Orexin (hypocretin) gene transfer diminishes narcoleptic sleep behavior in mice

Chapter 13 discusses sleep and dreams, which got me interested in sleep disorders.  This article looks at narcolepsy and possible treatments for the disorder in mice.  Narcolepsy is described as a disabling neurological disorder in which one experiences excessive daytime sleepiness, sleep attacks, rapid onset REM, etc.  It is believed to be the result of a loss of neurons containing the neuropeptide orexin.  Two other neurons, dynorphin and pentraxin, have also been found to be absent in cases of narcolepsy.  Orexin is excitatory, promotes wakefulness, and is located in the lateral hypothalamus.  From here, these neurons project to the brain and spinal cord.  Researchers have found that a condition similar to narcolepsy occurs in mice, rats, and canines when the orexin gene is deleted or destroyed in these animals.
In this study, they wanted to test if they could successfully transfer the gene for production of orexin to the lateral hypothalamus in mice.  They hypothesized that this would decrease the symptoms of the narcoleptic disorder.  They recorded the sleep of the mice with the gene deletion before the injection and after the injection of the gene.  The mice were implanted with electrodes to record EEG and EMG to monitor their sleep.  Researchers found that after the injection, the peptide product was found in the cerebrospinal fluid and somata and processes of lateral hypothalamus neurons.  This indicated that the gene transfer had been a success.  In addition, after comparing the sleep of the mice before and after the injection, researchers concluded that sleep quality had very much improved.  The narcoleptic symptoms decreased in the mice by 60%.  Cataplexy and excessive REM sleep had both decreased in occurrence.  It is possible that the results of this study could lead to more research in gene transfer and improvement in sleep disorders such as narcolepsy in humans.

Meng, L., Thankachan, S., Kaur, S., Begum, S., Blanco-Centurion, C., Sakurai, T., & ... Shiromani, P. J. (2008). Orexin (hypocretin) gene transfer diminishes narcoleptic sleep behavior in mice. European Journal of Neuroscience, 28(7), 1382-1393. Retrieved from EBSCOhost. doi:10.1111/j.1460-9568.2008.06446.x