A study at the University of Pennsylvania has found that by injecting genetically modified plasmids into the muscles of rats they were able to increase muscle mass by up to 30% when coupled with resistance training. The study also showed that muscle mass reduced at a lower rate when detrained.
The recombinant AAV plasmid (pSUB201) was used containing myosin light chain 1/3 promoter/enhancer, rat IGF-IA cDNA, and simian virus 40 polyade-nylation signal for viral production. Six hundred microlitres of 10% glycerol/PBS containing 1010 recombinant particles were injected into the rat’s flexor hallucis longus muscle (equivalent muscle in humans is the largest muscle in the calf that flexes the ankle) through an incision. The rat was allowed to recover then underwent resistance training.
This training consisted of the rats climbing a 1 metre ladder with 2cm increments at an 85° incline with weights attached to their tails. The rats were placed at the bottom of the ladder and were encouraged to climb by having their tails touched. If at any stage they refused to climb they received an electric shock to the tail. They could rest for 2 minutes at the top before having the weight increased and being placed at the bottom of the ladder.
The increased muscle growth (hypertrophy) is the result of viral expression of Insulin Growth Factor-I a result of the presence of the recombinant plasmid. IGF-I increases protein synthesis and proliferation of satellite cells thus leading to muscle growth.
The therapeutic applications of this research are very exciting in terms of rehabilitation and for the elderly. But there are concerns that it will find its way into sport and tip the scales in the war against performance enhancement.
by: Toby Kowal 41144774
http://www.msnbc.msn.com/id/4282866/
http://jap.physiology.org/ Search for article below.
Viral expression of insulin-like growth factor-I enhances muscle hypertrophy
in resistance-trained rats
Sukho Lee,1,* Elisabeth R. Barton,2,* H. Lee Sweeney,2 and Roger P. Farrar1
Department of Kinesiology, University of Texas, Austin, Texas 78712; and 2Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6021 Submitted 7 May 2003; accepted in final form 27 October 2003
