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He Q, Yuan Q, Shan H, Wu C, Gu Y, Wu K, Hu W, Zhang Y, He X, Xu HE, Zhao LH. Mechanisms of ligand recognition and activation of melanin-concentrating hormone receptors. Cell Discov 2024; 10:48. [PMID: 38710677 DOI: 10.1038/s41421-024-00679-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 04/10/2024] [Indexed: 05/08/2024] Open
Abstract
Melanin-concentrating hormone (MCH) is a cyclic neuropeptide that regulates food intake, energy balance, and other physiological functions by stimulating MCHR1 and MCHR2 receptors, both of which are class A G protein-coupled receptors. MCHR1 predominately couples to inhibitory G protein, Gi/o, and MCHR2 can only couple to Gq/11. Here we present cryo-electron microscopy structures of MCH-activated MCHR1 with Gi and MCH-activated MCHR2 with Gq at the global resolutions of 3.01 Å and 2.40 Å, respectively. These structures reveal that MCH adopts a consistent cysteine-mediated hairpin loop configuration when bound to both receptors. A central arginine from the LGRVY core motif between the two cysteines of MCH penetrates deeply into the transmembrane pocket, triggering receptor activation. Integrated with mutational and functional insights, our findings elucidate the molecular underpinnings of ligand recognition and MCH receptor activation and offer a structural foundation for targeted drug design.
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Affiliation(s)
- Qian He
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Qingning Yuan
- College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Hong Shan
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Canrong Wu
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Yimin Gu
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Kai Wu
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Wen Hu
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Yumu Zhang
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Xinheng He
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - H Eric Xu
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
- University of Chinese Academy of Sciences, Beijing, China.
| | - Li-Hua Zhao
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
- University of Chinese Academy of Sciences, Beijing, China.
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Gao Y, Zhou Q, Li H, Zhao Y, Zhu H, Zhang X, Li Y. Melanin-Concentrating Hormone Is Associated With Delayed Neurocognitive Recovery in Older Adult Patients With Preoperative Sleep Disorders Undergoing Spinal Anesthesia. Anesth Analg 2024; 138:579-588. [PMID: 38051670 DOI: 10.1213/ane.0000000000006768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
BACKGROUND Aging and preoperative sleep disorders are the main risk factors affecting postoperative cognitive outcomes. However, the pathogenesis of delayed neurocognitive recovery after surgery remains ambiguous, and there is still a lack of potential biomarkers for delayed neurocognitive recovery in older adult patients with preoperative sleep disorders. Our study aimed to explore the relationship between melanin-concentrating hormone (MCH) and delayed neurocognitive recovery early after surgery in older adult patients with preoperative sleep disorders. METHODS In this monocentric prospective observational study, 156 older adult patients (aged 65 years or older) with preoperative sleep disorders undergoing elective total hip arthroplasty (THA) or total knee arthroplasty (TKA) were included at an academic medical center in Inner Mongolia, China, from October 2021 to November 2022, and all patients underwent spinal anesthesia. The Pittsburgh Sleep Quality Index (PSQI) was applied to assess the preoperative sleep quality of all patients, and preoperative sleep disorders were defined as a score of PSQI >5. We measured the levels of cerebrospinal fluid (CSF) MCH and plasma MCH of all patients. The primary outcome was delayed neurocognitive recovery early after surgery. All patients received cognitive function assessment through the Montreal Cognitive Assessment (MoCA) 1 day before and 7 days after surgery (postoperative day 7 [POD7]). Delayed neurocognitive recovery was defined as a score of POD7 MoCA <26. The potential confounders included variables with P < .2 in the univariate logistic analysis, as well as the important risk factors of delayed neurocognitive recovery reported in the literature. Multivariable logistic regression model based on the Enter method assessed the association of MCH and delayed neurocognitive recovery in older adult patients with preoperative sleep disorders. RESULTS Fifty-nine (37.8%) older adult patients with preoperative sleep disorders experienced delayed neurocognitive recovery at POD7. Increase in CSF MCH levels (odds ratio [OR] for an increase of 1 pg/mL = 1.16, 95% confidence interval [CI], 1.09-1.23, P < .001) and decrease in plasma MCH levels (OR for an increase of 1 pg/mL = 0.92, 95% CI, 0.86-0.98, P = .003) were associated with delayed neurocognitive recovery, after adjusting for age, sex, education, baseline MoCA scores, American Society of Anesthesiologists (ASA) grade, and coronary heart disease (CHD). CONCLUSIONS In older adult patients with preoperative sleep disorders, MCH is associated with the occurrence of delayed neurocognitive recovery after surgery. Preoperative testing of CSF MCH or plasma MCH may increase the likelihood of identifying the high-risk population for delayed neurocognitive recovery in older adult patients with preoperative sleep disorders.
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Affiliation(s)
- Yi Gao
- From the Chifeng Clinical Medical College of Inner Mongolia Medical University, Chifeng, China
- Department of Anesthesiology, Chifeng Municipal Hospital, Chifeng, China
| | - Qi Zhou
- From the Chifeng Clinical Medical College of Inner Mongolia Medical University, Chifeng, China
- Department of Anesthesiology, Chifeng Municipal Hospital, Chifeng, China
| | - Haibo Li
- From the Chifeng Clinical Medical College of Inner Mongolia Medical University, Chifeng, China
- Department of Anesthesiology, Chifeng Municipal Hospital, Chifeng, China
| | - Yunjiao Zhao
- From the Chifeng Clinical Medical College of Inner Mongolia Medical University, Chifeng, China
| | - Hongyan Zhu
- From the Chifeng Clinical Medical College of Inner Mongolia Medical University, Chifeng, China
- Department of Anesthesiology, Chifeng Municipal Hospital, Chifeng, China
| | - Xizhe Zhang
- From the Chifeng Clinical Medical College of Inner Mongolia Medical University, Chifeng, China
- Department of Anesthesiology, Chifeng Municipal Hospital, Chifeng, China
| | - Yun Li
- Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin Research Institute of Anesthesiology, Tianjin, China
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Vetrivelan R, Bandaru SS. Neural Control of REM Sleep and Motor Atonia: Current Perspectives. Curr Neurol Neurosci Rep 2023; 23:907-923. [PMID: 38060134 DOI: 10.1007/s11910-023-01322-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/2023] [Indexed: 12/08/2023]
Abstract
PURPOSE OF REVIEW Since the formal discovery of rapid eye movement (REM) sleep in 1953, we have gained a vast amount of knowledge regarding the specific populations of neurons, their connections, and synaptic mechanisms regulating this stage of sleep and its accompanying features. This article discusses REM sleep circuits and their dysfunction, specifically emphasizing recent studies using conditional genetic tools. RECENT FINDINGS Sublaterodorsal nucleus (SLD) in the dorsolateral pons, especially the glutamatergic subpopulation in this region (SLDGlut), are shown to be indispensable for REM sleep. These neurons appear to be single REM generators in the rodent brain and may initiate and orchestrate all REM sleep events, including cortical and hippocampal activation and muscle atonia through distinct pathways. However, several cell groups in the brainstem and hypothalamus may influence SLDGlut neuron activity, thereby modulating REM sleep timing, amounts, and architecture. Damage to SLDGlut neurons or their projections involved in muscle atonia leads to REM behavior disorder, whereas the abnormal activation of this pathway during wakefulness may underlie cataplexy in narcolepsy. Despite some opposing views, it has become evident that SLDGlut neurons are the sole generators of REM sleep and its associated characteristics. Further research should prioritize a deeper understanding of their cellular, synaptic, and molecular properties, as well as the mechanisms that trigger their activation during cataplexy and make them susceptible in RBD.
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Affiliation(s)
- Ramalingam Vetrivelan
- Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, USA.
| | - Sathyajit Sai Bandaru
- Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, USA
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Prolactin-Releasing Peptide Contributes to Stress-Related Mood Disorders and Inhibits Sleep/Mood Regulatory Melanin-Concentrating Hormone Neurons in Rats. J Neurosci 2023; 43:846-862. [PMID: 36564184 PMCID: PMC9899089 DOI: 10.1523/jneurosci.2139-21.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 08/31/2022] [Accepted: 09/30/2022] [Indexed: 12/24/2022] Open
Abstract
Stress disorders impair sleep and quality of life; however, their pathomechanisms are unknown. Prolactin-releasing peptide (PrRP) is a stress mediator; we therefore hypothesized that PrRP may be involved in the development of stress disorders. PrRP is produced by the medullary A1/A2 noradrenaline (NA) cells, which transmit stress signals to forebrain centers, and by non-NA cells in the hypothalamic dorsomedial nucleus. We found in male rats that both PrRP and PrRP-NA cells innervate melanin-concentrating hormone (MCH) producing neurons in the dorsolateral hypothalamus (DLH). These cells serve as a key hub for regulating sleep and affective states. Ex vivo, PrRP hyperpolarized MCH neurons and further increased the hyperpolarization caused by NA. Following sleep deprivation, intracerebroventricular PrRP injection reduced the number of REM sleep-active MCH cells. PrRP expression in the dorsomedial nucleus was upregulated by sleep deprivation, while downregulated by REM sleep rebound. Both in learned helplessness paradigm and after peripheral inflammation, impaired coping with sustained stress was associated with (1) overactivation of PrRP cells, (2) PrRP protein and receptor depletion in the DLH, and (3) dysregulation of MCH expression. Exposure to stress in the PrRP-insensitive period led to increased passive coping with stress. Normal PrRP signaling, therefore, seems to protect animals against stress-related disorders. PrRP signaling in the DLH is an important component of the PrRP's action, which may be mediated by MCH neurons. Moreover, PrRP receptors were downregulated in the DLH of human suicidal victims. As stress-related mental disorders are the leading cause of suicide, our findings may have particular translational relevance.SIGNIFICANCE STATEMENT Treatment resistance to monoaminergic antidepressants is a major problem. Neuropeptides that modulate the central monoaminergic signaling are promising targets for developing alternative therapeutic strategies. We found that stress-responsive prolactin-releasing peptide (PrRP) cells innervated melanin-concentrating hormone (MCH) neurons that are crucial in the regulation of sleep and mood. PrRP inhibited MCH cell activity and enhanced the inhibitory effect evoked by noradrenaline, a classic monoamine, on MCH neurons. We observed that impaired PrRP signaling led to failure in coping with chronic/repeated stress and was associated with altered MCH expression. We found alterations of the PrRP system also in suicidal human subjects. PrRP dysfunction may underlie stress disorders, and fine-tuning MCH activity by PrRP may be an important part of the mechanism.
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Nollet M, Franks NP, Wisden W. Understanding Sleep Regulation in Normal and Pathological Conditions, and Why It Matters. J Huntingtons Dis 2023; 12:105-119. [PMID: 37302038 PMCID: PMC10473105 DOI: 10.3233/jhd-230564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2023] [Indexed: 06/12/2023]
Abstract
Sleep occupies a peculiar place in our lives and in science, being both eminently familiar and profoundly enigmatic. Historically, philosophers, scientists and artists questioned the meaning and purpose of sleep. If Shakespeare's verses from MacBeth depicting "Sleep that soothes away all our worries" and "relieves the weary laborer and heals hurt minds" perfectly epitomize the alleviating benefits of sleep, it is only during the last two decades that the growing understanding of the sophisticated sleep regulatory mechanisms allows us to glimpse putative biological functions of sleep. Sleep control brings into play various brain-wide processes occurring at the molecular, cellular, circuit, and system levels, some of them overlapping with a number of disease-signaling pathways. Pathogenic processes, including mood disorders (e.g., major depression) and neurodegenerative illnesses such Huntington's or Alzheimer's diseases, can therefore affect sleep-modulating networks which disrupt the sleep-wake architecture, whereas sleep disturbances may also trigger various brain disorders. In this review, we describe the mechanisms underlying sleep regulation and the main hypotheses drawn about its functions. Comprehending sleep physiological orchestration and functions could ultimately help deliver better treatments for people living with neurodegenerative diseases.
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Affiliation(s)
- Mathieu Nollet
- UK Dementia Research Institute and Department of Life Sciences, Imperial College London, London, UK
| | - Nicholas P. Franks
- UK Dementia Research Institute and Department of Life Sciences, Imperial College London, London, UK
| | - William Wisden
- UK Dementia Research Institute and Department of Life Sciences, Imperial College London, London, UK
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New Perspectives on Sleep Regulation by Tea: Harmonizing Pathological Sleep and Energy Balance under Stress. Foods 2022; 11:foods11233930. [PMID: 36496738 PMCID: PMC9738644 DOI: 10.3390/foods11233930] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 11/25/2022] [Accepted: 11/26/2022] [Indexed: 12/09/2022] Open
Abstract
Sleep, a conservative evolutionary behavior of organisms to adapt to changes in the external environment, is divided into natural sleep, in a healthy state, and sickness sleep, which occurs in stressful environments or during illness. Sickness sleep plays an important role in maintaining energy homeostasis under an injury and promoting physical recovery. Tea, a popular phytochemical-rich beverage, has multiple health benefits, including lowering stress and regulating energy metabolism and natural sleep. However, the role of tea in regulating sickness sleep has received little attention. The mechanism underlying tea regulation of sickness sleep and its association with the maintenance of energy homeostasis in injured organisms remains to be elucidated. This review examines the current research on the effect of tea on sleep regulation, focusing on the function of tea in modulating energy homeostasis through sickness sleep, energy metabolism, and damage repair in model organisms. The potential mechanisms underlying tea in regulating sickness sleep are further suggested. Based on the biohomology of sleep regulation, this review provides novel insights into the role of tea in sleep regulation and a new perspective on the potential role of tea in restoring homeostasis from diseases.
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Potter LE, Burgess CR. The melanin-concentrating hormone system as a target for the treatment of sleep disorders. Front Neurosci 2022; 16:952275. [PMID: 36177357 PMCID: PMC9513178 DOI: 10.3389/fnins.2022.952275] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 08/24/2022] [Indexed: 11/13/2022] Open
Abstract
Given the widespread prevalence of sleep disorders and their impacts on health, it is critical that researchers continue to identify and evaluate novel avenues of treatment. Recently the melanin-concentrating hormone (MCH) system has attracted commercial and scientific interest as a potential target of pharmacotherapy for sleep disorders. This interest emerges from basic scientific research demonstrating a role for MCH in regulating sleep, and particularly REM sleep. In addition to this role in sleep regulation, the MCH system and the MCH receptor 1 (MCHR1) have been implicated in a wide variety of other physiological functions and behaviors, including feeding/metabolism, reward, anxiety, depression, and learning. The basic research literature on sleep and the MCH system, and the history of MCH drug development, provide cause for both skepticism and cautious optimism about the prospects of MCH-targeting drugs in sleep disorders. Extensive efforts have focused on developing MCHR1 antagonists for use in obesity, however, few of these drugs have advanced to clinical trials, and none have gained regulatory approval. Additional basic research will be needed to fully characterize the MCH system’s role in sleep regulation, for example, to fully differentiate between MCH-neuron and peptide/receptor-mediated functions. Additionally, a number of issues relating to drug design will continue to pose a practical challenge for novel pharmacotherapies targeting the MCH system.
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Affiliation(s)
- Liam E. Potter
- Department of Molecular and Integrative Physiology, Michigan Medicine, Ann Arbor, MI, United States
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, United States
- *Correspondence: Liam E. Potter,
| | - Christian R. Burgess
- Department of Molecular and Integrative Physiology, Michigan Medicine, Ann Arbor, MI, United States
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, United States
- Christian R. Burgess,
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Murillo-Rodríguez E, Coronado-Álvarez A, López-Muciño LA, Pastrana-Trejo JC, Viana-Torre G, Barberena JJ, Soriano-Nava DM, García-García F. Neurobiology of dream activity and effects of stimulants on dreams. Curr Top Med Chem 2022; 22:1280-1295. [PMID: 35761491 DOI: 10.2174/1568026622666220627162032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Revised: 03/18/2022] [Accepted: 04/11/2022] [Indexed: 11/22/2022]
Abstract
The sleep-wake cycle is the result of the activity of a multiple neurobiological network interaction. Dreaming feature is one interesting sleep phenomena that represents sensorial components, mostly visual perceptions, accompanied with intense emotions. Further complexity has been added to the topic of the neurobiological mechanism of dreams generation by the current data that suggests the influence of drugs on dream generation. Here, we discuss the review on some of the neurobiological mechanism of the regulation of dream activity, with special emphasis on the effects of stimulants on dreaming.
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Affiliation(s)
- Eric Murillo-Rodríguez
- Laboratorio de Neurociencias Moleculares e Integrativas, Escuela de Medicina, División Ciencias de la Salud. Universidad Anáhuac Mayab. Mérida, Yucatán. México.,Intercontinental Neuroscience Research Group
| | - Astrid Coronado-Álvarez
- Laboratorio de Neurociencias Moleculares e Integrativas, Escuela de Medicina, División Ciencias de la Salud. Universidad Anáhuac Mayab. Mérida, Yucatán. México.,Intercontinental Neuroscience Research Group
| | - Luis Angel López-Muciño
- Health Sciences Program. Health Sciences Institute. Veracruzana University. Xalapa. Veracruz. Mexico
| | - José Carlos Pastrana-Trejo
- Laboratorio de Neurociencias Moleculares e Integrativas, Escuela de Medicina, División Ciencias de la Salud. Universidad Anáhuac Mayab. Mérida, Yucatán. México.,Intercontinental Neuroscience Research Group
| | - Gerardo Viana-Torre
- Laboratorio de Neurociencias Moleculares e Integrativas, Escuela de Medicina, División Ciencias de la Salud. Universidad Anáhuac Mayab. Mérida, Yucatán. México.,Intercontinental Neuroscience Research Group
| | - Juan José Barberena
- Laboratorio de Neurociencias Moleculares e Integrativas, Escuela de Medicina, División Ciencias de la Salud. Universidad Anáhuac Mayab. Mérida, Yucatán. México.,Intercontinental Neuroscience Research Group.,Escuela de Psicología, División Ciencias de la Salud. Universidad Anáhuac Mayab. Mérida, Yucatán. México
| | - Daniela Marcia Soriano-Nava
- Laboratorio de Neurociencias Moleculares e Integrativas, Escuela de Medicina, División Ciencias de la Salud. Universidad Anáhuac Mayab. Mérida, Yucatán. México.,Intercontinental Neuroscience Research Group
| | - Fabio García-García
- Intercontinental Neuroscience Research Group.,Health Sciences Program. Health Sciences Institute. Veracruzana University. Xalapa. Veracruz. Mexico
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MCH-R1 Antagonist GPS18169, a Pseudopeptide, Is a Peripheral Anti-Obesity Agent in Mice. Molecules 2021; 26:molecules26051291. [PMID: 33673598 PMCID: PMC7957705 DOI: 10.3390/molecules26051291] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 02/17/2021] [Accepted: 02/22/2021] [Indexed: 01/01/2023] Open
Abstract
Melanin-concentrating hormone (MCH) is a 19 amino acid long peptide found in the brain of animals, including fishes, batrachians, and mammals. MCH is implicated in appetite and/or energy homeostasis. Antagonists at its receptor (MCH-R1) could be major tools (or ultimately drugs) to understand the mechanism of MCH action and to fight the obesity syndrome that is a worldwide societal health problem. Ever since the deorphanisation of the MCH receptor, we cloned, expressed, and characterized the receptor MCH-R1 and started a vast medicinal chemistry program aiming at the discovery of such usable compounds. In the present final work, we describe GPS18169, a pseudopeptide antagonist at the MCH-R1 receptor with an affinity in the nanomolar range and a Ki for its antagonistic effect in the 20 picomolar range. Its metabolic stability is rather ameliorated compared to its initial parent compound, the antagonist S38151. We tested it in an in vivo experiment using high diet mice. GPS18169 was found to be active in limiting the accumulation of adipose tissues and, correlatively, we observed a normalization of the insulin level in the treated animals, while no change in food or water consumption was observed.
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Giardino WJ, Pomrenze MB. Extended Amygdala Neuropeptide Circuitry of Emotional Arousal: Waking Up on the Wrong Side of the Bed Nuclei of Stria Terminalis. Front Behav Neurosci 2021; 15:613025. [PMID: 33633549 PMCID: PMC7900561 DOI: 10.3389/fnbeh.2021.613025] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 01/15/2021] [Indexed: 12/25/2022] Open
Abstract
Sleep is fundamental to life, and poor sleep quality is linked to the suboptimal function of the neural circuits that process and respond to emotional stimuli. Wakefulness ("arousal") is chiefly regulated by circadian and homeostatic forces, but affective mood states also strongly impact the balance between sleep and wake. Considering the bidirectional relationships between sleep/wake changes and emotional dynamics, we use the term "emotional arousal" as a representative characteristic of the profound overlap between brain pathways that: (1) modulate wakefulness; (2) interpret emotional information; and (3) calibrate motivated behaviors. Interestingly, many emotional arousal circuits communicate using specialized signaling molecules called neuropeptides to broadly modify neural network activities. One major neuropeptide-enriched brain region that is critical for emotional processing and has been recently implicated in sleep regulation is the bed nuclei of stria terminalis (BNST), a core component of the extended amygdala (an anatomical term that also includes the central and medial amygdalae, nucleus accumbens shell, and transition zones betwixt). The BNST encompasses an astonishing diversity of cell types that differ across many features including spatial organization, molecular signature, biological sex and hormonal milieu, synaptic input, axonal output, neurophysiological communication mode, and functional role. Given this tremendous complexity, comprehensive elucidation of the BNST neuropeptide circuit mechanisms underlying emotional arousal presents an ambitious set of challenges. In this review, we describe how rigorous investigation of these unresolved questions may reveal key insights to enhancing psychiatric treatments and global psychological wellbeing.
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