Steroids and Athletes: Genes Work Overtime 0/8
Why Can’t Users Stop Taking Steroids Abruptly? Is it an Addiction?
The answer is “not really.” An addiction1 to a substance indicates that the person uses the drug2 compulsively, with a loss of control in their intake, despite negative consequences. Most athletes are not compulsive users of steroids3 (although there may be a few out there!) – if they were, they would not be able to stop taking the steroids prior to competition. However, chronic users can become dependent on steroids. A dependence4 means that the athlete’s body adapts to the presence of the steroid, and if the steroid is withdrawn suddenly, physiologic symptoms emerge. Withdrawal symptoms include nausea, headaches, dizziness, increased blood pressure, decreased libido (sex drive), depression and craving. The basis for this dependence involves the brain and the gonads. More specifically, the hypothalamus, found at the base of the brain, releases hormones5 that direct other tissues in the body to produce steroids (Figure 10). In the case of the sex steroids, the hypothalamus produces a hormone called “gonadotropin releasing factor” or GNRH. This hormone binds to GNRH receptors6 on the pituitary gland (located near the hypothalamus, but not actually part of the brain), where it activates the release of lutenizing hormone (LH) and follicular stimulating hormone (FSH). These pituitary hormones travel throughout the bloodstream and when they reach the gonads (i.e., testes and ovaries), they bind to LH and FSH receptors in gonadal cells to cause the release of testosterone and estrogen. The body attempts to keep the steroid levels in balance using “feedback regulation.” When the sex steroid levels in the blood become elevated, the hypothalamus reduces its production of GNRH, the pituitary reduces production of LH and FSH, and the gonads reduce production of testosterone and estrogen. [In women taking birth control pills, this is the basis for the contraceptive activity – without enough LH and FSH, they can’t ovulate.] So, when the athlete takes the steroids chronically, his/her hypothalamus stops producing GNRH and the gonadal tissues stop producing testosterone or estrogen due to this negative feedback. Now, if athletes stop taking the steroids abruptly, they won’t have enough testosterone or estrogen. It takes some time (it can take 6 months!) for their hypothalamus, pituitary, and gonads to recover normal activity and start producing these hormones again. Therefore, all people who use steroids, even for therapeutic purposes, must taper off the drug slowly to give their hypothalamus, pituitary and gonads time to recover normal hormone production.
1 a behavior pattern that occurs when a person uses drugs compulsively, with a loss of control of their intake, despite negative consequences.
2 a substance that affects the structure or function of a cell or organism.
3 a class of hormones synthesized from cholesterol by specific cells in the body. They are powerful compounds that alter genetic function, causing numerous effects in the body.
4 the body functions normally in the presence of the drug. When the drug is present, the body has adapted physiologically to its presence. When the drug is removed, withdrawal symptoms are produced, usually in opposition to the effects produced by the drug’s presence.
5 chemicals in the body that are synthesized in one tissue and secreted into the bloodstream for actions in tissues some distance away. They regulate many physiologic functions.
6 a protein to which hormones, neurotransmitters and drugs bind. They are usually located on cell membranes and elicit a function once bound.
Figure 10 Circulating testosterone or estradiol signal the hypothalamus to shut down GNRH release via feedback inhibition. This decreases the production of testosterone in the testes or estrogen in the ovaries.