nautica said:
Receptor sites??? Steroid's are nonpolar molecules, which freely diffusion through the plasma membrane of cells with no need for "receptor sites" or plasma membrane receptors required to bring them into the cell. There are NO "receptor sites" for steroid molecules. There are steroid molecule receptors inside, the cells, which when in complex with the steroid will bind and activate transcription (or protein synsthesis).
nautica
With all due respect, that's splitting hairs and misinformation IMO. Call it a semantics game here but there are in fact receptor "sites". Every hormone in the body (insulin, cortisol, testosterone, estrogen, etc..) has "receptor site" it communicates with!
"Steroid hormones work by stimulation of receptor molecules in muscle cells, which activate specific genes to produce proteins (see Figure 1). They also affect the activation rate of enzyme systems involved in protein metabolism, thus enhancing protein synthesis and inhibiting protein degradation (called an anti-catabolic effect). Heavy resistance training seems to be necessary for anabolic steroids to exert any beneficial effect on physical performance. Most research studies that have demonstrated improved performance with anabolic steroids used experienced weight lifters who were capable of training with heavier weights and producing relatively greater muscle tension during exercise than novice subjects. The effectiveness of anabolic steroids is dependent upon unbound receptor sites in muscle. Intense strength training may increase the number of unbound receptor sites. This would increase the effectiveness of anabolic steroids."
References
American Medical Association, Council on Scientific Affairs. Medical and non-medical uses of anabolic-androgenic steroids. J. Amer. Med. Assoc. 264: 2923-2927, 1990.
Bahrke, M.S., C.E. Yesalosk, and J.E. Wright. Psychological and behavioural effects of endogenous testosterone levels and anabolic-androgenic steroids among males: a review. Sports Med. 10: 303-337, 1990.
Buckley, W.E., C.E. Yasalis, K.E. Friedl, W.A. Anderson, A.L. Streit, and J.E. Wright. Estimated prevalance of anabolic steroid use among male high school seniors. J. Amer. Med. Assoc. 260: 3441-3445, 1988.
Rogozkin, V. Metabolism of Anabolic Androgenic Steroids. Leningrad: Nauka, 1988.
United States Olympic Committee. USOC Drug Education Handbook. Colorado Springs: USOC, 1989.