How do anabolic steroids work in the brain?
Anabolic steroids act at androgen receptors to influence cellular functioning and gene expression. In addition to regulating pathways involved in the development of male characteristics,103 activation of androgen receptors also produces rapid increases in calcium levels within skeletal muscle, heart, and brain cells.104 Calcium plays important roles in neuronal signaling.Research with human cells demonstrates that anabolic steroids also interact with certain types of GABAA receptors, which could mediate the increased anxiety reported by steroid users.105,106 In addition, animal studies show that anabolic steroids increase serotonin levels in brain regions involved in mood107 and dopamine levels in reward-related brain regions.107,108 Chronic use of anabolic steroids has also been shown to cause dysfunction of these reward pathways in animals. Specifically, rats given twice daily nandrolone injections for four weeks showed loss of sweet preference (a sign of reward dysfunction) that was accompanied by reductions of dopamine, serotonin, and noradrenaline in the nucleus accumbens, a reward-related brain region.109
