On 16 Oct 2003 16:13:06 GMT, "Dag Stenberg"
<dag.stenberg at nospam.helsinki.fi.invalid> wrote:
>James Michael Howard <jmhoward at arkansas.net> wrote:
>> Mr. Stenberg, thank you for your response. What you presented makes good sense.
>> However, I wish to push the explanation back just a step. Testosterone reduces
>> melatonin, which produces sleep. Melatonin suppresses leptin. Therefore,
>> testosterone reduces leptin itself and reduces melatonin which reduces leptin.
>>1. Where do you find any evidence that testosterone reduces melatonin?
>Melatonin does reduce testosterone in rats, but the other way around??
>>2. Melatonin is a weak and unreliable hypnotic, and its role in
>physiological sleep regulation is in doubt.
>>3. I agree that melatonin reduces leptin in some mammals (like
>middle-aged rats), but increases leptin in minks.
>In postmenopausal women, melatonin does not affect leptin levels. I am
>not aware of other studies of the effect of melatonin on leptin in humans.
Testosterone reduces melatonin. In treatment of a 14 year-old boy, Luboshitzky,
et al., conclude that "These results indicate that circulating testosterone
down-regulates pineal melatonin." (J Pediatr Endocrinol Metab 1995; 8: 295-9).
In another study, Luboshitzky, et al., testosterone treatment reduced melatonin
secretion in sex male patients with increased nocturnal melatonin (J Pineal Res
1997; 22: 95-101).
There is a controversy re melatonin and sleep. I happen to be on the side that
melatonin is involved in sleep: www.anthropogeny.com/physiology.html .
Well, you are correct re melatonin and leptin in rats. We will just have to
wait and see.