Low hypocretin levels depend on narcolepsy or hypersomnia?

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We have conducted two parts of research (1)hypocretin levels with hypersomnia patients and (2)the autoimmune hypothesis of narcolepsy.(1)Hypocretin levels with hypersomnia patients.It is not clear whether the low hypocretin levels depend on narcolepsy or hypersomnia. In order to clear this question, we measured the samples of patients with narcolepsy-cataplexy (N/C), narcolepsy without cataplexy (N/noC), essential hypersomnia (EHS), idiopathic hypersomnia (IHS), sleep apnea syndrome (SAS), Niemann-pick type C (NPC) and neurological disorders.In 25 patients with N/C, 20 patients with N/C and DR2+ had low hypocretin levels. While 5 patients with N/C and DR2-had normal levels. In 10 patients with N/noC, 4 patients with N/noC and DR2+ had low levels and remaining 6 patients had normal levels. The patients with EHS (n=6), IHS (n=8) and SAS (n=16) had normal levels. In 2 patients with NPC, one patient with cataplexy had intermediate level and the other without cataplexy had normal level. In … More 200 patients with neurological disorders, only several patients with Guillain-Barre syndrome (GBS) had low levels.Low hypocretin levels only depends on the disease of N/C and DR2+, not the condition of hypersomnia On the other hand, we found some patients with hypersomnia and hypothalamic lesion due to tumor or demyelinating disorders.(2)The autoimmune hypothesis of narcolepsy.Human narcolepsy has been shown to be closely associated with a specific HLA. Because most diseases associated with a specific HLA are autoimmune in nature, the finding suggests that autoimmunity is involved in the pathophysiology of narcolepsy. However, at present, all attempts to demonstrate that human narcolepsy is an autoimmune disease have failed. Thus, it is important to know whether hypocretin changes are found in any definite neuroimmunological diseases (NID).Samples of CSF were obtained from 52 Japanese patients with NID (GBS, n=28, Fisher syndrome n=12, CIDP, n=12) and 48 patients with non-NID.Levels of CSF hypocretin-1 did not differ between the non-NID patients and the healthy controls previously reported (280pg/ml). In the 28 patients with GBS, 7 patients had lower levels and 5 patients had intermediate levels. Five out of 12 patients with Fisher syndrome and 1 out of 12 patients with CIDP had intermediate levels. Seven GBS patients with low hypocretin-1 levels were clinically severe cases (tetraplegia, dyspnea). Antibodies to gangliosides can be seen in the plasma and CSF of approximately 25% of patients. Sixteen of 21 GBS subjects tested had anti-ganglioside antibodies. There was also no correlation between hypocretin-1 levels and anti-ganglioside antibodies. The mechanism for low hypocretin-1 in GBS is unclear but may involve immune-mediated hypothalamic dysfunction. A subset of GBS and Fisher syndrome may be a good model for studying possible autoimmune damage to the hypocretin system in narcolepsy. Less