UCLA researchers have come up with a new hypothesis about human narcolepsy. Narcolepsy is characterized by uncontrollable periods of deep sleep.
The team of researchers, who first published findings showing that people suffering from the disease have 90 percent fewer neurons containing the neuropeptide hypocretin in their brains than healthy people.
Subsequent work by this group and others also explained the sleepiness of narcolepsy by demonstrating that hypocretin is an arousing chemical that keeps us awake and elevates both mood and alertness.
Now, the same UCLA team has reported that an excess of another brain cell type- this one containing histamine - may be the cause of the loss of hypocretin cells in human narcoleptics.
UCLA professor of psychiatry Jerome Siegel and colleagues have found that people with the disorder have nearly 65 percent more brain cells containing the chemical histamine.
The research suggested that this excess of histamine cells causes the loss of hypocretin cells in human narcoleptics.
Histamine is a body chemical that works as part of the immune system to kill invading cells.
For the study, researchers examined five narcoleptic brains and seven control brains from human cadavers. Prior to death, all the narcoleptics had been diagnosed by a sleep disorder center as having narcolepsy with cataplexy.
These brains were also compared with the brains of three narcoleptic mouse models and to the brains of narcoleptic dogs.
The study was published in online edition of the journal Annals of Neurology.