Dihydrotestosterone, more commonly referred to as DHT, this hormone is in fact measured to be approximately three to four times stronger than testosterone itself. It is clearly the most potent steroid found naturally in the human body, and important to discuss if we are to understand the full activity of testosterone, as well as other anabolic/androgenic steroids that undergo a similar conversion.
Testosterone is converted to dihydrotestosterone upon interaction with the 5-alpha reductase enzyme. More specifically, this enzyme removes the C4-5 double bond of testosterone by the addition of two hydrogen atoms to its structure (hence the name di-hydro-testosterone). The removal of this bond is important, as in this case it creates a steroid that binds to the androgen receptor much more avidly than does its parent steroid. 5-alpha reductase is present in high amounts in tissues of the prostate, skin, scalp, liver and various regions of the central nervous system, and as such represents a mechanism for the body to increase the potency of testosterone specifically where strong androgenic action is needed.
Local potentiation of testosterone's activity may be unwelcome in some regards, as the higher androgenic activity in certain tissues may produce a number of unwelcome side effects. Acne for example is often triggered by dihydrotestosterone activity in the sebaceous glands, and the local formation of dihydrotestosterone in the scalp is typically the problem that causes male pattern hair loss. Yet it is unquestionable to just blame dihydrotestosterone for this effect, because it is not just isolated in DHT but other various anabolic/androgenic steroids as well.
Dihydrotestosterone (DHT) plays an important role in the organization and functioning of the central nervous system. Many neural cells contain active androgen receptors, and it is thought that there may even be a specific importance of dihydrotestosterone in this area of the body. Studies have shown DHT to have a profoundly greater impact in these cells compared to testosterone. Animal models demonstrated that both testosterone and DHT would result in increased androgen receptor proliferation in neural cells three and seven hours after being administered, however only DHT was able to sustain this increase at the twenty-one hour mark.
The strong interaction between the central nervous system and skeletal muscles, collectively referred to as the neuromuscular system, is of key importance to the athlete. There appears little doubt that the ability of the body to adapt to training and its ability to activate nerve endings in muscle tissue are reliant on the interactions of the neuromuscular system. Inhibiting the formation of DHT during a testosterone cycle may therefore inadvertently interfere with strength and muscle mass gains. That’s why most people complain on the sudden drop in the steroid potency when a 5-alpha reductase inhibitor finasteride to a testosterone cycle.