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Costello A, Linning-Duffy K, Vandenbrook C, Lonstein JS, Yan L. Effects of bright light therapy on neuroinflammatory and neuroplasticity markers in a diurnal rodent model of Seasonal Affective Disorder. Ann Med 2023; 55:2249015. [PMID: 37625385 PMCID: PMC10461522 DOI: 10.1080/07853890.2023.2249015] [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: 07/05/2023] [Revised: 08/09/2023] [Accepted: 08/14/2023] [Indexed: 08/27/2023] Open
Abstract
BACKGROUND Bright light therapy (BLT) is widely used for treating Seasonal Affective Disorder (SAD). However, the neural mechanisms underlying the therapeutic effects of BLT remain largely unexplored. The present study used a diurnal rodent (Nile grass rats; Arvicanthis niloticus) to test the hypothesis that the therapeutic effects of BLT could be, in part, due to reduced neuroinflammation and/or enhanced neuroplasticity. Our previous research has demonstrated that compared to grass rats housed in a summer-like daytime bright light condition (1000 lux), those housed in a winter-like daytime dim light condition (50 lux) showed increased depression- and anxiety-like behaviours, as well as impaired sociosexual behaviours and spatial memory, similar to what is observed in patients suffering from SAD. MATERIALS AND METHODS In the present study, male and female grass rats were housed under the winter-like dim daytime light condition (lights on 600-1800 hr, 50 lux). The experimental groups received daily 1-h early morning BLT from 0600-0700 using full-spectrum light (10,000 lux), while the control groups received narrowband red light (λmax, 780 nm). Following 4 weeks of treatment, the expression of several neuroinflammatory or plasticity markers was examined in the medial prefrontal cortex (mPFC), basolateral amygdala (BLA), and the CA1 of the dorsal hippocampus. RESULTS For the neuroinflammatory markers, BLT reduced TNF-α in the BLA of females, and upregulated CD11b in the mPFC and IL6 in the BLA in males. For the neuroplasticity markers, BLT downregulated BDNF in the CA1 and TrkB in all three brain regions in females but upregulated BDNF in the BLA and CA1 in males. CONCLUSIONS These results indicate that the therapeutic effects of BLT on sleep, mood, and cognition may be attributed in part to mechanisms involving neuroinflammation and neuroplasticity in corticolimbic brain regions. Moreover, these effects appear to vary between sexes.
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Affiliation(s)
| | | | | | - Joseph S. Lonstein
- Department of Psychology, MI State University, MI, USA
- Neuroscience Program, Michigan State University, MI, USA
| | - Lily Yan
- Department of Psychology, MI State University, MI, USA
- Neuroscience Program, Michigan State University, MI, USA
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Abstract
Sleep homeostasis is a complex neurobiologic phenomenon involving a number of molecular pathways, neurotransmitter release, synaptic activity, and factors modulating neural networks. Sleep plasticity allows for homeostatic optimization of neural networks and the replay-based consolidation of specific circuits, especially important for cognition, behavior, and information processing. Furthermore, research is currently moving from an essentially brain-focused to a more comprehensive view involving other systems, such as the immune system, hormonal status, and metabolic pathways. When dysfunctional, these systems contribute to sleep loss and fragmentation as well as to sleep need. In this chapter, the implications of neural plasticity and sleep homeostasis for the diagnosis and treatment of some major sleep disorders, such as insomnia and sleep deprivation, obstructive sleep apnea syndrome, restless legs syndrome, REM sleep behavior disorder, and narcolepsy are discussed in detail with their therapeutical implications. This chapter highlights that sleep is necessary for the maintenance of an optimal brain function and is sensitive to both genetic background and environmental enrichment. Even in pathologic conditions, sleep acts as a resilient plastic state that consolidates prior information and prioritizes network activity for efficient brain functioning.
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Insulin-like growth factor I mitigates post-traumatic stress by inhibiting AMP-kinase in orexin neurons. Mol Psychiatry 2022; 27:2182-2196. [PMID: 35115701 PMCID: PMC9126821 DOI: 10.1038/s41380-022-01442-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 12/14/2021] [Accepted: 01/11/2022] [Indexed: 12/21/2022]
Abstract
Maladaptive coping behaviors are probably involved in post-traumatic stress disorders (PTSD), but underlying mechanisms are incompletely understood. We now report that mice lacking functional insulin-like growth factor I (IGF-I) receptors in orexin neurons of the lateral hypothalamus (Firoc mice) are unresponsive to the anxiolytic actions of IGF-I and develop PTSD-like behavior that is ameliorated by inhibition of orexin neurons. Conversely, systemic IGF-I treatment ameliorated PTSD-like behavior in a wild-type mouse model of PTSD (PTSD mice). Further, systemic IGF-I modified the GABA/Glutamate synaptic structure in orexin neurons of naïve wild-type mice by increasing the dephosphorylation of GABA(B) receptor subunit through inhibition of AMP-kinase (AMPK). Significantly, pharmacological inhibition of AMPK mimicked IGF-I, normalizing fear behavior in PTSD mice. Thus, we suggest that IGF-I enables coping behaviors by balancing E/I input onto orexin neurons in a context-dependent manner. These observations provide a novel therapeutic approach to PTSD through modulation of AMPK.
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Tenorio-Lopes L, Fournier S, Henry MS, Bretzner F, Kinkead R. Disruption of estradiol regulation of orexin neurons: a novel mechanism in excessive ventilatory response to CO 2 inhalation in a female rat model of panic disorder. Transl Psychiatry 2020; 10:394. [PMID: 33173029 PMCID: PMC7656265 DOI: 10.1038/s41398-020-01076-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/01/2020] [Accepted: 10/20/2020] [Indexed: 12/27/2022] Open
Abstract
Panic disorder (PD) is ~2 times more frequent in women. An excessive ventilatory response to CO2 inhalation is more likely during the premenstrual phase. While ovarian hormones appear important in the pathophysiology of PD, their role remains poorly understood as female animals are rarely used in pre-clinical studies. Using neonatal maternal separation (NMS) to induce a "PD-like" respiratory phenotype, we tested the hypothesis that NMS disrupts hormonal regulation of the ventilatory response to CO2 in female rats. We then determined whether NMS attenuates the inhibitory actions of 17-β estradiol (E2) on orexin neurons (ORX). Pups were exposed to NMS (3 h/day; postnatal day 3-12). The ventilatory response to CO2-inhalation was tested before puberty, across the estrus cycle, and following ovariectomy. Plasma E2 and hypothalamic ORXA were measured. The effect of an ORX1 antagonist (SB334867; 15 mg/kg) on the CO2 response was tested. Excitatory postsynaptic currents (EPSCs) were recorded from ORX neurons using whole-cell patch-clamp. NMS-related increase in the CO2 response was observed only when ovaries were functional; the largest ventilation was observed during proestrus. SB334867 blocked this effect. NMS augmented levels of ORXA in hypothalamus extracts. EPSC frequency varied according to basal plasma E2 levels across the estrus cycle in controls but not NMS. NMS reproduces developmental and cyclic changes of respiratory manifestations of PD. NMS disrupts the inhibitory actions of E2 on the respiratory network. Impaired E2-related inhibition of ORX neurons during proestrus is a novel mechanism in respiratory manifestations of PD in females.
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Affiliation(s)
- Luana Tenorio-Lopes
- Hotchkiss Brain Institute; Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Stéphanie Fournier
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec. Département de Pédiatrie. Université Laval, Québec, QC, Canada
| | - Mathilde S Henry
- INRAE, Université de Bordeaux, Bordeaux INP, Nutrineuro, UMR 1286, F-33000, Bordeaux, France
| | - Frédéric Bretzner
- Centre de Recherche du CHU de Québec-Université Laval, Axe Neurosciences. Département de Psychiatrie et de Neurosciences, Université Laval, Québec, QC, Canada
| | - Richard Kinkead
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec. Département de Pédiatrie. Université Laval, Québec, QC, Canada.
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Significance of the orexinergic system in modulating stress-related responses in an animal model of post-traumatic stress disorder. Transl Psychiatry 2020; 10:10. [PMID: 32066707 PMCID: PMC7026175 DOI: 10.1038/s41398-020-0698-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 10/02/2019] [Accepted: 10/20/2019] [Indexed: 01/23/2023] Open
Abstract
Converging evidence indicates that orexins (ORXs), the regulatory neuropeptides, are implicated in anxiety- and depression-related behaviors via the modulation of neuroendocrine, serotonergic, and noradrenergic systems. This study evaluated the role of the orexinergic system in stress-associated physiological responses in a controlled prospective animal model. The pattern and time course of activation of hypothalamic ORX neurons in response to predator-scent stress (PSS) were examined using c-Fos as a marker for neuronal activity. The relationship between the behavioral response pattern 7 days post-exposure and expressions of ORXs was evaluated. We also investigated the effects of intracerebroventricular microinfusion of ORX-A or almorexant (ORX-A/B receptor antagonist) on behavioral responses 7 days following PSS exposure. Hypothalamic levels of ORX-A, neuropeptide Y (NPY), and brain-derived neurotrophic factor (BDNF) were assessed. Compared with rats whose behaviors were extremely disrupted (post-traumatic stress disorder [PTSD]-phenotype), those whose behaviors were minimally selectively disrupted displayed significantly upregulated ORX-A and ORX-B levels in the hypothalamic nuclei. Intracerebroventricular microinfusion of ORX-A before PSS reduced the prevalence of the PTSD phenotype compared with that of artificial cerebrospinal fluid or almorexant, and rats treated with almorexant displayed a higher prevalence of the PTSD phenotype than did untreated rats. Activated ORX neurons led to upregulated expressions of BDNF and NPY, which might provide an additional regulatory mechanism for the modulation of adaptive stress responses. The study indicates that the activated ORX system might promote adaptive responses to PSS probably via stimulation of BDNF and NPY secretion, and early intervention with ORX-A reduces the prevalence of the PTSD phenotype and increases the prevalence of adaptive phenotypes. The findings provide some insights into the mechanisms underlying the involvement of the ORX system in stress-related disorders.
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Nevárez N, de Lecea L. Recent advances in understanding the roles of hypocretin/orexin in arousal, affect, and motivation. F1000Res 2018; 7. [PMID: 30254737 PMCID: PMC6127742 DOI: 10.12688/f1000research.15097.1] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/24/2018] [Indexed: 12/11/2022] Open
Abstract
The hypocretins (Hcrts) are two alternatively spliced neuropeptides (Hcrt1/Ox-A and Hcrt2/Ox-B) that are synthesized exclusively in the hypothalamus. Data collected in the 20 years since their discovery have supported the view that the Hcrts play a broad role in the control of arousal with a particularly important role in the maintenance of wakefulness and sleep-to-wake transitions. While this latter point has received an overwhelming amount of research attention, a growing literature has begun to broaden our understanding of the many diverse roles that the Hcrts play in physiology and behavior. Here, we review recent advances in the neurobiology of Hcrt in three sections. We begin by surveying findings on Hcrt function within normal sleep/wake states as well as situations of aberrant sleep (that is, narcolepsy). In the second section, we discuss research establishing a role for Hcrt in mood and affect (that is, anxiety, stress, and motivation). Finally, in the third section, we briefly discuss future directions for the field and place an emphasis on analytical modeling of Hcrt neural activity. We hope that the data discussed here provide a broad overview of recent progress in the field and make clear the diversity of roles played by these neuromodulators.
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Affiliation(s)
- Natalie Nevárez
- Department of Psychiatry & Behavioral Sciences, Stanford University, Stanford, California, USA
| | - Luis de Lecea
- Department of Psychiatry & Behavioral Sciences, Stanford University, Stanford, California, USA
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Ozsoy S, Olguner Eker O, Abdulrezzak U, Esel E. Relationship between orexin A and childhood maltreatment in female patients with depression and anxiety. Soc Neurosci 2016; 12:330-336. [DOI: 10.1080/17470919.2016.1169216] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Gao XB, Hermes G. Neural plasticity in hypocretin neurons: the basis of hypocretinergic regulation of physiological and behavioral functions in animals. Front Syst Neurosci 2015; 9:142. [PMID: 26539086 PMCID: PMC4612503 DOI: 10.3389/fnsys.2015.00142] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 10/02/2015] [Indexed: 12/22/2022] Open
Abstract
The neuronal system that resides in the perifornical and lateral hypothalamus (Pf/LH) and synthesizes the neuropeptide hypocretin/orexin participates in critical brain functions across species from fish to human. The hypocretin system regulates neural activity responsible for daily functions (such as sleep/wake homeostasis, energy balance, appetite, etc.) and long-term behavioral changes (such as reward seeking and addiction, stress response, etc.) in animals. The most recent evidence suggests that the hypocretin system undergoes substantial plastic changes in response to both daily fluctuations (such as food intake and sleep-wake regulation) and long-term changes (such as cocaine seeking) in neuronal activity in the brain. The understanding of these changes in the hypocretin system is essential in addressing the role of the hypocretin system in normal physiological functions and pathological conditions in animals and humans. In this review, the evidence demonstrating that neural plasticity occurs in hypocretin-containing neurons in the Pf/LH will be presented and possible physiological, behavioral, and mental health implications of these findings will be discussed.
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Affiliation(s)
- Xiao-Bing Gao
- Section of Comparative Medicine, Yale University School of Medicine New Haven, CT, USA ; Program on Integrative Cell Signaling and Neurobiology of Metabolism (ICSNM), Yale University School of Medicine New Haven, CT, USA
| | - Gretchen Hermes
- Department of Psychiatry, Yale University School of Medicine New Haven, CT, USA
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Feng Z, Zhong YJ, Wang L, Wei TQ. Resuscitation therapy for traumatic brain injury-induced coma in rats: mechanisms of median nerve electrical stimulation. Neural Regen Res 2015; 10:594-8. [PMID: 26170820 PMCID: PMC4424752 DOI: 10.4103/1673-5374.155433] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2014] [Indexed: 11/30/2022] Open
Abstract
In this study, rats were put into traumatic brain injury-induced coma and treated with median nerve electrical stimulation. We explored the wake-promoting effect, and possible mechanisms, of median nerve electrical stimulation. Electrical stimulation upregulated the expression levels of orexin-A and its receptor OX1R in the rat prefrontal cortex. Orexin-A expression gradually increased with increasing stimulation, while OX1R expression reached a peak at 12 hours and then decreased. In addition, after the OX1R antagonist, SB334867, was injected into the brain of rats after traumatic brain injury, fewer rats were restored to consciousness, and orexin-A and OXIR expression in the prefrontal cortex was downregulated. Our findings indicate that median nerve electrical stimulation induced an up-regulation of orexin-A and OX1R expression in the prefrontal cortex of traumatic brain injury-induced coma rats, which may be a potential mechanism involved in the wake-promoting effects of median nerve electrical stimulation.
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Affiliation(s)
- Zhen Feng
- Department of Rehabilitation Medicine, the First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, China
| | - Ying-Jun Zhong
- Department of Rehabilitation Medicine, the First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, China
| | - Liang Wang
- Department of Rehabilitation Medicine, the First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, China
| | - Tian-Qi Wei
- Department of Rehabilitation Medicine, the First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, China
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ZHONG YINGJUN, FENG ZHEN, WANG LIANG, WEI TIANQI. Wake-promoting actions of median nerve stimulation in TBI-induced coma: An investigation of orexin-A and orexin receptor 1 in the hypothalamic region. Mol Med Rep 2015; 12:4441-4447. [DOI: 10.3892/mmr.2015.3898] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 05/08/2015] [Indexed: 11/06/2022] Open
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Abad VC, Guilleminault C. Pharmacological treatment of sleep disorders and its relationship with neuroplasticity. Curr Top Behav Neurosci 2015; 25:503-53. [PMID: 25585962 DOI: 10.1007/7854_2014_365] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Sleep and wakefulness are regulated by complex brain circuits located in the brain stem, thalamus, subthalamus, hypothalamus, basal forebrain, and cerebral cortex. Wakefulness and NREM and REM sleep are modulated by the interactions between neurotransmitters that promote arousal and neurotransmitters that promote sleep. Various lines of evidence suggest that sleep disorders may negatively affect neuronal plasticity and cognitive function. Pharmacological treatments may alleviate these effects but may also have adverse side effects by themselves. This chapter discusses the relationship between sleep disorders, pharmacological treatments, and brain plasticity, including the treatment of insomnia, hypersomnias such as narcolepsy, restless legs syndrome (RLS), obstructive sleep apnea (OSA), and parasomnias.
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Affiliation(s)
- Vivien C Abad
- Psychiatry and Behavioral Science-Division of Sleep Medicine, Stanford University School of Medicine, Palo Alto, CA, USA
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12
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The effects of acute stress-induced sleep disturbance on acoustic trauma-induced tinnitus in rats. BIOMED RESEARCH INTERNATIONAL 2014; 2014:724195. [PMID: 25162023 PMCID: PMC4137606 DOI: 10.1155/2014/724195] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 07/03/2014] [Indexed: 11/18/2022]
Abstract
Chronic tinnitus is a debilitating condition and often accompanied by anxiety, depression, and sleep disturbance. It has been suggested that sleep disturbance, such as insomnia, may be a risk factor/predictor for tinnitus-related distress and the two conditions may share common neurobiological mechanisms. This study investigated whether acute stress-induced sleep disturbance could increase the susceptibility to acoustic trauma-induced tinnitus in rats. The animals were exposed to unilateral acoustic trauma 24 h before sleep disturbance being induced using the cage exchange method. Tinnitus perception was assessed behaviourally using a conditioned lick suppression paradigm 3 weeks after the acoustic trauma. Changes in the orexin system in the hypothalamus, which plays an important role in maintaining long-lasting arousal, were also examined using immunohistochemistry. Cage exchange resulted in a significant reduction in the number of sleep episodes and acoustic trauma-induced tinnitus with acoustic features similar to a 32 kHz tone at 100 dB. However, sleep disturbance did not exacerbate the perception of tinnitus in rats. Neither tinnitus alone nor tinnitus plus sleep disturbance altered the number of orexin-expressing neurons. The results suggest that acute sleep disturbance does not cause long-term changes in the number of orexin neurons and does not change the perception of tinnitus induced by acoustic trauma in rats.
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Gao XB. Plasticity in neurons synthesizing wake/arousal promoting hormone hypocretin/orexin. VITAMINS AND HORMONES 2012; 89:35-59. [PMID: 22640607 DOI: 10.1016/b978-0-12-394623-2.00003-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The hypothalamus is a critical brain structure regulating physiological functions essential to the survival of individuals and species. One of the striking characteristics of this brain region is the abundance of nerve cells (neurons) expressing a great numbers of neurotransmitters and neuromodulators, among which are hormones released into the blood stream through brain neuroendocrinological routes. The neurons in the lateral hypothalamus take part in intra- and extrahypothalamic circuits controlling basic physiological functions essential for the well being of animal bodies (such as cardiovascular function, respiratory function, immune responses, etc.), animal behaviors required for the maintenance of the survival of individuals (food foraging, flight, fight, etc.) and species (reproductive function), and higher brain functions (learning and memory, mental state, etc.). Hypocretin (also called orexin) comprises of two neuropeptides exclusively synthesized by neurons in the perifornical/lateral hypothalamus. Although hypocretin/orexin was initially found to enhance food intake, it is now clear that the functions mediated by hypocretin/orexin are well beyond what were originally proposed. Specifically, hypocretin/orexin is a crucial promoter of wakefulness; deficiency in the hypocretin/orexin system leads to diseases and disorders such as narcolepsy. It is clear that neurons synthesizing hypocretin/orexin are consistently under regulation originating from various parts of the brain and that the status of activity in hypocretin/orexin neurons is closely related with the nutritional and behavioral state of animals. Therefore, the demand to make adaptive changes in hypocretin/orexin neurons to accommodate the changes in the external environment and behavioral state of animals is expected. The latest developments in the studies of plasticity in hypocretin/orexin neurons under the challenges from environmental and behavioral factors have dramatically shaped the understanding of the roles of hypocretin/orexin neurons in the maintenance of the survival of animals. More importantly, the studies of plasticity in hypocretin/orexin neurons as the consequence of physiological, behavioral, and environmental challenges may shed new insight on the understanding and treatment of sleep disorders (such as insomnia).
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Affiliation(s)
- Xiao-Bing Gao
- Section of Comparative Medicine, Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, New Haven, Connecticut, USA
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Cao M, Guilleminault C. Hypocretin and its emerging role as a target for treatment of sleep disorders. Curr Neurol Neurosci Rep 2011; 11:227-34. [PMID: 21170610 DOI: 10.1007/s11910-010-0172-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The neuropeptides hypocretin-1 and -2 (orexin A and B) are critical in the regulation of arousal and maintenance of wakefulness. Understanding the role of the hypocretin system in sleep/wake regulation has come from narcolepsy-cataplexy research. Deficiency of hypocretin results in loss of sleep/wake control with consequent unstable transitions from wakefulness into non-rapid eye movement (REM) and REM sleep, and clinical manifestations including daytime hypersomnolence, sleep attacks, and cataplexy. The hypocretin system regulates sleep/wake control through complex interactions between monoaminergic/cholinergic wake-promoting and GABAergic sleep-promoting neuronal systems. Research for the hypocretin agonist and the hypocretin antagonist for the treatment of sleep disorders has vigorously increased over the past 10 years. This review will focus on the origin, functions, and mechanisms in which the hypocretin system regulates sleep and wakefulness, and discuss its emerging role as a target for the treatment of sleep disorders.
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Affiliation(s)
- Michelle Cao
- Stanford University Sleep Medicine, 450 Broadway Street, Pavilion C, 2nd Floor, M/C 5704, Redwood City, CA 94063, USA.
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Berthoud HR, Münzberg H. The lateral hypothalamus as integrator of metabolic and environmental needs: from electrical self-stimulation to opto-genetics. Physiol Behav 2011; 104:29-39. [PMID: 21549732 DOI: 10.1016/j.physbeh.2011.04.051] [Citation(s) in RCA: 167] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 04/22/2011] [Accepted: 04/26/2011] [Indexed: 12/23/2022]
Abstract
As one of the evolutionary oldest parts of the brain, the diencephalon evolved to harmonize changing environmental conditions with the internal state for survival of the individual and the species. The pioneering work of physiologists and psychologists around the middle of the last century clearly demonstrated that the hypothalamus is crucial for the display of motivated behaviors, culminating in the discovery of electrical self-stimulation behavior and providing the first neurological hint accounting for the concepts of reinforcement and reward. Here we review recent progress in understanding the role of the lateral hypothalamic area in the control of ingestive behavior and the regulation of energy balance. With its vast array of interoceptive and exteroceptive afferent inputs and its equally rich efferent connectivity, the lateral hypothalamic area is in an ideal position to integrate large amounts of information and orchestrate adaptive responses. Most important for energy homeostasis, it receives metabolic state information through both neural and humoral routes and can affect energy assimilation and energy expenditure through direct access to behavioral, autonomic, and endocrine effector pathways. The complex interplays of classical and peptide neurotransmitters such as orexin carrying out these integrative functions are just beginning to be understood. Exciting new techniques allowing selective stimulation or inhibition of specific neuronal phenotypes will greatly facilitate the functional mapping of both input and output pathways.
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Affiliation(s)
- Hans-Rudi Berthoud
- Neurobiology of Nutrition Laboratory, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana 70808, USA.
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