Gene transfer has proven to be an effective neurobiological tool in a number of neurodegenerative diseases and we have used it to correct a sleep disorder. We have focused on narcolepsy, a neurodegenerative sleep disorder linked to the loss of neurons containing the neuropeptide hypocretin, also known as orexin. To restore orexin levels we have inserted the gene for orexin into surrogate neurons and blocked narcoleptic behavior in two reliable and valid mice models of narcolepsy. The effects were site specific and depended on the connectivity of the surrogate neurons. We now propose to further narrow the site-specificity by confining expression of orexin only in MCH neurons and selectively activating them during waking. The MCH neurons are still viable in human narcolepsy and are connected to the same downstream targets as the orexin neurons. These neurons are normally silent during waking and we hypothesize that by selectively activating them during waking we will block cataplexy and lengthen waking bouts.
In aim 1 we will insert the genes for channelrhodopsin-2 (ChR2), a light sensitive cation channel, and orexin only in MCH neurons (MCH promoter driven). Optogenetic stimulation will drive the MCH-ChR2-Orexin containing neurons and its effects on cataplexy and wake duration will be determined during both the day and night cycles.
Aim 2 will utilize a new emerging methodology that relies on Designer Receptors Exclusively Activated by Designer Drugs to activate the MCH neurons. Experiments with appropriate controls, including orexin receptor antagonist are proposed to strengthen the conclusions. C-Fos will identify activation of the MCH neurons and an in vitro calcium imaging study will determine functionality of the genetically inserted ChR2 and hM3Dq receptors. These studies will for the first time identify neurons that can be selectively activated to block narcoleptic behavior.

Public Health Relevance

Current pharmacological approaches for treating narcolepsy lack specificity since the drugs bathe the entire brain and body. The proposed studies will utilize optogenetics and DREADD to identify neurons that can be selectively activated to block narcoleptic behavior and lengthen wake bouts. We believe that the gene transfer approach can serve as a methodological tool to quickly and cost-effectively identify these neurons.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21NS079940-02
Application #
8488510
Study Section
Neuroendocrinology, Neuroimmunology, Rhythms and Sleep Study Section (NNRS)
Program Officer
He, Janet
Project Start
2012-06-15
Project End
2014-05-31
Budget Start
2013-06-01
Budget End
2014-05-31
Support Year
2
Fiscal Year
2013
Total Cost
$213,506
Indirect Cost
$68,756
Name
Medical University of South Carolina
Department
Psychiatry
Type
Schools of Medicine
DUNS #
183710748
City
Charleston
State
SC
Country
United States
Zip Code
29425
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Liu, Meng; Blanco-Centurion, Carlos; Konadhode, Roda Rani et al. (2016) Orexin gene transfer into the amygdala suppresses both spontaneous and emotion-induced cataplexy in orexin-knockout mice. Eur J Neurosci 43:681-8
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Blanco-Centurion, Carlos; Liu, Meng; Konadhode, Roda P et al. (2016) Optogenetic activation of melanin-concentrating hormone neurons increases non-rapid eye movement and rapid eye movement sleep during the night in rats. Eur J Neurosci 44:2846-2857
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