It was decades later that the secret behind this spectacular success became known. The East German Sports Federation had, with the help of the Stasi, used Performance Enhancing Drugs or PEDs to ensure that their athletes gained international recognition by winning the Olympic events. This systematic plan had been initiated in 1974 as a means to guarantee international glory through the achievement of gold medals at the prestigious sporting event. Oral- Turinabol , a testosterone derivative was used extensively to improve muscle mass and cut down recovery time. This allowed the German athletes to train harder and longer than other world athletes.
Prolactin is a protein hormone that in female mammals initiates and maintains the secretion of milk, the mammary glands having been previously prepared for this function by the action of other hormones. In the female rat, prolactin also maintains the secretion of the hormone progesterone , which is formed by the corpus luteum , an endocrine gland of the ovary . Thus, prolactin is a gonadotropin , its target being an endocrine gland. Moreover, the molecular structures of prolactin and growth hormone are similar, which may explain why they show some overlap in biological properties. In particular, administration of prolactin promotes some growth in many terrestrial vertebrates. Human growth hormone has prolactin-like luteotropic properties.
Sex hormone-binding globulin (SHBG) is thought to mainly function as a transporter and reservoir for the estradiol and testosterone sex hormones. However it has also been demonstrated that SHBG can bind to a cell surface receptor (SHBG-R). The SHBG-R has not been completely characterized. A subset of steroids are able to bind to the SHBG/SHBG-R complex resulting in an activation of adenylyl cyclase and synthesis of the cAMP second messenger.  Hence the SHBG/SHBG-R complex appears to act as a transmembrane steroid receptor that is capable of transmitting signals to the interior of cells.