Message Number: SG16351 | New FHL Archives Search
From: Sukie Crandall
Date: 2006-01-08 04:03:40 UTC
Subject: [ferrethealth] melatonin

This is a human health report, but there are aspects which may relate
to studies of tumors in ferrets, especially adrenal tumors.

Some excerpts:

>It was just as Stevens had suspected. He
>had hypothesized that nighttime
>illumination, by interrupting the body's mainly
>nocturnal production of the hormone
>melatonin, might increase the risk...

>A woman's blood provides better sustenance
>for breast cancer just after she's been exposed
>to bright light than when she's been in steady darkness

>"Light at night is now clearly a risk factor for breast cancer,"
>Blask says. "Breast tumors are awake during the day, and >melatonin
puts them to sleep at night." Add artificial light to >the night
environment, and "cancer cells become >insomniacs," he says.

>"Sleep per se is not important for melatonin," says Russel J.
>Reiter, a neuroendocrinologist at the University of Texas >Health
Science Center in San Antonio. "But darkness is."

>The new study has far-reaching implications, says Reiter. >First,
it could spawn trials that test whether malignancies can >be slowed
down by altering a person's light environment or >by using melatonin
supplements. Second, he says, similar >studies could show whether
exposure ... promotes other >cancers

> tumor cells divided most rapidly when supplied by blood >taken
from women either in daylight or at night after >exposure to the
bright artificial light. Those blood samples >had low melatonin
concentrations. Spiking the samples with >synthetic melatonin removed
their capacity to promote cancer.

>Moreover, melatonin-rich blood from women who had been >in darkness
spurred cell division only when the researchers >added a chemical
that blocks melatonin's biological activity.

>Blask's team determined that melatonin blocks cancer cells'
>metabolism of linoleic acid ... 13-hydroxyoctadecadienoic >acid,
the product of linoleic acid metabolism, spurs cancer >cells to divide.

Obviously, a person doesn't want to make assumptions and
inappropriately use melatonin. There is much more to learn.
Melatonin can cause drowsiness which increases accident risks, it at
times reduces fertility, in some children with seizure disorders it
can cause worse seizures, and there may be risk factors which are not
in the references I used, BUT I think that this report helps
underline (as do multiple other studies in other species) that for
our ferrets -- who are descended from crepuscular burrow dwellers who
would have had little light exposure -- perhaps we should not negate
the possible benefits of darkness and the melatonin created during
darkness. Taken in conjunction with existing work on ferrets I think
that it underlines some points for consideration in relation to at
least some tumors.

As opposed to melatonin implants note this caution on oral melatonin:

>"I personally would be pretty cautious about taking over-the-
>counter melatonin supplements," says Scott Davis, an
>epidemiologist at the University of Washington in Seattle.
>"Melatonin supplements are not regulated" the way drugs >are, he
notes. "There may be all kinds of impurities and >contaminants."

Here is an excellent write-up on melatonin in ferrets:

>Reiter offers some other strategies for maintaining melatonin
>production. Blue or white light suppresses melatonin more
>effectively than red or yellow does

I have read in a previous study that green lights also are bad
melatonin suppressors.

Now that the "sleeping" effect of melatonin on some tumors is being
considered perhaps there is yet another benefit for ferrets which had
not been considered before.

Research in multiple species also shows that staying physically fit
has all sorts of benefits -- including reductions in rates of some
types of malignancies. Perhaps part (but only part) of that is
hinted at in the following words, which also give another reason to
not smoke around ferrets:

>She notes that light is not the only relevant factor. Age and
>obesity both reduce a person's melatonin production, and >heavy
smoking may do the same

-- Sukie (not a vet)
Ferret Health List co-moderator
FHL Archives fan
International Ferret Congress advisor

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