AMHERST, Mass. — Athletes taking the controversial performance enhancer known as "andro" may be affecting their moods as well as their muscles, suggests a study published by University of Massachusetts researchers in the July issue of the journal Endocrinology. The study was conducted by doctoral students Constanza Villalba and Catherine Auger under the direction of professor Geert de Vries. Auger is now a postdoctoral researcher at Johns Hopkins University. Although the study was conducted on rats, the implications for humans are important, according to the scientists.
"Andro," or androstenedione, is a steroid; a hormone that is produced in the body by males and females. It is sometimes sold as an over-the-counter nutritional supplement. Andro garnered attention last year when St. Louis Cardinals star hitter Mark McGwire acknowledged using it to help him train. Since then, scientists, doctors, and ethicists have been working to understand the effects of andro on the body. But while many researchers have been concentrating on how andro affects muscles and athletic performance, the UMass group of scientists has focused on what andro does to the brain. The study was conducted through the University's Center for Neuroendocrine Studies, the Neuroscience and Behavior Program, and the department of psychology.
"Steroids like andro and its more potent counterpart, testosterone, affect more than just muscle mass and home-run ability," said Villalba. "They can also affect the brain by changing the levels of neurotransmitters and consequently stimulating libido and aggression." Steroids, she explains, are critically important hormones produced in the body, in both males and females. While steroids are responsible for puberty, they also have a role in growth, behaviors, and brain development.
"Humans taking andro could potentially be susceptible to steroid-induced rage, or increased aggression as a result of the extra source of hormone," said Villalba.
Specifically, researchers studied andro's effect on a neurotransmitter called vasopressin. Vasopressin plays several roles in the brain: it governs thirst, wake-sleep cycles, and "the focus of the research" aggression. The scientists determined that, like testosterone, andro enables males to maintain high levels of vasopressin. This held true even in rats that lacked the ability to make their own male hormones.