SEATTLE, WA – Combining genetic manipulation and weight training in rats yields leg muscles that are bigger and stronger than the muscles of rats exposed to just one of these two muscle-building techniques, according to a new study. These findings will frame a discussion at the 2004 AAAS (Triple-A-S) Annual Meeting on potential uses of genetic enhancement in competitive sports, from the perspective of athletic organizations, athletes, scientists, and ethicists.
Genetic enhancement of skeletal muscles could potentially benefit elite athletes, patients rehabilitating from injury-induced muscle wasting, and elderly people who have diminished mobility due to muscular weakness, Lee Sweeney and coauthors report in a study appearing in the March 2004 issue of the Journal of Applied Physiology. The research debuted at the Annual Meeting of the American Association for the Advancement of Science (AAAS).
Sweeney suggests that exercise and genetic enhancement work together to increase mass and strength in rat muscles. One technique somehow boosts the other.
The authors suggest that muscle-precursor stem cells called "satellite cells" contributed to the higher muscle mass and strength reported in the exercised, genetically enhanced rats. Their findings support the hypothesis that ladder-climbing exercise primed the satellite cells of these rats. The receptive satellite cells expressed IGF-I receptors that made them responsive to increased levels of IGF-I which, in turn, led to increased mass and strength in genetically enhanced and exercised muscle.
The scientists also report that muscles from rats with genetically elevated levels of IGF-I retain more of their muscle mass after they stop exercising than rats without elevated levels of the growth factor.
The scientists injected a recombinant virus that contained an IGF-I rat gene into a hind-leg muscle (the flexor hallucis longus) of rats. The gene increases production of the growth factor IGF-I, which promotes gains in muscle strength and mass.
Genetically enhanced rats that worked their way through ladder-climbing, weight-bearing exercise regimens bulked up more and retained more of their muscles after they stopped working out than exercise-only and genetic-enhancement-only rats.
While the leap from laboratory animals to human beings is still hypothetical, the speakers in this AAAS symposium predict human trials of gene enhancement for muscle diseases in the near future.
The participants will discuss the scientific concerns associated with the expected "off-label" application of genetic tools in athletic settings outside the reach of review and regulatory bodies. Pressure for effective and less detectable methods for altering athletic physiology from groups within the lucrative, high-profile world of competitive athletics could spur such off-label uses of genetic enhancements.
Thomas Murray, bioethicist and president of The Hastings Center, will describe interdisciplinary research focused on ethical issues relating to endurance enhancements. Can banned endurance enhancement practices, such as taking erythropoietin (EPO), the naturally occurring hormone that stimulates the body to produce more red blood cells, be distinguished from allowed practices such as "train-low-and-rest-high" regimens? What are the ethical reasons from prohibiting some endurance enhancement techniques and allowing others? How should distinctions be drawn? Is the ethics of competitive athletics connected to the meaning we attach to sports? If so, do meanings change?
Donald Catlin, the head of the lab at the University of California, Los Angeles, that recently identified the previously unknown designer steroid, THG, will outline current pharmacological doping methods and banned substances. Catlin will describe how steroids get on the banned list, how THG is unique, and what the lab went through to identify the new steroid.
Finally, Richard Pound from the World Anti-Doping Agency and McGill University will provide an international perspective on genetic enhancement and athletics.
With respect to genetic enhancements for competitive athletes, Pound explains that the current situation parallels that of performance-enhancing drugs 30 or 40 years ago– a time when detection techniques and regulatory mechanisms were not in place.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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