Supstand P (SP) is a neuropeptide associated with inflammatory processes. It seems to play an important role in hair growth and was found to increase hair growth and transition hairs from resting to actively growing.
It seems to be linked to inflammatory/immune responses involved in hair loss.
DHT (the hormone that leads male pattern hair loss in some men) seems to lead to an increase in inflammatory cytokines, which ultimate can be very destructive to hair follicles — particularly if it leads to perifollicular fibrosis, which can be irreversibly destructive.
I hypothesise that there is a link that has yet to be fully explored between DHT, inflammatory cytokines and SP. I will be investigating this connection further over the coming weeks as part of a study I am conducting on the specific reasons that DHT sets off the destructive inflammatory process in the hair follicles leading to perifollicular fibrosis.
I’ll be releasing some of my new findings over the next few days. In the meantime, here are some extracts on past studies explaining the link between SP and hair growth:
Results: Both capsaicin and SP induced significant hair growth (anagen) in the back skin of telogen mice. This was associated with substantial mast cell degranulation. The endogenous SP skin concentration showed significant, hair cycle-dependent fluctuations during the induced murine hair cycle, which were largely independent of the activity of neutral endopeptidase.
In the previous study conducted by us, substance P (SP) did not have a statistically significant effect on the rate of linear hair growth in cultured hair follicles. However, it prolonged the anagen stage of the hair cycle. From this result, we can suppose that the expression of a certain growth factor or apoptosis-ralated molecules in hair follicle is changed when SP is pretreated.
In this study, after pretreatment of SP used by cultured hair follicle and dermal papilla cells, we examined the change of expression of hair growth factors (FGF-7, IGF-1, VEGF, TGF-β, IL-1β) and apoptosis-related molecules (p53, caspase-3). From these results, in the hair follicle, the expression of FGF-7, a hair growth factor, is increased above control, while the expression of caspase-3, an apoptosis-related molecule, is decreased relative to control. In dermal papilla cells, it is not found that the change of expression of hair growth factors and apoptosis-related molecules.
Here’s an extract from another study on the role of substance P (SP) in hair growth:
Cutaneous SP expression and the number of SP-immunoreactive nerve fibers are significantly increased during the early active growth phase (anagen II–III) of the murine hair cycle (Paus et al., 1994; Peters et al., 2001). SP was shown to act as a growth factor for cultured keratinocytes (Tanaka et al., 1988), and treatment of mice with SP induces anagen in resting HFs and promotes anagen progression in denervated, organ cultured murine skin (Paus et al., 1994; Peters et al., 2001).
What does this mean for hair loss sufferers?
I suspect that, like VEGF, increasing SP in the scalp, will prolong hair growth, enabling hair to grow longer and thicker and reducing shedding. But it also seems that SP has the function of taking hairs out of resting and into growth. It seems to me that SP might be even more important than VEGF, which is currently the main growth factor of focus in the world’s most common hair loss treatment — Minoxidil.