Gentamicin treatment in exercised mdx mice: Identification of dystrophin-sensitive pathways and evaluation of efficacy in work-loaded dystrophic muscle.
Aminoglycosides force read through of premature stop codon mutations and introduce new mutation-specific gene-corrective strategies in Duchenne muscular dystrophy. A chronic treatment with gentamicin (32 mg/kg/daily i.p., 8-12 weeks) was performed in exercised mdx mice with the dual aim to clarify the dependence on dystrophin of the functional, biochemical and histological alterations present in dystrophic muscle and to verify the long term efficiency of small molecule gene-corrective strategies in work-loaded dystrophic muscle. The treatment counteracted the exercise-induced impairment of in vivo forelimb strength after 6-8 weeks. We observed an increase in dystrophin expression level in all the fibers, although lower than that observed in normal fibers, and found a concomitant recovery of aquaporin-4 at sarcolemma. A significant reduction in centronucleated fibers, in the area of necrosis and in the percentage of nuclear factor-kB-positive nuclei was observed in gastrocnemious muscle of treated animals. Plasma creatine kinase was reduced by 70%. Ex vivo, gentamicin restored membrane ionic conductance in mdx diaphragm and limb muscle fibers. No effects were observed on the altered calcium homeostasis and sarcolemmal calcium permeability, detected by electrophysiological and microspectrofluorimetric approaches. Thus, the maintenance of a partial level of dystrophin is sufficient to reinforce sarcolemmal stability, reducing leakiness, inflammation and fiber damage, while correction of altered calcium homeostasis needs greater expression of dystrophin or direct interventions on the channels involved.
De Luca
Annamaria
A
Unit of Pharmacology, Department of Pharmacobiology, Faculty of Pharmacy, University of Bari, Italy. adeluca@farmbiol.uniba.it
Nico
Beatrice
B
Rolland
Jean-François
JF
Cozzoli
Anna
A
Burdi
Rosa
R
Mangieri
Domenica
D
Giannuzzi
Viviana
V
Liantonio
Antonella
A
Cippone
Valentina
V
De Bellis
Michela
M
Nicchia
Grazia Paola
GP
Camerino
Giulia Maria
GM
Frigeri
Antonio
A
Svelto
Maria
M
Camerino
Diana Conte
DC
D000818:Animals; D051401:Aquaporin 4 / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D016189:Dystrophin / Q000378:metabolism*; D005839:Gentamicins / Q000627:therapeutic use*; D006706:Homeostasis / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D018101:Mice, Inbred mdx; D053580:Muscle Strength / Q000187:drug effects; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism*; D009137:Muscular Dystrophy, Animal / Q000188:drug therapy / Q000209:etiology / Q000473:pathology; D018408:Patch-Clamp Techniques; D010805:Physical Conditioning, Animal / Q000009:adverse effects; D011500:Protein Synthesis Inhibitors / Q000627:therapeutic use*; D012508:Sarcolemma / Q000187:drug effects / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
C496031:Aqp4 protein, mouse; D051401:Aquaporin 4; D016189:Dystrophin; D005839:Gentamicins; D011500:Protein Synthesis Inhibitors; D002118:Calcium