Chap 49-2
Melatonin and sleep/wake cycles
B9902021 周予婷B9902033 侯如盈
Melatonin• A hormone secreted by the pineal gland
– contains light-sensitive cells or has nervous connection from the eyes
– converts serotonin into melatonin
• The Melatonin/Serotonin cycle
tryptophanmelatonin
serotoninneurotransmitter of the sleeping-producing centersneurotransmitter of the sleeping-producing centers
high in milkhigh in milk
• a vital part of many biochemical systems – including sleep and learning
• free radical scavenging in all cells– a potent antioxidant with anti-aging and anti-cancer
properties
• helps to protect embryonic fetuses• mediates many hormone functions• assists in maintaining immune system health
and virus protection
Functions of melatonin
The regulation of the melatonin secretion
SCN (suprachiasmatic nucleus)
melatonin
project the information about illumination
ganglion cells
the pineal gland
interprets the information on the lengths of the day and night
secretes
feedback(unknown): decrease the activity of SCN
Fig. The biochemical mediation system for serotonin transformation to melatonin in the pinealocytes showing the signal transduction pathways from the retina to the cell and the cell receptor, through cyclic AMP and NAT to the transformation process, Reiter (1994).
PVN:室旁核paraventricular nucleus
SCG:上頸神經節superior cervical ganglia
NE:正腎上腺素Norepinephrine
NAT: N-乙醯轉移酶N-acetyltransferase
N- Acetylserotonin O-methyltransferase
松果體細胞
Potential medical indications
• Cancer • Immunology• Menstrual cycle - fertility• Puberty onset • Learning and memory • Treatment of circadian rhythm disorders • Mood disorders
Insomnia• Types of insomnia– jet lag– the chronic circadian rhythm disorders
• Treatment– Melatonin and melatonin agonists relatively mild side-effect without altering the sleep pattern– Antidepressants – Antihistamines
Seasonal affective disorder (SAD)
• Mood disorder • the normal biorhythm is disturbed during a
season, especially autumn-winter• Symptoms– oversleep / over eat / difficulty concentrating/
depression
• Treatment – light therapy and supplementation of melatonin.
The 24-Hour Cycle of Melatonin Production
EEG-α wave ↑
一生中褪黑素的變化
參考資料• Campbell• Wiki
– Melatonin/Circadian rhythm/N-acetyltransferase /SAD/Insomnia
• 內分泌精義• 臨床睡眠檢查學• Dr Neil Cherry, 2000: EMR Reduces Melatonin in Animals
and People– (http://www.feb.se/EMFguru/Research/emf-emr/EMR-
Reduces-Melatonin.htm)