George Kimeldorf (kmldorf at utdallas.edu) wrote:
: My understanding is that anti-ageing properties of melatonin have only been
: proven in nocturnal animals (such as mice and rats), which are active
: when their melatonin levels are highest. Am I correct? If so, do you
: know whether any experiments are underway to test the possible anti-aging
: effects of melatonin on any diurnal animals?
You're right. Melatonin has been given only to nocturnal rodents
as an anti-aging strategy.
Well, except for one "experiment" that I'll mention only because
it's my own. For two years, I've been giving melatonin at night to our
aging Airedale. He is now 11. We noticed a dramatic change within 3 months.
To our surprise, he came back in his "puppy" coat - the same rich colors,
soft texture, and glossy hairs. Our vet and groomer were both amazed.
(I have pictures that are really quite astounding.) In a way this is
a legitimate experiment in that we also have Max's littermate who is
not being given melatonin. SHe has the coarse, fading coat typical of a
dog her age. Also, when Max had an operation recently, his pre-op
blood test revealed that he had liver and kidney function of a much
younger dog. (The operation was for an impacted seed in his foot)
We won't know if melatonin has a true life-extending effect for
several years, for some Airedales live as long as 14 years. (Although
this is rare.) Even if he does live longer than his littermate, an
"n" of two is not very convincing.
However, more to the point, it matters not whether an animal
is nocturnal or diurnal when it comes to free-radical scavanging activity.
Except for this one interesting possibility, one that maybe one of you can
enlighten me about. Melatonin peaks in humans around 2-3 A.M., which
is also when the circadian rhythm of cell division is at low ebb.
(Cells seem to be arrested in the S phase -
is this correct?) It could be that melatonin serves to repair the DNA
molecule while cells are in this resting phase -- thus allowing the damage
to be corrected before replication. So, if this is correct -- and this
is my own, private theory -- then it would matter that peak secretion of
melatonin coincides with the slowest rate of cell division. Now, the
question of the day --, do rodents have a circadian cycle of cell division?
ANd if so, when does cell division occur at the slowest pace??
Jo
--
+-----------------------------------+-----------------------------------------+
| Jo Robinson | jor at teleport.com |
| (503)284-4676 | 2826 NE 18th Portland, OR 97212 |
+-----------------------------------+------------------------------------y-----+
