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The hypocretin/orexin system in health and disease
1Center for Narcolepsy, Stanford University, School of Medicine, Psychiatry and Behavioral Sciences, Palo Alto, California 94304, USA.
Abstract:
Using positional cloning in a canine model of narcolepsy and mouse gene knockouts, genes involved in the pathogenesis of narcolepsy in animals have been identified. Hypocretin/orexin ligand and hypocretin/orexin receptor genes are key to the pathogenesis of narcolepsy in animals. Mutations in hypocretin-related genes are rare in humans, but hypocretin-ligand deficiency is found in many cases. Hypocretins/orexins are novel hypothalamic neuropeptides involved in various hypothalamic mechanisms, such as energy homeostasis and neuroendocrine function. Hypocretin-deficient human narcolepsy appears to be a more complex condition than a simple sleep disorder, and it may serve as an important disease model for studying hypothalamic function in health and disease.
Insights
Researchers identified hypocretin/orexin genes as key to narcolepsy in animals. Hypocretin deficiency, not gene mutations, is linked to human narcolepsy, suggesting a complex hypothalamic disorder.
Area of Science:
- Neuroscience
- Genetics
- Sleep Medicine
Background:
- Narcolepsy pathogenesis in animals has been elucidated through genetic studies.
- Hypocretin/orexin ligand and receptor genes are critical in animal models of narcolepsy.
Purpose of the Study:
- To identify genes involved in narcolepsy pathogenesis.
- To investigate the role of hypocretins/orexins in narcolepsy.
- To understand the complexity of hypocretin-deficient human narcolepsy.
Main Methods:
- Positional cloning in a canine model of narcolepsy.
- Gene knockouts in mice.
Main Results:
- Hypocretin/orexin ligand and receptor genes identified as key to narcolepsy in animals.
- Mutations in hypocretin-related genes are rare in humans.
- Hypocretin-ligand deficiency is prevalent in human narcolepsy cases.
Conclusions:
- Hypocretin-ligand deficiency is a primary cause of human narcolepsy.
- Human narcolepsy is a complex hypothalamic disorder, not just a sleep disorder.
- This condition serves as a model for studying hypothalamic function.