Define of melatonin.
Biosynthesis and metabolism of melatonin.
melatonin secretion and it levels and how it
Physiological role of melatonin .
Adverse effect .
What is melatonin?
Hormone that is naturally produced by the
Arone lerner in 1958 was discovered this
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.
Generated from amino acid tryptophan and
Is made predominantly at night in the pineal
Tryptophan hydroxylase activity where
presence in the mitochondrial
increase during darkness
about 2 fold.
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
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
How melatonin works??
Melatonin levels cycle
Low levels during daylight, rise during
Peak levels between 11PM and 3AM
Levels continue to cycle in constant darkness
Can slowly adjust to environmental changes
Free radical =bearing one unpaired electron.
Hydroxyl free radical (OH.), Is one of dangerous and reactive
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,
Vitamin C and E also can act as radical
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.
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.
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
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
An important property of melatonin is its ability
to influence circadian rythmicity .
One of the claimed action of melatonin that anti-
Melatonin supplements by humans with jet lag,
delay sleep phase(alzheimers disease), epilepsy.
Excess melatonin can lead to daytime
sleepiness, impaired mental and physical
performance, hypothermia, and high levels of
Menstrual irregularities, impotence decreased