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Iyer SH, Hinman JE, Warren T, Matthews SA, Simeone TA, Simeone KA. Altered ventilatory responses to hypercapnia-hypoxia challenges in a preclinical SUDEP model involve orexin neurons. Neurobiol Dis 2024; 199:106592. [PMID: 38971479 DOI: 10.1016/j.nbd.2024.106592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 06/25/2024] [Accepted: 07/02/2024] [Indexed: 07/08/2024] Open
Abstract
Failure to recover from repeated hypercapnia and hypoxemia (HH) challenges caused by severe GCS and postictal apneas may contribute to sudden unexpected death in epilepsy (SUDEP). Our previous studies found orexinergic dysfunction contributes to respiratory abnormalities in a preclinical model of SUDEP, Kcna1-/- mice. Here, we developed two gas challenges consisting of repeated HH exposures and used whole body plethysmography to determine whether Kcna1-/- mice have detrimental ventilatory responses. Kcna1-/- mice exhibited an elevated ventilatory response to a mild repeated hypercapnia-hypoxia (HH) challenge compared to WT. Moreover, 71% of Kcna1-/- mice failed to survive a severe repeated HH challenge, whereas all WT mice recovered. We next determined whether orexin was involved in these differences. Pretreating Kcna1-/- mice with a dual orexin receptor antagonist rescued the ventilatory response during the mild challenge and all subjects survived the severe challenge. In ex vivo extracellular recordings in the lateral hypothalamus of coronal brain slices, we found reducing pH either inhibits or stimulates putative orexin neurons similar to other chemosensitive neurons; however, a significantly greater percentage of putative orexin neurons from Kcna1-/-mice were stimulated and the magnitude of stimulation was increased resulting in augmentation of the calculated chemosensitivity index relative to WT. Collectively, our data suggest that increased chemosensitive activity of orexin neurons may be pathologic in the Kcna1-/- mouse model of SUDEP, and contribute to elevated ventilatory responses. Our preclinical data suggest that those at high risk for SUDEP may be more sensitive to HH challenges, whether induced by seizures or other means; and the depth and length of the HH exposure could dictate the probability of survival.
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Affiliation(s)
- Shruthi H Iyer
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE 68178, USA
| | - Jillian E Hinman
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE 68178, USA
| | - Ted Warren
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE 68178, USA
| | - Stephanie A Matthews
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE 68178, USA
| | - Timothy A Simeone
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE 68178, USA
| | - Kristina A Simeone
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE 68178, USA.
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2
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Braga A, Chiacchiaretta M, Pellerin L, Kong D, Haydon PG. Astrocytic metabolic control of orexinergic activity in the lateral hypothalamus regulates sleep and wake architecture. Nat Commun 2024; 15:5979. [PMID: 39013907 PMCID: PMC11252394 DOI: 10.1038/s41467-024-50166-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 06/17/2024] [Indexed: 07/18/2024] Open
Abstract
Neuronal activity undergoes significant changes during vigilance states, accompanied by an accommodation of energy demands. While the astrocyte-neuron lactate shuttle has shown that lactate is the primary energy substrate for sustaining neuronal activity in multiple brain regions, its role in regulating sleep/wake architecture is not fully understood. Here we investigated the involvement of astrocytic lactate supply in maintaining consolidated wakefulness by downregulating, in a cell-specific manner, the expression of monocarboxylate transporters (MCTs) in the lateral hypothalamus of transgenic mice. Our results demonstrate that reduced expression of MCT4 in astrocytes disrupts lactate supply to wake-promoting orexin neurons, impairing wakefulness stability. Additionally, we show that MCT2-mediated lactate uptake is necessary for maintaining tonic firing of orexin neurons and stabilizing wakefulness. Our findings provide both in vivo and in vitro evidence supporting the role of astrocyte-to-orexinergic neuron lactate shuttle in regulating proper sleep/wake stability.
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Affiliation(s)
- Alice Braga
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Martina Chiacchiaretta
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, 02111, USA.
| | - Luc Pellerin
- Inserm U1313, University and CHU of Poitiers, 86021, Poitiers, France
| | - Dong Kong
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, 02111, USA
- Division of Endocrinology, Department of Pediatrics, F.M. Kirby Neurobiology Center, Boston Children's Hospital and Harvard Medical School, Boston, MA, 02115, USA
| | - Philip G Haydon
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, 02111, USA.
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3
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Viskaitis P, Tesmer AL, Liu Z, Karnani MM, Arnold M, Donegan D, Bracey E, Grujic N, Patriarchi T, Peleg-Raibstein D, Burdakov D. Orexin neurons track temporal features of blood glucose in behaving mice. Nat Neurosci 2024; 27:1299-1308. [PMID: 38773350 PMCID: PMC11239495 DOI: 10.1038/s41593-024-01648-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 04/10/2024] [Indexed: 05/23/2024]
Abstract
Does the brain track how fast our blood glucose is changing? Knowing such a rate of change would enable the prediction of an upcoming state and a timelier response to this new state. Hypothalamic arousal-orchestrating hypocretin/orexin neurons (HONs) have been proposed to be glucose sensors, yet whether they track glucose concentration (proportional tracking) or rate of change (derivative tracking) is unknown. Using simultaneous recordings of HONs and blood glucose in behaving male mice, we found that maximal HON responses occur in considerable temporal anticipation (minutes) of glucose peaks due to derivative tracking. Analysis of >900 individual HONs revealed glucose tracking in most HONs (98%), with derivative and proportional trackers working in parallel, and many (65%) HONs multiplexed glucose and locomotion information. Finally, we found that HON activity is important for glucose-evoked locomotor suppression. These findings reveal a temporal dimension of brain glucose sensing and link neurobiological and algorithmic views of blood glucose perception in the brain's arousal orchestrators.
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Affiliation(s)
- Paulius Viskaitis
- Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH Zürich), Zurich, Switzerland
| | - Alexander L Tesmer
- Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH Zürich), Zurich, Switzerland
| | - Ziyu Liu
- Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH Zürich), Zurich, Switzerland
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Mahesh M Karnani
- Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH Zürich), Zurich, Switzerland
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Myrtha Arnold
- Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH Zürich), Zurich, Switzerland
| | - Dane Donegan
- Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH Zürich), Zurich, Switzerland
| | - Eva Bracey
- Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH Zürich), Zurich, Switzerland
| | - Nikola Grujic
- Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH Zürich), Zurich, Switzerland
| | - Tommaso Patriarchi
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Daria Peleg-Raibstein
- Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH Zürich), Zurich, Switzerland
| | - Denis Burdakov
- Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH Zürich), Zurich, Switzerland.
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4
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Grujic N, Polania R, Burdakov D. Neurobehavioral meaning of pupil size. Neuron 2024:S0896-6273(24)00406-9. [PMID: 38925124 DOI: 10.1016/j.neuron.2024.05.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 03/22/2024] [Accepted: 05/31/2024] [Indexed: 06/28/2024]
Abstract
Pupil size is a widely used metric of brain state. It is one of the few signals originating from the brain that can be readily monitored with low-cost devices in basic science, clinical, and home settings. It is, therefore, important to investigate and generate well-defined theories related to specific interpretations of this metric. What exactly does it tell us about the brain? Pupils constrict in response to light and dilate during darkness, but the brain also controls pupil size irrespective of luminosity. Pupil size fluctuations resulting from ongoing "brain states" are used as a metric of arousal, but what is pupil-linked arousal and how should it be interpreted in neural, cognitive, and computational terms? Here, we discuss some recent findings related to these issues. We identify open questions and propose how to answer them through a combination of well-defined tasks, neurocomputational models, and neurophysiological probing of the interconnected loops of causes and consequences of pupil size.
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Affiliation(s)
- Nikola Grujic
- Neurobehavioural Dynamics Lab, ETH Zürich, Department of Health Sciences and Technology, Schorenstrasse 16, 8603 Schwerzenbach, Switzerland.
| | - Rafael Polania
- Decision Neuroscience Lab, ETH Zürich, Department of Health Sciences and Technology, Winterthurstrasse 190, 8057 Zürich, Switzerland
| | - Denis Burdakov
- Neurobehavioural Dynamics Lab, ETH Zürich, Department of Health Sciences and Technology, Schorenstrasse 16, 8603 Schwerzenbach, Switzerland.
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5
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Mavanji V, Pomonis BL, Shekels L, Kotz CM. Interactions between Lateral Hypothalamic Orexin and Dorsal Raphe Circuitry in Energy Balance. Brain Sci 2024; 14:464. [PMID: 38790443 PMCID: PMC11117928 DOI: 10.3390/brainsci14050464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 04/30/2024] [Accepted: 05/04/2024] [Indexed: 05/26/2024] Open
Abstract
Orexin/hypocretin terminals innervate the dorsal raphe nucleus (DRN), which projects to motor control areas important for spontaneous physical activity (SPA) and energy expenditure (EE). Orexin receptors are expressed in the DRN, and obesity-resistant (OR) rats show higher expression of these receptors in the DRN and elevated SPA/EE. We hypothesized that orexin-A in the DRN enhances SPA/EE and that DRN-GABA modulates the effect of orexin-A on SPA/EE. We manipulated orexin tone in the DRN either through direct injection of orexin-A or through the chemogenetic activation of lateral-hypothalamic (LH) orexin neurons. In the orexin neuron activation experiment, fifteen minutes prior to the chemogenetic activation of orexin neurons, the mice received either the GABA-agonist muscimol or antagonist bicuculline injected into the DRN, and SPA/EE was monitored for 24 h. In a separate experiment, orexin-A was injected into the DRN to study the direct effect of DRN orexin on SPA/EE. We found that the activation of orexin neurons elevates SPA/EE, and manipulation of GABA in the DRN does not alter the SPA response to orexin neuron activation. Similarly, intra-DRN orexin-A enhanced SPA and EE in the mice. These results suggest that orexin-A in the DRN facilitates negative energy balance by increasing physical activity-induced EE, and that modulation of DRN orexin-A is a potential strategy to promote SPA and EE.
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Affiliation(s)
- Vijayakumar Mavanji
- Research Service, Veterans Affairs Health Care System, Minneapolis, MN 55417, USA; (V.M.); (B.L.P.); (L.S.)
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Brianna L. Pomonis
- Research Service, Veterans Affairs Health Care System, Minneapolis, MN 55417, USA; (V.M.); (B.L.P.); (L.S.)
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Laurie Shekels
- Research Service, Veterans Affairs Health Care System, Minneapolis, MN 55417, USA; (V.M.); (B.L.P.); (L.S.)
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Catherine M. Kotz
- Research Service, Veterans Affairs Health Care System, Minneapolis, MN 55417, USA; (V.M.); (B.L.P.); (L.S.)
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN 55455, USA
- Geriatric Research, Education and Clinical Center, Minneapolis VA Health Care System, Minneapolis, MN 55417, USA
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6
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Zhang X, Perry RJ. Metabolic underpinnings of cancer-related fatigue. Am J Physiol Endocrinol Metab 2024; 326:E290-E307. [PMID: 38294698 DOI: 10.1152/ajpendo.00378.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 01/23/2024] [Accepted: 01/23/2024] [Indexed: 02/01/2024]
Abstract
Cancer-related fatigue (CRF) is one of the most prevalent and detrimental complications of cancer. Emerging evidence suggests that obesity and insulin resistance are associated with CRF occurrence and severity in cancer patients and survivors. In this narrative review, we analyzed recent studies including both preclinical and clinical research on the relationship between obesity and/or insulin resistance and CRF. We also describe potential mechanisms for these relationships, though with the caveat that because the mechanisms underlying CRF are incompletely understood, the mechanisms mediating the association between obesity/insulin resistance and CRF are similarly incompletely delineated. The data suggest that, in addition to their effects to worsen CRF by directly promoting tumor growth and metastasis, obesity and insulin resistance may also contribute to CRF by inducing chronic inflammation, neuroendocrinological disturbance, and metabolic alterations. Furthermore, studies suggest that patients with obesity and insulin resistance experience more cancer-induced pain and are at more risk of emotional and behavioral disruptions correlated with CRF. However, other studies implied a potentially paradoxical impact of obesity and insulin resistance to reduce CRF symptoms. Despite the need for further investigation utilizing interventions to directly elucidate the mechanisms of cancer-related fatigue, current evidence demonstrates a correlation between obesity and/or insulin resistance and CRF, and suggests potential therapeutics for CRF by targeting obesity and/or obesity-related mediators.
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Affiliation(s)
- Xinyi Zhang
- Departments of Cellular & Molecular Physiology and Medicine (Endocrinology), Yale University School of Medicine, New Haven, Connecticut, United States
| | - Rachel J Perry
- Departments of Cellular & Molecular Physiology and Medicine (Endocrinology), Yale University School of Medicine, New Haven, Connecticut, United States
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7
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Dempsey JA, Welch JF. Control of Breathing. Semin Respir Crit Care Med 2023; 44:627-649. [PMID: 37494141 DOI: 10.1055/s-0043-1770342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
Substantial advances have been made recently into the discovery of fundamental mechanisms underlying the neural control of breathing and even some inroads into translating these findings to treating breathing disorders. Here, we review several of these advances, starting with an appreciation of the importance of V̇A:V̇CO2:PaCO2 relationships, then summarizing our current understanding of the mechanisms and neural pathways for central rhythm generation, chemoreception, exercise hyperpnea, plasticity, and sleep-state effects on ventilatory control. We apply these fundamental principles to consider the pathophysiology of ventilatory control attending hypersensitized chemoreception in select cardiorespiratory diseases, the pathogenesis of sleep-disordered breathing, and the exertional hyperventilation and dyspnea associated with aging and chronic diseases. These examples underscore the critical importance that many ventilatory control issues play in disease pathogenesis, diagnosis, and treatment.
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Affiliation(s)
- Jerome A Dempsey
- John Rankin Laboratory of Pulmonary Medicine, Department of Population Health Sciences, University of Wisconsin, Madison, Wisconsin
| | - Joseph F Welch
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
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8
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Peleg-Raibstein D, Viskaitis P, Burdakov D. Eat, seek, rest? An orexin/hypocretin perspective. J Neuroendocrinol 2023; 35:e13259. [PMID: 36994677 DOI: 10.1111/jne.13259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 03/06/2023] [Accepted: 03/10/2023] [Indexed: 03/19/2023]
Abstract
Seeking and ingesting nutrients is an essential cycle of life in all species. In classical neuropsychology these two behaviours are viewed as fundamentally distinct from each other, and known as appetitive and consummatory, respectively. Appetitive behaviour is highly flexible and diverse, but typically involves increased locomotion and spatial exploration. Consummatory behaviour, in contrast, typically requires reduced locomotion. Another long-standing concept is "rest and digest", a hypolocomotive response to calorie intake, thought to facilitate digestion and storage of energy after eating. Here, we note that the classical seek➔ingest➔rest behavioural sequence is not evolutionarily advantageous for all ingested nutrients. Our limited stomach capacity should be invested wisely, rather than spent on the first available nutrient. This is because nutrients are not simply calories: some nutrients are more essential for survival than others. Thus, a key choice that needs to be made soon after ingestion: to eat more and rest, or to terminate eating and search for better food. We offer a perspective on recent work suggesting how nutrient-specific neural responses shape this choice. Specifically, the hypothalamic hypocretin/orexin neurons (HONs) - cells that promote hyperlocomotive explorative behaviours - are rapidly and differentially modulated by different ingested macronutrients. Dietary non-essential (but not essential) amino acids activate HONs, while glucose depresses HONs. This nutrient-specific HON modulation engages distinct reflex arcs, seek➔ingest➔seek and seek➔ingest➔rest, respectively. We propose that these nutri-neural reflexes evolved to facilitate optimal nutrition despite the limitations of our body.
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Affiliation(s)
- Daria Peleg-Raibstein
- ETH Zürich, Department of Health Sciences and Technology, Schorenstrasse 16, 8603 Schwerzenbach, Switzerland
| | - Paulius Viskaitis
- ETH Zürich, Department of Health Sciences and Technology, Schorenstrasse 16, 8603 Schwerzenbach, Switzerland
| | - Denis Burdakov
- ETH Zürich, Department of Health Sciences and Technology, Schorenstrasse 16, 8603 Schwerzenbach, Switzerland
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9
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Gonye EC, Bayliss DA. Criteria for central respiratory chemoreceptors: experimental evidence supporting current candidate cell groups. Front Physiol 2023; 14:1241662. [PMID: 37719465 PMCID: PMC10502317 DOI: 10.3389/fphys.2023.1241662] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Accepted: 08/16/2023] [Indexed: 09/19/2023] Open
Abstract
An interoceptive homeostatic system monitors levels of CO2/H+ and provides a proportionate drive to respiratory control networks that adjust lung ventilation to maintain physiologically appropriate levels of CO2 and rapidly regulate tissue acid-base balance. It has long been suspected that the sensory cells responsible for the major CNS contribution to this so-called respiratory CO2/H+ chemoreception are located in the brainstem-but there is still substantial debate in the field as to which specific cells subserve the sensory function. Indeed, at the present time, several cell types have been championed as potential respiratory chemoreceptors, including neurons and astrocytes. In this review, we advance a set of criteria that are necessary and sufficient for definitive acceptance of any cell type as a respiratory chemoreceptor. We examine the extant evidence supporting consideration of the different putative chemoreceptor candidate cell types in the context of these criteria and also note for each where the criteria have not yet been fulfilled. By enumerating these specific criteria we hope to provide a useful heuristic that can be employed both to evaluate the various existing respiratory chemoreceptor candidates, and also to focus effort on specific experimental tests that can satisfy the remaining requirements for definitive acceptance.
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Affiliation(s)
- Elizabeth C. Gonye
- Department of Pharmacology, University of Virginia, Charlottesville, VA, United States
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10
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Kinkead R, Ambrozio-Marques D, Fournier S, Gagnon M, Guay LM. Estrogens, age, and, neonatal stress: panic disorders and novel views on the contribution of non-medullary structures to respiratory control and CO 2 responses. Front Physiol 2023; 14:1183933. [PMID: 37265841 PMCID: PMC10229816 DOI: 10.3389/fphys.2023.1183933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 04/21/2023] [Indexed: 06/03/2023] Open
Abstract
CO2 is a fundamental component of living matter. This chemical signal requires close monitoring to ensure proper match between metabolic production and elimination by lung ventilation. Besides ventilatory adjustments, CO2 can also trigger innate behavioral and physiological responses associated with fear and escape but the changes in brain CO2/pH required to induce ventilatory adjustments are generally lower than those evoking fear and escape. However, for patients suffering from panic disorder (PD), the thresholds for CO2-evoked hyperventilation, fear and escape are reduced and the magnitude of those reactions are excessive. To explain these clinical observations, Klein proposed the false suffocation alarm hypothesis which states that many spontaneous panics occur when the brain's suffocation monitor erroneously signals a lack of useful air, thereby maladaptively triggering an evolved suffocation alarm system. After 30 years of basic and clinical research, it is now well established that anomalies in respiratory control (including the CO2 sensing system) are key to PD. Here, we explore how a stress-related affective disorder such as PD can disrupt respiratory control. We discuss rodent models of PD as the concepts emerging from this research has influenced our comprehension of the CO2 chemosensitivity network, especially structure that are not located in the medulla, and how factors such as stress and biological sex modulate its functionality. Thus, elucidating why hormonal fluctuations can lead to excessive responsiveness to CO2 offers a unique opportunity to gain insights into the neuroendocrine mechanisms regulating this key aspect of respiratory control and the pathophysiology of respiratory manifestations of PD.
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11
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Maruyama T, Ueta Y. Internal and external modulation factors of the orexin system (REVIEW). Peptides 2023; 165:171009. [PMID: 37054895 DOI: 10.1016/j.peptides.2023.171009] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 04/10/2023] [Accepted: 04/11/2023] [Indexed: 04/15/2023]
Abstract
Orexin-A and -B (identical to hypocretin-1 and -2) are neuropeptides synthesized in the lateral hypothalamus and perifornical area, and orexin neurons project their axon terminals broadly throughout the entire central nervous system (CNS). The activity of orexins is mediated by two specific G protein-coupled receptors (GPCRs), termed orexin type1 receptor (OX1R) and orexin type2 receptor (OX2R). The orexin system plays a relevant role in various physiological functions, including arousal, feeding, reward, and thermogenesis, and is key to human health. Orexin neurons receive various signals related to environmental, physiological, and emotional stimuli. Previous studies have reported that several neurotransmitters and neuromodulators influence the activation or inhibition of orexin neuron activity. In this review, we summarize the modulating factors of orexin neurons in the sleep/wake rhythm and feeding behavior, particularly in the context of the modulation of appetite, body fluids, and circadian signaling. We also describe the effects of life activity, behavior, and diet on the orexin system. Some studies have observed phenomena that have been verified in animal experiments, revealing the detailed mechanism and neural pathway, while their applications to humans is expected in future research.
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Affiliation(s)
- Takashi Maruyama
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Japan.
| | - Yoichi Ueta
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Japan
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12
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Krohn F, Novello M, van der Giessen RS, De Zeeuw CI, Pel JJM, Bosman LWJ. The integrated brain network that controls respiration. eLife 2023; 12:83654. [PMID: 36884287 PMCID: PMC9995121 DOI: 10.7554/elife.83654] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 01/29/2023] [Indexed: 03/09/2023] Open
Abstract
Respiration is a brain function on which our lives essentially depend. Control of respiration ensures that the frequency and depth of breathing adapt continuously to metabolic needs. In addition, the respiratory control network of the brain has to organize muscular synergies that integrate ventilation with posture and body movement. Finally, respiration is coupled to cardiovascular function and emotion. Here, we argue that the brain can handle this all by integrating a brainstem central pattern generator circuit in a larger network that also comprises the cerebellum. Although currently not generally recognized as a respiratory control center, the cerebellum is well known for its coordinating and modulating role in motor behavior, as well as for its role in the autonomic nervous system. In this review, we discuss the role of brain regions involved in the control of respiration, and their anatomical and functional interactions. We discuss how sensory feedback can result in adaptation of respiration, and how these mechanisms can be compromised by various neurological and psychological disorders. Finally, we demonstrate how the respiratory pattern generators are part of a larger and integrated network of respiratory brain regions.
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Affiliation(s)
- Friedrich Krohn
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands
| | - Manuele Novello
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands
| | | | - Chris I De Zeeuw
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands.,Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences, Amsterdam, Netherlands
| | - Johan J M Pel
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands
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13
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Mogavero MP, Silvani A, Lanza G, DelRosso LM, Ferini-Strambi L, Ferri R. Targeting Orexin Receptors for the Treatment of Insomnia: From Physiological Mechanisms to Current Clinical Evidence and Recommendations. Nat Sci Sleep 2023; 15:17-38. [PMID: 36713640 PMCID: PMC9879039 DOI: 10.2147/nss.s201994] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 01/08/2023] [Indexed: 01/23/2023] Open
Abstract
After a detailed description of orexins and their roles in sleep and other medical disorders, we discuss here the current clinical evidence on the effects of dual (DORAs) or selective (SORAs) orexin receptor antagonists on insomnia with the aim to provide recommendations for their further assessment in a context of personalized and precision medicine. In the last decade, many trials have been conducted with orexin receptor antagonists, which represent an innovative and valid therapeutic option based on the multiple mechanisms of action of orexins on different biological circuits, both centrally and peripherally, and their role in a wide range of medical conditions which are often associated with insomnia. A very interesting aspect of this new category of drugs is that they have limited abuse liability and their discontinuation does not seem associated with significant rebound effects. Further studies on the efficacy of DORAs are required, especially on children and adolescents and in particular conditions, such as menopause. Which DORA is most suitable for each patient, based on comorbidities and/or concomitant treatments, should be the focus of further careful research. On the contrary, studies on SORAs, some of which seem to be appropriate also in insomnia in patients with psychiatric diseases, are still at an early stage and, therefore, do not allow to draw definite conclusions.
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Affiliation(s)
- Maria P Mogavero
- Vita-Salute San Raffaele University, Milan, Italy.,Sleep Disorders Center, Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
| | - Alessandro Silvani
- PRISM Lab, Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Giuseppe Lanza
- Sleep Research Centre, Oasi Research Institute - IRCCS, Troina, Italy.,Department of Surgery and Medical-Surgical Specialties, University of Catania, Catania, Italy
| | - Lourdes M DelRosso
- Pulmonary and Sleep Medicine, University of California San Francisco-Fresno, Fresno, CA, USA
| | - Luigi Ferini-Strambi
- Vita-Salute San Raffaele University, Milan, Italy.,Sleep Disorders Center, Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
| | - Raffaele Ferri
- Sleep Research Centre, Oasi Research Institute - IRCCS, Troina, Italy
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14
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Sithirungson S, Sonsuwan N, Chattipakorn SC, Chattipakorn N, Shinlapawittayatorn K. Functional roles of orexin in obstructive sleep apnea: From clinical observation to mechanistic insights. Sleep Med 2023; 101:40-49. [PMID: 36334500 DOI: 10.1016/j.sleep.2022.10.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 09/23/2022] [Accepted: 10/17/2022] [Indexed: 11/06/2022]
Abstract
Obstructive sleep apnea is the most common sleep-related breathing disorder. Repetitive episodes of the obstructive respiratory events lead to arousal, sleep fragmentation, and excessive daytime sleepiness. Orexin, also known as hypocretin, is one of the most important neurotransmitters responsible for sleep and arousal regulation. Deficiency of orexin has been shown to be involved in the pathogenesis of narcolepsy, which shares cardinal symptoms of sleep apnea and excessive daytime sleep with obstructive sleep apnea. However, the relationship between orexin and obstructive sleep apnea is not well defined. In this review, we summarize the current evidence, from in vitro, in vivo, and clinical data, regarding the association between orexin and obstructive sleep apnea. The effects of orexin on sleep apnea, as well as how the consequences of obstructive sleep apnea affect the orexin system function are also discussed. Additionally, the contrary findings are also included and discussed.
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Affiliation(s)
- Suchanya Sithirungson
- Department of Otolaryngology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Nuntigar Sonsuwan
- Department of Otolaryngology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Siriporn C Chattipakorn
- Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand; Center of Excellence in Cardiac Electrophysiology Research, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Nipon Chattipakorn
- Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand; Center of Excellence in Cardiac Electrophysiology Research, Chiang Mai University, Chiang Mai, 50200, Thailand; Cardiac Electrophysiology Unit, Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Krekwit Shinlapawittayatorn
- Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand; Center of Excellence in Cardiac Electrophysiology Research, Chiang Mai University, Chiang Mai, 50200, Thailand; Cardiac Electrophysiology Unit, Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.
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15
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Smits JAJ, Monfils MH, Otto MW, Telch MJ, Shumake J, Feinstein JS, Khalsa SS, Cobb AR, Parsons EM, Long LJ, McSpadden B, Johnson D, Greenberg A. CO 2 reactivity as a biomarker of exposure-based therapy non-response: study protocol. BMC Psychiatry 2022; 22:831. [PMID: 36575425 PMCID: PMC9793569 DOI: 10.1186/s12888-022-04478-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 12/15/2022] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Exposure-based therapy is an effective first-line treatment for anxiety-, obsessive-compulsive, and trauma- and stressor-related disorders; however, many patients do not improve, resulting in prolonged suffering and poorly used resources. Basic research on fear extinction may inform the development of a biomarker for the selection of exposure-based therapy. Growing evidence links orexin system activity to deficits in fear extinction and we have demonstrated that reactivity to an inhaled carbon dioxide (CO2) challenge-a safe, affordable, and easy-to-implement procedure-can serve as a proxy for orexin system activity and predicts fear extinction deficits in rodents. Building upon this basic research, the goal for the proposed study is to validate CO2 reactivity as a biomarker of exposure-based therapy non-response. METHODS We will assess CO2 reactivity in 600 adults meeting criteria for one or more fear- or anxiety-related disorders prior to providing open exposure-based therapy. By incorporating CO2 reactivity into a multivariate model predicting treatment non-response that also includes reactivity to hyperventilation as well as a number of related predictor variables, we will establish the mechanistic specificity and the additive predictive utility of the potential CO2 reactivity biomarker. By developing models independently within two study sites (University of Texas at Austin and Boston University) and predicting the other site's data, we will validate that the results are likely to generalize to future clinical samples. DISCUSSION Representing a necessary stage in translating basic research, this investigation addresses an important public health issue by testing an accessible clinical assessment strategy that may lead to a more effective treatment selection (personalized medicine) for patients with anxiety- and fear-related disorders, and enhanced understanding of the mechanisms governing exposure-based therapy. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT05467683 (20/07/2022).
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Affiliation(s)
- Jasper A. J. Smits
- grid.89336.370000 0004 1936 9924Department of Psychology and Institute for Mental Health Research, University of Texas at Austin, 1 University Station, Austin, TX 78712 USA
| | - Marie-H. Monfils
- grid.89336.370000 0004 1936 9924Department of Psychology and Institute for Mental Health Research, University of Texas at Austin, 1 University Station, Austin, TX 78712 USA
| | - Michael W. Otto
- grid.189504.10000 0004 1936 7558Department of Psychological and Brain Sciences, Boston University, 900 Commonwealth Avenue, Floor 2, Boston, MA 02215 USA
| | - Michael J. Telch
- grid.89336.370000 0004 1936 9924Department of Psychology and Institute for Mental Health Research, University of Texas at Austin, 1 University Station, Austin, TX 78712 USA
| | - Jason Shumake
- grid.89336.370000 0004 1936 9924Department of Psychology and Institute for Mental Health Research, University of Texas at Austin, 1 University Station, Austin, TX 78712 USA
| | - Justin S. Feinstein
- grid.417423.70000 0004 0512 88633The Laureate Institute for Brain Research, 6655 South Yale Ave., Tulsa, Oklahoma 74136 USA
| | - Sahib S. Khalsa
- grid.417423.70000 0004 0512 88633The Laureate Institute for Brain Research, 6655 South Yale Ave., Tulsa, Oklahoma 74136 USA
| | - Adam R. Cobb
- grid.89336.370000 0004 1936 9924Department of Psychology and Institute for Mental Health Research, University of Texas at Austin, 1 University Station, Austin, TX 78712 USA ,grid.259828.c0000 0001 2189 3475Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina and Ralph H. Johnson VAHCS, 67 President Street MSC 862, Charleston, SC 29425 USA
| | - E. Marie Parsons
- grid.189504.10000 0004 1936 7558Department of Psychological and Brain Sciences, Boston University, 900 Commonwealth Avenue, Floor 2, Boston, MA 02215 USA
| | - Laura J. Long
- grid.189504.10000 0004 1936 7558Department of Psychological and Brain Sciences, Boston University, 900 Commonwealth Avenue, Floor 2, Boston, MA 02215 USA
| | - Bryan McSpadden
- grid.89336.370000 0004 1936 9924Department of Psychology and Institute for Mental Health Research, University of Texas at Austin, 1 University Station, Austin, TX 78712 USA
| | - David Johnson
- grid.89336.370000 0004 1936 9924Department of Psychology and Institute for Mental Health Research, University of Texas at Austin, 1 University Station, Austin, TX 78712 USA
| | - Alma Greenberg
- grid.189504.10000 0004 1936 7558Department of Psychological and Brain Sciences, Boston University, 900 Commonwealth Avenue, Floor 2, Boston, MA 02215 USA
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16
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CO 2 exposure enhances Fos expression in hypothalamic neurons in rats during the light and dark phases of the diurnal cycle. Brain Struct Funct 2022; 227:2667-2679. [PMID: 36109371 DOI: 10.1007/s00429-022-02562-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 08/29/2022] [Indexed: 12/30/2022]
Abstract
Orexinergic (OX) neurons in the lateral hypothalamus (LH), perifornical area (PFA) and dorsomedial hypothalamus (DMH) play a role in the hypercapnic ventilatory response, presumably through direct inputs to central pattern generator sites and/or through interactions with other chemosensitive regions. OX neurons can produce and release orexins, excitatory neuropeptides involved in many functions, including physiological responses to changes in CO2/pH. Thus, in the present study, we tested the hypothesis that different nuclei (LH, PFA and DMH) where the orexinergic neurons are located, show distinct activation by CO2 during the light-dark cycle phases. For this purpose, we evaluated the Fos and OXA expression by immunohistochemistry to identify neurons that co-localize Fos + OXA in the LH, LPeF, MPeF and DMH in the light-inactive and dark-active phase in Wistar rats subjected to 3 h of normocapnia or hypercapnia (7% CO2). Quantitative analyses of immunoreactive neurons show that hypercapnia caused an increase in the number of neurons expressing Fos in the LH, LPeF, MPeF and DMH in the light and dark phases. In addition, the number of Fos + OXA neurons increased in the LPeF and DMH independently of the phases of the diurnal cycle; whereas in the MPeF, this increase was observed exclusively in the light phase. Thus, we suggest that OX neurons are selectively activated by hypercapnia throughout the diurnal cycle, reinforcing the differential role of nuclei in the hypothalamus during central chemosensitivity.
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17
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Rodrigues LTC, Patrone LGA, Gargaglioni LH, Dias MB. Melanin-concentrating hormone regulates the hypercapnic chemoreflex by acting in the lateral hypothalamic area. Exp Physiol 2022; 107:1298-1311. [PMID: 35930596 DOI: 10.1113/ep090318] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 07/22/2022] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? MCH suppresses the hypercapnic chemoreflex but the mechanism by which this effect is produced has not been previously explored. What is the main finding and its importance? MCH acting in the lateral hypothalamic area but not in the locus coeruleus in rats, in the light period, attenuates the hypercapnic chemoreflex. Our data provide new insight regarding the role of MCH in the modulation of the hypercapnic ventilatory response. ABSTRACT Melanin-concentrating hormone (MCH) is a hypothalamic neuropeptide involved in a broad range of homeostatic functions including regulation of the hypercapnic chemoreflex. We evaluated whether MCH modulates the hypercapnic ventilatory response by acting in the lateral hypothalamic area (LHA) and/or in the locus coeruleus (LC). Here, we measured pulmonary ventilation (VE ), body temperature, electroencephalogram (EEG) and electromyogram (EMG) of unanesthetized adult male Wistar rats before and after microinjection of MCH [0.4 mM] or MCH1-R antagonist (SNAP-94847 [63 mM]) into the LHA and LC, in room air and 7% CO2 conditions during wakefulness and sleep, in the dark and light periods. MCH intra-LHA caused a decreased CO2 ventilatory response during wakefulness and sleep in the light period, while SNAP-94847 intra-LHA increased this response, during wakefulness in the light period. In the LC, MCH or the MCH1-R antagonist caused no change in the hypercapnic ventilatory response. Our results suggest that MCH, in the LHA, exerts an inhibitory modulation of the hypercapnic ventilatory response during the light-inactive period in rats. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Laísa T C Rodrigues
- Department of Structural and Functional Biology, Institute of Biosciences, Sao Paulo State University-UNESP, Botucatu, SP, Brazil
| | - Luis Gustavo A Patrone
- Department of Animal Morphology and Physiology, Sao Paulo State University-FCAV, Jaboticabal, SP, Brazil
| | - Luciane H Gargaglioni
- Department of Animal Morphology and Physiology, Sao Paulo State University-FCAV, Jaboticabal, SP, Brazil
| | - Mirela B Dias
- Department of Structural and Functional Biology, Institute of Biosciences, Sao Paulo State University-UNESP, Botucatu, SP, Brazil
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Hampson JP, Lacuey N, Rani MRS, Hampson JS, Simeone KA, Simeone TA, Narayana PA, Lemieux L, Lhatoo SD. Functional MRI Correlates of Carbon Dioxide Chemosensing in Persons With Epilepsy. Front Neurol 2022; 13:896204. [PMID: 35873766 PMCID: PMC9301231 DOI: 10.3389/fneur.2022.896204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 06/03/2022] [Indexed: 11/17/2022] Open
Abstract
Objectives Sudden unexpected death in epilepsy (SUDEP) is a catastrophic epilepsy outcome for which there are no reliable premortem imaging biomarkers of risk. Percival respiratory depression is seen in monitored SUDEP and near SUDEP cases, and abnormal chemosensing of raised blood carbon dioxide (CO2) is thought to contribute. Damage to brainstem respiratory control and chemosensing structures has been demonstrated in structural imaging and neuropathological studies of SUDEP. We hypothesized that functional MRI (fMRI) correlates of abnormal chemosensing are detectable in brainstems of persons with epilepsy (PWE) and are different from healthy controls (HC). Methods We analyzed fMRI BOLD activation and brain connectivity in 10 PWE and 10 age- and sex-matched HCs during precisely metered iso-oxic, hypercapnic breathing challenges. Segmented brainstem responses were of particular interest, along with characterization of functional connectivity metrics between these structures. Regional BOLD activations during hypercapnic challenges were convolved with hemodynamic responses, and the resulting activation maps were passed on to group-level analyses. For the functional connectivity analysis, significant clusters from BOLD results were used as seeds. Each individual seed time-series activation map was extracted for bivariate correlation coefficient analyses to study changes in brain connectivity between PWE and HCs. Results (1) Greater brainstem BOLD activations in PWE were observed compared to HC during hypercapnic challenges in several structures with respiratory/chemosensing properties. Group comparison between PWE vs. HC showed significantly greater activation in the dorsal raphe among PWE (p < 0.05) compared to HCs. (2) PWE had significantly greater seed-seed connectivity and recruited more structures during hypercapnia compared to HC. Significance The results of this study show that BOLD responses to hypercapnia in human brainstem are detectable and different in PWE compared to HC. Increased dorsal raphe BOLD activation in PWE and increased seed-seed connectivity between brainstem and adjacent subcortical areas may indicate abnormal chemosensing in these individuals. Imaging investigation of brainstem respiratory centers involved in respiratory regulation in PWE is an important step toward identifying suspected dysfunction of brainstem breathing control that culminates in SUDEP and deserve further study as potential imaging SUDEP biomarkers.
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Affiliation(s)
- Johnson P. Hampson
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Nuria Lacuey
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, United States
| | - MR Sandhya Rani
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Jaison S. Hampson
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Kristina A. Simeone
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE, United States
| | - Timothy A. Simeone
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE, United States
| | - Ponnada A. Narayana
- Department of Diagnostic and Interventional Imaging, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Louis Lemieux
- Department of Clinical and Experimental Epilepsy, University College London (UCL) Institute of Neurology, National Hospital for Neurology and Neurosurgery, London, United Kingdom
| | - Samden D. Lhatoo
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, United States
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19
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Burtscher J, Niedermeier M, Hüfner K, van den Burg E, Kopp M, Stoop R, Burtscher M, Gatterer H, Millet GP. The interplay of hypoxic and mental stress: Implications for anxiety and depressive disorders. Neurosci Biobehav Rev 2022; 138:104718. [PMID: 35661753 DOI: 10.1016/j.neubiorev.2022.104718] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 12/14/2022]
Abstract
Adequate oxygen supply is essential for the human brain to meet its high energy demands. Therefore, elaborate molecular and systemic mechanism are in place to enable adaptation to low oxygen availability. Anxiety and depressive disorders are characterized by alterations in brain oxygen metabolism and of its components, such as mitochondria or hypoxia inducible factor (HIF)-pathways. Conversely, sensitivity and tolerance to hypoxia may depend on parameters of mental stress and the severity of anxiety and depressive disorders. Here we discuss relevant mechanisms of adaptations to hypoxia, as well as their involvement in mental stress and the etiopathogenesis of anxiety and depressive disorders. We suggest that mechanisms of adaptations to hypoxia (including metabolic responses, inflammation, and the activation of chemosensitive brain regions) modulate and are modulated by stress-related pathways and associated psychiatric diseases. While severe chronic hypoxia or dysfunctional hypoxia adaptations can contribute to the pathogenesis of anxiety and depressive disorders, harnessing controlled responses to hypoxia to increase cellular and psychological resilience emerges as a novel treatment strategy for these diseases.
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Affiliation(s)
- Johannes Burtscher
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland; Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland.
| | - Martin Niedermeier
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Katharina Hüfner
- Department of Psychiatry, Psychotherapy, Psychosomatics and Medical Psychology, University Clinic for Psychiatry II, Innsbruck Medical University, Innsbruck, Austria
| | - Erwin van den Burg
- Department of Psychiatry, Center of Psychiatric Neuroscience (CNP), University Hospital of Lausanne (CHUV), Prilly, Lausanne, Switzerland
| | - Martin Kopp
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Ron Stoop
- Department of Psychiatry, Center of Psychiatric Neuroscience (CNP), University Hospital of Lausanne (CHUV), Prilly, Lausanne, Switzerland
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Hannes Gatterer
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Grégoire P Millet
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland; Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
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20
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Spinieli RL, Ben Musa R, Cornelius-Green J, Hasser EM, Cummings KJ. Orexin facilitates the ventilatory and behavioral responses of rats to hypoxia. Am J Physiol Regul Integr Comp Physiol 2022; 322:R581-R596. [PMID: 35380477 PMCID: PMC9109809 DOI: 10.1152/ajpregu.00334.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 03/22/2022] [Accepted: 03/30/2022] [Indexed: 02/03/2023]
Abstract
Orexin neurons are sensitive to CO2 and contribute to cardiorespiratory homeostasis as well as sensorimotor control. Whether orexin facilitates respiratory and behavioral responses to acute hypoxia is unclear. We hypothesized that orexin neurons are activated by acute hypoxia and that orexin facilitates the hypoxic ventilatory response (HVR), as well as the arterial blood pressure (ABP) and behavioral (movement) responses to acute hypoxia. We further hypothesized that orexin has greater effects in the active phase of the rat circadian cycle, when orexin neurons have high activity. Using whole body plethysmography with EEG, EMG, and the dual-orexin receptor (OxR) antagonist suvorexant (20 mg/kg ip), we determined the effect of OxR blockade on the respiratory, ABP, and behavioral responses of adult rats to acute, graded hypoxia ([Formula: see text]= 0.15, 0.13, 0.11, and 0.09) and hyperoxic hypercapnia ([Formula: see text]= 0.05; [Formula: see text]= 0.95). OxR blockade had no effect on eupnea. OxR blockade significantly reduced the HVR in both inactive and active phases, with a stronger effect in the active phase. OxR blockade reduced the behavioral response to acute hypoxia in the active phase. The central component of the ventilatory and the ABP responses to hypercapnia were reduced by OxR blockade solely in the inactive phase. In the inactive phase, hypoxia activated ∼10% of orexin neurons in the perifornical hypothalamus. These data suggest that orexin neurons participate in the peripheral chemoreflex to facilitate the ventilatory and behavioral responses to acute hypoxia in rats, particularly in the active phase. Orexin also facilitates central chemoreflex responses to CO2 in the inactive phase.
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Affiliation(s)
- Richard L Spinieli
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Ruwaida Ben Musa
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Jennifer Cornelius-Green
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Eileen M Hasser
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Kevin J Cummings
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
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21
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Ritz T. An apnea-hypothesis of anxiety generation: Novel, respiratory, and falsifiable. Biol Psychol 2022; 170:108304. [DOI: 10.1016/j.biopsycho.2022.108304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 03/03/2022] [Accepted: 03/03/2022] [Indexed: 11/02/2022]
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22
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Abstract
Brain PCO2 is sensed primarily via changes in [H+]. Small pH changes are detected in the medulla oblongata and trigger breathing adjustments that help maintain arterial PCO2 constant. Larger perturbations of brain CO2/H+, possibly also sensed elsewhere in the CNS, elicit arousal, dyspnea, and stress, and cause additional breathing modifications. The retrotrapezoid nucleus (RTN), a rostral medullary cluster of glutamatergic neurons identified by coexpression of Phoxb and Nmb transcripts, is the lynchpin of the central respiratory chemoreflex. RTN regulates breathing frequency, inspiratory amplitude, and active expiration. It is exquisitely responsive to acidosis in vivo and maintains breathing autorhythmicity during quiet waking, slow-wave sleep, and anesthesia. The RTN response to [H+] is partly an intrinsic neuronal property mediated by proton sensors TASK-2 and GPR4 and partly a paracrine effect mediated by astrocytes and the vasculature. The RTN also receives myriad excitatory or inhibitory synaptic inputs including from [H+]-responsive neurons (e.g., serotonergic). RTN is silenced by moderate hypoxia. RTN inactivity (periodic or sustained) contributes to periodic breathing and, likely, to central sleep apnea. RTN development relies on transcription factors Egr2, Phox2b, Lbx1, and Atoh1. PHOX2B mutations cause congenital central hypoventilation syndrome; they impair RTN development and consequently the central respiratory chemoreflex.
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Affiliation(s)
- Patrice G Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, VA, United States.
| | - Douglas A Bayliss
- Department of Pharmacology, University of Virginia, Charlottesville, VA, United States
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23
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Vaseghi S, Zarrabian S, Haghparast A. Reviewing the role of the orexinergic system and stressors in modulating mood and reward-related behaviors. Neurosci Biobehav Rev 2021; 133:104516. [PMID: 34973302 DOI: 10.1016/j.neubiorev.2021.104516] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 12/24/2021] [Accepted: 12/27/2021] [Indexed: 01/22/2023]
Abstract
In this review study, we aimed to introduce the orexinergic system as an important signaling pathway involved in a variety of cognitive functions such as memory, motivation, and reward-related behaviors. This study focused on the role of orexinergic system in modulating reward-related behavior, with or without the presence of stressors. Cross-talk between the reward system and orexinergic signaling was also investigated, especially orexinergic signaling in the ventral tegmental area (VTA), the nucleus accumbens (NAc), and the hippocampus. Furthermore, we discussed the role of the orexinergic system in modulating mood states and mental illnesses such as depression, anxiety, panic, and posttraumatic stress disorder (PTSD). Here, we narrowed down our focus on the orexinergic signaling in three brain regions: the VTA, NAc, and the hippocampus (CA1 region and dentate gyrus) for their prominent role in reward-related behaviors and memory. It was concluded that the orexinergic system is critically involved in reward-related behavior and significantly alters stress responses and stress-related psychiatric and mood disorders.
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Affiliation(s)
- Salar Vaseghi
- Medicinal Plants Research Center, Institute of Medicinal Plants, ACECR, Karaj, Iran
| | - Shahram Zarrabian
- Department of Anatomical Sciences & Cognitive Neuroscience, Faculty of Medicine, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Abbas Haghparast
- Neuroscience Research Center, School of Medicine, Shahid Beheshti University of Medical Sciences, P.O. Box 19615-1178, Tehran, Iran.
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24
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Moslehi E, Minasian V, Sadeghi H. Subcutaneous Adipose Tissue Browning, Serum Orexin-A, and Insulin Resistance Following Aerobic Exercise in High-Fat Diet Obesity Male Wistar Rats. Int J Prev Med 2021; 12:132. [PMID: 34912508 PMCID: PMC8631127 DOI: 10.4103/ijpvm.ijpvm_110_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 12/04/2019] [Indexed: 11/04/2022] Open
Abstract
Background Subcutaneous adipose tissue (SAT) relative to the other adipose tissues may have different roles in health and insulin resistance. The purpose of this study was to investigate the effectiveness of aerobic exercise on SAT thermogenesis indices, serum orexin-A (OXA), and insulin resistance in high-fat diet-induced obesity male Wistar rats. Methods Thirty-two male Wistar rats with an average weight of 180-200 g were randomly assigned into 4 equal groups: normal fat diet (NFD), high-fat diet obesity (HFDO), normal fat diet after high-fat diet obesity (HFDO-NFD), and aerobic exercise group with normal fat diet after high-fat diet obesity (HFDO-AEX). Fasting levels of serum OXA, insulin, FBS, high-density lipoproteins, low-density lipoproteins, cholesterol and gene expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and UCP1 in SAT were evaluated. Samples were taken in the HFDO group after obesity-induced and in other groups 48 h after 8 weeks of aerobic exercise. Results The results showed that HFD significantly decreased serum levels of OXA, HDL-c and gene expression of PGC1α and UCP1 in SAT. In addition, it caused a significant increase in Lee index, FBS, insulin resistance, and serum lipid profile in comparison with the NFD group (P ≤ 0.001). Aerobic exercise significantly modified the changes caused by HFD to the normal levels (P ≤ 0.001). Conclusions These data suggest that aerobic exercise caused an improvement in insulin resistance and blood lipid profiles through an increase in the serum level of OXA and alteration in the SAT phenotype from white to brown or beige.
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Affiliation(s)
- Ebrahim Moslehi
- Department of Exercise Physiology, University of Isfahan, Isfahan, Iran
| | - Vazgen Minasian
- Department of Exercise Physiology, University of Isfahan, Isfahan, Iran
| | - Heibatollah Sadeghi
- Medicinal Plants Research Center, Yasuj University of Medical Sciences, Yasuj, I.R. Iran
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25
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Peleg-Raibstein D, Burdakov D. Do orexin/hypocretin neurons signal stress or reward? Peptides 2021; 145:170629. [PMID: 34416308 DOI: 10.1016/j.peptides.2021.170629] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/04/2021] [Accepted: 08/14/2021] [Indexed: 12/23/2022]
Abstract
Hypothalamic neurons that produce the peptide transmitters orexins/hypocretins (HONs) broadcast their predominantly neuroexcitatory outputs to the entire brain via their extremely wide axonal projections. HONs were originally reported to be activated by food deprivation, and to stimulate arousal, energy expenditure, and eating. This led to extensive studies of HONs in the context of nutrient-sensing and energy balance control. While activation of HONs by body energy depletion continues to be supported by experimental evidence, it has also become clear that HONs are robustly activated not only by nutrient depletion, but also by diverse sensory stimuli (both neutral and those associated with rewarding or aversive events), seemingly unrelated to each other or to energy balance. One theory that could unify these findings is that all these stimuli signal "stress" - defined either as a potentially harmful state, or an awareness of reward deficiency. If HON activity is conceptualized as a cumulative representation of stress, then many of the reported HONs outputs - including EEG arousal, sympathetic activation, place avoidance, and exploratory behaviours - could be viewed as logical stress-counteracting responses. We discuss evidence for and against this unifying theory of HON function, including the alterations in HON activity observed in anxiety and depression disorders. We propose that, in order to orchestrate stress-countering responses, HONs need to coactivate motivation and aversion brain systems, and the impact of HON stimulation on affective states may be perceived as rewarding or aversive depending on the baseline HON activity.
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Affiliation(s)
| | - Denis Burdakov
- Department of Health Sciences and Technology, ETH Zürich, Switzerland.
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Pan J, Chen G, Shan P, Chen C, Jiang D, Wang L, Li G, Chen M, Zhuo C, Fang T, Yu H. Plasma Orexin Levels Related to Altered Brain Activity During Abstinence in Patients with Alcohol Dependence. PSYCHIAT CLIN PSYCH 2021; 31:286-291. [PMID: 38765947 PMCID: PMC11079708 DOI: 10.5152/pcp.2021.20011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 07/10/2020] [Indexed: 05/22/2024] Open
Abstract
Objectives In vivo studies have correlated brain activity with alcohol-seeking behavior, while clinical studies have identified altered brain activity in patients with alcohol dependence (AD) even during abstinence. We aimed to explore the relationship between plasma orexin levels, brain activity, and alcohol-craving scores in patients with AD. Methods In this pilot study, we evaluated 24 male patients with AD in remission and 25 male controls. Alcohol craving was assessed using the Obsessive Compulsive Drinking Scale (OCDS). An adapted MRI technique was used to assess global functional connectivity density (gFCD), and plasma orexin concentrations were measured by radioimmunoassay. Associations were analyzed by the Pearson correlation. Results Plasma orexin levels in AD patients in remission were significantly higher than those in the controls. OCDS scores correlated to orexin concentrations (r = 0.47, P < .05). Compared to the controls, all AD patients demonstrated reduced gFCD, primarily in the frontal, temporal, and parietal lobes, and increased gFCD in the accumbens nuclei and posterior insular cortex. Mean gFCD values in the accumbens nuclei significantly correlated to craving scores (r = 0.55, P < .05). Although assessed during abstinence, the reward circuits in AD patients exhibited increased activity. Orexin levels correlated to increased activity in the accumbens nuclei and craving scores. Conclusions The potential clinical utility of plasma orexin levels to assess the risk of relapse in AD patients in treatment and prevention programs deserves further study.
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Affiliation(s)
- Jianshe Pan
- Department of Psychiatry, Wenzhou Kangning Hospital, Wenzhou, Zhejiang Province, China
| | - Guangdong Chen
- Department of Psychiatric-Neuroimage Center, Radiology Center, Wenzhou Seventh People’s Hospital, Wenzhou, Zhejiang Province, China
| | - Peiwei Shan
- Department of Psychiatric-Neuroimage Center, Radiology Center, Wenzhou Seventh People’s Hospital, Wenzhou, Zhejiang Province, China
| | - Ce Chen
- Department of Psychiatric-Neuroimage Center, Radiology Center, Wenzhou Seventh People’s Hospital, Wenzhou, Zhejiang Province, China
| | - Deguo Jiang
- Department of Psychiatric-Neuroimage Center, Radiology Center, Wenzhou Seventh People’s Hospital, Wenzhou, Zhejiang Province, China
| | - Lina Wang
- Psychiatric-Neuroimaging-Genetics-Comorbidity (PNGC) Laboratory, Tianjin Anding Hospital, Nankai University Affiliated Anding Hospital, Tianjin Mental Health Center, Tianjin, China
| | - Gongying Li
- Department of Psychiatry, School of Mental Health, Jining Medical University, Jining, Shandong Province, China
| | - Min Chen
- Department of Psychiatry, School of Mental Health, Jining Medical University, Jining, Shandong Province, China
| | - Chuanjun Zhuo
- Department of Psychiatry, School of Mental Health, Jining Medical University, Jining, Shandong Province, China
| | - Tao Fang
- Laboratory of Neurology-Psychiatry Biological-Neuroimaging (NPBI-Lab), Tianjin Fourth Center Hospital, Tianjin, China
| | - Haiping Yu
- Department of Psychiatric-Neuroimage Center, Radiology Center, Wenzhou Seventh People’s Hospital, Wenzhou, Zhejiang Province, China
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Wang X, Guan R, Zhao X, Chen J, Zhu D, Shen L, Song N. TASK1 and TASK3 in orexin neuron of lateral hypothalamus contribute to respiratory chemoreflex by projecting to nucleus tractus solitarius. FASEB J 2021; 35:e21532. [PMID: 33817828 DOI: 10.1096/fj.202002189r] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 02/19/2021] [Accepted: 03/01/2021] [Indexed: 11/11/2022]
Abstract
TWIK-related acid-sensitive potassium channels (TASKs)-like current was recorded in orexin neurons in the lateral hypothalamus (LH), which are essential in respiratory chemoreflex. However, the specific mechanism responsible for the pH-sensitivity remains elusive. Thus, we hypothesized that TASKs contribute to respiratory chemoreflex. In the present study, we found that TASK1 and TASK3 were expressed in orexin neurons. Blocking TASKs or microinjecting acid artificial cerebrospinal fluid (ACSF) in the LH stimulated breathing. In contrast, alkaline ACSF inhibited breathing, which was attenuated by blocking TASK1. Damage of orexin neurons attenuated the stimulatory effect on respiration caused by microinjection of acid ACSF (at a pH of 6.5) or TASKs antagonists. The orexinA-positive fiber and orexin type 1 receptor (OX1R) neurons were located in the nucleus tractus solitarius (NTS). The exciting effect of acidosis in the LH on respiration was inhibited by blocking OX1R of the NTS. Taken together, we conclude that orexin neurons sense the extracellular pH change through TASKs and regulate respiration by projecting to the NTS.
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Affiliation(s)
- Xia Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China.,Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiaotong University, Shanghai, China
| | - Ruijuan Guan
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Xiaomei Zhao
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Jun Chen
- Department of Pathology, Changzheng Hospital, Naval Military Medical University, Shanghai, China
| | - Danian Zhu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Linlin Shen
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention, Fudan University, Shanghai, China
| | - Nana Song
- Division of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China
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Astrocytic contribution to glutamate-related central respiratory chemoreception in vertebrates. Respir Physiol Neurobiol 2021; 294:103744. [PMID: 34302992 DOI: 10.1016/j.resp.2021.103744] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 07/01/2021] [Accepted: 07/18/2021] [Indexed: 12/24/2022]
Abstract
Central respiratory chemoreceptors play a key role in the respiratory homeostasis by sensing CO2 and H+ in brain and activating the respiratory neural network. This ability of specific brain regions to respond to acidosis and hypercapnia is based on neuronal and glial mechanisms. Several decades ago, glutamatergic transmission was proposed to be involved as a main mechanism in central chemoreception. However, a complete identification of mechanism has been elusive. At the rostral medulla, chemosensitive neurons of the retrotrapezoid nucleus (RTN) are glutamatergic and they are stimulated by ATP released by RTN astrocytes in response to hypercapnia. In addition, recent findings show that caudal medullary astrocytes in brainstem can also contribute as CO2 and H+ sensors that release D-serine and glutamate, both gliotransmitters able to activate the respiratory neural network. In this review, we describe the mammalian astrocytic glutamatergic contribution to the central respiratory chemoreception trying to trace in vertebrates the emergence of several components involved in this process.
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Multiple-dose clinical pharmacology of the selective orexin-1 receptor antagonist ACT-539313. Prog Neuropsychopharmacol Biol Psychiatry 2021; 108:110166. [PMID: 33159976 DOI: 10.1016/j.pnpbp.2020.110166] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 10/27/2020] [Accepted: 10/31/2020] [Indexed: 12/28/2022]
Abstract
AIMS Compounds that selectively target orexin-1 receptors may be beneficial for the treatment of various disorders. The role of selective orexin-1 receptor antagonists (1-SORAs) in addictive behavior and stress/anxiety-related disturbances has been demonstrated in animals. ACT-539313, an orally active, potent 1-SORA, has been assessed in a clinical single-ascending dose study and exhibited good safety and tolerability. In the two reported studies on ACT-539313, multiple-dose pharmacokinetics (PK), pharmacodynamics (PD), safety, and tolerability were investigated and in a proof-of-mechanism study a CO2 challenge was applied as pharmacological model for induction of anxiety and panic symptoms (sequential inhalation of air, 7.5% CO2, and 35% CO2). METHODS Two double-blind, placebo-controlled, randomized, multiple-dose studies included 58 healthy male and female subjects. In Study 1, multiple-ascending oral doses of 30, 100, and 200 mg twice daily (b.i.d.) ACT-539313 were investigated in 3 dose groups of 8 or 12 subjects (of whom 2 received placebo per dose group). Study 2 was conducted as a randomized two-way crossover design, enrolling 21 male and 9 female subjects who received 200 mg ACT-539313 or matching placebo b.i.d. for 2.5 days followed by a CO2 challenge, with a washout period in between. PK, PD (objective and subjective measures of sedation, alertness, effects on central nervous system (CNS), and anxiety/panic symptoms), safety, and tolerability were assessed. RESULTS At steady state, ACT-539313 was rapidly absorbed with a median time to maximum plasma concentration of 1.8-2.3 h and eliminated with a mean half-life of 3.8-6.5 h. Overall exposure increased dose-proportionally. In Study 1, PD effects confirmed activity of ACT-539313 on the CNS, without consistent or marked effects of sedation, reduced alertness or visuo-motor impairment. In the CO2 challenge, cortisol concentrations were lower during initial air inhalation after treatment with ACT-539313 compared to placebo, while no difference was detected after CO2 inhalation. Trends for lower scores in subjective anxiety assessments were observed for ACT-539313. Besides reports of stress related to the challenge, the most frequently reported adverse events were somnolence and headache. No clinically relevant effects in other safety assessments were observed. CONCLUSIONS Multiple-dose administration of ACT-539313 was safe and well tolerated up to multiple doses of 200 mg b.i.d. The drug's PK properties as well as the pattern of a decrease in stress-related symptoms after the CO2 challenge support further investigations of ACT-539313.
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Regulatory Role of Orexin in the Antistress Effect of "Press Tack Needle" Acupuncture Treatment. Healthcare (Basel) 2021; 9:healthcare9050503. [PMID: 33925438 PMCID: PMC8146164 DOI: 10.3390/healthcare9050503] [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: 02/17/2021] [Revised: 04/16/2021] [Accepted: 04/22/2021] [Indexed: 11/18/2022] Open
Abstract
The aim of this research was to investigate the antistress effect of press tack needle (PTN) acupuncture treatment using rats with social isolation stress (SIS). Rats were divided into non-stress group (Grouped+sham), stress group (SIS+sham), and PTN-treated SIS group (SIS+PTN). Rats in the SIS+PTN and SIS+sham groups were housed alone for eight days. For the SIS+PTN group, a PTN (length, 0.3 or 1.2 mm) was fixed on the GV20 acupoint on day 7. We measured stress behavior based on the time the rats showed aggressive behavior and the levels of plasma corticosterone and orexin A on day 8. In addition, the orexin-1 receptor or orexin-2 receptor antagonist was administered to rats that were exposed to SIS. The duration of aggressive behavior was significantly prolonged in the SIS+sham group, and the prolonged duration was inhibited in the SIS+PTN (1.2 mm) group. The levels of plasma corticosterone and orexin A were significantly increased in the SIS+sham group; however, these increases were inhibited in the SIS+PTN group. The aggressive behavior was significantly reduced after the orexin-2 receptor antagonist was administered. These findings suggest that PTN treatment at GV20 may have an antistress effect, and the control of orexin is a mechanism underlying this phenomenon.
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Concetti C, Burdakov D. Orexin/Hypocretin and MCH Neurons: Cognitive and Motor Roles Beyond Arousal. Front Neurosci 2021; 15:639313. [PMID: 33828450 PMCID: PMC8019792 DOI: 10.3389/fnins.2021.639313] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 03/01/2021] [Indexed: 02/01/2023] Open
Abstract
The lateral hypothalamus (LH) is classically implicated in sleep-wake control. It is the main source of orexin/hypocretin and melanin-concentrating hormone (MCH) neuropeptides in the brain, which have been both implicated in arousal state switching. These neuropeptides are produced by non-overlapping LH neurons, which both project widely throughout the brain, where release of orexin and MCH activates specific postsynaptic G-protein-coupled receptors. Optogenetic manipulations of orexin and MCH neurons during sleep indicate that they promote awakening and REM sleep, respectively. However, recordings from orexin and MCH neurons in awake, moving animals suggest that they also act outside sleep/wake switching. Here, we review recent studies showing that both orexin and MCH neurons can rapidly (sub-second-timescale) change their firing when awake animals experience external stimuli, or during self-paced exploration of objects and places. However, the sensory-behavioral correlates of orexin and MCH neural activation can be quite different. Orexin neurons are generally more dynamic, with about 2/3rds of them activated before and during self-initiated running, and most activated by sensory stimulation across sensory modalities. MCH neurons are activated in a more select manner, for example upon self-paced investigation of novel objects and by certain other novel stimuli. We discuss optogenetic and chemogenetic manipulations of orexin and MCH neurons, which combined with pharmacological blockade of orexin and MCH receptors, imply that these rapid LH dynamics shape fundamental cognitive and motor processes due to orexin and MCH neuropeptide actions in the awake brain. Finally, we contemplate whether the awake control of psychomotor brain functions by orexin and MCH are distinct from their “arousal” effects.
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Affiliation(s)
- Cristina Concetti
- Department of Health Sciences and Technology, ETH Zürich, Zurich, Switzerland
| | - Denis Burdakov
- Department of Health Sciences and Technology, ETH Zürich, Zurich, Switzerland
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32
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Guillaumin MCC, Burdakov D. Neuropeptides as Primary Mediators of Brain Circuit Connectivity. Front Neurosci 2021; 15:644313. [PMID: 33776641 PMCID: PMC7991401 DOI: 10.3389/fnins.2021.644313] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 02/18/2021] [Indexed: 11/21/2022] Open
Abstract
Across sleep and wakefulness, brain function requires inter-neuronal interactions lasting beyond seconds. Yet, most studies of neural circuit connectivity focus on millisecond-scale interactions mediated by the classic fast transmitters, GABA and glutamate. In contrast, neural circuit roles of the largest transmitter family in the brain–the slow-acting peptide transmitters–remain relatively overlooked, or described as “modulatory.” Neuropeptides may efficiently implement sustained neural circuit connectivity, since they are not rapidly removed from the extracellular space, and their prolonged action does not require continuous presynaptic firing. From this perspective, we review actions of evolutionarily-conserved neuropeptides made by brain-wide-projecting hypothalamic neurons, focusing on lateral hypothalamus (LH) neuropeptides essential for stable consciousness: the orexins/hypocretins. Action potential-dependent orexin release inside and outside the hypothalamus evokes slow postsynaptic excitation. This excitation does not arise from modulation of classic neurotransmission, but involves direct action of orexins on their specific G-protein coupled receptors (GPCRs) coupled to ion channels. While millisecond-scale, GABA/glutamate connectivity within the LH may not be strong, re-assessing LH microcircuits from the peptidergic viewpoint is consistent with slow local microcircuits. The sustained actions of neuropeptides on neuronal membrane potential may enable core brain functions, such as temporal integration and the creation of lasting permissive signals that act as “eligibility traces” for context-dependent information routing and plasticity. The slowness of neuropeptides has unique advantages for efficient neuronal processing and feedback control of consciousness.
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Affiliation(s)
| | - Denis Burdakov
- Department of Health Sciences and Technology, ETH Zürich, Zurich, Switzerland
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33
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Holton P, Huang Y, Bahuri NFA, Boccard S, Hyam JA, Paterson DJ, Dorrington KL, Aziz TZ, Moosavi SH, Green AL. Differential responses to breath-holding, voluntary deep breathing and hypercapnia in left and right dorsal anterior cingulate. Exp Physiol 2020; 106:726-735. [PMID: 33369804 DOI: 10.1113/ep088961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 12/22/2020] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? What is the role of dorsal anterior cingulate cortex (ACC) in respiration control in humans? What is the main finding and its importance? Direct evidence is provided for a role of the ACC in respiratory control in humans. The neurophysiological responses in dorsal ACC to different breathing tasks varied and were different between left and right ACC. ABSTRACT The role of subcortical structures and cerebral cortex in the maintenance of respiratory homeostasis in humans remains poorly understood. Emerging evidence suggests an important role of the anterior cingulate cortex (ACC) in respiratory control. In this study, local field potentials (LFPs) from dorsal ACC were recorded in humans through implanted deep brain electrodes during several breathing activities, including voluntary activities of breath-holding and deep breathing, and involuntary activities of inspiration of varying concentrations of carbon dioxide (1%, 3%, 5% and 7%). We found that the breath-holding task induced significant unilateral left-sided ACC changes in LFP power, including an increased activity in lower frequency bands (3-5 Hz) and decreased activity in higher frequency bands (12-26 Hz). The respiratory task involving reflex increase in ventilation due to hypercapnia (raised inspired CO2 ) was associated with bilateral changes in activity of the ACC (again with increased activity in lower frequency bands and reduced activity in higher frequency bands). The voluntary breathing task with associated hypocapnia (deep breathing) induced bilateral changes in activity within low frequency bands. Furthermore, probabilistic diffusion tractography analysis showed left-sided connection of the ACC with the insula and frontal operculum, and bilateral connections within subsections of the cingulate gyrus and the thalamus. This electrophysiological analysis provides direct evidence for a role of the ACC in respiratory control in humans.
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Affiliation(s)
- Patrick Holton
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK
| | - Yongzhi Huang
- Tianjin International Joint Research Center for Neural Engineering, Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, China
| | | | - Sandra Boccard
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK
| | - Jonathan A Hyam
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK
| | - David J Paterson
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Keith L Dorrington
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Tipu Z Aziz
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK
| | - Shakeeb H Moosavi
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, UK
| | - Alexander L Green
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK
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Fonseca EM, Vicente MC, Fournier S, Kinkead R, Bícego KC, Gargaglioni LH. Influence of light/dark cycle and orexins on breathing control in green iguanas (Iguana iguana). Sci Rep 2020; 10:22105. [PMID: 33328521 PMCID: PMC7744544 DOI: 10.1038/s41598-020-79107-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 12/01/2020] [Indexed: 11/17/2022] Open
Abstract
Light/dark cycle affects the physiology of vertebrates and hypothalamic orexin neurons (ORX) are involved in this function. The breathing pattern of the green iguana changes from continuous to episodic across the light/dark phases. Since the stimulatory actions of ORX on breathing are most important during arousal, we hypothesized that ORX regulates changes of breathing pattern in iguanas. Thus, we: (1) Localized ORX neurons with immunohistochemistry; (2) Quantified cyclic changes in plasma orexin-A levels by ELISA; (3) Compared breathing pattern at rest and during hypoxia and hypercarbia; (4) Evaluated the participation of the ORX receptors in ventilation with intracerebroventricular microinjections of ORX antagonists during light and dark phases. We show that the ORX neurons of I. iguana are located in the periventricular hypothalamic nucleus. Orexin-A peaks during the light/active phase and breathing parallels these cyclic changes: ventilation is higher during the light phase than during the dark phase. However, inactivation of ORX-receptors does not affect the breathing pattern. Iguanas increase ventilation during hypoxia only during the light phase. Conversely, CO2 promotes post-hypercarbic hyperpnea during both phases. We conclude that ORXs potentiate the post-hypercarbic (but not the hypoxic)-drive to breathe and are not involved in light/dark changes in the breathing pattern.
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Affiliation(s)
- Elisa M Fonseca
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, Unesp, Via de Acesso Prof. Paulo Donato Castellane s/n, Jaboticabal, SP, CEP 14884-900, Brazil
| | - Mariane C Vicente
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, Unesp, Via de Acesso Prof. Paulo Donato Castellane s/n, Jaboticabal, SP, CEP 14884-900, Brazil
| | - Stephanie Fournier
- Department of Pediatrics, Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec, QC, Canada
| | - Richard Kinkead
- Department of Pediatrics, Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec, QC, Canada
| | - Kênia C Bícego
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, Unesp, Via de Acesso Prof. Paulo Donato Castellane s/n, Jaboticabal, SP, CEP 14884-900, Brazil
| | - Luciane H Gargaglioni
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, Unesp, Via de Acesso Prof. Paulo Donato Castellane s/n, Jaboticabal, SP, CEP 14884-900, Brazil.
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Moreira TS, Sobrinho CR, Falquetto B, Oliveira LM, Lima JD, Mulkey DK, Takakura AC. The retrotrapezoid nucleus and the neuromodulation of breathing. J Neurophysiol 2020; 125:699-719. [PMID: 33427575 DOI: 10.1152/jn.00497.2020] [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] [Indexed: 12/17/2022] Open
Abstract
Breathing is regulated by a host of arousal and sleep-wake state-dependent neuromodulators to maintain respiratory homeostasis. Modulators such as acetylcholine, norepinephrine, histamine, serotonin (5-HT), adenosine triphosphate (ATP), substance P, somatostatin, bombesin, orexin, and leptin can serve complementary or off-setting functions depending on the target cell type and signaling mechanisms engaged. Abnormalities in any of these modulatory mechanisms can destabilize breathing, suggesting that modulatory mechanisms are not overly redundant but rather work in concert to maintain stable respiratory output. The present review focuses on the modulation of a specific cluster of neurons located in the ventral medullary surface, named retrotrapezoid nucleus, that are activated by changes in tissue CO2/H+ and regulate several aspects of breathing, including inspiration and active expiration.
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Affiliation(s)
- Thiago S Moreira
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Cleyton R Sobrinho
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Barbara Falquetto
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Luiz M Oliveira
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Janayna D Lima
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Daniel K Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut
| | - Ana C Takakura
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
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Liguori C, Maestri M, Spanetta M, Placidi F, Bonanni E, Mercuri NB, Guarnieri B. Sleep-disordered breathing and the risk of Alzheimer's disease. Sleep Med Rev 2020; 55:101375. [PMID: 33022476 DOI: 10.1016/j.smrv.2020.101375] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 05/28/2020] [Accepted: 05/28/2020] [Indexed: 12/15/2022]
Abstract
Sleep-disordered breathing is highly prevalent in the elderly population. Obstructive sleep apnea (OSA) represents the most common sleep disorder among the adult and elderly population. Recently, OSA diagnosis has been associated with an increased risk of developing cognitive decline and dementia, including vascular dementia and Alzheimer's disease (AD). Subsequently, there have been studies on AD biomarkers investigating cerebrospinal fluid, blood, neuroimaging, and nuclear medicine biomarkers in patients with OSA. Furthermore, studies have attempted to assess the possible effects of continuous positive airway pressure (CPAP) treatment on the cognitive trajectory and AD biomarkers in patients with OSA. This review summarizes the findings of studies on each AD biomarker (cognitive, biofluid, neuroimaging, and nuclear medicine imaging) in patients with OSA, also accounting for the related effects of CPAP treatment. In addition, the hypothetical model connecting OSA to AD in a bi-directional interplay is analyzed. Finally, the sex-based differences in prevalence and clinical symptoms of OSA between men and women have been investigated in relation to AD risk. Further studies investigating AD biomarkers changes in patients with OSA and the effect of CPAP treatment should be auspicated in future for identifying strategies to prevent the development of AD.
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Affiliation(s)
- Claudio Liguori
- Sleep Medicine Centre, Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy; Neurology Unit, Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy.
| | - Michelangelo Maestri
- Department of Clinical and Experimental Medicine, Neurology Unit, University of Pisa, Pisa, Italy
| | - Matteo Spanetta
- Sleep Medicine Centre, Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy
| | - Fabio Placidi
- Sleep Medicine Centre, Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy; Neurology Unit, Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy
| | - Enrica Bonanni
- Department of Clinical and Experimental Medicine, Neurology Unit, University of Pisa, Pisa, Italy
| | - Nicola B Mercuri
- Neurology Unit, Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy; Santa Lucia Foundation, Rome, Italy
| | - Biancamaria Guarnieri
- Center of Sleep Medicine, Department of Neurology, Villa Serena Hospital, Città S. Angelo, Pescara, Italy; Villa Serena Foundation for the Research, Città S. Angelo, Pescara, Italy
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Si L, Zhang J, Wang Y, Cao J, Chen BY, Guo HJ. Obstructive sleep apnea and respiratory center regulation abnormality. Sleep Breath 2020; 25:563-570. [PMID: 32870421 DOI: 10.1007/s11325-020-02175-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 08/14/2020] [Accepted: 08/19/2020] [Indexed: 11/27/2022]
Abstract
PURPOSE Obstructive sleep apnea (OSA) is a complex disease in which phenotypic analysis and understanding pathological mechanisms facilitate personalized treatment and outcomes. However, the pathophysiology responsible for this robust observation is incompletely understood. The objective of the present work was to review how respiratory center regulation varies during sleep and wakeness in patients with OSA. DATA SOURCES We searched for relevant articles up to December 31, 2019 in PubMed database. METHODS This review examines the current literature on the characteristics of respiratory center regulation during wakefulness and sleep in OSA, detection method, and phenotypic treatment for respiratory center regulation. RESULTS Mechanisms for ventilatory control system instability leading to OSA include different sleep stages in chemoresponsiveness to hypoxia and hypercapnia and different chemosensitivity at different time. One can potentially stabilize the breathing center in sleep-related breathing disorders by identifying one or more of these pathophysiological mechanisms. CONCLUSIONS Advancing mechanism research in OSA will guide symptom research and provide alternate and novel opportunities for effective treatment for patients with OSA.
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Affiliation(s)
- Liang Si
- Respiratory Department, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Jing Zhang
- Respiratory Department, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Yan Wang
- Respiratory Department, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Jie Cao
- Respiratory Department, Tianjin Medical University General Hospital, Tianjin, 300052, China.
| | - Bao-Yuan Chen
- Respiratory Department, Tianjin Medical University General Hospital, Tianjin, 300052, China.
| | - Heng-Juan Guo
- Respiratory Department, Tianjin Medical University General Hospital, Tianjin, 300052, China
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Nichols KE, Holliday-White KL, Bogie HM, Swearingen KM, Fine MS, Doyle J, Tiesma SR. Cardiovascular and Metabolic Responses to Carbon Dioxide Euthanasia in Conscious and Anesthetized Rats. JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE 2020; 59:742-749. [PMID: 32873368 DOI: 10.30802/aalas-jaalas-19-000166] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Euthanasia is a necessary component in research and must be conducted humanely. Currently, regulated CO₂ exposure in conscious rats is acceptable, but data are divided on whether CO₂ alone is more distressing than anesthesia prior to CO₂. To evaluate distress in rats, we compared physiologic responses to CO₂ euthanasia with and without isoflurane preanesthesia. Male Sprague-Dawley rats were implanted with telemetry devices to measure mean arterial pressure (MAP), heart rate (HR), and blood glucose. Animals recovered for 2 wk and were then exposed to either 5% isoflurane (n = 6) or 100% CO₂ (n = 7; calculated 30% chamber volume/min displacement) in their home cages to induce loss of consciousness. Euthanasia was then completed with CO₂ in both groups. MAP and HR increased when the gas delivery lids were placed on the home cages of both groups. Both MAP and HR gradually decreased with isoflurane exposure. MAP increased and HR decreased with CO₂ exposure. Glucose levels remained stable throughout the procedure, except for a small drop in conscious animals initially exposed to 100% CO₂. These data suggest that both gases affect the measured parameters in a similar manner, and that environmental factors, such as gas delivery lid placement, also change these measurements.
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Affiliation(s)
- Kathryn E Nichols
- Surgical Services, Data Sciences International, St Paul, Minnesota;,
| | | | - Heather M Bogie
- Surgical Services, Data Sciences International, St Paul, Minnesota
| | - Kim M Swearingen
- Surgical Services, Data Sciences International, St Paul, Minnesota; Envigo, Denver, Pennsylvania
| | - Megan S Fine
- Surgical Services, Data Sciences International, St Paul, Minnesota; Boston Scientific, St Paul, Minnesota
| | - Jennifer Doyle
- Data Services, Data Sciences International, St Paul, Minnesota
| | - Scott R Tiesma
- Marketing, Data Sciences International, St Paul, Minnesota; Medtronic, Minneapolis, Minnesota
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39
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Fast sensory representations in the lateral hypothalamus and their roles in brain function. Physiol Behav 2020; 222:112952. [DOI: 10.1016/j.physbeh.2020.112952] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 03/26/2020] [Accepted: 04/28/2020] [Indexed: 01/12/2023]
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40
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Garau C, Blomeley C, Burdakov D. Orexin neurons and inhibitory Agrp→orexin circuits guide spatial exploration in mice. J Physiol 2020; 598:4371-4383. [PMID: 32667686 DOI: 10.1113/jp280158] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 07/13/2020] [Indexed: 01/08/2023] Open
Abstract
KEY POINTS Photoinhibition of endogenous activity of lateral hypothalamic orexin neurons causes place preference and reduces innate avoidance Endogenous activity of orexin neurons correlates with place preference Mediobasal hypothalamic Agrp neurons inhibit orexin neurons via GABA, and chemogenetic suppression of Agrp neurons increases avoidance in an orexin receptor-dependent manner. ABSTRACT Hypothalamic orexin/hypocretin neurons integrate multiple sensory cues and project brain-wide to orchestrate diverse innate behaviours. Their loss impairs many context-appropriate actions, but the motivational characteristics of orexin cell activity remain unclear. We and others previously approached this question by artificial orexin stimulation, which could induce either rewarding (positive valence) or aversive (negative valence) brain activity. It is unknown to what extent such approaches replicate natural/endogenous orexin signals, which rapidly fluctuate during wakefulness. Here we took an alternative approach, focusing on observing and silencing natural orexin cell signals associated with a fundamental innate behaviour, self-paced spatial exploration. We found that mice are more likely to stay in places paired with orexin cell optosilencing. The orexin cell optosilencing also reduced avoidance of places that mice find innately aversive. Correspondingly, calcium recordings revealed that orexin cell activity rapidly reduced upon exiting the innately aversive places. Furthermore, we provide optogenetic evidence for an inhibitory GABAergic Agrp→orexin hypothalamic neurocircuit, and find that Agrp cell suppression increases innate avoidance behaviour, consistent with orexin disinhibition. These results imply that exploration may be motivated and oriented by a need to reduce aversive orexin cell activity, and suggest a hypothalamic circuit for fine-tuning orexin signals to changing ethological priorities.
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Affiliation(s)
- Celia Garau
- The Francis Crick Institute, London, NW1 1AT, UK
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Hill E, Dale N, Wall MJ. Moderate Changes in CO 2 Modulate the Firing of Neurons in the VTA and Substantia Nigra. iScience 2020; 23:101343. [PMID: 32683315 PMCID: PMC7371905 DOI: 10.1016/j.isci.2020.101343] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/30/2020] [Accepted: 07/01/2020] [Indexed: 12/21/2022] Open
Abstract
The substantia nigra (SN) and ventral tegmental area (VTA) are vital for the control of movement, goal-directed behavior, and encoding reward. Here we show that the firing of specific neuronal subtypes in these nuclei can be modulated by physiological changes in the partial pressure of carbon dioxide (PCO2). The resting conductance of substantia nigra dopaminergic neurons in young animals (postnatal days 7-10) and GABAergic neurons in the VTA is modulated by changes in the level of CO2. We provide several lines of evidence that this CO2-sensitive conductance results from connexin 26 (Cx26) hemichannel expression. Since the levels of PCO2 in the blood will vary depending on physiological activity and pathology, this suggests that changes in PCO2 could potentially modulate motor activity, reward behavior, and wakefulness.
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Affiliation(s)
- Emily Hill
- School of Life Sciences, University of Warwick, Gibbet Hill, Coventry CV4 7AL, UK.
| | - Nicholas Dale
- School of Life Sciences, University of Warwick, Gibbet Hill, Coventry CV4 7AL, UK
| | - Mark J Wall
- School of Life Sciences, University of Warwick, Gibbet Hill, Coventry CV4 7AL, UK.
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Abstract
The aim of this review is to summarize evidence regarding rat emotional experiences during carbon dioxide (CO2) exposure. The studies reviewed show that CO2 exposure is aversive to rats, and that rats respond to CO2 exposure with active and passive defense behaviors. Plasma corticosterone and bradycardia increased in rats exposed to CO2. As with anxiogenic drugs, responses to CO2 are counteracted by the administration of anxiolytics, SRIs, and SSRI's. Human studies reviewed indicate that, when inhaling CO2, humans experience feelings of anxiety fear and panic, and that administration of benzodiazepines, serotonin precursors, and SSRIs ameliorate these feelings. In vivo and in vitro rat studies reviewed show that brain regions, ion channels, and neurotransmitters involved in negative emotional responses are activated by hypercapnia and acidosis associated with CO2 exposure. On the basis of the behavioral, physiological, and neurobiological evidence reviewed, we conclude that CO2 elicits negative emotions in rats.
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43
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Wells AM, García-Cabezas MÁ, Barbas H. Topological atlas of the hypothalamus in adult rhesus monkey. Brain Struct Funct 2020; 225:1777-1803. [PMID: 32556476 PMCID: PMC7321918 DOI: 10.1007/s00429-020-02093-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 05/22/2020] [Indexed: 12/31/2022]
Abstract
The prosomeric model explains the embryological development of the central nervous system (CNS) shared by all vertebrates as a Bauplan. As a primary event, the early neural plate is patterned by intersecting longitudinal plates and transverse segments, forming a mosaic of progenitor units. The hypothalamus is specified by three prosomeres (hp1, hp2, and the acroterminal domain) of the secondary prosencephalon with corresponding alar and basal plate parts, which develop apart from the diencephalon. Mounting evidence suggests that progenitor units within alar and basal plate parts of hp1 and hp2 give rise to distinct hypothalamic nuclei, which preserve their relative invariant positioning (topology) in the adult brain. Nonetheless, the principles of the prosomeric model have not been applied so far to the hypothalamus of adult primates. We parcellated hypothalamic nuclei in adult rhesus monkeys (Macaca mulatta) using various stains to view architectonic boundaries. We then analyzed the topological relations of hypothalamic nuclei and adjacent hypothalamic landmarks with homology across rodent and primate species to trace the origin of adult hypothalamic nuclei to the alar or basal plate components of hp1 and hp2. We generated a novel atlas of the hypothalamus of the adult rhesus monkey with developmental ontologies for each hypothalamic nucleus. The result is a systematic reinterpretation of the adult hypothalamus whose prosomeric ontology can be used to study relationships between the hypothalamus and other regions of the CNS. Further, our atlas may serve as a tool to predict causal patterns in physiological and pathological pathways involving the hypothalamus.
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Affiliation(s)
- Anne Marie Wells
- Graduate Medical Sciences, Boston University School of Medicine, Boston, MA, 02215, USA
- Department of Health Sciences, Neural Systems Laboratory, Boston University, Boston, MA, 02215, USA
| | | | - Helen Barbas
- Department of Health Sciences, Neural Systems Laboratory, Boston University, Boston, MA, 02215, USA.
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MA, USA.
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Reimann HM, Niendorf T. The (Un)Conscious Mouse as a Model for Human Brain Functions: Key Principles of Anesthesia and Their Impact on Translational Neuroimaging. Front Syst Neurosci 2020; 14:8. [PMID: 32508601 PMCID: PMC7248373 DOI: 10.3389/fnsys.2020.00008] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 01/27/2020] [Indexed: 12/11/2022] Open
Abstract
In recent years, technical and procedural advances have brought functional magnetic resonance imaging (fMRI) to the field of murine neuroscience. Due to its unique capacity to measure functional activity non-invasively, across the entire brain, fMRI allows for the direct comparison of large-scale murine and human brain functions. This opens an avenue for bidirectional translational strategies to address fundamental questions ranging from neurological disorders to the nature of consciousness. The key challenges of murine fMRI are: (1) to generate and maintain functional brain states that approximate those of calm and relaxed human volunteers, while (2) preserving neurovascular coupling and physiological baseline conditions. Low-dose anesthetic protocols are commonly applied in murine functional brain studies to prevent stress and facilitate a calm and relaxed condition among animals. Yet, current mono-anesthesia has been shown to impair neural transmission and hemodynamic integrity. By linking the current state of murine electrophysiology, Ca2+ imaging and fMRI of anesthetic effects to findings from human studies, this systematic review proposes general principles to design, apply and monitor anesthetic protocols in a more sophisticated way. The further development of balanced multimodal anesthesia, combining two or more drugs with complementary modes of action helps to shape and maintain specific brain states and relevant aspects of murine physiology. Functional connectivity and its dynamic repertoire as assessed by fMRI can be used to make inferences about cortical states and provide additional information about whole-brain functional dynamics. Based on this, a simple and comprehensive functional neurosignature pattern can be determined for use in defining brain states and anesthetic depth in rest and in response to stimuli. Such a signature can be evaluated and shared between labs to indicate the brain state of a mouse during experiments, an important step toward translating findings across species.
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Affiliation(s)
- Henning M. Reimann
- Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrück Center for Molecular Medicine, Helmholtz Association of German Research Centers (HZ), Berlin, Germany
| | - Thoralf Niendorf
- Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrück Center for Molecular Medicine, Helmholtz Association of German Research Centers (HZ), Berlin, Germany
- Experimental and Clinical Research Center, A Joint Cooperation Between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany
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Pokusa M, Hajduchova D, Budaj T, Kralova Trancikova A. Respiratory Function and Dysfunction in Parkinson-Type Neurodegeneration. Physiol Res 2020; 69:S69-S79. [DOI: 10.33549/physiolres.934405] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Parkinson's disease (PD) is most commonly manifested by the presence of motor symptoms. However, non-motor symptoms occur several years before the onset of motor symptoms themselves. Hallmarks of dysfunction of the respiratory system are still outside the main focus of interest, whether by clinicians or scientists, despite their indisputable contribution to the morbidity and mortality of patients suffering from PD. In addition, many of the respiratory symptoms are already present in the early stages of the disease and efforts to utilize these parameters in the early diagnosis of PD are now intensifying. Mechanisms that lead to the development and progression of respiratory symptoms are only partially understood. This review focuses mainly on the comparison of respiratory problems observed in clinical studies with available findings obtained from experimental animal models. It also explains pathological changes observed in non-neuronal tissues in subjects with PD.
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Affiliation(s)
| | | | | | - A. Kralova Trancikova
- Biomedical Center Martin, Jessenius Faculty of Medicine in Martin, Comenius University Bratislava, Martin, Slovak Republic.
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46
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Barnett S, Li A. Orexin in Respiratory and Autonomic Regulation, Health and Diseases. Compr Physiol 2020; 10:345-363. [DOI: 10.1002/cphy.c190013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Rodrigues LTC, Salata B, Horta-Júnior JDAC, Gargaglioni LH, Dias MB. Adenosine in the lateral hypothalamus/perifornical area does not participate on the CO 2 chemoreflex. Respir Physiol Neurobiol 2020; 276:103368. [PMID: 32061712 DOI: 10.1016/j.resp.2020.103368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 12/26/2019] [Accepted: 01/03/2020] [Indexed: 11/18/2022]
Abstract
The Lateral Hypothalamus/Perifornical Area (LH/PFA) has been shown to be involved with the hypercapnic ventilatory response, in a state-dependent manner. We have demonstrated that purinergic signaling through ATP in the LH/PFA has an excitatory effect in ventilatory response to CO2 in awake rats in the dark phase of the diurnal cycle, but it is unknown whether the ATP metabolite adenosine, acting in the LH/PFA, modulates the ventilatory responses to hypercapnia. Here, we studied the effects of the microdialysis of adenosine (A1/A2 adenosine receptors agonist; 17 mM) and an A1 receptor antagonist (DPCPX; 0.1 mM) into the LH/PFA of conscious rats on ventilation in room air and in 7% CO2 during the light and the dark phases of the diurnal cycle. The microdialysis of adenosine and DPCPX caused no change in the CO2 ventilatory responses of rats during wakefulness or NREM sleep in either the dark or light period. Our data suggest that adenosine in the LH/PFA does not contribute to the hypercapnic ventilatory response in conscious rats.
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Affiliation(s)
| | - Bruno Salata
- Department of Physiology, Institute of Biosciences, Sao Paulo State University-UNESP, Botucatu, SP, Brazil.
| | | | - Luciane H Gargaglioni
- Department of Animal Morphology and Physiology, Sao Paulo State University-FCAV, Jaboticabal, SP, Brazil.
| | - Mirela Barros Dias
- Department of Physiology, Institute of Biosciences, Sao Paulo State University-UNESP, Botucatu, SP, Brazil.
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Iyer SH, Aggarwal A, Warren TJ, Hallgren J, Abel PW, Simeone TA, Simeone KA. Progressive cardiorespiratory dysfunction in Kv1.1 knockout mice may provide temporal biomarkers of pending sudden unexpected death in epilepsy (SUDEP): The contribution of orexin. Epilepsia 2020; 61:572-588. [PMID: 32030748 DOI: 10.1111/epi.16434] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 12/19/2019] [Accepted: 01/06/2020] [Indexed: 12/30/2022]
Abstract
OBJECTIVE Immediately preceding sudden unexpected death in epilepsy (SUDEP), patients experienced a final generalized tonic-clonic seizure (GTCS), rapid ventilation, apnea, bradycardia, terminal apnea, and asystole. Whether a progressive pathophysiology develops and increases risk of SUDEP remains unknown. Here, we determined (a) heart rate, respiratory rate, and blood oxygen saturation (SaO2 ) in low-risk and high-risk knockout (KO) mice; and (b) whether blocking receptors for orexin, a cardiorespiratory neuromodulator, influences cardiorespiratory function mice or longevity in high-risk KO mice. METHODS Heart rate and SaO2 were determined noninvasively with ECGenie and pulse oximetry. Respiration was determined with noninvasive airway mechanics technology. The role of orexin was determined within subject following acute treatment with a dual orexin receptor antagonist (DORA, 100 mg/kg). The number of orexin neurons in the lateral hypothalamus was determined with immunohistochemistry. RESULTS Intermittent bradycardia was more prevalent in high-risk KO mice, an effect that may be the result of increased parasympathetic drive. High-risk KO mice had more orexin neurons in the lateral hypothalamus. Blocking of orexin receptors differentially influenced heart rate in KO, but not wild-type (WT) mice. When DORA administration increased heart rate, it also decreased heart rate variability, breathing frequency, and/or hypopnea-apnea. Blocking orexin receptors prevented the methacholine (MCh)-induced increase in breathing frequency in KO mice and reduced MCh-induced seizures, via a direct or indirect mechanism. DORA improved oxygen saturation in KO mice with intermittent hypoxia. Daily administration of DORA to high-risk KO mice increased longevity. SIGNIFICANCE High-risk KO mice have a unique cardiorespiratory phenotype that is characterized by progressive changes in five interdependent endpoints. Blocking of orexin receptors attenuates some of these endpoints and increases longevity, supporting the notion that windows of opportunity for intervention exist in this preclinical SUDEP model.
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Affiliation(s)
- Shruthi H Iyer
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA
| | - Ankita Aggarwal
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA
| | - Ted J Warren
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA
| | - Jodi Hallgren
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA
| | - Peter W Abel
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA
| | - Timothy A Simeone
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA
| | - Kristina A Simeone
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA
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Escape From Oblivion: Neural Mechanisms of Emergence From General Anesthesia. Anesth Analg 2019; 128:726-736. [PMID: 30883418 DOI: 10.1213/ane.0000000000004006] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The question of how general anesthetics suppress consciousness has persisted since the mid-19th century, but it is only relatively recently that the field has turned its focus to a systematic understanding of emergence. Once assumed to be a purely passive process, spontaneously occurring as residual levels of anesthetics dwindle below a critical value, emergence from general anesthesia has been reconsidered as an active and controllable process. Emergence is driven by mechanisms that can be distinct from entry to the anesthetized state. In this narrative review, we focus on the burgeoning scientific understanding of anesthetic emergence, summarizing current knowledge of the neurotransmitter, neuromodulators, and neuronal groups that prime the brain as it prepares for its journey back from oblivion. We also review evidence for possible strategies that may actively bias the brain back toward the wakeful state.
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50
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Loiseau C, Casciato A, Barka B, Cayetanot F, Bodineau L. Orexin Neurons Contribute to Central Modulation of Respiratory Drive by Progestins on ex vivo Newborn Rodent Preparations. Front Physiol 2019; 10:1200. [PMID: 31611806 PMCID: PMC6776592 DOI: 10.3389/fphys.2019.01200] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 09/03/2019] [Indexed: 11/13/2022] Open
Abstract
Dysfunction of central respiratory CO2/H+ chemosensitivity is a pivotal factor that elicits deep hypoventilation in patients suffering from central hypoventilation syndromes. No pharmacological treatment is currently available. The progestin desogestrel has been suggested to allow recovery of respiratory response to CO2/H+ in patients suffering from central hypoventilation, but except the fact that supramedullary regions may be involved, mechanisms are still unknown. Here, we tested in neonates whether orexin systems contribute to desogestrel’s central effects on respiratory function. Using isolated ex vivo central nervous system preparations from newborn rats, we show orexin and almorexant, an antagonist of orexin receptors, supressed strengthening of the increase in respiratory frequency induced by prolonged metabolic acidosis under exposure to etonogestrel, the active metabolite of desogestrel. In parallel, almorexant suppressed the increase and enhanced increase in c-fos expression in respiratory-related brainstem structures induced by etonogestrel. These results suggest orexin signalisation is a key component of acidosis reinforcement of respiratory drive by etonogestrel in neonates. Although stage of development used is different as that for progestin clinical observations, presents results provide clues about conditions under which desogestrel or etonogestrel may enhance ventilation in patients suffering from central hypoventilation syndromes.
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Affiliation(s)
- Camille Loiseau
- Institut National de la Santé et de la Recherche Médicale, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Sorbonne Université, Paris, France
| | - Alexis Casciato
- Institut National de la Santé et de la Recherche Médicale, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Sorbonne Université, Paris, France
| | - Besma Barka
- Institut National de la Santé et de la Recherche Médicale, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Sorbonne Université, Paris, France
| | - Florence Cayetanot
- Institut National de la Santé et de la Recherche Médicale, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Sorbonne Université, Paris, France
| | - Laurence Bodineau
- Institut National de la Santé et de la Recherche Médicale, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Sorbonne Université, Paris, France
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