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Research links adolescent steroid use to reduction in serotonin, altered signaling

09.08.2002


Study hypothesizes that adolescent steroid exposure may permanently alter the production of the ’feel good’ receptor



"With more than one in ten boys admitting to using steroids, muscle- and strength-enhancing drug use among teenagers has caused considerable concern among parents and researchers over the past decade, but until now, the longer-term physiological and neurological effects of its use on the developing brain have not been fully examined. Now, new research from Northeastern University, published in the latest issue of the journal Pharmacology, Biochemistry and Behavior, documents the link between adolescent anabolic steroid use and aggression and partly associates the increases in aggression with deficits in the brain"s serotonin system. The study will examine longer-term deficiencies of serotonin levels in the brain as a result of damage from steroid use, suggesting that a tendency toward aggression and impulsiveness may actually linger long after both the steroid use and the muscles and strength developed have waned.

With funding from the National Institute of Health, Northeastern University psychology professor Richard Melloni and graduate student Jill Grimes examined the phenomenon of long-term steroid use through a series of experiments on groups of adolescent male Syrian hamsters. During adolescence, this particular breed of hamster displays a natural form of territorial aggression, has similar neurological circuitry to human beings and similar aggression and dominance patterns during its adolescent years, making it a natural model for neurological and behavioral experiments.


During the first experiment, the researchers administered a "high dose" of anabolic steroids to adolescent hamsters over the course of a month, a period corresponding to five years repeated dosage in human adolescents. Those hamsters given steroids were, as other studies have shown, more aggressive than those not treated with steroids.

In the second stage of the experiment, the researchers administered fluoxtine (Prozac), commonly used in treating depression in humans by encouraging the presence of serotonin (the "feel good" receptor), to the hamsters treated with chronic levels of steroids, and found that the previously aggressive tendencies were notably decreased. As in humans, aggressions were mellowed in the presence of Prozac, or serotonin.

Finally, the brains of the anabolic steroid-treated hamsters were examined under a microscope to determine the effect the drugs have on the developing nervous system. In those animals exposed to steroids, significantly lower levels of serotonin were present in the neural connections in their brains, particularly in areas related to aggression and violence.

Melloni and his students plan to conduct a series of follow-up experiments to examine whether the observed serotonin deficits in light of steroid use cause permanent and irreversible damage to the brain and how the neural abnormalities of adolescent anabolic steroid use may affect humans into adulthood. The researchers hypothesize that steroid exposure during adolescence decreases naturally occurring levels of the feel good receptor serotonin particularly in the hypothalamus, the area of the brain pinpointed for aggression and violence, and they plan to conduct a series of follow-up experiments to examine whether the serotonin deficiencies linger and what the longer-term abnormalities of adolescent steroid use actually are into adulthood.

"We know testosterone or steroids affect the development of serotonin nerve cells, which, in turn, decreases serotonin availability in the brain," Melloni said. "The serotonin neural system is still developing during adolescence and the use of anabolic steroids during this critical period appears to have immediate neural and behavioral consequences. Further research will allow us to determine whether or not these deficits are present into adulthood."

Continued steroid use during adolescence is linked not only to aggression and violence, but to a host of physiological problems, including liver diseases, problems with physical growth and development, and sexual dysfunction. Melloni notes that there is currently no long-term understanding of the effects of certain drug use on young people, and that drugs like Ritalin, among others, have no research indicating what aftereffects remain well into adulthood.

Steroid use, he says, is considerably on the rise, with more than ten percent of boys and three percent of girls admitting to regular use.

"Given the fact that we know so little about steroid"s long-term effects, the prospect of results from our research will be doubtlessly interesting and perhaps even frightening," Melloni said. "Perhaps through this sort of research we"ll be able to decrease the popularity of steroid use among teenagers."


Northeastern University, a private research institution located in Boston, Massachusetts, is a world leader in practice-oriented education. Building on its flagship cooperative education program, Northeastern links classroom learning with workplace experience and integrates professional preparation with study in the liberal arts and sciences. For more information, please visit www.northeastern.edu


Christine Phelan | EurekAlert!

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