Single dose testosterone increases total cholesterol levels and induces the expression of HMG CoA Reductase

39 healthy male volunteers were given 500 mg testosterone enanthate as single intramuscular dose of Testoviron？--Depot. The total cholesterol levels prior to and two days after testosterone administration were analysed. Protein expression of HMGCR in whole blood was investigated by Western blotting. In order to study whether testosterone regulates the mRNA expression of HMGCR, in vitro studies were performed in a human liver cell-line (HepG2).The total cholesterol level was significantly increased 15% two days after the testosterone injection (p = 0.007). This is the first time a perturbation in the lipoprotein profile is observed after only a single dose of testosterone. Moreover, the HMGCR mRNA and protein expression was induced by testosterone in vitro and in vivo, respectively.Here we provide a molecular explanation how anabolic androgenic steroids may impact on the cholesterol homeostasis, i.e. via an increase of the HMGCR expression. Increasing knowledge and understanding of AAS induced side-effects is important in order to find measures for treatment and care of these abusers.Anabolic androgenic steroids (AAS) including testosterone, other endogenous androgenic hormones and synthetic substances structurally related to these compounds are the most frequently detected doping agents in the society and sports. The abuse of these agents for cosmetic purposes among non-competitive recreational body-builders and non-athletes is a considerable health concern. According to studies in Western societies the prevalence of abuse of anabolic androgenic steroids among high school and college students ranges from 1 to 5% [1-3].There is a comprehensive body of evidence documenting that AAS induce various deleterious alterations of the lipoprotein profile. The most prominent changes include elevations of low density lipoprotein (LDL) and decreases of high density lipoprotein (HDL) [4-7]. The long-term consequences of these alterations are still unknown but it is possible that