vanilloid receptor signaling and capsaicin inhibitory effects
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Vanilloid receptor signaling and capsaicin inhibitory effects

Contained in the human hair follicle is something known as the Vanillioid receptor-1 or "TRPV". Scientists have recently discovered that this Vanillioid receptor-1 is very significant for hair growth. The receptor can be signaled by certain processes so as to inspire new hair growth where there was previously very little. Alternatively, the signaling of this receptor can be inhibited by other agents, one of which is known as Capsaicin. Capsaicin is a chemical that is found in hot peppers can be used to de-activate the Vanilloid receptor and thereby regulate the growth of hair. Other proteins and genetic building blocks such as TGF-b2 have also been tested to see the affects on the Vanillioid receptor. So far, however, Capsaicin has proven to have the most potent effect.

The Vanillioid receptor-1 or "TRPV" as it is sometimes referred, can be activated in certain cells of the skin such as mast cells, glial cells, bronchial epithelial cells, uroepithelial cells and keratinocytes. When the TRPV expressing cells are activated in hair follicles, there is often a change in the cell proliferation of hair follicles. Scientists have experimented with these findings in order to discover not just the basic proliferation changes but the effects on hair elongation, pigmentation and growth cycle patterns of hair follicles.

A study was done in which hair follicles were first taken from a number of female patients who were undergoing facelift surgery. The hair follicles were individually measured at the start of the experiment so as to test for any changes that would come about later in the experiment. Some hair follicles were also examined to determine the presenceo f distribution of different proteins and cell receptors. The follicles were prepared under 24 different plates, treated with the various agents and often colored with certain pigments to determine various results.

Early in the experiment, scientists measured the protein and calcium changes in the hair follicles after they were combined with certain agents. Some proteins and calcium changes were discovered and documented in relation to their affect on hair growth. Scientists also measured other changes such as the proliferation change which came about in the presence of TRPV. This proliferation change was measured through a process known as flow cytometry.

On the human scalp, it was discovered that specific localized expression of TRPV existed in two important areas of the hair follicle. The most prominent area was found to be the outer root sheath or ORS and the less prominent area was the hair matrix. With these initial findings, scientists were able to focus their observations on other agents and the more specific effects that they had on TRPV and hair growth.

It was later discovered that the signaling of TRPV by certain proteins and chemical agents had a profound effect on the production of keratinocyte proliferation. With an increase in keratinocyte proliferation, there was a significant increase in hair growth and a change in growth characteristics. Once these initial discoveries were made, an alternate approach was ready for testing.

Capsaicin was added to the areas where TRPV had been originally expressed but, instead of getting positive changes as had first been the case, there was a reverse in the process of TRPV signaling. The Capsaicin inhibited the elongation of the hair follicles by slowing down the activity of the TRPV and keratinocyte proliferation in the follicles. The pigmentation was also depleted in the hair follicles when Capsaicin was applied.

Capsaicin was observed in relation to many features but only one feature remained unchanged by its effects. The in situ differentiation of the hair follicles was not affected by the Capsaicin. This differentiation was the only quality of the hair follicles that remained unaffected. Although scientists had discovered that Capsaicin could produce inhibitory effects on the TRPV in terms of the proliferation of hair follicles, the elongation and the pigmentation of the hair follicles, it had not affected the differentiation characteristics at all.

TGF-b2, was also experimented with in combination with the Capsaicin to see the resultant effect on the TRPV signaling. Scientists wanted to know if TGF-b2 would also have an inhibitory affect on hair growth and help along the work of the Capsaicin. In fact, the TGF-b2 showed a tendency to partially negate the effects of the Capsaicin. The hair growth was no longer inhibited as it had been by using the Capsaicin agent alone. Other experiments like this one have become an ongoing focus for scientists.

Other proteins and organic agents have been tested to determine the effects that different genes may have in TRPV signaling. Some of these agents include activin BA and matrix GLA-protein precursor. These studies into the effects of genetic manipulation in hair follicles promise new discoveries for patients who wish to remove unwanted hair and to inspire new growth in areas where there has been unwanted hair loss.

Vanilloid receptor signaling and capsaicin inhibitory effects references

  • Bodo E, Biro T, Telek A, Czifra G, Griger Z, Toth BI, Mescalchin A, Ito T, Bettermann A, Kovacs L, Paus R. A hot new twist to hair biology: involvement of vanilloid receptor-1 (VR1/TRPV1) signaling in human hair growth control. Am J Pathol. 2005 Apr;166(4):985-98. PMID: 15793280
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