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Nirogi R, Jayarajan P, Benade V, Abraham R, Goyal VK. Hits and misses with animal models of narcolepsy and the implications for drug discovery. Expert Opin Drug Discov 2024; 19:755-768. [PMID: 38747534 DOI: 10.1080/17460441.2024.2354293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Accepted: 05/08/2024] [Indexed: 05/22/2024]
Abstract
INTRODUCTION Narcolepsy is a chronic and rare neurological disorder characterized by disordered sleep. Based on animal models and further research in humans, the dysfunctional orexin system was identified as a contributing factor to the pathophysiology of narcolepsy. Animal models played a larger role in the discovery of some of the pharmacological agents with established benefit/risk profiles. AREAS COVERED In this review, the authors examine the phenotypes observed in animal models of narcolepsy and the characteristics of clinically used pharmacological agents in these animal models. Additionally, the authors compare the effects of clinically used pharmacological agents on the phenotypes in animal models with those observed in narcolepsy patients. EXPERT OPINION Research in canine and mouse models have linked narcolepsy to the O×R2mutation and orexin deficiency, leading to new diagnostic criteria and a drug development focus. Advancements in pharmacological therapies have significantly improved narcolepsy management, with insights from both clinical experience and from animal models having led to new treatments such as low sodium oxybate and solriamfetol. However, challenges persist in addressing symptoms beyond excessive daytime sleepiness and cataplexy, highlighting the need for further research, including the development of diurnal animal models to enhance understanding and treatment options for narcolepsy.
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Affiliation(s)
- Ramakrishna Nirogi
- Drug Discovery & Development, Suven Life Sciences Limited, Hyderabad, India
| | - Pradeep Jayarajan
- Drug Discovery & Development, Suven Life Sciences Limited, Hyderabad, India
| | - Vijay Benade
- Drug Discovery & Development, Suven Life Sciences Limited, Hyderabad, India
| | - Renny Abraham
- Drug Discovery & Development, Suven Life Sciences Limited, Hyderabad, India
| | - Vinod Kumar Goyal
- Drug Discovery & Development, Suven Life Sciences Limited, Hyderabad, India
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Viudez-Martínez A, Torregrosa AB, Navarrete F, García-Gutiérrez MS. Understanding the Biological Relationship between Migraine and Depression. Biomolecules 2024; 14:163. [PMID: 38397400 PMCID: PMC10886628 DOI: 10.3390/biom14020163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 01/08/2024] [Accepted: 01/09/2024] [Indexed: 02/25/2024] Open
Abstract
Migraine is a highly prevalent neurological disorder. Among the risk factors identified, psychiatric comorbidities, such as depression, seem to play an important role in its onset and clinical course. Patients with migraine are 2.5 times more likely to develop a depressive disorder; this risk becomes even higher in patients suffering from chronic migraine or migraine with aura. This relationship is bidirectional, since depression also predicts an earlier/worse onset of migraine, increasing the risk of migraine chronicity and, consequently, requiring a higher healthcare expenditure compared to migraine alone. All these data suggest that migraine and depression may share overlapping biological mechanisms. Herein, this review explores this topic in further detail: firstly, by introducing the common epidemiological and risk factors for this comorbidity; secondly, by focusing on providing the cumulative evidence of common biological aspects, with a particular emphasis on the serotoninergic system, neuropeptides such as calcitonin-gene-related peptide (CGRP), pituitary adenylate cyclase-activating polypeptide (PACAP), substance P, neuropeptide Y and orexins, sexual hormones, and the immune system; lastly, by remarking on the future challenges required to elucidate the etiopathological mechanisms of migraine and depression and providing updated information regarding new key targets for the pharmacological treatment of these clinical entities.
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Affiliation(s)
- Adrián Viudez-Martínez
- Hospital Pharmacy Service, Hospital General Dr. Balmis de Alicante, 03010 Alicante, Spain;
| | - Abraham B. Torregrosa
- Instituto de Neurociencias, Universidad Miguel Hernández, 03550 San Juan de Alicante, Spain; (A.B.T.); (F.N.)
- Research Network on Primary Addictions, Instituto de Salud Carlos III, MICINN and FEDER, 28029 Madrid, Spain
- Instituto de Investigación Sanitaria y Biomédica de Alicante (ISABIAL), 03010 Alicante, Spain
| | - Francisco Navarrete
- Instituto de Neurociencias, Universidad Miguel Hernández, 03550 San Juan de Alicante, Spain; (A.B.T.); (F.N.)
- Research Network on Primary Addictions, Instituto de Salud Carlos III, MICINN and FEDER, 28029 Madrid, Spain
- Instituto de Investigación Sanitaria y Biomédica de Alicante (ISABIAL), 03010 Alicante, Spain
| | - María Salud García-Gutiérrez
- Instituto de Neurociencias, Universidad Miguel Hernández, 03550 San Juan de Alicante, Spain; (A.B.T.); (F.N.)
- Research Network on Primary Addictions, Instituto de Salud Carlos III, MICINN and FEDER, 28029 Madrid, Spain
- Instituto de Investigación Sanitaria y Biomédica de Alicante (ISABIAL), 03010 Alicante, Spain
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Simonetta I, Riolo R, Todaro F, Tuttolomondo A. New Insights on Metabolic and Genetic Basis of Migraine: Novel Impact on Management and Therapeutical Approach. Int J Mol Sci 2022; 23:3018. [PMID: 35328439 PMCID: PMC8955051 DOI: 10.3390/ijms23063018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 03/05/2022] [Accepted: 03/07/2022] [Indexed: 12/12/2022] Open
Abstract
Migraine is a hereditary disease, usually one-sided, sometimes bilateral. It is characterized by moderate to severe pain, which worsens with physical activity and may be associated with nausea and vomiting, may be accompanied by photophobia and phonophobia. The disorder can occur at any time of the day and can last from 4 to 72 h, with and without aura. The pathogenic mechanism is unclear, but extensive preclinical and clinical studies are ongoing. According to electrophysiology and imaging studies, many brain areas are involved, such as cerebral cortex, thalamus, hypothalamus, and brainstem. The activation of the trigeminovascular system has a key role in the headache phase. There also appears to be a genetic basis behind the development of migraine. Numerous alterations have been identified, and in addition to the genetic cause, there is also a close association with the surrounding environment, as if on the one hand, the genetic alterations may be responsible for the onset of migraine, on the other, the environmental factors seem to be more strongly associated with exacerbations. This review is an analysis of neurophysiological mechanisms, neuropeptide activity, and genetic alterations that play a fundamental role in choosing the best therapeutic strategy. To date, the goal is to create a therapy that is as personalized as possible, and for this reason, steps forward have been made in the pharmacological field in order to identify new therapeutic strategies for both acute treatment and prophylaxis.
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Affiliation(s)
- Irene Simonetta
- Internal Medicine and Stroke Care Ward, Department of Promoting Health, Maternal-Infant Excellence and Internal and Specialized Medicine (ProMISE) G. D’Alessandro, University of Palermo, Piazza delle Cliniche n.2, 90127 Palermo, Italy; (I.S.); (R.R.); (F.T.)
- Molecular and Clinical Medicine PhD Programme, University of Palermo, P.zza delle Cliniche n.2, 90127 Palermo, Italy
| | - Renata Riolo
- Internal Medicine and Stroke Care Ward, Department of Promoting Health, Maternal-Infant Excellence and Internal and Specialized Medicine (ProMISE) G. D’Alessandro, University of Palermo, Piazza delle Cliniche n.2, 90127 Palermo, Italy; (I.S.); (R.R.); (F.T.)
| | - Federica Todaro
- Internal Medicine and Stroke Care Ward, Department of Promoting Health, Maternal-Infant Excellence and Internal and Specialized Medicine (ProMISE) G. D’Alessandro, University of Palermo, Piazza delle Cliniche n.2, 90127 Palermo, Italy; (I.S.); (R.R.); (F.T.)
| | - Antonino Tuttolomondo
- Internal Medicine and Stroke Care Ward, Department of Promoting Health, Maternal-Infant Excellence and Internal and Specialized Medicine (ProMISE) G. D’Alessandro, University of Palermo, Piazza delle Cliniche n.2, 90127 Palermo, Italy; (I.S.); (R.R.); (F.T.)
- Molecular and Clinical Medicine PhD Programme, University of Palermo, P.zza delle Cliniche n.2, 90127 Palermo, Italy
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Orexin 2 receptor stimulation enhances resilience, while orexin 2 inhibition promotes susceptibility, to social stress, anxiety and depression. Neuropharmacology 2018; 143:79-94. [PMID: 30240784 DOI: 10.1016/j.neuropharm.2018.09.016] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Revised: 08/28/2018] [Accepted: 09/11/2018] [Indexed: 02/08/2023]
Abstract
Knockdown of orexin/hypocretin 2 receptor (Orx2) in the basolateral amygdala (BLA) affects anxious and depressive behavior. We use a new behavioral paradigm, the Stress Alternatives Model (SAM), designed to improve translational impact. The SAM induces social stress in adult male mice by aggression from larger mice, allowing for adaptive decision-making regarding escape. In this model, mice remain (Stay) in the oval SAM arena or escape from social aggression (Escape) via routes only large enough for the smaller mouse. We hypothesized intracerebroventricular (icv) stimulation of Orx2 receptors would be anxiolytic and antidepressive in SAM-related social behavior and the Social Interaction/Preference (SIP) test. Conversely, we predicted that icv antagonism of Orx2 receptors would promote anxious and depressive behavior in these same tests. Anxious behaviors such as freezing (both cued and conflict) and startle are exhibited more often in Stay compared with Escape phenotype mice. Time spent attentive to the escape route is more frequent in Escape mice. In Stay mice, stimulation of Orx2 receptors reduces fear conditioning, conflict freezing and startle, and promotes greater attention to the escape hole. This anxiolysis was accompanied by activation of a cluster of inhibitory neurons in the amygdala. A small percentage of those Stay mice also begin escaping; whereas Escape is reversed by the Orx2 antagonist. Escape mice were also Resilient, and Stay mice Susceptible to stress (SIP), with both conditions reversed by Orx2 antagonism or stimulation respectively. Together, these results suggest that the Orx2 receptor may be a useful potential target for anxiolytic or antidepressive therapeutics.
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Reinscheid RK, Xu YL. Neuropeptide S and Its Receptor: A Newly Deorphanized G Protein–Coupled Receptor System. Neuroscientist 2016; 11:532-8. [PMID: 16282594 DOI: 10.1177/1073858405276405] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Neuropeptide S (NPS) is a recently discovered bioactive peptide that has shed new light on the neurobiology of sleep/wakefulness regulation and anxiety-like behavior. NPS can potently promote arousal and suppress all stages of sleep. This effect might be modulated by NPS receptors expressed in thalamic centers that are relays for transmitting arousing stimuli originating from the brainstem to the cortex. The peptide precursor is expressed most prominently in a novel nucleus located directly adjacent to the nora-drenergic locus coeruleus, a brain structure with well-defined functions in arousal, stress, and anxiety. NPS was also found to induce anxiolytic-like behavior in a battery of four different tests of innate responses to stress. This unique pharmacological profile of NPS offers significant potential for developing new drugs for the treatment of sleep and/or anxiety disorders.
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Affiliation(s)
- Rainer K Reinscheid
- Department of Pharmacology, University of California, Irvine, 92697-4625, USA.
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Amin R, Simakajornboon N, Szczesniak R, Inge T. Early improvement in obstructive sleep apnea and increase in orexin levels after bariatric surgery in adolescents and young adults. Surg Obes Relat Dis 2016; 13:95-100. [PMID: 27720196 DOI: 10.1016/j.soard.2016.05.023] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 05/02/2016] [Accepted: 05/25/2016] [Indexed: 11/18/2022]
Abstract
BACKGROUND Obstructive sleep apnea (OSA) associated with obesity is known to improve after bariatric surgery, but little is known about early changes in this condition after surgery. OBJECTIVES To study the clinical course of OSA after bariatric surgery SETTING: Children's hospital in the United States METHODS: Adolescents and young adults with obstructive sleep apnea undergoing vertical sleeve gastrectomy (n = 6) or gastric bypass (n = 1) were enrolled in this prospective study. Participants underwent formal polysomnography before and at 3 and 5 weeks after bariatric surgery. Anthropometric measurements and assay for orexin and leptin were also performed at study visits. Thirty-one adolescents who underwent 2 polysomnography studies that were 4 weeks apart served as control patients. RESULTS Baseline mean (range) age of participants was 17.8 (15.4-20.7) years, 71% were male, with body mass index of 55.2 (41.3-61.6) kg/m2 and had a median apnea hypopnea index (AHI) of 15.8 (7.1-23.8) events/hour. Differences in least-square means from longitudinal analysis did not show significant differences in AHI in the control group but showed significant postoperative decline in AHI relative to baseline. AHI declined postoperatively from baseline by 9.2 events/hour (95% confidence interval: 3.8 to 14.5) at 3 weeks (P = .002) and 9.1 events/hour (95% confidence interval: 3.8 to 14.5) at 5 weeks (P = .002); there was no significant change from 3 to 5 weeks in AHI. Leptin decreased and orexin levels increased significantly by 3 weeks postoperatively. CONCLUSIONS These observations suggest that OSA responds early and out of proportion to weight loss after metabolic and or bariatric surgery, thus weight independent factors may at least in part be responsible for early improvement in OSA postoperatively.
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Affiliation(s)
- Raouf Amin
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Sleep Disorders Center, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.
| | - Narong Simakajornboon
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Sleep Disorders Center, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Rhonda Szczesniak
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; University of Cincinnati Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Thomas Inge
- Surgical Weight Loss Center for Teens, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
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Tajti J, Szok D, Majláth Z, Tuka B, Csáti A, Vécsei L. Migraine and neuropeptides. Neuropeptides 2015; 52:19-30. [PMID: 26094101 DOI: 10.1016/j.npep.2015.03.006] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 03/22/2015] [Accepted: 03/25/2015] [Indexed: 12/25/2022]
Abstract
Migraine is a common disabling neurovascular primary headache disorder. The pathomechanism is not clear, but extensive preclinical and clinical studies are ongoing. The structural basis of the leading hypothesis is the trigeminovascular system, which includes the trigeminal ganglion, the meningeal vasculature, and the distinct nuclei of the brainstem, the thalamus and the somatosensory cortex. This review covers the effects of sensory (calcitonin gene-related peptide, pituitary adenylate cyclase-activating polypeptide and substance P), sympathetic (neuropeptide Y) and parasympathetic (vasoactive intestinal peptide) migraine-related neuropeptides and the functions of somatostatin, nociceptin and the orexins in the trigeminovascular system. These neuropeptides may take part in neurogenic inflammation (plasma protein extravasation and vasodilatation) of the intracranial vasculature and peripheral and central sensitization of the trigeminal system. The results of human clinical studies are discussed with regard to the alterations in these neuropeptides in the plasma, saliva and cerebrospinal fluid during or between migraine attacks, and the therapeutic possibilities involving migraine-related neuropeptides in the acute and prophylactic treatment of migraine headache are surveyed.
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Affiliation(s)
- János Tajti
- Department of Neurology, University of Szeged, Semmelweis u. 6, Szeged H-6725, Hungary.
| | - Délia Szok
- Department of Neurology, University of Szeged, Semmelweis u. 6, Szeged H-6725, Hungary
| | - Zsófia Majláth
- Department of Neurology, University of Szeged, Semmelweis u. 6, Szeged H-6725, Hungary
| | - Bernadett Tuka
- MTA - SZTE Neuroscience Research Group, Semmelweis u. 6, Szeged H-6725, Hungary
| | - Anett Csáti
- MTA - SZTE Neuroscience Research Group, Semmelweis u. 6, Szeged H-6725, Hungary
| | - László Vécsei
- Department of Neurology, University of Szeged, Semmelweis u. 6, Szeged H-6725, Hungary; MTA - SZTE Neuroscience Research Group, Semmelweis u. 6, Szeged H-6725, Hungary
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Hoffmann J, Supronsinchai W, Akerman S, Andreou AP, Winrow CJ, Renger J, Hargreaves R, Goadsby PJ. Evidence for orexinergic mechanisms in migraine. Neurobiol Dis 2015; 74:137-43. [DOI: 10.1016/j.nbd.2014.10.022] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 10/08/2014] [Accepted: 10/29/2014] [Indexed: 11/29/2022] Open
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Abstract
A detailed appreciation of the control of adipose tissue whether it be white, brown or brite/beige has never been more important to the development of a framework on which to build therapeutic strategies to combat obesity. This is because 1) the rate of fatty acid release into the circulation from lipolysis in white adipose tissue (WAT) is integrally important to the development of obesity, 2) brown adipose tissue (BAT) has now moved back to center stage with the realization that it is present in adult humans and, in its activated form, is inversely proportional to levels of obesity and 3) the identification and characterization of "brown-like" or brite/beige fat is likely to be one of the most exciting developments in adipose tissue biology in the last decade. Central to all of these developments is the role of the CNS in the control of different fat cell functions and central to CNS control is the integrative capacity of the hypothalamus. In this chapter we will attempt to detail key issues relevant to the structure and function of hypothalamic and downstream control of WAT and BAT and highlight the importance of developing an understanding of the neural input to brite/beige fat cells as a precursor to its recruitment as therapeutic target.
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Affiliation(s)
- A Stefanidis
- Department of Physiology, Monash University, Clayton, 3800, Australia
| | - N M Wiedmann
- Department of Physiology, Monash University, Clayton, 3800, Australia
| | - E S Adler
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - B J Oldfield
- Department of Physiology, Monash University, Clayton, 3800, Australia.
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Jalewa J, Wong-Lin K, McGinnity TM, Prasad G, Hölscher C. Increased number of orexin/hypocretin neurons with high and prolonged external stress-induced depression. Behav Brain Res 2014; 272:196-204. [DOI: 10.1016/j.bbr.2014.05.030] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 05/13/2014] [Accepted: 05/16/2014] [Indexed: 01/14/2023]
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Arcamone N, D’Angelo L, de Girolamo P, Lucini C, Pelagalli A, Castaldo L. Orexin and orexin receptor like peptides in the gastroenteric tract of Gallus domesticus: An immunohistochemical survey on presence and distribution. Res Vet Sci 2014; 96:234-40. [DOI: 10.1016/j.rvsc.2014.02.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 12/06/2013] [Accepted: 02/01/2014] [Indexed: 01/22/2023]
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Jalewa J, Joshi A, McGinnity TM, Prasad G, Wong-Lin K, Hölscher C. Neural circuit interactions between the dorsal raphe nucleus and the lateral hypothalamus: an experimental and computational study. PLoS One 2014; 9:e88003. [PMID: 24516577 PMCID: PMC3916338 DOI: 10.1371/journal.pone.0088003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 01/02/2014] [Indexed: 12/22/2022] Open
Abstract
Orexinergic/hypocretinergic (Ox) neurotransmission plays an important role in regulating sleep, as well as in anxiety and depression, for which the serotonergic (5-HT) system is also involved in. However, little is known regarding the direct and indirect interactions between 5-HT in the dorsal raphe nucleus (DRN) and Ox neurons in the lateral hypothalamus (LHA). In this study, we report the additional presence of 5-HT1BR, 5-HT2AR, 5-HT2CR and fast ligand-gated 5-HT3AR subtypes on the Ox neurons of transgenic Ox-enhanced green fluorescent protein (Ox-EGFP) and wild type C57Bl/6 mice using single and double immunofluorescence (IF) staining, respectively, and quantify the colocalization for each 5-HT receptor subtype. We further reveal the presence of 5-HT3AR and 5-HT1AR on GABAergic neurons in LHA. We also identify NMDAR1, OX1R and OX2R on Ox neurons, but none on adjacent GABAergic neurons. This suggests a one-way relationship between LHA's GABAergic and Ox neurons, wherein GABAergic neurons exerts an inhibitory effect on Ox neurons under partial DRN's 5-HT control. We also show that Ox axonal projections receive glutamatergic (PSD-95 immunopositive) and GABAergic (Gephyrin immunopositive) inputs in the DRN. We consider these and other available findings into our computational model to explore possible effects of neural circuit connection types and timescales on the DRN-LHA system's dynamics. We find that if the connections from 5-HT to LHA's GABAergic neurons are weakly excitatory or inhibitory, the network exhibits slow oscillations; not observed when the connection is strongly excitatory. Furthermore, if Ox directly excites 5-HT neurons at a fast timescale, phasic Ox activation can lead to an increase in 5-HT activity; no significant effect with slower timescale. Overall, our experimental and computational approaches provide insights towards a more complete understanding of the complex relationship between 5-HT in the DRN and Ox in the LHA.
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Affiliation(s)
- Jaishree Jalewa
- School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, United Kingdom
| | - Alok Joshi
- Intelligent Systems Research Centre, University of Ulster, Magee Campus, Londonderry, Northern Ireland, United Kingdom
| | - T. Martin McGinnity
- Intelligent Systems Research Centre, University of Ulster, Magee Campus, Londonderry, Northern Ireland, United Kingdom
| | - Girijesh Prasad
- Intelligent Systems Research Centre, University of Ulster, Magee Campus, Londonderry, Northern Ireland, United Kingdom
| | - KongFatt Wong-Lin
- Intelligent Systems Research Centre, University of Ulster, Magee Campus, Londonderry, Northern Ireland, United Kingdom
- * E-mail: (CH); (KW)
| | - Christian Hölscher
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, United Kingdom
- * E-mail: (CH); (KW)
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Herzig KH. Regulatory Peptides--past, present and future. REGULATORY PEPTIDES 2014; 188:iv. [PMID: 24560295 DOI: 10.1016/s0167-0115(14)00012-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 07/09/2013] [Indexed: 06/03/2023]
Affiliation(s)
- Karl-Heinz Herzig
- Institute of Biomedicine and Biocenter of Oulu, Medical Center Oulu and Oulu University Hospital, Oulu, Finland.
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Maniyar FH, Sprenger T, Monteith T, Schankin C, Goadsby PJ. Brain activations in the premonitory phase of nitroglycerin-triggered migraine attacks. ACTA ACUST UNITED AC 2013; 137:232-41. [PMID: 24277718 DOI: 10.1093/brain/awt320] [Citation(s) in RCA: 314] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Our aim was identify brain areas involved in the premonitory phase of migraine using functional neuroimaging. To this end, we performed positron emission tomography scans with H2(15)O to measure cerebral blood flow as a marker of neuronal activity. We conducted positron emission tomography scans at baseline, in the premonitory phase without pain and during migraine headache in eight patients. We used glyceryl trinitrate (nitroglycerin) to trigger premonitory symptoms and migraine headache in patients with episodic migraine without aura who habitually experienced premonitory symptoms during spontaneous attacks. The main outcome was comparing the first premonitory scans in all patients to baseline scans in all patients. We found activations in the posterolateral hypothalamus, midbrain tegmental area, periaqueductal grey, dorsal pons and various cortical areas including occipital, temporal and prefrontal cortex. Brain activations, in particular of the hypothalamus, seen in the premonitory phase of glyceryl trinitrate-triggered migraine attacks can explain many of the premonitory symptoms and may provide some insight into why migraine is commonly activated by a change in homeostasis.
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Affiliation(s)
- Farooq Husain Maniyar
- Headache Group, Department of Neurology, University of California-San Francisco, San Francisco, CA, USA
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Tsujino N, Sakurai T. Role of orexin in modulating arousal, feeding, and motivation. Front Behav Neurosci 2013; 7:28. [PMID: 23616752 PMCID: PMC3629303 DOI: 10.3389/fnbeh.2013.00028] [Citation(s) in RCA: 175] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 03/25/2013] [Indexed: 01/15/2023] Open
Abstract
Orexin deficiency results in narcolepsy in humans, dogs, and rodents, suggesting that the orexin system is particularly important for maintenance of wakefulness. However, orexin neurons are “multi-tasking” neurons that regulate sleep/wake states as well as feeding behavior, emotion, and reward processes. Orexin deficiency causes abnormalities in energy homeostasis, stress-related behavior, and reward systems. Orexin excites waking-active monoaminergic and cholinergic neurons in the hypothalamus and brain stem regions to maintain a long, consolidated waking period. Orexin neurons also have reciprocal links with the hypothalamic nuclei, which regulates feeding. Moreover, the responsiveness of orexin neurons to peripheral metabolic cues suggests that these neurons have an important role as a link between energy homeostasis and vigilance states. The link between orexin and the ventral tegmental nucleus serves to motivate an animal to engage in goal-directed behavior. This review focuses on the interaction of orexin neurons with emotion, reward, and energy homeostasis systems. These connectivities are likely to be highly important to maintain proper vigilance states.
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Affiliation(s)
- Natsuko Tsujino
- Department of Molecular Neuroscience and Integrative Physiology, Graduate School of Medical Science, Kanazawa University Kanazawa, Japan
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Shahid IZ, Rahman AA, Pilowsky PM. Orexin and Central Regulation of Cardiorespiratory System. SLEEP HORMONES 2012; 89:159-84. [DOI: 10.1016/b978-0-12-394623-2.00009-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Abstract
The orexins/hypocretins are endogenous, modulatory and multifunctional neuropeptides with prominent influence on several physiological processes. The influence of orexins on energy expenditure is highlighted with focus on orexin action on individual components of energy expenditure. As orexin stabilizes and maintains normal states of arousal and the sleep/wake cycle, we also highlight orexin mediation of sleep and how sleep interacts with energy expenditure.
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Affiliation(s)
- Jennifer A Teske
- Department of Nutritional Sciences, University of Arizona and Southern Arizona VA Health Care System, Tucson, Arizona, USA
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Sokołowska P, Urbańska A, Namiecińska M, Biegańska K, Zawilska JB. Orexins promote survival of rat cortical neurons. Neurosci Lett 2011; 506:303-6. [PMID: 22138089 DOI: 10.1016/j.neulet.2011.11.028] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 11/14/2011] [Accepted: 11/16/2011] [Indexed: 11/24/2022]
Abstract
Orexin A and B (hypocretin-1 and -2) are hypothalamic peptides that exert their biological functions by stimulation of two specific, membrane-bound receptors, OX(1)R and OX(2)R. Recently, we have demonstrated the expression of both types of orexin receptors in rat cortical neurons, with the OX(2)R level being markedly higher compared to OX(1)R. In the present study we investigated the receptor-mediated effects of orexin A, an agonist of OX(1)R and OX(2) R, orexin B and [Ala(11)-D-Leu(15)]orexin B, preferential agonists of OX(2)R, on survival of cultured neurons derived from rat cerebral cortex. The three tested peptides markedly increased neuronal viability in a concentration-dependent manner. The pro-survival properties of orexins were associated with an attenuation of caspase-3 activity. Comparable potency of orexin A, orexin B and [Ala(11)-D-Leu(15)]orexin B suggests a predominant role of OX(2)R in the studied phenomenon. Our findings provide new insights into the role of orexins in CNS as potential neuroprotective factors.
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Affiliation(s)
- Paulina Sokołowska
- Institute of Medical Biology, Polish Academy of Sciences, Lodowa 106, PL 93-232 Łódź, Poland.
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The orexin OX(1) receptor exists predominantly as a homodimer in the basal state: potential regulation of receptor organization by both agonist and antagonist ligands. Biochem J 2011; 439:171-83. [PMID: 21770891 DOI: 10.1042/bj20110230] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
It is unclear what proportion of a G-protein-coupled receptor is present in cells as dimers or oligomers. Saturation bioluminescence resonance energy transfer studies demonstrated the orexin OX(1) receptor to be present in such complexes. Forms of this receptor containing a minimal epitope tag, with the C-terminus linked to yellow fluorescent protein or modified at the N-terminus to incorporate a SNAP tag, migrated in SDS/PAGE gels as monomers, indicating a lack of covalent interactions. Solubilization with dodecylmaltoside, followed by Blue native-PAGE, indicated that the receptor constructs migrated predominantly as anticipated for dimeric species with evidence for further, higher-order, complexes, and this was true over a wide range of expression levels. Addition of SDS prior to separation by Blue native-PAGE resulted in much of the previously dimeric, and all of the higher-order, complexes being dissociated and now migrating at the size predicted for monomeric species. Expression of forms of the OX(1) receptor capable of generating enzyme complementation confirmed that solubilization itself did not result in interaction artefacts. Addition of the endogenous agonist orexin A enhanced the proportion of higher-order OX(1) receptor complexes, whereas selective OX(1) antagonists increased the proportion the OX(1) receptor migrating in Blue native-PAGE as a monomer. The antagonist effects were produced in a concentration-dependent manner, consistent with the affinity of the ligands for the receptor. Homogeneous time-resolved fluorescence resonance energy transfer studies using Tag-Lite™ reagents on cells expressing the SNAP-tagged OX(1) receptor identified cell-surface OX(1) homomers. Predominantly at low receptor expression levels, orexin A increased such fluorescence resonance energy transfer signals, also consistent with ligand-induced reorganization of the homomeric complex.
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Sakurai T, Mieda M. Connectomics of orexin-producing neurons: interface of systems of emotion, energy homeostasis and arousal. Trends Pharmacol Sci 2011; 32:451-62. [PMID: 21565412 DOI: 10.1016/j.tips.2011.03.007] [Citation(s) in RCA: 164] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 03/15/2011] [Accepted: 03/15/2011] [Indexed: 12/21/2022]
Abstract
Avoiding danger and finding food, which are life-sustaining activities that are regulated by emotion, reward and energy balance, require proper wakefulness. The orexin system controls sleep and wakefulness through interactions with systems that regulate emotion, reward and energy homeostasis. Recent findings have brought about the possibility of novel therapies targeting the orexin system for sleep disorders, including insomnia and narcolepsy-cataplexy, as well as other pathological conditions such as obesity and drug addiction [1]. In this review, we will discuss the current understanding of the integrative physiology and clinical perspectives of the orexin system. We will briefly review signaling through orexin A and B receptors and discuss the role of orexins in the pathophysiology of narcolepsy. We will also examine connections between orexin neurons and other brain areas involved in feeding behavior, reward and emotion. Finally, we will consider the therapeutic potential of drugs that target orexin receptors.
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Affiliation(s)
- Takeshi Sakurai
- Department of Molecular Neuroscience and Integrative Physiology, Faculty of Medicine, Kanazawa University, 13-1 Takaramachi, Kanazawa, Ishikawa 920-8640, Japan. )
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21
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Ward RJ, Pediani JD, Milligan G. Ligand-induced internalization of the orexin OX(1) and cannabinoid CB(1) receptors assessed via N-terminal SNAP and CLIP-tagging. Br J Pharmacol 2011; 162:1439-52. [PMID: 21175569 PMCID: PMC3058174 DOI: 10.1111/j.1476-5381.2010.01156.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 10/26/2010] [Accepted: 11/22/2010] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND AND PURPOSE Many G protein-coupled receptors internalize following agonist binding. The studies were designed to identify novel means to effectively quantify this process using the orexin OX(1) receptor and the cannabinoid CB(1) receptor as exemplars. EXPERIMENTAL APPROACH The human OX(1) and CB(1) receptors were modified to incorporate both epitope tags and variants (SNAP and CLIP) of the enzyme O(6)-alkylguanine-DNA-alkyltransferase within their extracellular, N-terminal domain. Cells able to regulate expression of differing amounts of these constructs upon addition of an antibiotic were developed and analysed. KEY RESULTS Cell surface forms of each receptor construct were detected by both antibody recognition of the epitope tags and covalent binding of fluorophores to the O(6)-alkylguanine-DNA-alkyltransferase variants. Receptor internalization in response to agonists but not antagonists could be monitored by each approach but sensitivity was up to six- to 10-fold greater than other approaches when employing a novel, time-resolved fluorescence probe for the SNAP tag. Sensitivity was not enhanced, however, for the CLIP tag, possibly due to higher levels of nonspecific binding. CONCLUSIONS AND IMPLICATIONS These studies demonstrate that highly sensitive and quantitative assays that monitor cell surface CB(1) and OX(1) receptors and their internalization by agonists can be developed based on introduction of variants of O(6)-alkylguanine-DNA-alkyltransferase into the N-terminal domain of the receptor. This should be equally suitable for other G protein-coupled receptors.
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MESH Headings
- Alkyl and Aryl Transferases/chemistry
- Alkyl and Aryl Transferases/metabolism
- Benzoxazoles/metabolism
- Benzoxazoles/pharmacology
- Cell Line
- Cell Membrane/drug effects
- Cloning, Molecular
- Cyclohexanols/metabolism
- Cyclohexanols/pharmacology
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Humans
- Intracellular Signaling Peptides and Proteins/metabolism
- Intracellular Signaling Peptides and Proteins/pharmacology
- Ligands
- Naphthyridines
- Neuropeptides/metabolism
- Neuropeptides/pharmacology
- Orexin Receptors
- Orexins
- Phenylurea Compounds/metabolism
- Phenylurea Compounds/pharmacology
- Phosphorylation/drug effects
- Piperidines/metabolism
- Piperidines/pharmacology
- Plasmids
- Pyrazoles/metabolism
- Pyrazoles/pharmacology
- Pyrrolidines/metabolism
- Pyrrolidines/pharmacology
- Receptor, Cannabinoid, CB1/agonists
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptor, Cannabinoid, CB1/chemistry
- Receptor, Cannabinoid, CB1/metabolism
- Receptors, G-Protein-Coupled/agonists
- Receptors, G-Protein-Coupled/antagonists & inhibitors
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Neuropeptide/agonists
- Receptors, Neuropeptide/antagonists & inhibitors
- Receptors, Neuropeptide/chemistry
- Receptors, Neuropeptide/metabolism
- Rimonabant
- Thiazoles/metabolism
- Thiazoles/pharmacology
- Urea/analogs & derivatives
- Urea/metabolism
- Urea/pharmacology
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Affiliation(s)
- Richard J Ward
- Molecular Pharmacology Group, Neuroscience and Molecular Pharmacology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
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23
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Holland PR. Modulation of trigeminovascular processing: novel insights into primary headache disorders. Cephalalgia 2010; 29 Suppl 3:1-6. [PMID: 20017748 DOI: 10.1177/03331024090290s302] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Dysfunction of the descending circuitry that modulates nociceptive processing is thought to facilitate primary headache disorders such as migraine and cluster headache, either by reducing inhibition or increasing facilitation of neural signals. The identification of novel neurotransmitter systems (orexinergic, cannabinoid and dopaminergic) within this descending pathway and their interaction with 5-HT(1B/1D) (triptan) receptors provides important clues about several of the risk factors and comorbidities associated with primary headache disorders and indicates that triptans exert central as well as peripheral activity. Current research supports the early treatment of primary headache disorders in order to prevent structural changes in the brain and to minimize dysfunction in the descending modulation of pain control.
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Affiliation(s)
- P R Holland
- Headache Group, Department of Neurology, University of California, San Francisco, San Francisco, CA 94143-0114, USA.
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24
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Tsujino N, Sakurai T. Orexin/hypocretin: a neuropeptide at the interface of sleep, energy homeostasis, and reward system. Pharmacol Rev 2010; 61:162-76. [PMID: 19549926 DOI: 10.1124/pr.109.001321] [Citation(s) in RCA: 341] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Recent studies have implicated the orexin system as a critical regulator of sleep/wake states as well as feeding behavior and reward processes. Orexin deficiency results in narcolepsy in humans, dogs, and rodents, suggesting that the orexin system is particularly important for maintenance of wakefulness. In addition, orexin deficiency also cause abnormalities in energy homeostasis and reward systems. Orexin activates waking active monoaminergic and cholinergic neurons in the hypothalamus and brainstem regions to maintain a long, consolidated waking period. Orexin neurons receive abundant input from the limbic system. Orexin neurons also have reciprocal links with the hypothalamic arcuate nucleus, which regulates feeding. Moreover, the responsiveness of orexin neurons to peripheral metabolic cues, such as leptin and glucose, suggest that these neurons have important role as a link between the energy homeostasis and vigilance states. Orexin neurons also have a link with the dopaminergic reward system in the ventral tegmental nucleus. These findings suggest that the orexin system interacts with systems that regulate emotion, reward, and energy homeostasis to maintain proper vigilance states. Therefore, this system may be a potentially important therapeutic target for treatment of sleep disorder, obesity, emotional stress, and addiction.
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Affiliation(s)
- Natsuko Tsujino
- Department of Molecular Neuroscience and Integrative Physiology, Graduate School of Medical Science, Kanazawa University, 13-1 Takaramachi, Kanazawa-shi, Ishikawa 920-8640, Japan
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25
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Abstract
Dysfunction of the descending circuitry that modulates nociceptive processing is thought to facilitate primary headache disorders such as migraine and cluster headache, either by reducing inhibition or increasing facilitation of neural signals. The identification of novel neurotransmitter systems (orexinergic, cannabinoid and dopaminergic) within this descending pathway and their interaction with 5-HT(1B/1D) (triptan) receptors provides important clues about several of the risk factors and comorbidities associated with primary headache disorders and indicates that triptans exert central as well as peripheral activity. Current research supports the early treatment of primary headache disorders in order to prevent structural changes in the brain and to minimize dysfunction in the descending modulation of pain control.
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Affiliation(s)
- P R Holland
- Headache Group, Department of Neurology, University of California, San Francisco, San Francisco, CA 94143-0114, USA.
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26
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Selective loss of GABA(B) receptors in orexin-producing neurons results in disrupted sleep/wakefulness architecture. Proc Natl Acad Sci U S A 2009; 106:4459-64. [PMID: 19246384 DOI: 10.1073/pnas.0811126106] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Hypothalamic neurons that contain the neuropeptide orexin (hypocretin) play important roles in the regulation of sleep/wake. Here we analyze the in vivo and in vitro phenotype of mice lacking the GABA(B1) gene specifically in orexin neurons (oxGKO mice) and demonstrate that GABA(B) receptors on orexin neurons are essential in stabilizing and consolidating sleep/wake states. In oxGKO brain slices, we show that the absence of GABA(B) receptors decreases the sensitivity of orexin neurons to both excitatory and inhibitory inputs because of augmented GABA(A)-mediated inhibition that increases the membrane conductance and shunts postsynaptic currents in these neurons. This increase in GABA(A)-mediated inhibitory tone is apparently the result of an orexin receptor type 1-mediated activation of local GABAergic interneurons that project back onto orexin neurons. oxGKO mice exhibit severe fragmentation of sleep/wake states during both the light and dark periods, without showing an abnormality in total sleep time or signs of cataplexy. Thus, GABA(B) receptors on orexin neurons are crucial in the appropriate control of the orexinergic tone through sleep/wake states, thereby stabilizing the state switching mechanisms.
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27
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Abizaid A, Horvath TL. Brain circuits regulating energy homeostasis. REGULATORY PEPTIDES 2008; 149:3-10. [PMID: 18514925 PMCID: PMC2605273 DOI: 10.1016/j.regpep.2007.10.006] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2007] [Accepted: 10/30/2007] [Indexed: 11/21/2022]
Abstract
Recent years have seen an impetus in the study for central mechanisms regulating energy balance, and caloric intake possibly as a response to the obesity pandemic. This renewed interest as well as drastic improvements in the tools that are now currently available to neuroscientists, has yielded a great deal of insight into the mechanisms by which the brain regulates metabolic function, and volitional aspects of feeding in response to metabolic signals like leptin, insulin and ghrelin. Among these mechanisms are the complex intracellular signals elicited by these hormones in neurons. Moreover, these signals produce and modulate the metabolism of the cell at the level of the mitochondria. Finally, these signals promote plastic changes that alter the synaptic circuitry in a number of circuits and ultimately affect cellular, physiological and behavioral responses in defense of energy homeostasis. These mechanisms are surveyed in this review.
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Affiliation(s)
- Alfonso Abizaid
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale University School of Medicine, USA.
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28
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29
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Fetissov SO, Hamze Sinno M, Coëffier M, Bole-Feysot C, Ducrotté P, Hökfelt T, Déchelotte P. Autoantibodies against appetite-regulating peptide hormones and neuropeptides: putative modulation by gut microflora. Nutrition 2008; 24:348-59. [PMID: 18262391 PMCID: PMC7126273 DOI: 10.1016/j.nut.2007.12.006] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Revised: 11/12/2007] [Accepted: 12/10/2007] [Indexed: 12/30/2022]
Abstract
Objective Peptide hormones synthesized in gastrointestinal and adipose tissues in addition to neuropeptides regulate appetite and body weight. Previously, autoantibodies directed against melanocortin peptides were found in patients with eating disorders; however, it remains unknown whether autoantibodies directed against other appetite-regulating peptides are present in human sera and whether their levels are influenced by gut-related antigens. Methods Healthy women were studied for the presence of immunoglobulin (Ig) G and IgA autoantibodies directed against 14 key appetite-regulating peptides. The concept of molecular mimicry was applied to search in silico whether bacteria, viruses, or fungi contain proteins with amino acid sequences identical to appetite-regulating peptides. In addition, autoantibodies serum levels were studied in germ-free and specific pathogen-free rats. Results We found these IgG and IgA autoantibodies directed against leptin, ghrelin, peptide YY, neuropeptide Y, and other appetite-regulating peptides are present in human sera at levels of 100–900 ng/mL. Numerous cases of sequence homology with these peptides were identified among commensal and pathogenic micro-organisms including Lactobacilli, bacteroides, Helicobacter pylori, Escherichia coli, and Candida species. Decreased levels of IgA autoantibodies directed against several appetite-regulating peptides and increased levels of antighrelin IgG were found in germ-free rats compared with specific pathogen-free rats. Conclusion Healthy humans and rats display autoantibodies directed against appetite-regulating peptide hormones and neuropeptides, suggesting that these autoantibodies may have physiologic implications in hunger and satiety pathways. Gut-related antigens including the intestinal microflora may influence production of theses autoantibodies, suggesting a new link between the gut and appetite control.
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Affiliation(s)
- Sergueï O Fetissov
- Digestive System and Nutrition Laboratory (ADEN EA3234), Institute of Biomedical Research, Rouen University and Hospital, IFRMP23, Rouen, France.
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30
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Su J, Lei Z, Zhang W, Ning H, Ping J. Distribution of orexin B and its relationship with GnRH in the pig hypothalamus. Res Vet Sci 2008; 85:315-23. [PMID: 18255106 DOI: 10.1016/j.rvsc.2007.12.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Revised: 11/28/2007] [Accepted: 12/11/2007] [Indexed: 11/30/2022]
Abstract
Increasing evidence suggests that orexins--hypothalamic neuropeptides--act as neurotransmitters or neuromediators in the brain, regulating autonomic and neuroendocrine functions. Orexins are closely associated with gonadotropin-releasing hormone (GnRH) neurons in the preoptic area and alter luteinizing hormone (LH) release, suggesting that they regulate reproduction. Here, we investigated the distribution of orexin B (immunohistochemical technique) and the relationship between orexin B and GnRH containing fibres and neurons in the pig hypothalamus using double immunofluorescence and laser-scanning confocal microscopy. Orexin B immunoreactive neurons were mainly localized in the perifornical area (PeF), dorsomedial hypothalamic nucleus (DMH), zona incerta (ZI) and the posterior hypothalamic area (PH), with a sparser distribution in the preoptic and anterior hypothalamic area. Immunoreactive fibres were distributed throughout the central nervous system. Approximately 30% GnRH neurons were in close contact with orexin B immunoreactive fibres, among these approximately 6% of GnRH neurons co-localized with orexin B perikarya in the region between the caudal preoptic area and the anterior hypothalamic area. Orexin B may regulate reproduction by altering LH release in the hypothalamus.
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Affiliation(s)
- Juan Su
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, Jiangsu, China
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31
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Matsuki T, Sakurai T. Orexins and orexin receptors: from molecules to integrative physiology. Results Probl Cell Differ 2008; 46:27-55. [PMID: 18204827 DOI: 10.1007/400_2007_047] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Recent studies have implicated the orexin system as a critical regulator of sleep/wake states, feeding behavior, and reward processes. Orexin deficiency results in narcolepsy-cataplexy in humans, dogs, and rodents, suggesting that the orexin system is particularly important for maintenance of wakefulness. Orexin agonists and antagonists are thought to be promising avenues toward the treatment of sleep disorders, eating disorders, and drug addiction. In this chapter, we discuss the current understanding of the physiological roles of orexins in regulation of arousal, sleep/wake states, energy homeostasis, and reward systems.
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Affiliation(s)
- Taizo Matsuki
- Department of Pharmacology, Institute of Basic Medical Science, University of Tsukuba, Tsukuba, Ibaraki, Japan
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32
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Kalantar-Zadeh K. CARDIOVASCULAR AND SURVIVAL PARADOXES IN DIALYSIS PATIENTS: What Is So Bad about Reverse Epidemiology Anyway? Semin Dial 2007; 20:593-601. [DOI: 10.1111/j.1525-139x.2007.00360.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Blakeney JS, Reid RC, Le GT, Fairlie DP. Nonpeptidic Ligands for Peptide-Activated G Protein-Coupled Receptors. Chem Rev 2007; 107:2960-3041. [PMID: 17622179 DOI: 10.1021/cr050984g] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jade S Blakeney
- Centre for Drug Design and Development, Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
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Abstract
The primary headaches are a group of distinct individually characterized attack forms, which although varying in presentation, share some common anatomical basis responsible for the pain component of the attack. The hypothalamus is known to modulate a multitude of functions and has been shown to be involved in the pathophysiology of a variety of primary headaches including cluster headache and chronic migraine. It seems likely that it may be involved in other primary headache disorders due to their episodic nature and may underlie many of their diverse symptoms. We discuss the hypothalamic involvement in the modulation of trigeminovascular processing and examine the involvement of the hypothalamic orexinergic system as a key regulator of this function.
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Affiliation(s)
- Philip Holland
- Headache Group, Institute of Neurology, The National Hospital for Neurology and Neurosurgery, London, UK
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35
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Tokita S. [Emerging progress and strategies for the exploration of therapeutic targets]. Nihon Yakurigaku Zasshi 2007; 129:119-23. [PMID: 17299239 DOI: 10.1254/fpj.129.119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
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36
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Holland PR, Akerman S, Goadsby PJ. Modulation of nociceptive dural input to the trigeminal nucleus caudalis via activation of the orexin 1 receptor in the rat. Eur J Neurosci 2006; 24:2825-33. [PMID: 17156207 DOI: 10.1111/j.1460-9568.2006.05168.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Migraine pathophysiology is thought to involve the trigeminal innervation of the dura mater and intracranial blood vessels. Electrical stimulation of dural blood vessels is painful in humans and causes activation of neurons in the caudal-most portion of the trigeminal nucleus in experimental animals. The hypothalamic neuropeptides orexin A and B are selectively synthesized in the lateral and posterior hypothalamus, and recent findings have implicated their involvement in nociceptive processing. To evaluate the potential for orexin receptor modulation of trigeminovascular nociceptive afferents, we examined the effects of intravenous orexin A and B on responses of neurons in the trigeminal nucleus caudalis. To dissect the receptor pharmacology of responses to stimulation we utilized the novel orexin 1 receptor (OX(1)R) antagonist N-(2-methyl-6-benzoxazolyl)-N''-1,5-naphthyridin-4-yl urea (SB-334867). Orexin A 30 microg/kg (F(1.9,9.8) = 21.93, P < 0.001) and 50 microg/kg (F(3.2,16.4) = 3.28, P < 0.045) inhibited the A-fibre responses to dural electrical stimulation over 60 min. Maximum inhibition was achieved at 25 min for both 30 microg/kg (t(5) = 19.83, n = 6, P < 0.001) and 50 microg/kg (t(5) = 7.74, n = 6, P < 0.001). The response with orexin A 30 microg/kg was reversed by pretreatment with the OX(1)R antagonist SB-334867 (F(3.5,17.5) = 0.49, P = 0.73), which had no effect when given alone. Orexin B and control vehicle administration had no significant effect on trigeminal neuronal firing. The current study demonstrates that orexin A is able to inhibit A-fibre responses to dural electrical stimulation via activation of the OX(1)R.
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Affiliation(s)
- P R Holland
- Headache Group, Institute of Neurology, Queen Square, London, UK
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Kishi T, Tsumori T, Yokota S, Yasui Y. Topographical projection from the hippocampal formation to the amygdala: a combined anterograde and retrograde tracing study in the rat. J Comp Neurol 2006; 496:349-68. [PMID: 16566004 DOI: 10.1002/cne.20919] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The hippocampal formation and amygdala are responsible for regulating emotion, learning, and behavior. The hippocampal projection to the amygdala has been demonstrated to originate in the subiculum and adjacent portion of field CA1 of the Ammon's horn (Sub/CA1) in the rat; however, the topographical organization of this pathway is still understudied. To make it clear, we performed anterograde and retrograde tracing with biotinylated dextran amine (BDA) and cholera toxin B subunit (CTb), respectively, in the rat. A series of BDA experiments revealed that the temporal-to-septal axis of origin determined a medial-to-lateral axis of termination in the amygdala. Briefly, the temporal region of the Sub/CA1 projects preferentially to the medial amygdaloid region including the medial, intercalated, and basomedial nuclei and the amygdalohippocampal transition area, and progressively more septal portions of the Sub/CA1 distribute their efferents in more lateral regions of the amygdala. Sub/CA1 fibers distributed in the central amygdaloid nucleus were relatively few. Retrograde tracing with CTb confirmed this topography and revealed little hippocampal innervation of the central nucleus of the amygdala. These observations suggest that distinct Sub/CA1 regions arranged along the longitudinal hippocampal axis may influence distinct modalities of the amygdala function.
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Affiliation(s)
- Toshiro Kishi
- Department of Anatomy and Morphological Neuroscience, Shimane University School of Medicine, Izumo, Japan
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Spinazzi R, Andreis PG, Rossi GP, Nussdorfer GG. Orexins in the regulation of the hypothalamic-pituitary-adrenal axis. Pharmacol Rev 2006; 58:46-57. [PMID: 16507882 DOI: 10.1124/pr.58.1.4] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Orexin-A and orexin-B are hypothalamic peptides that act via two G protein-coupled receptors, named orexin type 1 and type 2 receptors (OX1-Rs and OX2-Rs). The most studied biological functions of orexins are the central control of feeding and sleep, but in the past few years findings that orexin system modulates the hypothalamic-pituitary-adrenal (HPA) axis, acting on both its central and peripheral branches, have accumulated. Orexins and their receptors are expressed in the hypothalamic paraventricular nucleus and median eminence and orexin receptors in pituitary corticotropes, adrenal cortex, and medulla. Whereas the effects of orexins on adrenal aldosterone secretion are doubtful, compelling evidence indicates that these peptides enhance glucocorticoid production in rats and humans. This effect involves a 2-fold mechanism: 1) stimulation of the adrenocorticotropin-releasing hormone-mediated pituitary release of adrenocorticotropin, which in turn raises adrenal glucocorticoid secretion; and 2) direct stimulation of adrenocortical cells via OX1-Rs coupled to the adenylate cyclase-dependent cascade. The effects of orexins on catecholamine release from adrenal medulla are unclear and probably of minor relevance, but there are indications that orexins can stimulate in vitro secretion of human pheochromocytoma cells via OX2-Rs coupled to the phospholipase C-dependent cascade. Evidence is also available that orexins enhance the growth in vitro of adrenocortical cells, mainly acting via OX2-Rs. Moreover, findings suggest that the orexin system may favor HPA axis responses to stresses and play a role in the pathophysiology of cortisol-secreting adrenal adenomas.
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Affiliation(s)
- Raffaella Spinazzi
- Department of Human Anatomy and Physiology, School of Medicine, University of Padua, Italy
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Cerri M, Morrison SF. Activation of lateral hypothalamic neurons stimulates brown adipose tissue thermogenesis. Neuroscience 2006; 135:627-38. [PMID: 16125857 DOI: 10.1016/j.neuroscience.2005.06.039] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Revised: 05/25/2005] [Accepted: 06/09/2005] [Indexed: 10/25/2022]
Abstract
The lateral hypothalamic area, containing orexin neurons, is involved in several aspects of autonomic regulation, including thermoregulation and energy expenditure. To determine if activation of lateral hypothalamic area neurons influences sympathetically-regulated thermogenesis in brown adipose tissue, we microinjected bicuculline (120 pmol, 60 nl, unilateral) into the lateral hypothalamic area in urethane/chloralose-anesthetized, artificially-ventilated rats. Disinhibition of neurons in lateral hypothalamic area evoked a significant increase (+1309%) in brown adipose tissue sympathetic nerve activity accompanied by parallel increases in brown adipose tissue temperature (+2.0 degrees C), in expired CO2 (+0.6%), in heart rate (+88 bpm) and in mean arterial pressure (+11 mm Hg). Subsequent microinjections of glycine (30 nmol, 60 nl) to inhibit local neurons in raphe pallidus or in dorsomedial hypothalamus or of glutamate receptor antagonists into dorsomedial hypothalamus promptly reversed the increases in brown adipose tissue sympathetic nerve activity, brown adipose tissue temperature and heart rate evoked by disinhibition of neurons in lateral hypothalamic area. We conclude that neurons in the lateral hypothalamic area can influence brown adipose tissue sympathetic nerve activity, brown adipose tissue thermogenesis and heart rate through pathways that are dependent on the activation of neurons in dorsomedial hypothalamus and raphe pallidus.
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Affiliation(s)
- M Cerri
- Neurological Sciences Institute, Oregon Health and Science University, Beaverton, OR 97006, USA
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Abstract
The discovery of cannabinoid receptors, together with the development of selective cannabinoid receptor antagonists, has encouraged a resurgence of cannabinoid pharmacology. With the identification of endogenous agonists, such as anandamide, scientists have sought to uncover the biological role of endocannabinoid systems; initially guided by the long-established actions of cannabis and exogenous cannabinoids such as delta9-tetrahydrocannabinol (THC). In particular, considerable research has examined endocannabinoid involvement in appetite, eating behaviour and body weight regulation. It is now confirmed that endocannabinoids, acting at brain CB1 cannabinoid receptors, stimulate appetite and ingestive behaviours, partly through interactions with more established orexigenic and anorexigenic signals. Key structures such as the nucleus accumbens and hypothalamic nuclei are sensitive sites for the hyperphagic actions of these substances, and endocannabinoid activity in these regions varies in relation to nutritional status and feeding expression. Behavioural studies indicate that endocannabinoids increase eating motivation by enhancing the incentive salience and hedonic evaluation of ingesta. Moreover, there is strong evidence of an endocannabinoid role in energy metabolism and fuel storage. Recent developments point to potential clinical benefits of cannabinoid receptor antagonists in the management of obesity, and of agonists in the treatment of other disorders of eating and body weight regulation.
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Affiliation(s)
- T C Kirkham
- School of Psychology, University of Liverpool, Liverpool, England.
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Holland PR, Akerman S, Goadsby PJ. Orexin 1 Receptor Activation Attenuates Neurogenic Dural Vasodilation in an Animal Model of Trigeminovascular Nociception. J Pharmacol Exp Ther 2005; 315:1380-5. [PMID: 16160082 DOI: 10.1124/jpet.105.090951] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The pathophysiology underlying the pulsating quality of the pain of a migraine attack is not fully understood, although trigeminal vascular afferents containing the sensory neuropeptide calcitonin gene-related peptide (CGRP) must have a role. Antimigraine drugs, such as triptans, serotonin 5-hydroxytryptamine(1B/1D) receptor agonists, reproducibly block neurogenic vasodilation associated with CGRP release. We examined the effects of the hypothalamic neuropeptides orexin A and orexin B on neurogenic dural vasodilation, dissecting out the receptor pharmacology with the novel orexin 1 (OX1) receptor antagonist N-(2-methyl-6-benzoxazolyl)-N''-1,5-naphthyridin-4-yl urea (SB-334867). Electrical stimulation of dural afferents (50-300 microA) resulted in reproducible dural vasodilation of 136 +/- 9%. Orexin A 30 microg kg(-1), but not 3 and 10 microg kg(-1), inhibited the dilation brought about by electrical stimulation over 60 min and maximally after 15 min by 60% (t7= 7.138; P < 0.001; n = 8). This response was reversed by pretreatment with the OX1 receptor antagonist SB-334867. Addition of CGRP(8-37) at the point of maximal effect of orexin A produced a further significant decrease in neurogenic dural vasodilation compared with orexin A only. CGRP administration (1 microg kg(-1)) produced a reproducible dural blood vessel dilation of 145 +/- 7% that was not inhibited by intravenous administration of orexin A (30 microg kg(-1)). Orexin B had no significant effect even at the highest dose. The current study demonstrates that orexin A is able to inhibit neurogenic dural vasodilation via activation of the OX1 receptor, resulting in inhibition of prejunctional release of CGRP from trigeminal neurons.
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Affiliation(s)
- P R Holland
- Headache Group, Institute of Neurology, Queen Square, London WC1N 3BG, UK
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