GSE
MELATONIN - The Darkness Hormone - Body's Natural Sleep Aid
MELATONIN - "The darkness hormone"
/ natural sleep aidWhat is MELATONIN
?
MELATONIN
is a hormone and a neurotransmitter produced
/secreted by the pineal gland
(pea-sized gland located in the center of the brain)
during darkness
under control of the body's
master "Biological Clock" (Body's central circadian pacemaker / Suprachiasmatic nucleus (SCN) in the
hypothalamus).
MELATONIN is well-known for promoting
sleep, but has many other benefits These include preventing / treating::
Cardiovascular disease
Cancer
Alzheimer's disease
Migraines
ADHD
Mood disorders (e.g. depression)
Gallstones
ALS
Obesity
GERD / GI tract ulcers
Study-supported health benefits
MELATONIN performs
several functions in the body:
Stimulates and modulates immune system
Powerful antioxidant
Enhances bone mass
Anticancer agent
Protects GI tract and pancreas
MELATONIN Functions
MELATONIN
is both lipid and water soluble. Facilitates
passage both in the blood and across cell membranes.After release into circulation,
it gains access to various fluids, tissues and cellular compartments (E.g. saliva,
urine, cerebrospinal fluid, pre-ovulatory follicle, semen, amniotic fluid, milk).
MELATONIN is rapidly metabolized (chiefly
in the liver) and is excreted in the urine.
MELATONIN productionThe master biological clock
(SCN) generates a circadian
(24 hour cycle) and annual rhythm of
MELATONIN production, which is
inhibited by light .
During darkness the
SCN stimulates the release of NOREPINEPHRINE (NE) (from superior cervical
ganglion), which activates
MELATONIN
secretion.
MELATONIN synchronizes
body tissues to the daily cycle of light dark
MELATONIN is not stored in the pineal gland.
Activated by
darkness
MELATONIN leaves the pineal cells through
simple diffusion into the bloodstream. We cannot rely on yesterday's
MELATONIN for today and so need a liberal
supply each evening
MELATONIN production peaks in the middle of the night.
Then gradually falls during the second half of the night
MELATONIN
production declines with age
Peaks at puberty
Production levels rapidly decline until middle-age, continuing
into later years
MELATONIN
can also be produced directly by the retina, lens, GI tract, skin and other
tissues/cells (E.g. bone marrow
cells, lymphocytes and epithelial cells). These are NOT regulated by light/dark.
MELATONIN Production
MELATONIN
has 3 cell-signaling actions:
Endocrine - secreted by pineal gland into bloodstream .
Also GI enterochromaffin cells release MELATONIN, some of which fnds its way
to the bloodstream,Autocrine - MELATONIN binds to receptors of same cell which secreted
itParacrine - secreted by tissues/cells to act on local target cells
MELATONIN is involved in the regulation of seasonal and circadian
fluctuations of other hormones/neurotransmitters:
MELATONIN promotes or inhibits synthesis/secretion of other hormones/neurotransmitters
Promotes
PROLACTIN - Positive relationship between the nocturnal concentrations of MELATONIN and PROLACTIN , and a stimulation of PROLACTIN after MELATONIN administration in young men.
PubMed
Inhibits
LEPTIN is downregulated by MELATONIN
PubMed , except in the presence of INSULIN, which increases
LEPTIN
PubMed ;
LEPTIN is secreted by adipocytes and is called the appetite suppressant hormone, informing the brain about the body's overall
With INSULIN, MELATONIN
increases LEPTIN ▲, suppressing appetite▼during sleep, so you stay asleep instead of being hungry all night. In a feedback loop:LEPTIN tells your brain you are not hungry, such that you stay asleep and make more MELATONIN
Estrogen production
DOPAMINE ;
GABA ;
GnRH -Down-regulates gonadotropin-releasing hormone (GnRH) mRNA production in hypothalamic GnHR-secreting neurons - a link to sexual development and puberty.
Comments
Reciprocal with CORTISOL - which rises in the morning to its highest level sas MELATONIN declines
Other hormones involved
Gonadal steroids, pituitary gonadotrophins, thyroxine, and the adrenal hormones
Spiegel K, Leproult R, Van Cauter E. [Impact of sleep
debt on physiological rhythms]
[Article in French]. Rev Neurol (Paris). 2003 Nov;159(11
Suppl):6S11-20.
