More Related Content



  1. M. Sc. Razhan S. Othman HOD medical lab technique
  2.  Define of melatonin.  Biosynthesis and metabolism of melatonin.  melatonin secretion and it levels and how it work?  Physiological role of melatonin .  Adverse effect .
  3. What is melatonin?  Hormone that is naturally produced by the pineal gland.  Arone lerner in 1958 was discovered this hormone.  Pinal gland ,in humans resembling the shape of a pine cone ,its location is either central in the brain .  The pineal weight in humans brain is 100- 150mg ,whereas in rat 1-1.5mg.
  4. Biosynthesis:  Generated from amino acid tryptophan and serotonin  Is made predominantly at night in the pineal gland.  Tryptophan hydroxylase activity where presence in the mitochondrial increase during darkness about 2 fold. melatonin
  5. Metabolism :  There are several metabolic pathways: 1-brain :one is the formation of N-acetyle- 5methoxykynurenamin after dioxygenase of melatonin compound cleavage pyrol cycle. 2- liver : by dimethylation to N-acetyl serotonin. **Metabolism pathway of exogenously administrated melatonin in humans are reported half-lives 3 and 45 minute.
  6. Melatonin secretion  Melatonin secretion starts at 3-4 months of age when nighttime sleeping consolidates.  Peak levels at 1-3 years of age.  Slightly lower levels through early adulthood.  Marked decline in levels afterwards.  Peak levels for 70 year olds is ¼ of levels for young adults.
  7. How melatonin works??  Melatonin levels cycle  Low levels during daylight, rise during nighttime  Peak levels between 11PM and 3AM  Levels continue to cycle in constant darkness  Can slowly adjust to environmental changes
  8. Physiological role of melatonin 1-Radical scavenger 2-Sleep 3-Cancer 4-Immune system 5-Other
  9. Radical scavenger  Free radical =bearing one unpaired electron.  Hydroxyl free radical (OH.), Is one of dangerous and reactive radical.  5% of all O2 taken in will be converted to superoxide anion O2.-  Oxidative stress: continuous forming radical .e  Oxidative stress can be increase by toxin, excessive exercise, radiation, infection, ischemia etc.  Vitamin C and E also can act as radical scavenger.
  10. Sleep  Melatonin is “opening the sleep gate “  Suprachiasmatic Nucleus (SCN) is the site of internal biological clock.  Elevated melatonin level occur at night coincident with sleep humans.  Melatonin is not to be a direct soporific.
  11. Cancer  Melatonin is inhibitory action of tumor growth.  The apparent melatonin induced suppression of prolactin , when prolactin is a hormone that can promote mammary cancer.  Several studies reported that ,during the initial state of tumor development ,melatonin is increased an early stage of cancer with malignant cells that do not growth.  The relationship between pineal gland and cancer is a dynamic.  Doses of 10-20mg of melatonin to advanced cancer patients in the afternoon.
  12. Immune system  Melatonin hormone directly effect of the immune system when suppression of melatonin production by propranolol or the inhibitor of serotonin biosynthesis Para- chlorophenylalanin resulted in reduced immune responses toward T-dependent antigens.
  13. OTHER FUNCTION  Melatonin can act as an antioxidant .  Exogenous melatonin decrease leptin production .  Reported that melatonin intake reduced blood pressure during sleep ,without effect of the heart rate.  An important property of melatonin is its ability to influence circadian rythmicity .  One of the claimed action of melatonin that anti- aging effect.  Melatonin supplements by humans with jet lag, delay sleep phase(alzheimers disease), epilepsy.
  14. Adverse effects  Excess melatonin can lead to daytime sleepiness, impaired mental and physical performance, hypothermia, and high levels of prolactin  Menstrual irregularities, impotence decreased libido.