Hair Loss News

[Study Summary - In this study researchers wanted to test whether adenosine directly stimulates hair growth.  It had been previously reported that the adenosine pathway may be implicated in the process whereby minoxidil stimulates hair to grow.

Adenosine is a high-energy molecule that stores the energy our cells need. It’s present in the cytoplasm and nucleoplasm of every cell in the body.  All the physiological mechanisms that require energy in order to function obtain it directly from the stored ATP (adenosine triphosphate.)

To test this theory the researchers took dermal papilla cells, which are the cells responsible for hair growth in the follicle, and analyzed the cell’s DNA.  They found that
adenosine stimulation increased the gene expression of fibroblast growth factor-7.

They then took fibroblast growth factor-7 (FGF-7) and found that at a concentration of 10 ng/ml, the FGF-7 significantly stimulated the length of the hair fibers in the hair follicle cultures in their lab.

The researchers then concluded that adenosine treatment of dermal papilla cells increases FGF-7 expression which results in increased hair growth.]

Adenosine Stimulates Fibroblast Growth Factor-7 Gene Expression Via Adenosine A2b Receptor Signaling in Dermal Papilla Cells.

Journal of Investigative Dermatology. 2007 Feb 15
Iino M, Ehama R, Nakazawa Y, Iwabuchi T, Ogo M, Tajima M, Arase S.
1Shiseido Research Center, Yokohama, Japan.

It has been previously reported that an adenosine receptor-mediated signal-transduction pathway in the dermal papilla cells (DPCs) of hair contributes to minoxidil-induced hair growth. In this study, we investigated this hypothesis further and have elucidated some underlying mechanisms. We performed DNA microarray analyses of DPCs and found that adenosine stimulation increases fibroblast growth factor-7 (FGF-7) gene expression levels by greater than 2-fold. Elevations of the extracellular FGF-7 protein levels were also observed. These upregulations of FGF-7 both at mRNA and protein levels were inhibited by A2b adenosine receptor-specific antagonist, alloxazine, but not by antagonists for other subtypes. In addition, the intracellular cAMP levels were raised by adenosine in a dose-dependent manner. Moreover, an increase of intracellular cAMP augmented the FGF-7 upregulation. Taken together, these results show that adenosine treatment of DPCs upregulates FGF-7 expression via the A2b adenosine receptor and that cAMP acts as one of the second messengers in this pathway. Furthermore, treatment with FGF-7 at concentrations of 10 ng/ml or greater significantly stimulated hair fiber elongation in human scalp hair follicle organ cultures. These data imply that adenosine might stimulate hair growth through FGF-7 upregulation in DPCs.

Source: PMID 17301835