Résumé :
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The aging process in mammals, including humans, is associated with a decline in neuromuscular function and performance. The main aspect of this decline, known as sarcopenia, is the reduction in skeletal muscle mass, related to a loss of muscle strength. As no pharmacological treatment was reported at present, we analyzed the effects of a Ginkgo biloba extract (EGb 761, IPSEN), which exhibits biochemical and pharmacological effects, mostly beneficial, in the nervous system, among other tissues. Recently, it was also shown that EGb 761 modifies the expression of many aged rat muscles genes (group of J.Mallet, CNRS UMR 7091). After a 2 months oral treatment, the 2 years old rats showed that EGb 761 had “rejuvenating”effects on aged muscles 1) the ratio muscle/rat weight increased, close to young rat values 2) muscle creatine kinase content decreased as compared to control muscles 3) the highly fragmented NMJ of aged control muscles recovered a more juvenile pattern 4) as a consequence, the axonal sprouting was reduced 4) the number of terminal Schwann cells doubled 5) the percentage of degenerating NMJ was decreased 6) in connection with these adaptative morphological responses to the treatment, EGb761 increased the evoked quantal transmitter release (Ach) and 6) as a result, the muscle contractile strength was enhanced. However, the muscle fibers diameter and the ratio of type 1 vs type 2 fibers was not modified in the treated slow and fast muscles. Similarities and differences between a slow-twitch muscle (Soleus) and a fast twitch muscle (EDL) will be emphasized. In conclusion, the muscles of rats treated with an herbal extract, Ginkgo biloba, show several “rejuvenated” patterns of neuromuscular junctions and of the major functions of muscle cell physiology, which could provide a pharmacological treatment of sarcopenia in humans.
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