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Toplu A, Mutlu N, Erdeve ET, Sariyildiz Ö, Çelik M, Öz-Arslan D, Akman Ö, Molnár Z, Çarçak N, Onat F. Involvement of orexin type-2 receptors in genetic absence epilepsy rats. Front Neurol 2023; 14:1282494. [PMID: 38107640 PMCID: PMC10721972 DOI: 10.3389/fneur.2023.1282494] [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: 08/24/2023] [Accepted: 11/10/2023] [Indexed: 12/19/2023] Open
Abstract
Introduction Orexin is a neuropeptide neurotransmitter that regulates the sleep/wake cycle produced by the lateral hypothalamus neurons. Recent studies have shown the involvement of orexin system in epilepsy. Limited data is available about the possible role of orexins in the pathophysiology of absence seizures. This study aims to understand the role of orexinergic signaling through the orexin-type 2 receptor (OX2R) in the pathophysiology of absence epilepsy. The pharmacological effect of a selective OX2R agonist, YNT-185 on spike-and-wave-discharges (SWDs) and the OX2R receptor protein levels in the cortex and thalamus in adult GAERS were investigated. Methods The effect of intracerebroventricular (ICV) (100, 300, and 600 nmol/10 μL), intrathalamic (30 and 40 nmol/500 nL), and intracortical (40 nmol/500 nL) microinjections of YNT-185 on the duration and number of spontaneous SWDs were evaluated in adult GAERS. The percentage of slow-wave sleep (SWS) and spectral characteristics of background EEG were analyzed after the ICV application of 600 nmol YNT-185. The level of OX2R expression in the somatosensory cortex and projecting thalamic nuclei of adult GAERS were examined by Western blot and compared with the non-epileptic Wistar rats. Results We showed that ICV administration of YNT-185 suppressed the cumulative duration of SWDs in GAERS compared to the saline-administered control group (p < 0.05). However, intrathalamic and intracortical microinjections of YNT-185 did not show a significant effect on SWDs. ICV microinjections of YNT-185 affect sleep states by increasing the percentage of SWS and showed a significant treatment effect on the 1-4 Hz delta frequency band power during the 1-2 h post-injection period where YNT-185 significantly decreased the SWDs. OXR2 protein levels were significantly reduced in the cortex and thalamus of GAERS when compared to Wistar rats. Conclusion This study investigated the efficacy of YNT-185 for the first time on absence epilepsy in GAERS and revealed a suppressive effect of OX2R agonist on SWDs as evidenced by the significantly reduced expression of OX2R in the cortex and thalamus. YNT-185 effect on SWDs could be attributed to its regulation of wake/sleep states. The results constitute a step toward understanding the effectiveness of orexin neuropeptides on absence seizures in GAERS and might be targeted by therapeutic intervention for absence epilepsy.
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Affiliation(s)
- Aylin Toplu
- Department of Medical Pharmacology, School of Medicine, Marmara University, Istanbul, Türkiye
- Department of Neuroscience, Health Sciences Institute, Acibadem Mehmet Ali Aydinlar University, Istanbul, Türkiye
| | - Nursima Mutlu
- Department of Molecular Biotechnology and Genetics, Institute of Science, Istanbul University, Istanbul, Türkiye
| | - Elif Tuğçe Erdeve
- Department of Pharmacology, Health Sciences Institute, Istanbul University, Istanbul, Türkiye
| | - Özge Sariyildiz
- Department of Neuroscience, Health Sciences Institute, Acibadem Mehmet Ali Aydinlar University, Istanbul, Türkiye
| | - Musa Çelik
- Department of Biophysics, Health Sciences Institute, Acibadem Mehmet Ali Aydinlar University, Istanbul, Türkiye
| | - Devrim Öz-Arslan
- Department of Neuroscience, Health Sciences Institute, Acibadem Mehmet Ali Aydinlar University, Istanbul, Türkiye
- Department of Biophysics, Health Sciences Institute, Acibadem Mehmet Ali Aydinlar University, Istanbul, Türkiye
- Department of Biophysics, School of Medicine, Acibadem Mehmet Ali Aydinlar University, Istanbul, Türkiye
| | - Özlem Akman
- Department of Physiology, Faculty of Medicine, Demiroglu Bilim University, Istanbul, Türkiye
| | - Zoltan Molnár
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Nihan Çarçak
- Department of Neuroscience, Health Sciences Institute, Acibadem Mehmet Ali Aydinlar University, Istanbul, Türkiye
- Department of Pharmacology, Faculty of Pharmacy, Istanbul University, Istanbul, Türkiye
| | - Filiz Onat
- Department of Neuroscience, Health Sciences Institute, Acibadem Mehmet Ali Aydinlar University, Istanbul, Türkiye
- Department of Medical Pharmacology, School of Medicine, Acibadem Mehmet Ali Aydinlar University, Istanbul, Türkiye
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Mogavero MP, Godos J, Grosso G, Caraci F, Ferri R. Rethinking the Role of Orexin in the Regulation of REM Sleep and Appetite. Nutrients 2023; 15:3679. [PMID: 37686711 PMCID: PMC10489991 DOI: 10.3390/nu15173679] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 08/12/2023] [Accepted: 08/21/2023] [Indexed: 09/10/2023] Open
Abstract
Orexin plays a significant role in the modulation of REM sleep, as well as in the regulation of appetite and feeding. This review explores, first, the current evidence on the role of orexin in the modulation of sleep and wakefulness and highlights that orexin should be considered essentially as a neurotransmitter inhibiting REM sleep and, to a much lesser extent, a wake promoting agent. Subsequently, the relationship between orexin, REM sleep, and appetite regulation is examined in detail, shedding light on their interconnected nature in both physiological conditions and diseases (such as narcolepsy, sleep-related eating disorder, idiopathic hypersomnia, and night eating syndrome). Understanding the intricate relationship between orexin, REM sleep, and appetite regulation is vital for unraveling the complex mechanisms underlying sleep-wake patterns and metabolic control. Further research in this field is encouraged in order to pave the way for novel therapeutic approaches to sleep disorders and metabolic conditions associated with orexin dysregulation.
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Affiliation(s)
- Maria P. Mogavero
- Department of Psychology, Vita-Salute San Raffaele University, 20132 Milan, Italy;
- San Raffaele Scientific Institute, Division of Neuroscience, Sleep Disorders Center, 20127 Milan, Italy
| | - Justyna Godos
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy; (J.G.); (G.G.)
| | - Giuseppe Grosso
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy; (J.G.); (G.G.)
| | - Filippo Caraci
- Neuropharmacology and Translational Neurosciences Research Unit, Oasi Research Institute—IRCCS, 94018 Troina, Italy;
- Department of Drug and Health Sciences, University of Catania, 95125 Catania, Italy
| | - Raffaele Ferri
- Sleep Research Centre, Oasi Research Institute—IRCCS, 94018 Troina, Italy
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