Alfatradiol binds to the ERα and ERβ with 58% and 11% of the relative binding affinity of 17β-estradiol.  However, it has 100-fold lower estrogenic activity relative to estradiol,  which may in part be due to differences in the intrinsic activity of the two compounds. [ citation needed ] On the other hand, alfatradiol has been found to bind to and activate the brain -expressed ER-X with a greater potency than estradiol, indicating that it may be the predominant endogenous ligand for the receptor. 
Anabolic steroids are synthetic versions of hormones that human body produces naturally. Their main role is to assure increased physical performance in all sports and athletic pursuits. Steroidal compounds enhance stamina, strength, weight and size of muscles and may improve the energy levels during physical training. Oral and injectable steroids posses the ability to increase athletic performance, have a positive effect on red blood cells production and bones density. The steroids are used in accordance with requirement and needs of any athlete individually. There are special compounds which are not suitable for women and a series of anti-estrogen products which main role is to counter the eventual side effects of steroids use and to restore natural testosterone levels of the human body. These compounds nowadays became an important part of muscle building process among professional athletes and bodybuilders, as well as regular people, males and females that have the goal to become more attractive and exhibit good looks. Follow us on Twitter | Steroids Store - Pinterest .