5-HTP increases leptin, carbidopa decreases

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Thursday, April 01, 2004 5:08 am Email this article
5-Hydroxytryptophan (5-HTP) dose-dependently increases leptin in mice, however, pretreatment with carbidopa suppresses this increase according to a study from Kobe Pharmaceutical University in Kobe, Japan.

Carbidopa is a decarboxylase inhibitor used to increase the amount of 5-HTP reaching the brain by preventing the conversion of 5-HTP to serotonin before reaching the brain.

5-HTP is the immediate precursor to serotonin.

The authors noted that the appetite-reducing effects of leptin are associated with a reduction of the naturally-occurring appetite-stimulants neuropeptide-Y, melanin-concentrating hormone and galanin.

They also noted that leptin release is stimulated by glucocorticoids and insulin but inhibited by catecholamines.

The authors concluded that “Our results show that the [appetite-reducing] effects of 5-HTP may be related to the elevation of circulating leptin levels.”

Hopefully someone will follow-up with a study to determine which is better for appetite suppression—5-HTP alone or 5-HTP-plus-carbidopa—as well as verifying the results in humans.

Contact information for the lead author is as follows:

Jun Yamada
+81-78-441-7573 phone
+81-78-441-7574 fax
.(JavaScript must be enabled to view this email address)

REFERENCE

Yamada J; Sugimoto Y; Ujikawa M. The serotonin precursor 5-hydroxytryptophan elevates serum leptin levels in mice. Eur J Pharmacol, 1999 Oct 21;383(1):49-51.

Articles on the same subject can be found here:

• 5-HTP (5-Hydroxytryptophan)

• Leptin

• Tryptophan