Melatonin and HPTA suppression

**powerman2000** · 05-10-2006, 10:43 AM

Well, I've been doing a lot of research on melatonin since I use it so much to help me as a day sleeper and I am definitely going to quit taking it after what I've learned.

Several studies published on pubmed.com state that melatonin does inhibit testosterone secretion.

Here is a direct quote from one such article.

"CONCLUSIONS: Our results suggest that melatonin inhibits testosterone secretion by acting at hypothalamo-pituitary axis. There is a functional relationship and feedback regulation between the pineal gland and the testes."

Now I know why my normally very strong libido has recently taken a turn downward.

And I just bought another bottle. Anyone want it?

**powerman2000** · 05-10-2006, 10:45 AM

VA Puget Sound Health Care System, and Department of Medicine, University of Washington, Seattle 98195, USA. drasmuss@u.washington.edu

"Human and rat pineal melatonin secretion decline with aging, whereas visceral fat and plasma insulin levels increase. Melatonin modulates fat metabolism in some mammalian species, so these aging-associated melatonin, fat and insulin changes could be functionally related. Accordingly, we investigated the effects of daily melatonin supplementation to male Sprague-Dawley rats, starting at middle age (10 months) and continuing into old age (22 months). Melatonin was added to the drinking water (92% of which was consumed at night) at a dosage (4 microg/ml) previously reported to attenuate the aging-associated decrease in survival rate in male rats, as well as at a 10-fold lower dosage. The higher dosage produced nocturnal plasma melatonin levels in middle-aged rats which were 15-fold higher than in young (4 months) rats; nocturnal plasma melatonin levels in middle-aged rats receiving the lower dosage were not significantly different from young or middle-aged controls. Relative (% of body wt) retroperitoneal and epididymal fat, as well as plasma insulin and leptin levels, were all significantly increased at middle age when compared to young rats. All were restored within 10 weeks to youthful (4 month) levels in response to both dosages of melatonin. Continued treatment until old age maintained suppression of visceral (retroperitoneal + epididymal) fat levels. Plasma corticosterone and total thyroxine (T4) levels were not significantly altered by aging or melatonin treatment. Plasma testosterone, insulin-like growth factor I (IGF-I) and total triiodothyronine (T3) decreased by middle age; these aging-associated decreases were not significantly altered by melatonin treatment. Thus, visceral fat, insulin and leptin responses to melatonin administration may be independent of marked changes in gonadal, thyroid, adrenal or somatotropin regulation. Since increased visceral fat is associated with increased insulin resistance, diabetes, and cardiovascular disease, these results suggest that appropriate melatonin supplementation may potentially provide prophylaxis or therapy for some prominent pathologies associated with aging."
http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_docsum

Now what am I supposed to think? I guess I'll still drop the melatonin and see if my libido returns to where it was. That will decide it for me.

**powerman2000** · 05-10-2006, 11:07 AM

Dipartimento di Biomedicina, Universita degli Studi di Torino, Ospedale S. Luigi, Italy.

"Six healthy adult male volunteers underwent serial blood drawings at 4-hour intervals over 24 hours for the definition of melatonin (MT), prolactin (PRL), cortisol, and testosterone circadian patterns. Serum levels of triiodotironine (T3) and thyroxine (T4) were determined at 0800. Systolic and diastolic blood pressure and heart rate were automatically recorded every 30 minutes for 24 hours. The responses of luteinizing hormone (LH), follicle stimulating hormone (FSH), PRL, thyroid stimulating hormone (TSH), cortisol, and aldosterone to a stimulation test with gonadotrophin-releasing hormone (Gn-RH), thyrotrophin-releasing hormone (TRH), adrenocorticotrophin (ACTH), and testosterone to human chorionic gonadotrophin (HCG) were also evaluated. The same protocol was repeated after a two-month course of treatment with MT, 2 mg per os daily at 1800. After treatment, we recorded a marked elevation of mean serum MT levels with a significant phase-advance of its circadian rhythm. The 24-hour patterns of cortisol and testosterone displayed an anticipation of the morning acrophase of about 1.5 hour (not significant) for cortisol and three hours (P less than 0.05) for testosterone. PRL pattern was unchanged as well as serum levels of thyroid hormones. The circadian organization of the cardiovascular variables did not show any changes after MT supplementation; the pituitary, adrenal, and testicular responses to specific stimuli were comparable before and after treatment. These results are compatible with the view that the MT signal may provide temporal cues to the neuroendocrine network for the organization of testicular circadian periodicity."

http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_docsum

Jakl · 05-11-2006, 08:25 PM

Thanx for the info... I use it from time to time. I am rethinking it now.

**powerman2000** · 05-23-2006, 06:44 AM

Quote:

Originally Posted by Jakl

Thanx for the info... I use it from time to time. I am rethinking it now.

I think only long term use would have such negative affects.

**builtbeast** · 05-23-2006, 10:35 AM

Well long term for me is only a couple of days before I have bad side effects.

It seems I need to up the dose after a few days for it to have the same efficacy. And after about a week of using it I have bad headaches when I'm up. Since discontinuing it they've gone away.

05-10-2006, 10:43 AM	#1
powerman2000 The Old Moderator Join Date: Apr 2005 Location: Colorado Posts: 4,127 Recipes: 0 Rep Power: 200	Melatonin and HPTA suppression Well, I've been doing a lot of research on melatonin since I use it so much to help me as a day sleeper and I am definitely going to quit taking it after what I've learned. Several studies published on pubmed.com state that melatonin does inhibit testosterone secretion. Here is a direct quote from one such article. "CONCLUSIONS: Our results suggest that melatonin inhibits testosterone secretion by acting at hypothalamo-pituitary axis. There is a functional relationship and feedback regulation between the pineal gland and the testes." Now I know why my normally very strong libido has recently taken a turn downward. And I just bought another bottle. Anyone want it? __________________ Don't forget to periodize Best BP 507 lbs competitive Best Squat 705 lbs competitive Best DL 650 lbs competitive Guns don't kill people, men who come home early do. My workout log http://www.ironmass.com/forums/showthread.php?t=6247

05-10-2006, 10:45 AM	#2
powerman2000 The Old Moderator Join Date: Apr 2005 Location: Colorado Posts: 4,127 Recipes: 0 Rep Power: 200	Also found on pubmed.com VA Puget Sound Health Care System, and Department of Medicine, University of Washington, Seattle 98195, USA. drasmuss@u.washington.edu "Human and rat pineal melatonin secretion decline with aging, whereas visceral fat and plasma insulin levels increase. Melatonin modulates fat metabolism in some mammalian species, so these aging-associated melatonin, fat and insulin changes could be functionally related. Accordingly, we investigated the effects of daily melatonin supplementation to male Sprague-Dawley rats, starting at middle age (10 months) and continuing into old age (22 months). Melatonin was added to the drinking water (92% of which was consumed at night) at a dosage (4 microg/ml) previously reported to attenuate the aging-associated decrease in survival rate in male rats, as well as at a 10-fold lower dosage. The higher dosage produced nocturnal plasma melatonin levels in middle-aged rats which were 15-fold higher than in young (4 months) rats; nocturnal plasma melatonin levels in middle-aged rats receiving the lower dosage were not significantly different from young or middle-aged controls. Relative (% of body wt) retroperitoneal and epididymal fat, as well as plasma insulin and leptin levels, were all significantly increased at middle age when compared to young rats. All were restored within 10 weeks to youthful (4 month) levels in response to both dosages of melatonin. Continued treatment until old age maintained suppression of visceral (retroperitoneal + epididymal) fat levels. Plasma corticosterone and total thyroxine (T4) levels were not significantly altered by aging or melatonin treatment. Plasma testosterone, insulin-like growth factor I (IGF-I) and total triiodothyronine (T3) decreased by middle age; these aging-associated decreases were not significantly altered by melatonin treatment. Thus, visceral fat, insulin and leptin responses to melatonin administration may be independent of marked changes in gonadal, thyroid, adrenal or somatotropin regulation. Since increased visceral fat is associated with increased insulin resistance, diabetes, and cardiovascular disease, these results suggest that appropriate melatonin supplementation may potentially provide prophylaxis or therapy for some prominent pathologies associated with aging." http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_docsum Now what am I supposed to think? I guess I'll still drop the melatonin and see if my libido returns to where it was. That will decide it for me. __________________ Don't forget to periodize Best BP 507 lbs competitive Best Squat 705 lbs competitive Best DL 650 lbs competitive Guns don't kill people, men who come home early do. My workout log http://www.ironmass.com/forums/showthread.php?t=6247

05-10-2006, 11:07 AM	#3
powerman2000 The Old Moderator Join Date: Apr 2005 Location: Colorado Posts: 4,127 Recipes: 0 Rep Power: 200	Here is another good one Dipartimento di Biomedicina, Universita degli Studi di Torino, Ospedale S. Luigi, Italy. "Six healthy adult male volunteers underwent serial blood drawings at 4-hour intervals over 24 hours for the definition of melatonin (MT), prolactin (PRL), cortisol, and testosterone circadian patterns. Serum levels of triiodotironine (T3) and thyroxine (T4) were determined at 0800. Systolic and diastolic blood pressure and heart rate were automatically recorded every 30 minutes for 24 hours. The responses of luteinizing hormone (LH), follicle stimulating hormone (FSH), PRL, thyroid stimulating hormone (TSH), cortisol, and aldosterone to a stimulation test with gonadotrophin-releasing hormone (Gn-RH), thyrotrophin-releasing hormone (TRH), adrenocorticotrophin (ACTH), and testosterone to human chorionic gonadotrophin (HCG) were also evaluated. The same protocol was repeated after a two-month course of treatment with MT, 2 mg per os daily at 1800. After treatment, we recorded a marked elevation of mean serum MT levels with a significant phase-advance of its circadian rhythm. The 24-hour patterns of cortisol and testosterone displayed an anticipation of the morning acrophase of about 1.5 hour (not significant) for cortisol and three hours (P less than 0.05) for testosterone. PRL pattern was unchanged as well as serum levels of thyroid hormones. The circadian organization of the cardiovascular variables did not show any changes after MT supplementation; the pituitary, adrenal, and testicular responses to specific stimuli were comparable before and after treatment. These results are compatible with the view that the MT signal may provide temporal cues to the neuroendocrine network for the organization of testicular circadian periodicity." http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_docsum __________________ Don't forget to periodize Best BP 507 lbs competitive Best Squat 705 lbs competitive Best DL 650 lbs competitive Guns don't kill people, men who come home early do. My workout log http://www.ironmass.com/forums/showthread.php?t=6247

05-23-2006, 10:35 AM	#6
builtbeast Großer Moderator Join Date: May 2005 Location: In a very red state Posts: 1,430 Recipes: 0 Rep Power: 94	Well long term for me is only a couple of days before I have bad side effects. It seems I need to up the dose after a few days for it to have the same efficacy. And after about a week of using it I have bad headaches when I'm up. Since discontinuing it they've gone away. __________________ http://www.youtube.com/watch?v=arjjb1u64Kc ********.com

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05-11-2006, 08:25 PM	#4
Jakl Pro Stature Join Date: Apr 2006 Location: Salt Lake City Posts: 160 Recipes: 0 Rep Power: 4	Thanx for the info... I use it from time to time. I am rethinking it now.