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.

What is Saw Palmetto?

Saw Palmetto is an extract of the fruit of Serenoa Repens. It is rich in fatty acids and phytosterols. It has been used in alternative medicine for a variety of indications, most notably benign prostatic hyperplasia (BPH).

Indications:

Prostate treatment

Saw Palmetto has also been used in treatment of benign prostatic hyperplasia (BPH), a condition known by enlarged prostate size to the degree that it makes urinating difficult.

Hair loss prevention

The role of Saw Palmetto in hair loss prevention has also been documented. Saw Palmetto is one of the few effective herbal treatments that can reverse hair loss process in some people to some degree and slow down the process of  balding in men. Saw Palmetto bio active ingredients prevent conversion of testosterone into dihydrotestosterone (DHT).

That is how Saw Palmetto helps to stop the process of balding on the hair follicle level. It can help increase the thickness of miniaturized hair and make them grow longer. The Saw Palmetto effect is comparable to finasteride or other DHT blockers by mechanism. Saw Palmetto is available in oil extract for topical use on scalp or as pills used for prostate enlargement treatment.