Chronic or intermittent sleep disorders such as narcolepsy, sleep apnea, and insomnia afflict nearly 40 million people in the United States. Yet the neural mechanisms controlling both normal sleep and its pathologies remain poorly understood. Considerable evidence indicates that mesopontine cholinergic neurons are critical for this control and that their disregulation is involved in narcolepsy, Parkinson's disease, supranuclear palsy and depression. The long term goal of this project is to understand the synaptic and non- synaptic mechanisms regulating activity of mesopontine cholinergic neurons. Recent compelling evidence indicates that disruption of the novel Hypocretin/Orexin (Hcrt/Orx) peptide system results in narcolepsy - a sleep disorder characterized by excessive daytime sleepiness, sleep fragmentation and the intrusion of rapid eye movement sleep behaviors into wakefulness. Building on the finding from the last funding period, which showed that mesopontine cholinergic neurons are important targets of these peptides, we will continue to investigate the general hypothesis that Hcrt/Orx peptides regulate both the short-term and long-term excitability of these neurons and that loss of Hcrt/Orx signaling upregulates the cholinergic phenotype of MPCh neurons and thereby contributes to the expression of cataplexy. To do so we will 1) continue to identify the ion channels activated by Hcrt/Orx and investigate their impact on the excitability of MPCh neurons;2) investigate the microsircuitry within the LOT to determine if functionaly related subsets of cholinergic neurons are differentially modulated by Hcrt/Orx and 3) determine if the upregulation of the enzymes responsible for cholinergic transmission following the loss of Hcrt/Orx signalling contributes to cataplexy. These experiments will use whole-cell patch clamp recording and calcium imaging methods in brain slices, tract tracing, tissue biochemistry, a novel extracellular probe to measure Ach release and behavioral pharmacology in control mice and mice lacking the two known orexin receptors to investigate these issues. Collectively, these results will advance the understanding of the molecular and cellular mechanisms underlying sleep regulation and its pathology.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-IFCN-D (02))
Program Officer
Mitler, Merrill
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
New York Medical College
Schools of Medicine
United States
Zip Code
Ishibashi, Masaru; Gumenchuk, Iryna; Miyazaki, Kenichi et al. (2016) Hypocretin/Orexin Peptides Alter Spike Encoding by Serotonergic Dorsal Raphe Neurons through Two Distinct Mechanisms That Increase the Late Afterhyperpolarization. J Neurosci 36:10097-115
Ishibashi, Masaru; Gumenchuk, Iryna; Kang, Bryan et al. (2015) Orexin Receptor Activation Generates Gamma Band Input to Cholinergic and Serotonergic Arousal System Neurons and Drives an Intrinsic Ca(2+)-Dependent Resonance in LDT and PPT Cholinergic Neurons. Front Neurol 6:120
Leonard, C S; Kukkonen, J P (2014) Orexin/hypocretin receptor signalling: a functional perspective. Br J Pharmacol 171:294-313
Christensen, Mark H; Ishibashi, Masaru; Nielsen, Michael L et al. (2014) Age-related changes in nicotine response of cholinergic and non-cholinergic laterodorsal tegmental neurons: implications for the heightened adolescent susceptibility to nicotine addiction. Neuropharmacology 85:263-83
Kukkonen, J P; Leonard, C S (2014) Orexin/hypocretin receptor signalling cascades. Br J Pharmacol 171:314-31
Kohlmeier, Kristi A; Tyler, Christopher J; Kalogiannis, Mike et al. (2013) Differential actions of orexin receptors in brainstem cholinergic and monoaminergic neurons revealed by receptor knockouts: implications for orexinergic signaling in arousal and narcolepsy. Front Neurosci 7:246
Kohlmeier, Kristi A; Ishibashi, Masaru; Wess, Jurgen et al. (2012) Knockouts reveal overlapping functions of M(2) and M(4) muscarinic receptors and evidence for a local glutamatergic circuit within the laterodorsal tegmental nucleus. J Neurophysiol 108:2751-66
Kalogiannis, Mike; Hsu, Emily; Willie, Jon T et al. (2011) Cholinergic modulation of narcoleptic attacks in double orexin receptor knockout mice. PLoS One 6:e18697
Kalogiannis, M; Grupke, S L; Potter, P E et al. (2010) Narcoleptic orexin receptor knockout mice express enhanced cholinergic properties in laterodorsal tegmental neurons. Eur J Neurosci 32:130-42
Konduri, G Ganesh; Vohr, Betty; Robertson, Charlene et al. (2007) Early inhaled nitric oxide therapy for term and near-term newborn infants with hypoxic respiratory failure: neurodevelopmental follow-up. J Pediatr 150:235-40, 240.e1