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.

Dihydrotestosterone (DHT) is a byproduct of the hormone testosterone, which is formed in different areas such as the prostate gland and hair follicles.  Hair follicles which are susceptible to genetic male patterned baldness contain DHT receptors.  Over time as males produce more and more DHT the molecules affect hair follicles and cause them to become decrease in size, and eventually fall out permanently.

DHT and having the gene of male pattern baldness are the primary contributing factors for male pattern baldness. Women with female-pattern baldness, unlike men with male-pattern baldness, are usually not characterized by increased production rates of DHT due to their low levels of testosterone.  However if for any reason a woman has increased testosterone, she may develop female patterned baldness just like a man does with the same mechanism.

Hair in the areas that are prone to male patterned baldness such as corners, top and crown areas are loaded with DHT receptors in men with Androgenetic Alopecia.  However, the hair on donor areas such as back and sides do not have as much DHT receptors.  This is why hair is more permanent on the sides and back as opposed to the top and front.

The distinction in hair quality on different areas (donor vs. recipient) allows a hair transplant surgeon to remove hair from one area and transplant it to the balding portions of the scalp.  These transplanted hairs are permanent and won’t be affected by circulating DHT. Finasteride (Propecia) is a drug that blocks the conversion of testosterone to DHT by blocking the enzyme alpha reductase.  DHT levels in hair loss patients decrease when they are on Propecia and this helps maintain healthy hair, and this helps some of the miniaturized hair become stronger.

We recommend medical treatment with DHT blockers in many of our patients who undergo a hair transplant procedure to help maintaining their own hair in addition to restoring the balding areas with hair restoration surgery.

Avodart (dutasteride) and Propecia (finasteride) have recently been in the news for the report of some studies regarding their role in increased or decreased risk of prostate cancer.  Avodart and Propecia are both 5-alpha reductase inhibitors (5-ARI), which help prevent production of DHT (dihydrotestosterone).  This class of medications is indicated for the treatment of benign prostate (BPH) hypertrophy.  These DHT blockers also help with the prevention of male patterned hair loss and have been recommended and prescribed for hair loss treatment, for many years.

On one hand, several studies have indicated that DHT blockers could decrease the rate of prostate cancer.  On the other hand,  there are some studies that indicate they may increase the incidence of high-grade prostate cancers.  Those studies performed on both finasteride (7 years study) and dutasteride (4 years study).  It has been concluded that the patients who take DHT blockers should have prior knowledge of whether they have a lower risk of prostate cancer.  However, if the patient gets prostate cancer it might be in a category which is more advanced.

Doctors should be aware DHT blockers can decrease the levels of PSA artificially, so a small increase in PSA levels might reflect a higher activity of prostate tissue in comparison to patients who are not on DHT blockers. Overall, it is good practice to make sure all patients age 50 and older have a baseline PSA reading before they get started on finasteride.  This will determine their PSA levels before they begin taking medications, and the doctor will be able to monitor changes in PSA with greater precision.

Minoxidil (Rogaine) is one of the two proven treatments for hair loss along with hair transplant. Although minoxidil mechanism of action for hair growth is not fully understood, there have been several suggested mechanisms such as:

• Nitric oxide chemical agonist effect impactig scalp blood vessels
• Potassium channel opener causing hyperpolarization of follicles cell membrane
• Vasodilation possibly due to its nitric oxide effect

This new study is done in Department of Immunology of Kyungpook National University in Korea. The result of the study was published in The Journal of Dermatological Science shows a new mechanism for minoxidil as activator of β-catenin pathway in human dermal papilla cells, one of the two stem cells involved in development and growth of hair. The investigators announced that this mechanism could be an explanation for anagen prolongation effect of minoxidil.

The length of the actively growing hair in anagen phase (growth phase) is responsible for hair length. The investigators indicated that maintenance of β-catenin activity in the dermal papilla cells (DPCs) enables hair follicles to keep growing actively. Minoxidil or Rogain promotes hair growth in male patterned baldness suggesting that minoxidil can prolong the growth phase in hair life cycle.

The study is done in mouse model with application of 3% minoxidil for ten days. DPCs were transfected with β-catenin responsive TCF reporter plasmid. They showed that extension of anagen phase was significantly promoted after minoxidil application. The researchers concluded that minoxidil extends the anagen phase by activating β-catenin activity in the DPCs and that can be one of the main pathways in its hair growth or hair loss prevention mechanism.

Studies like this increase our understanding of hair loss and hair growth and over time can help hair restoration field to have more options to fight hair loss in a more efficient way.

Q:

Dear Dr. Mohebi,

I have recently learned that Finasteride injected into scalp and or taken orally not only stops hair loss but makes hair growth as well.  What is your opinion on the use of this  medication for female with hereditary pattern hair loss?  Is it safe, is it effective, do you use this method of treatment in your office?

 Thx.

A:

Finasteride injection is not approved nor recommended for male or female patterned hair loss and we do not recommend it.  Finasteride is prescribed for male patterned baldness in men and also it could be beneficial for women with hair loss secondary to hyperandrogenism (increased levels of male hormones) in women* to prevent or minimize the process of hair loss.  Finasteride (Propecia) is prescribed for typical forms of female patterned baldness without elevation of testosterone levels by some doctors.  However, there is no evidence to support its effectiveness on women with hair loss without elevated testosterone.

* The use of finasteride for women should be under a physician supervision and it is contraindicated in pregnant women.

Q:

Dear Dr. Mohebi,

I’m in my sixties and  consulted with you a year ago at your clinic, and had tests done, all normal.   I have had hair loss ever since I was nineteen years old.  The onset  was when I traveled to Europe, and it never stopped until in two cases:

1. With each pregnancy my hair loss almost completely stopped and gained a lot of hair back, but fell out after a few months during the period I was nursing my babies.

2.  About twenty years ago, I saw Dr. XX XX in Beverly Hills who prescribed Rogaine a solution that at the time wasn’t available over the counter.  After six weeks of application, I saw results, and after about four months I gained abundance of hair back, but started itching of scalps, and discontinued it.  When after being out of town for a while, I started seeking help, he had moved away, and couldn’t find that doctor.

For the past ten years or so that Rogaine has been readily available, I attempted using it even at the strength of male 5%, but have had no results.

Hair loss has been in my family, from my grandfather, on mother’s side, to my mother, and to me and now to my children.

My main questions are:

1. What was in the initial solution of Rogan that worked, and then over the counter ones didn’t work?
2. What is the latest preventive measures/solutions/hopes for this type of hair loss at least for my children’s generation?

Thank you kindly for your response,

A:

Hair loss medications such as Rogaine work only if you have active hair loss.  The effect is mostly preventative, but since it may make some of the miniaturized hair (finer hair that is in process of balding) thicker, patients may experience some enhancement in their hair bulk only for the first year of its use.

Some women with genetic female patterned hair loss may be good candidates for hair transplant surgery as long as they have protected (Permanent) hair on their donor area on the back and sides of the scalp.  Hair transplant in this group of patients should be done only if they are trying to reinforce a limited area of scalp.  However, a hair transplant is not a good idea if their goal is to increase hair density throughout a large area or entire scalp.

To be able to say what options are out there for your children, they need to be individually evaluated by a good dermatologist or a hair transplant surgeon and treatment options should be tailored to their individual needs.

Q:

It seems to me that successful outcomes can, to a substantial degree, rely on the technicians handling the hair follicles. How do you measure your technicians skills?

A:

We have a great quality control system at US Hair Restoration in which every technician is monitored during cutting and placing.  We also have surveillance cameras in the OR to record the entire procedure for quality control.  We hire only highly qualified hair transplant technicians.  We still need to provide some special training to assure they can function according to US Hair Restoration standards.  We hold regular educational meeting for hair transplant techs to keep them all up to date on current procedures as well as US Hair Restoration quality expectations.

Check this post on my blog:  US Hair Restoration – Hiring Qualified Hair Transplant Technicians for more information on quality of hair transplant technicians.

Q:

What is the average hair loss after hair transplants? I.e. The number of grafts lost? I am sure that also relies heavily on techniques of hair transplantation.

A:

The survival of transplanted hair grafts should be over 95%.*

We do not expect to lose any grafts after hair restoration surgery.  There may be a 1-5% transection experienced with microscopic follicular unit transplants, but we have aimed to minimize this rate by enhancing the quality of our hair transplant techniques.

* According to some studies that were done on microscopic follicular unit transplant methods, 95-99% of newly transplanted grafts should take and hold.  We expect that the hairs should grow healthy hairs within a few months after hair transplant surgery.

Q:

Dr. Mohebi, I have already made an appointment for hair transplant surgery on Wed April 20th per your recommendations and paid the deposit. If you don’t mind I have a quick question.

Do you think it’s realistic for me to see patients on Monday following my procedure? I have clinic that day and OR the next (will need to wear surgical cap), is this okay in the week following?

A:

Because we will be transplanting a large number of hairs in the frontal area of your scalp, we expect significant swelling until day 4-5 after surgery.  Occasionally patients may experience swelling until day 6-7, but your surgical cap use is okay and should easily cover it.

In addition, some patients occassionally get swelling and bruising around their eyes (which may be difficult to cover). Probability of bruising/swelling around the eyes is minimal but its possibility should still be notated.

Hair loss is a common side effect with some types of chemotherapy and can be experienced by both men and women.  Chemotherapy medications attach rapidly to proliferating cells and hair follicles are some of those cells responsible for the continuous growth of the hair.

What do you need know about hair loss after chemotherapy?

Hair loss can typically be seen in the first few weeks after the start of chemotherapy and usually becomes worse with time.  It may be several months after the end of chemotherapy treatments before you notice that your hair growth is getting better.  The new hair may have a different color or texture than you are used to, but it will gain its normal characteristics back over time. 

Unfortunately, there is no known medication to completely prevent hair loss after chemotherapy.  It may take months for the hair to get back to normal following the end of chemotherapy treatments. While many patients will experience stabilization or regrowth of hair after completion of chemotherapy, some patients will experience accelerated hair loss that they were to have regardless.

If your hair growth is not back to normal after 2 years from completion of your chemotherapy, you are recommended to be evaluated by a dermatologist or hair specialist for hair loss medical treatments (hair transplantation is possible and eligibility should be determined for you by a quality hair transplant surgeon).