergic circuits, and that these circuits play a role in the autonomic and central arousal associated with pain.
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Affiliation(s)
- C Richard Chapman
- Department of Anesthesiology, Pain Research Center, University of Utah, Salt Lake City, UT, USA
| | - David H Bradshaw
- Department of Anesthesiology, Pain Research Center, University of Utah, Salt Lake City, UT, USA
| | - Gary W Donaldson
- Department of Anesthesiology, Pain Research Center, University of Utah, Salt Lake City, UT, USA
| | - Robert C Jacobson
- Department of Anesthesiology, Pain Research Center, University of Utah, Salt Lake City, UT, USA
| | - Yoshio Nakamura
- Department of Anesthesiology, Pain Research Center, University of Utah, Salt Lake City, UT, USA
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Reyes BAS, Bangasser DA, Valentino RJ, Van Bockstaele EJ. Using high resolution imaging to determine trafficking of corticotropin-releasing factor receptors in noradrenergic neurons of the rat locus coeruleus. Life Sci 2014; 112:2-9. [PMID: 25058917 DOI: 10.1016/j.lfs.2014.07.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 07/01/2014] [Accepted: 07/09/2014] [Indexed: 12/01/2022]
Abstract
Trafficking of G protein-coupled receptors (GPCRs) is a critical determinant of cellular sensitivity of neurons. To understand how endogenous or exogenous ligands impact cell surface expression of GPCRs, it is essential to employ approaches that achieve superior anatomical resolution at the synaptic level. In situations in which light and fluorescence microscopy techniques may provide only limited resolution, electron microscopy provides enhanced subcellular precision. Dual labeling immunohistochemistry employing visually distinct immunoperoxidase and immunogold markers has been an effective approach for elucidating complex receptor profiles at the synapse and to definitively establish the localization of individual receptors and neuromodulators to common cellular profiles. The immuno-electron microscopy approach offers the potential for determining membrane versus intracellular protein localization, as well as the association with various identifiable cellular organelles. Corticotropin-releasing factor (CRF) is an important regulator of endocrine, autonomic, immunological, behavioral and cognitive limbs of the stress response. Dysfunction of this neuropeptide system has been associated with several psychiatric disorders. This review summarizes findings from neuroanatomical studies, with superior spatial resolution, that indicate that the distribution of CRF receptors is a highly dynamic process that, in addition to being sexually dimorphic, involves complex regulation of receptor trafficking within extrasynaptic sites that have significant consequences for adaptations to stress, particularly within the locus coeruleus (LC), the major brain norepinephrine-containing nucleus.
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Affiliation(s)
- B A S Reyes
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States.
| | - D A Bangasser
- Psychology Department and Neuroscience Program, Temple University, Philadelphia, PA 19122, United States
| | - R J Valentino
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States
| | - E J Van Bockstaele
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States
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Chaijale NN, Curtis AL, Wood SK, Zhang XY, Bhatnagar S, Reyes BAS, Van Bockstaele EJ, Valentino RJ. Social stress engages opioid regulation of locus coeruleus norepinephrine neurons and induces a state of cellular and physical opiate dependence. Neuropsychopharmacology 2013; 38:1833-43. [PMID: 23660707 PMCID: PMC3746692 DOI: 10.1038/npp.2013.117] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 05/08/2013] [Accepted: 05/08/2013] [Indexed: 12/20/2022]
Abstract
Stress is implicated in diverse psychiatric disorders including substance abuse. The locus coeruleus-norepinephrine (LC-NE) system is a major stress response system that is also a point of intersection between stress neuromediators and endogenous opioids and so may be a site at which stress can influence drug-taking behaviors. As social stress is a common stressor for humans, this study characterized the enduring impact of repeated social stress on LC neuronal activity. Rats were exposed to five daily consecutive sessions of social stress using the resident-intruder model or control manipulation. LC discharge rate recorded 2 days after the last manipulation was decreased in stressed rats compared with controls. By 10 days after the last manipulation, LC rates were comparable between groups. Systemic administration of the opiate antagonist, naloxone, robustly increased LC discharge rate in a manner suggestive of opiate withdrawal, selectively in stressed rats when administered 2 or 10 days after the last manipulation. This was accompanied by behavioral signs of mild opiate withdrawal. Western blot and electron microscopic studies indicated that repeated social stress decreased corticotropin-releasing factor type 1 receptor and increased μ-opioid receptor levels in the LC. Together, the results suggest that repeated social stress engages endogenous opioid modulation of LC activity and induces signs of cellular and physical opiate dependence that endure after the stress. These cellular effects may predispose individuals with a history of repeated social stress to substance abuse behaviors.
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Affiliation(s)
- Nayla N Chaijale
- Division of Stress Neurobiology, Department of Anesthesiology, Abramson Research Center, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
| | - Andre L Curtis
- Division of Stress Neurobiology, Department of Anesthesiology, Abramson Research Center, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Susan K Wood
- Division of Stress Neurobiology, Department of Anesthesiology, Abramson Research Center, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Xiao-Yan Zhang
- Division of Stress Neurobiology, Department of Anesthesiology, Abramson Research Center, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Seema Bhatnagar
- Division of Stress Neurobiology, Department of Anesthesiology, Abramson Research Center, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Beverly AS Reyes
- Department of Neurosurgery, Thomas Jefferson University, Philadelphia, PA, USA
| | | | - Rita J Valentino
- Division of Stress Neurobiology, Department of Anesthesiology, Abramson Research Center, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
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George SA, Knox D, Curtis AL, Aldridge JW, Valentino RJ, Liberzon I. Altered locus coeruleus-norepinephrine function following single prolonged stress. Eur J Neurosci 2012; 37:901-9. [PMID: 23279008 DOI: 10.1111/ejn.12095] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Revised: 11/14/2012] [Accepted: 11/16/2012] [Indexed: 01/06/2023]
Abstract
Data from preclinical and clinical studies have implicated the norepinephrine system in the development and maintenance of post-traumatic stress disorder. The primary source of norepinephrine in the forebrain is the locus coeruleus (LC); however, LC activity cannot be directly measured in humans, and previous research has often relied upon peripheral measures of norepinephrine to infer changes in central LC-norepinephrine function. To directly assess LC-norepinephrine function, we measured single-unit activity of LC neurons in a validated rat model of post-traumatic stress disorder - single prolonged stress (SPS). We also examined tyrosine hydroxylase mRNA levels in the LC of SPS and control rats as an index of norepinephrine utilisation. For electrophysiological recordings, 92 LC neurons were identified from 19 rats (SPS, 12; control, 7), and spontaneous and evoked responses to a noxious event (paw compression) were recorded. Baseline and restraint stress-evoked tyrosine hydroxylase mRNA expression levels were measured in SPS and control rats (n = 16 per group) in a separate experiment. SPS rats showed lower spontaneous activity but higher evoked responses, leading to an enhanced signal-to-noise ratio of LC neurons, accompanied by impaired recovery from post-stimulus inhibition. In concert, tyrosine hydroxylase mRNA expression in the LC of SPS rats tended to be lower at baseline, but was exaggerated following restraint stress. These data demonstrate persistent changes in LC function following stress/trauma in a rat model of post-traumatic stress, as measured by differences in both the electrophysiological properties of LC neurons and tyrosine hydroxylase mRNA transcription.
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Affiliation(s)
- Sophie A George
- University of Michigan, Rachel Upjohn Building, 4250 Plymouth Rd (Box 5765), Ann Arbor, MI 48109-2700, USA.
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Hormigo S, Horta Júnior JDADCE, Gómez-Nieto R, López DE. The selective neurotoxin DSP-4 impairs the noradrenergic projections from the locus coeruleus to the inferior colliculus in rats. Front Neural Circuits 2012; 6:41. [PMID: 22754504 PMCID: PMC3385004 DOI: 10.3389/fncir.2012.00041] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Accepted: 06/12/2012] [Indexed: 11/30/2022] Open
Abstract
The inferior colliculus (IC) and the locus coeruleus (LC) are two midbrain nuclei that integrate multimodal information and play a major role in novelty detection to elicit an orienting response. Despite the reciprocal connections between these two structures, the projection pattern and target areas of the LC within the subdivisions of the rat IC are still unknown. Here, we used tract-tracing approaches combined with immunohistochemistry, densitometry, and confocal microscopy (CM) analysis to describe a projection from the LC to the IC. Biotinylated dextran amine (BDA) injections into the LC showed that the LC-IC projection is mainly ipsilateral (90%) and reaches, to a major extent, the dorsal and lateral part of the IC and the intercollicular commissure. Additionally, some LC fibers extend into the central nucleus of the IC. The neurochemical nature of this projection is noradrenergic, given that tyrosine hydroxylase (TH) and dopamine beta hydroxylase (DBH) colocalize with the BDA-labeled fibers from the LC. To determine the total field of the LC innervations in the IC, we destroyed the LC neurons and fibers using a highly selective neurotoxin, DSP-4, and then studied the distribution and density of TH- and DBH-immunolabeled axons in the IC. In the DSP-4 treated animals, the number of axonal fibers immunolabeled for TH and DBH were deeply decreased throughout the entire rostrocaudal extent of the IC and its subdivisions compared to controls. Our densitometry results showed that the IC receives up to 97% of its noradrenergic innervations from the LC neurons and only 3% from non-coeruleus neurons. Our results also indicate that TH immunoreactivity in the IC was less impaired than the immunoreactivity for DBH after DSP-4 administration. This is consistent with the existence of an important dopaminergic projection from the substantia nigra to the IC. In conclusion, our study demonstrates and quantifies the noradrenergic projection from the LC to the IC and its subdivisions. The re-examination of the TH and DBH immunoreactivity after DSP-4 treatment provides insights into the source, extent, and topographic distribution of the LC efferent network in the IC, and hence, contributes to our understanding of the role of the noradrenaline (NA) system in auditory processing.
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Affiliation(s)
- Sebastián Hormigo
- Institute for Neuroscience of Castilla y Leon, University of Salamanca Salamanca, Spain
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Bangasser DA, Valentino RJ. Sex differences in molecular and cellular substrates of stress. Cell Mol Neurobiol 2012; 32:709-23. [PMID: 22488525 DOI: 10.1007/s10571-012-9824-4] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 02/22/2012] [Indexed: 12/20/2022]
Abstract
Women are twice as likely as men to suffer from stress-related psychiatric disorders, like unipolar depression and post-traumatic stress disorder. Although the underlying neural mechanisms are not well characterized, the pivotal role of stress in the onset and severity of these diseases has led to the idea that sex differences in stress responses account for this sex bias. Corticotropin-releasing factor (CRF) orchestrates stress responses by acting both as a neurohormone to initiate the hypothalamic-pituitary-adrenal (HPA) axis and as a neuromodulator in the brain. One target of CRF modulation is the locus coeruleus (LC)-norepinephrine system, which coordinates arousal components of the stress response. Hypersecretion of CRF and dysregulation of targets downstream from CRF, such as the HPA axis and LC-norepinephrine system, are characteristic features of many stress-related psychiatric diseases, suggesting a causal role for CRF and its targets in the development of these disorders. This review will describe sex differences in CRF and the LC-norepinephrine system that can increase stress sensitivity in females, making them vulnerable to stress-related disorders. Evidence for gonadal hormone regulation of hypothalamic CRF is discussed as an effect that can lead to increased HPA axis activity in females. Sex differences in the structure of LC neurons that create the potential for hyperarousal in response to emotional stimuli are described. Finally, sex differences at the molecular level of the CRF(1) receptor that make the LC-norepinephrine system more reactive in females are reviewed. The implications of these sex differences for the treatment of stress-related psychiatric disorders also will be discussed.
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Affiliation(s)
- Debra A Bangasser
- Department of Anesthesiology and Critical Care Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
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Mapping patterns of depression-related brain regions with cytochrome oxidase histochemistry: Relevance of animal affective systems to human disorders, with a focus on resilience to adverse events. Neurosci Biobehav Rev 2011; 35:1876-89. [DOI: 10.1016/j.neubiorev.2011.02.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Revised: 02/24/2011] [Accepted: 02/25/2011] [Indexed: 12/28/2022]
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Van Bockstaele EJ, Reyes BAS, Valentino RJ. The locus coeruleus: A key nucleus where stress and opioids intersect to mediate vulnerability to opiate abuse. Brain Res 2010; 1314:162-74. [PMID: 19765557 PMCID: PMC3274960 DOI: 10.1016/j.brainres.2009.09.036] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 08/19/2009] [Accepted: 09/10/2009] [Indexed: 12/29/2022]
Abstract
The interaction between the stress axis and endogenous opioid systems has gained substantial clinical attention as it is increasingly recognized that stress predisposes to opiate abuse. For example, stress has been implicated as a risk factor in vulnerability to the initiation and maintenance of opiate abuse and is thought to play an important role in relapse in subjects with a history of abuse. Numerous reports indicating that stress alters individual sensitivity to opiates suggest that prior stress can influence the pharmacodynamics of opiates that are used in clinical settings. Conversely, the effects of opiates on different components of the stress axis can impact on individual responsivity to stressors and potentially predispose individuals to stress-related psychiatric disorders. One site at which opiates and stress substrates may interact to have global effects on behavior is within the locus coeruleus (LC), the major brain norepinephrine (NE)-containing nucleus. This review summarizes our current knowledge regarding the anatomical and neurochemical afferent regulation of the LC. It then presents physiological studies demonstrating opposing interactions between opioids and stress-related neuropeptides in the LC and summarizes results showing that chronic morphine exposure sensitizes the LC-NE system to corticotropin releasing factor and stress. Finally, new evidence for novel presynaptic actions of kappa-opioids on LC afferents is provided that adds another dimension to our model of how this central NE system is co-regulated by opioids and stress-related peptides.
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Affiliation(s)
- E J Van Bockstaele
- Department of Neurosurgery, Thomas Jefferson University, Farber Institute for Neurosciences, 900 Walnut Street, Suite 400, Philadelphia, PA 19107, USA.
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Reyes BAS, Valentino RJ, Van Bockstaele EJ. Stress-induced intracellular trafficking of corticotropin-releasing factor receptors in rat locus coeruleus neurons. Endocrinology 2008; 149:122-30. [PMID: 17947354 PMCID: PMC2194607 DOI: 10.1210/en.2007-0705] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Corticotropin-releasing factor (CRF) activates locus coeruleus (LC)-norepinephrine neurons during stress. Previous stress or CRF administration attenuates the magnitude of this response by decreasing postsynaptic sensitivity to CRF. Here we describe the fate of CRF receptors (CRFr) in LC neurons after stress. Rats were exposed to swim stress or handling and perfused 1 or 24 h later. Sections through the LC were processed for immunogold-silver labeling of CRFr. CRFr in LC dendrites was present on the plasma membrane and within the cytoplasm. In control rats, the ratio of cytoplasmic to total dendritic labeling was 0.55 +/- 0.01. Swim stress increased this ratio to 0.77 +/- 0.01 and 0.80 +/- 0.02 at 1 and 24 h after stress, respectively. Internalized CRFr was associated with different organelles at different times after stress. At 1 h after stress, CRFr was often associated with early endosomes in dendrites and perikarya. By 24 h, more CRFr was associated with multivesicular bodies, suggesting that some of the internalized receptor is targeted for degradation. In perikarya, more internalized CRFr was associated with Golgi apparatus 24 vs. 1 h after stress. This is suggestive of changes in CRFr synthesis. Alternatively, this may indicate communication between multivesicular bodies and Golgi apparatus in the process of recycling. Administration of the selective CRF(1) antagonist, antalarmin, before swim stress attenuated CRFr internalization. The present demonstration of stress-induced internalization of CRFr in LC neurons provides evidence that CRF is released in the LC during swim stress to activate this system and initiate cellular trafficking of the receptor that determines subsequent sensitivity of LC neurons to CRF.
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Affiliation(s)
- Beverly A S Reyes
- Department of Neurosurgery, Farber Institute for Neurosciences, Thomas Jefferson University, 900 Walnut Street, Suite 400, Philadelphia, Pennsylvania 19107, USA.
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Skelton KH, Oren D, Gutman DA, Easterling K, Holtzman SG, Nemeroff CB, Owens MJ. The CRF1 receptor antagonist, R121919, attenuates the severity of precipitated morphine withdrawal. Eur J Pharmacol 2007; 571:17-24. [PMID: 17610870 DOI: 10.1016/j.ejphar.2007.05.041] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Revised: 05/17/2007] [Accepted: 05/22/2007] [Indexed: 11/21/2022]
Abstract
Corticotropin-releasing factor (CRF) regulates the hypothalamic-pituitary-adrenal axis, coordinates the mammalian stress response, and acting primarily via the CRF(1) receptor, has been strongly implicated in the pathophysiology of depression and anxiety. Furthermore, the behavioral and autonomic activation that occurs following withdrawal in drug dependent animals resembles the mammalian stress response. Concordant with this view is evidence of enhanced CRF transcription, release and activity following withdrawal from several drugs of abuse. Conversely, CRF receptor antagonists have been demonstrated to reduce the severity of many drug withdrawal symptoms, implicating a specific role for activation of CRF neurons in mediating the anxiogenic and stress-like reactions observed during withdrawal. To extend these findings, we investigated whether pretreatment with a selective CRF(1) receptor antagonist, R121919, is capable of similarly decreasing the autonomic, behavioral and neuroendocrine activation observed following precipitation of morphine withdrawal in dependent rats. The results indicate that pretreatment with R121919 attenuates the global severity of the precipitated morphine withdrawal syndrome as measured by the Gellert-Holtzman scale. In addition, rats pretreated with R121919 prior to precipitation of morphine withdrawal demonstrated decreased hypothalamic-pituitary-adrenal axis activation, as measured by plasma ACTH concentrations, and decreased early expression of the CRF gene in the paraventricular nucleus of the hypothalamus, as measured by CRF heteronuclear RNA. These findings suggest that activation of CRF neuronal systems via the CRF(1) receptor may be one element of the neurobiological mechanisms activated during drug withdrawal and that CRF(1) receptor antagonists may have a potential therapeutic role in the treatment of human drug withdrawal syndromes.
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Affiliation(s)
- Kelly H Skelton
- Laboratory of Neuropsychopharmacology, Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, Georgia 30322 , USA.
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Miner LH, Jedema HP, Moore FW, Blakely RD, Grace AA, Sesack SR. Chronic stress increases the plasmalemmal distribution of the norepinephrine transporter and the coexpression of tyrosine hydroxylase in norepinephrine axons in the prefrontal cortex. J Neurosci 2006; 26:1571-8. [PMID: 16452680 PMCID: PMC6675488 DOI: 10.1523/jneurosci.4450-05.2006] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Norepinephrine (NE) potently modulates the cognitive and affective functions of the prefrontal cortex (PFC). Deficits in NE transmission are implicated in psychiatric disorders, and antidepressant drugs that block the NE transporter (NET) effectively treat these conditions. Our initial ultrastructural studies of the rat PFC revealed that most NE axons (85-90%) express NET primarily within the cytoplasm and lack detectable levels of the synthetic enzyme tyrosine hydroxylase (TH). In contrast, the remaining 10-15% of PFC NE axons exhibit predominantly plasmalemmal NET and evident TH immunoreactivity. These unusual characteristics suggest that most PFC NE axons have an unrecognized, latent capacity to enhance the synthesis and recovery of transmitter. In the present study, we used dual-labeling immunocytochemistry and electron microscopy to examine whether chronic cold stress, a paradigm that persistently increases NE activity, would trigger cellular changes consistent with this hypothesis. After chronic stress, neither the number of profiles exhibiting NET labeling nor their size was changed. However, the proportion of plasmalemmal NET nearly doubled from 29% in control animals to 51% in stressed rats. Moreover, the expression of detectable TH in NET-labeled axons increased from only 13% of profiles in control rats to 32% of profiles in stressed animals. Despite the consistency of these findings, the magnitude of the changes varied across individual rats. These data represent the first demonstration of activity-dependent trafficking of NET and expression of TH under physiological conditions and have important implications for understanding the pathophysiology and treatment of stress-related affective disorders.
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O'Donnell T, Hegadoren KM, Coupland NC. Noradrenergic mechanisms in the pathophysiology of post-traumatic stress disorder. Neuropsychobiology 2005; 50:273-83. [PMID: 15539856 DOI: 10.1159/000080952] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Post-traumatic stress disorder (PTSD) is a serious psychiatric illness that may develop in individuals after exposure to a traumatic event. Recent data suggest that trauma and/or long-term stressors can cause alterations in the functioning of neuroanatomical structures and neural networks throughout the central nervous system. Specifically, dysregulation in central and perhaps, peripheral noradrenergic neural networks has been implicated as the cause of specific symptom clusters in the pathophysiology of PTSD. In this review, both clinical and preclinical data are presented to highlight types of noradrenergic dysfunction observed in individuals with PTSD. Additionally, the role of noradrenaline dysregulation in the acquisition/initiation, and maintenance of hyperarousal and reexperiencing symptom clusters in PTSD will be addressed.
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Affiliation(s)
- T O'Donnell
- Department of Psychiatry, University of Alberta, Edmonton, Canada
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España RA, Valentino RJ, Berridge CW. Fos immunoreactivity in hypocretin-synthesizing and hypocretin-1 receptor-expressing neurons: effects of diurnal and nocturnal spontaneous waking, stress and hypocretin-1 administration. Neuroscience 2003; 121:201-17. [PMID: 12946712 DOI: 10.1016/s0306-4522(03)00334-8] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Hypocretin/orexin modulates sleep-wake state via actions across multiple terminal fields. Within waking, hypocretin may also participate in high-arousal processes, including those associated with stress. The current studies examined the extent to which alterations in neuronal activity, as measured by Fos immunoreactivity, occur within both hypocretin-synthesizing and hypocretin-1 receptor-expressing neurons across varying behavioral state/environmental conditions associated with varying levels of waking and arousal. Double-label immunohistochemistry was used to visualize Fos and either prepro-hypocretin in the lateral hypothalamus or hypocretin-1 receptors in the locus coeruleus and select basal forebrain regions involved in the regulation of behavioral state/arousal. Animals were tested under the following conditions: 1). diurnal sleeping; 2). diurnal spontaneous waking; 3). nocturnal spontaneous waking; and 4). high-arousal waking (diurnal novelty-stress). Additionally, the effects of hypocretin-1 administration (0.07 and 0.7 nmol) on levels of Fos were examined within these two neuronal populations. Time spent awake, scored for the 90-min preceding perfusion, was largely comparable in diurnal spontaneous waking, nocturnal spontaneous waking and high-arousal waking. Nocturnal spontaneous waking and high-arousal waking, but not diurnal spontaneous waking, were associated with increased levels of Fos within hypocretin-synthesizing neurons, relative to diurnal sleeping. Within hypocretin-1 receptor-expressing neurons, only high-arousal waking was associated with increased levels of Fos. Hypocretin-1 administration dose-dependently increased levels of Fos within hypocretin-1 receptor-expressing neurons to levels comparable to, or exceeding, levels observed in high-arousal waking. Combined, these observations support the hypothesis that hypocretin neuronal activity varies across the circadian cycle. Additionally, these data suggest that waking per se may not be associated with increased hypocretin neurotransmission. In contrast, high-arousal states, including stress, appear to be associated with substantially higher rates of hypocretin neurotransmission. Finally, these studies provide further evidence indicating coordinated actions of hypocretin across a variety of arousal-related basal forebrain and brainstem regions in the behavioral state modulatory actions of this peptide system.
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Affiliation(s)
- R A España
- University of Wisconsin, Department of Psychology, 1202 West Johnson Street, Madison, WI 53706-1611, USA
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Erb S, Funk D, Lê AD. Prior, repeated exposure to cocaine potentiates locomotor responsivity to central injections of corticotropin-releasing factor (CRF) in rats. Psychopharmacology (Berl) 2003; 170:383-9. [PMID: 12955298 DOI: 10.1007/s00213-003-1556-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2002] [Accepted: 05/29/2003] [Indexed: 02/07/2023]
Abstract
RATIONALE There is considerable evidence that the stress-related neuropeptide, corticotropin-releasing factor (CRF), plays an important role in mediating behavioural changes induced by prior experience with cocaine. From this perspective, it is conceivable that repeated exposure to cocaine induces a form of sensitization in CRF systems that makes animals more responsive to CRF following prolonged drug-free periods. OBJECTIVES To study the effects of repeated cocaine exposure on locomotor activity induced by different doses of CRF after drug-free periods ranging from 24 h to 28 days. METHODS Male Wistar rats were injected once daily for 7 days with cocaine (15 mg/kg, IP on days 1 and 7 in locomotor chambers; 30 mg/kg, IP, on days 2-6 in home cages) or saline. In experiment 1, starting 10 days after the last injection, animals were tested for their locomotor response to intracerebroventricular (ICV) injections of vehicle and three doses of CRF (0.25, 0.5, and 5 microg). In experiment 2, animals were tested for their locomotor response to ICV injections of 0.5 microg CRF after drug-free periods of 1-2, 10-11 and 28-29 days. RESULTS Compared to saline pre-exposed animals, cocaine pre-exposed animals showed a significantly greater locomotor response to CRF, relative to vehicle, at all doses tested (experiment 1) and after drug-free periods of up to 28 days (experiment 2). The effects were clear and extremely consistent in magnitude between experiments and conditions. CONCLUSIONS These results suggest that cocaine pre-exposure induces long-term changes in the responsivity of the central nervous system to CRF.
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Affiliation(s)
- Suzanne Erb
- Centre for the Neurobiology of Stress, Departments of Life Sciences and Psychology, University of Toronto at Scarborough, Scarborough, Ontario, Canada M1A 1C4.
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Merali Z, Michaud D, McIntosh J, Kent P, Anisman H. Differential involvement of amygdaloid CRH system(s) in the salience and valence of the stimuli. Prog Neuropsychopharmacol Biol Psychiatry 2003; 27:1201-12. [PMID: 14659475 DOI: 10.1016/j.pnpbp.2003.09.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Anxiety is a heterogeneous term encompassing not only state or trait characteristics but also a wide range of pathologies such as generalized anxiety disorders, phobias, panic and obsessive-compulsive disorders, acute stress disorder, and posttraumatic stress disorder. Given that diverse forms of anxiety exist, numerous animal models have been developed, which are considered to be useful in identifying mechanisms underlying anxiety states. Examples of such animal models include paradigms that assess the behavioral response to neurogenic (or painful stimuli) or psychogenic stressors or to cues that had previously been associated with painful stimuli. The present report presents data regarding the impact of stressors on corticotropin-releasing hormone (CRH), and relates these to changes in anxiety-like states. Specifically, we demonstrate that (1) psychogenic stressors influence the in vivo release of CRH at the central nucleus of the amygdala (CeA); (2) although CRH changes within the CeA are exquisitely sensitive to stressors, they are also elicited by positive stimuli; and (3) while treatment with diazepam attenuates behavioral signs of anxiety, the CRH release associated with a stressor is unaffected by the treatment. The position is offered that although release of CRH within the CeA is increased under stressful conditions, it is not a necessary condition for the consequent behavioral expression of anxiety-like reactions, at least not in minimally threatening situations. We suggest that the CRH responses at the CeA may be involved in a preparatory capacity and, as such, may accompany a range of emotionally significant stimuli, be they appetitive or aversive.
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Affiliation(s)
- Zul Merali
- Institute of Mental Health Research, Royal Ottawa Hospital, University of Ottawa, 1145 Carling Avenue, K1Z 7K4, Ottawa, ON, Canada.
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20
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Bissette G, Klimek V, Pan J, Stockmeier C, Ordway G. Elevated concentrations of CRF in the locus coeruleus of depressed subjects. Neuropsychopharmacology 2003; 28:1328-35. [PMID: 12784115 DOI: 10.1038/sj.npp.1300191] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Research evidence that corticotropin-releasing factor (CRF) plays a role in the pathophysiology of major depressive disorder (MDD) has accumulated over the past 20 years. The elevation of lumbar cerebrospinal fluid (CSF) concentrations of CRF decreased responsiveness of pituitary CRF receptors to challenge with synthetic CRF, and increased levels of serum cortisol in MDD subjects support the hypothesis that CRF is chronically hypersecreted in at least the endocrine circuits of the hypothalamic-pituitary-adrenal (HPA) axis and may also involve other CRF brain circuits mediating emotional responses and/or arousal. One such circuit includes the excitatory CRF input to the locus coeruleus (LC), the major source of norepinephrine in the brain. Furthermore, there are now reports of decreased levels of CRF in lumbar CSF from MDD patients after symptom relief from chronic treatment with antidepressant drugs or electroconvulsive therapy. Whether this normalization reflects therapeutic effects on both endocrine- and limbic-associated CRF circuits has not yet been effectively addressed. In this brief report, we describe increased concentrations of CRF-like immunoreactivity in micropunches of post-mortem LC from subjects with MDD symptoms as established by retrospective psychiatric diagnosis compared to nondepressed subjects matched for age and sex.
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Affiliation(s)
- Garth Bissette
- Division of Neurobiology and Behavioral Research, Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS 39216, USA.
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21
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Murphy EK, Sved AF, Finlay JM. Corticotropin-releasing hormone receptor blockade fails to alter stress-evoked catecholamine release in prefrontal cortex of control or chronically stressed rats. Neuroscience 2003; 116:1081-7. [PMID: 12617949 DOI: 10.1016/s0306-4522(02)00565-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although it is well documented that stress can increase the activity of central dopamine and norepinephrine neurons, little is known about the role of other neurotransmitters in modulating this response. Previous studies have implicated corticotropin-releasing hormone in modulating stress-evoked changes in the activity of locus coeruleus neurons. The present study examines whether corticotropin-releasing hormone contributes to stress-evoked increases in extracellular norepinephrine and dopamine in rat medial prefrontal cortex, as monitored by in vivo microdialysis. As noted previously, 30 min of tail-shock increased extracellular levels of norepinephrine and dopamine in the medial prefrontal cortex of naïve rats, and this was enhanced in rats previously exposed to chronic cold ( approximately 5 degrees C for 2-3 weeks). Previous intraventricular administration of a corticotropin-releasing hormone antagonist (D-Phe-corticotropin-releasing hormone; 3 and 9 microg) did not alter the tail-shock evoked in increase in extracellular levels of norepinephrine and dopamine in either naïve or chronically cold-exposed rats. Intraventricular administration of 3 microg of D-Phe-corticotropin-releasing hormone attenuated the increase in extracellular norepinephrine induced by co-administration of 3 microg of corticotropin-releasing hormone, confirming the efficacy of this compound. Results of the present study suggest that endogenous corticotropin-releasing hormone does not play a role in modulating the release of norepinephrine and dopamine occurring in response to acute tail-shock or the expression of a potentiated response to tail-shock in rats exposed chronically to cold.
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Affiliation(s)
- E K Murphy
- Department of Neuroscience, University of Pittsburgh, 446 Crawford Hall, Pittsburgh, PA 15260, USA
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22
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Berridge CW, Waterhouse BD. The locus coeruleus-noradrenergic system: modulation of behavioral state and state-dependent cognitive processes. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 2003; 42:33-84. [PMID: 12668290 DOI: 10.1016/s0165-0173(03)00143-7] [Citation(s) in RCA: 1702] [Impact Index Per Article: 81.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Through a widespread efferent projection system, the locus coeruleus-noradrenergic system supplies norepinephrine throughout the central nervous system. Initial studies provided critical insight into the basic organization and properties of this system. More recent work identifies a complicated array of behavioral and electrophysiological actions that have in common the facilitation of processing of relevant, or salient, information. This involves two basic levels of action. First, the system contributes to the initiation and maintenance of behavioral and forebrain neuronal activity states appropriate for the collection of sensory information (e.g. waking). Second, within the waking state, this system modulates the collection and processing of salient sensory information through a diversity of concentration-dependent actions within cortical and subcortical sensory, attention, and memory circuits. Norepinephrine-dependent modulation of long-term alterations in synaptic strength, gene transcription and other processes suggest a potentially critical role of this neurotransmitter system in experience-dependent alterations in neural function and behavior. The ability of a given stimulus to increase locus coeruleus discharge activity appears independent of affective valence (appetitive vs. aversive). Combined, these observations suggest that the locus coeruleus-noradrenergic system is a critical component of the neural architecture supporting interaction with, and navigation through, a complex world. These observations further suggest that dysregulation of locus coeruleus-noradrenergic neurotransmission may contribute to cognitive and/or arousal dysfunction associated with a variety of psychiatric disorders, including attention-deficit hyperactivity disorder, sleep and arousal disorders, as well as certain affective disorders, including post-traumatic stress disorder. Independent of an etiological role in these disorders, the locus coeruleus-noradrenergic system represents an appropriate target for pharmacological treatment of specific attention, memory and/or arousal dysfunction associated with a variety of behavioral/cognitive disorders.
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Affiliation(s)
- Craig W Berridge
- Departments of Psychology and Psychiatry, University of Wisconsin, Madison, WI 53706,USA.
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Jedema HP, Grace AA. Chronic exposure to cold stress alters electrophysiological properties of locus coeruleus neurons recorded in vitro. Neuropsychopharmacology 2003; 28:63-72. [PMID: 12496941 DOI: 10.1038/sj.npp.1300020] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Chronic stress exposure can alter central noradrenergic function. Previously, we reported that in chronically cold-exposed rats the release of norepinephrine and electrophysiological activation of locus coeruleus (LC) neurons is enhanced in response to multiple excitatory stimuli without alterations in basal activity. In the present studies, we used in vitro intracellular recording techniques to explore the effect of chronic cold exposure on the basal and evoked electrophysiological properties of LC neurons in horizontal slices of the rat brainstem. Consistent with our findings from in vivo experiments, chronic cold exposure did not affect basal firing rate. Furthermore, gross morphology of LC neurons and spike waveform characteristics were similar in slices from control and previously cold-exposed rats. However, excitability in response to intracellular current injection and input resistance were larger in slices from previously cold-exposed rats. In addition, the accommodation of spike firing in response to sustained current injection was smaller and the period of postactivation inhibition appeared to be less in LC neurons from cold-exposed rats. These data demonstrate that the stress-evoked sensitization of LC neurons observed in vivo is at least in part maintained in the slice preparation and suggest that alterations in electrophysiological properties of LC neurons contribute to the chronic stress-induced sensitization of central noradrenergic function observed in vivo. Furthermore, the present data suggest that an alteration in autoinhibitory control of LC activity is involved in the chronic stress-induced alterations. The enhanced functional capacity of LC neurons following cold exposure of rats may represent a unique model to study the mechanisms underlying the alterations in central noradrenergic function observed in humans afflicted with mood and anxiety disorders.
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Affiliation(s)
- Hank P Jedema
- Department of Neuroscience, University of Pittsburgh, PA 15260, USA.
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Harro J, Oreland L. Depression as a spreading adjustment disorder of monoaminergic neurons: a case for primary implication of the locus coeruleus. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 2001; 38:79-128. [PMID: 11750928 DOI: 10.1016/s0165-0173(01)00082-0] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A model for the pathophysiology of depression is discussed in the context of other existing theories. The classic monoamine theory of depression suggests that a deficit in monoamine neurotransmitters in the synaptic cleft is the primary cause of depression. More recent elaborations of the classic theory also implicitly include this postulate, other theories of depression frequently prefer to depart from the monoamine-based model altogether. We suggest that the primary defect emerges in the regulation of firing rates in brainstem monoaminergic neurons, which brings about a decrease in the tonic release of neurotransmitters in their projection areas, an increase in postsynaptic sensitivity, and concomitantly, exaggerated responses to acute increases in the presynaptic firing rate and transmitter release. It is proposed that the initial defect involves, in particular, the noradrenergic innervation from the locus coeruleus (LC). Dysregulation of the LC projection activities may lead in turn to dysregulation of serotonergic and dopaminergic neurotransmission. Failure of the LC function could explain the basic impairments in the processing of novel information, intensive processing of irrational beliefs, and anxiety. Concomitant impairments in the serotonergic neurotransmission may contribute to the mood changes and reduction in the mesotelencephalic dopaminergic activity to loss of motivation, and anhedonia. Dysregulation of CRF and other neuropeptides such as neuropeptide Y, galanin and substance P may reinforce the LC dysfunction and thus further weaken the adaptivity to stressful stimuli.
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Affiliation(s)
- J Harro
- Department of Psychology, University of Tartu, Tiigi 78, EE-50410 Tartu, Estonia.
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25
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Conti LH, Shannon MH, Murry JD, Printz MP. Repeated restraint stress-induced increase in baroreceptor reflex sensitivity: role of corticotropin-releasing factor. Neuropeptides 2001; 35:71-81. [PMID: 11384202 DOI: 10.1054/npep.2001.0847] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The effect of central administration of a corticotropin-releasing factor antagonist on repeated restraint stress-induced changes in the baroreceptor reflex response to phenylephrine was examined in male Wistar-Kyoto rats. Rats were instrumented with intracerebroventricular guide cannula and femoral arterial and venous catheters. On each of 5 consecutive days, two groups received either a central infusion of saline or an infusion of the corticotropin-releasing factor antagonist, astressin. One saline- and one astressin-treated group experienced 20 min of restraint stress 10 min after each infusion. The other saline- and astressin-treated groups served as non-stressed controls. Twenty-four hours later, each rat received 3 doses of phenylephrine which produced equivalent increases in mean arterial pressure in each of the 4 treatment groups. Reflex bradycardia was significantly greater in the saline-treated/repeated restraint group than in the saline-treated/no restraint group. This effect of repeated restraint on the baroreceptor reflex was attenuated by administration of astressin prior to each session of restraint. A single 20 min session of restraint stress failed to alter baroreceptor reflex sensitivity. However, repeated central infusions of exogenous CRF failed to alter BRR sensitivity. In a separate experiment, astressin failed to attenuate the increases in mean arterial pressure and heart rate which occurred during each session of restraint stress and, in fact, diminished habituation of the blood pressure response in the last session. The results suggest that repeated stress increases thesensitivity of the baroreceptor reflex and that corticotropin-releasing factor has a role in this stress-induced change.
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Affiliation(s)
- L H Conti
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA.
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26
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Jedema HP, Finlay JM, Sved AF, Grace AA. Chronic cold exposure potentiates CRH-evoked increases in electrophysiologic activity of locus coeruleus neurons. Biol Psychiatry 2001; 49:351-9. [PMID: 11239906 DOI: 10.1016/s0006-3223(00)01057-x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
BACKGROUND Chronic stress exposure can produce sensitization of norepinephrine release in the forebrain in response to subsequent stressors. Furthermore, the increase in norepinephrine release in response to the stress-related peptide corticotropin-releasing hormone (CRH) is potentiated by prior chronic stress exposure. To explore possible mechanisms underlying these alterations in norepinephrine release, we examined the effect of chronic stress on the electrophysiologic activity of locus coeruleus (LC) neurons in response to centrally applied CRH. METHODS Single-unit recordings of LC neurons in halothane-anesthetized rats were used to compare the effect of intraventricular administration of CRH (0.3-3.0 microg) in control and previously cold-exposed (2 weeks at 5 degrees C) rats. RESULTS The CRH-evoked increase in LC neuron activity was enhanced following chronic cold exposure, without alteration in basal activity of LC neurons. The enhanced CRH-evoked activation was apparent at higher doses of CRH but not at lower ones, resulting in an increased slope of the dose-response curve for CRH in previously cold-exposed rats. CONCLUSIONS These data, in combination with previous data, suggest that the sensitivity of LC neurons to excitatory inputs is increased following chronic cold exposure. The altered functional capacity of LC neurons in rats after continuous cold exposure may represent an experimental model to examine the role of central noradrenergic neurons in anxiety and mood disorders.
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Affiliation(s)
- H P Jedema
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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27
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Chronic administration of the triazolobenzodiazepine alprazolam produces opposite effects on corticotropin-releasing factor and urocortin neuronal systems. J Neurosci 2000. [PMID: 10648728 DOI: 10.1523/jneurosci.20-03-01240.2000] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In view of the substantial preclinical evidence that supports a seminal role of central corticotropin-releasing factor (CRF) neuronal systems in the physiology and pathophysiology of stress and anxiety, it is reasonable to suggest that the anxiolytic properties of benzodiazepines are mediated, at least in part, via regulation of CRFergic function. To begin to test this complex hypothesis, we examined the effects of acute and chronic administration of the triazolobenzodiazepine agonist alprazolam on CRF peptide concentrations, receptor-binding density, and mRNA expression in the CNS. Additionally, we measured mRNA expression for urocortin, a recently discovered neuropeptide that is generally considered to be a second endogenous ligand for CRF receptors. Both acute and chronic alprazolam administration was found to decrease CRF concentrations within the locus coeruleus. Furthermore, chronic alprazolam decreased basal activity of the hypothalamic-pituitary-adrenal axis, CRF mRNA expression in the central nucleus of the amygdala, and CRF(1) mRNA expression and receptor binding in the basolateral amygdala. In marked contrast, urocortin mRNA expression in the Edinger-Westphal nucleus and CRF(2A) receptor binding in the lateral septum and ventromedial hypothalamus were increased. Similar findings of an inverse relationship between the CRF(1) and CRF(2A) receptor systems have been reported in an anxiety model based on adverse early-life experience, suggesting the intriguing possibility that CRF neuronal systems may be comprised of two separate, but interrelated, subdivisions that can be coordinately and inversely regulated by stress, anxiety, or anxiolytic drugs.
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Ito M, Miyata M. Corticotropin-releasing factor (CRF) and its role in the central nervous system. Results Probl Cell Differ 1999; 26:43-66. [PMID: 10453459 DOI: 10.1007/978-3-540-49421-8_3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Affiliation(s)
- M Ito
- Laboratory for Memory and Learning, Institute of Physical and Chemical Research (RIKEN), Saitama, Japan
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29
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Sweerts BW, Jarrott B, Lawrence AJ. Expression of preprogalanin mRNA following acute and chronic restraint stress in brains of normotensive and hypertensive rats. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1999; 69:113-23. [PMID: 10350643 DOI: 10.1016/s0169-328x(99)00095-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Exposure to stress is known to induce widespread changes in the central nervous system (CNS) involving multiple neuropeptides. The neuropeptide galanin has been implicated in the central response to different stressors; however, the role of galanin in the response to restraint stress has not been reported. Therefore, this study utilised in situ hybridisation histochemistry to observe the effects of acute and chronic restraint stress on preprogalanin (preproGAL) mRNA expression in the CNS of normotensive (Wistar Kyoto; WKY) and Spontaneously Hypertensive (SHR) rats. Rats were exposed to 1 h of restraint for 0 (control), 1, 3, 5, or 10 consecutive days, and central preproGAL mRNA expression following these restraint periods was compared between strains. Significant differences in the basal expression of preproGAL mRNA were detected, with expression decreased by approximately 50% in the supraoptic nucleus (SON; P<0. 01) and increased by approximately 100% in the rostral ventrolateral medulla (RVLM; P<0.05) of SHR when compared to WKY. Following acute restraint (1 session), preproGAL mRNA expression was significantly increased by approximately 135% in the central nucleus of the amygdala (CeA; P<0.05) in WKY. In SHR, significant increases of up to 300% were observed in the CeA (P<0.01) and SON (P<0.05) following chronic restraint (up to 10 days). In addition, expression of preproGAL mRNA was significantly decreased in the locus coeruleus (LC) of SHR following acute restraint (1 session) (P<0.05). These results provide the first evidence that both acute (LC) and chronic (CeA, SON) restraint stress is associated with alterations in preproGAL mRNA expression. As such, the present study provides further evidence linking neurons containing galanin with the central response to restraint stress.
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Affiliation(s)
- B W Sweerts
- Department of Pharmacology, Monash University, Wellington Road, Clayton, Victoria 3168, Australia.
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Conti LH, Youngblood KL, Printz MP, Foote SL. Locus coeruleus electrophysiological activity and responsivity to corticotropin-releasing factor in inbred hypertensive and normotensive rats. Brain Res 1997; 774:27-34. [PMID: 9452188 DOI: 10.1016/s0006-8993(97)81683-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The spontaneously hypertensive rat (SHR) and its normotensive progenitor, the Wistar-Kyoto rat (WKY), have been shown to be differentially responsive to the behavioral and endocrine effects of both stress and corticotropin-releasing factor (CRF), both of which increase locus coeruleus (LC) electrophysiological activity. However, the effect of central administration of CRF in these rat strains has yet to be examined. In the present studies, LC electrophysiological responsivity to intracerebroventricular infusions of CRF was assessed in SHR, an inbred strain of WKY rats (the WKY[LJ] rat), and an outbred normotensive rat strain, Sprague-Dawley (SD) rats. Spontaneous LC discharge rate, mean arterial blood pressure and heart rate were also examined. LC activity was increased to the same extent in the three rat strains in response to a 3 microg dose of CRF. However, WKY(LJ) rats showed an exaggerated LC in response to a 1 microg dose of CRF in comparison to the other rat strains tested at this dose. Spontaneous discharge rates of individual LC neurons were lower in both SHR and WKY[LJ] rats than in SD rats. Further, the variability of the discharge rates of LC neurons was greater in WKY[LJ] rats than in the other two strains. These results indicate that the WKY[LJ] rat may provide a useful model for assessing the role of sensitivity to CRF in stress responsiveness.
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Affiliation(s)
- L H Conti
- Department of Psychiatry, University of California at San Diego, La Jolla 92093, USA
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