Chap 49-2 Melatonin and sleep/wake cycles B 周予婷 B 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 tryptophan melatonin serotonin neurotransmitter of the sleeping-producing centers high 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 – ( emr/EMR-Reduces-Melatonin.htm)