In this video, the 3D visualization of the neuropeptide orexin (hypocretin) is shown in mouse and human brain, using iDISCO volume imaging technology and light sheet microscopy.

The anatomy and function of orexin neurons and the possible mechanism of the sleep disorder narcolepsy are discussed in an interview with neurobiologist Dr. Csaba Adori, Department of Neuroscience, Karolinska Institutet. The transition between sleep and wakefulness is precisely regulated in the brain and one key element in this process is neurons in the hypothalamus. These neurons are glutamatergic and contain a neuropeptide as co-transmitter, called orexin or, in another name, hypocretin. If these cells die, the switch mechanisms between sleep and wakefulness become disabled with fragmented sleep, sudden daytime sleep attacks or dreamlike hallucinations, a disorder called narcolepsy. "Most scientists believe that these cells die because of a selective autoimmune attack on orexin neurons, but it is not known why this cell population is affected and why others are not", says Dr Adori. "These 3D pictures may help us to facilitate the visualization of the complex anatomical systems that are involved in the regulation and mechanisms of wakefulness and sleep, thus contribute to the understanding of conditions such as narcolepsy and other sleep related disorders".

Watch the Narcolepsy movie and other educational movies at the HPA YouTube channel.