Hair Restoration Blog

DHT and Hair Growth Inhibition in Mice

There is new research about hair growth and the effect of DHT which indicates more details of DHT (Dihydrotestosterone) mechanism on hair growth in mice through inhibition of insulin-like growth factor-1 in dermal papillae cells of hair.  The study results are published by Growth Hormone Research Society (Zhao et al.).
The researchers showed IGF-I [Insulin-like growth factor-I (IGF-I)] present in some hair follicle stem cells (dermal papillae) was increased following the stimulation of their sensory nerves in mice.

We know DHT inhibits hair growth by negatively modulating growth regulations.  The researchers found DHT blocks the release of calcitonin gene-related peptide (CGRP).  They noticed an increase in the IGF-I and proteins which are being made from that effect.  They demonstrated the administration of DHT for three weeks lowers the levels of CGRP, IGF-I AND IGF-I mRNA in the skin of mice. The number of growing hairs was decreased and the re-growth of hair follicles was blocked after the administration of DHT to those mice. Observations of this sort makes clear DHT causes its anti-growth effects on hair through decreasing IGF-I in dermal papillae hair cells.

These new research reports on hair, growth factors, and hair stem cells will lead us in the direction of finding more efficient ways for treating human hair loss in the future.

The growth cycle of hair follicles differs between each individual.  For that reason, transplanted hair grafts also may not follow a universal pattern.  We generally schedule follow up visits for our hair transplant patients on the day 1, day 10, month 5 and month 10 following their hair transplant surgery.  Our five month follow up is to make sure patients are having a smooth early growth without any problems or complications.  In most cases, early growth is seen at five months post op.   In some people who started growing hair earlier we may even see something close to their final result.  However, we have had some cases that we did not see impressive results at month five and patients experienced delayed growth of their transplanted grafts following the procedure.

Delayed hair growth after After a hair transplant procedure - Class VI baldness - Before (left), five months (middle) and ten months (right) after hair transplant with US Hair Restoration

Most of these patients do not have anything wrong with their transplanted hair and will only have to be more patient with their hair growth.  We bring all hair transplant patients back in month 10 after their surgery and the results at that time are much better.  This group of patients may see their final result more than 10 months from the time of their hair transplant and it may take 12 to 18 months to see full result.  If the results are still poor at month 10, more diagnostic tests such as a scalp biopsy may be needed to rule out other causes of hair loss that might have been involved with the growth of their transplanted hair.

I found another interesting case report on a very unusual location for hair growth recently published in the Journal of Oral Surgery and Oral Medicine the other week.  The case study was reported by Femiano et al. at the Second University of Naples, in Naples, Italy.

He reported a woman who was found to have hair growing inside her mouth due to a medical condition.  Nasal-like hair.  Scientists said it had to do with the the high level of testosterone in her system. They called it “oral hirsutism”, which I guess should be considered a new term in medical terminology.

Numerous conditions and serious diseases can result in high levels of circulating testosterone, although the most common cause of hirsutism is polycystic ovary syndrome (PCOS).  In the future, maybe someday scientists specializing in hair follicle growth may utilize hormonal manipulations to grow hair on the scalps of men and women who qualify for  hair loss treatment.