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Capogrosso RF, Mantuano P, Cozzoli A, Sanarica F, Massari AM, Conte E, Fonzino A, Giustino A, Rolland JF, Quaranta A, De Bellis M, Camerino GM, Grange RW, De Luca A. Contractile efficiency of dystrophic mdx mouse muscle: in vivo and ex vivo assessment of adaptation to exercise of functional end points. J Appl Physiol (1985) 2017; 122:828-843. [PMID: 28057817 DOI: 10.1152/japplphysiol.00776.2015] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 01/03/2017] [Accepted: 01/03/2017] [Indexed: 11/22/2022] Open
Abstract
Progressive weakness is a typical feature of Duchenne muscular dystrophy (DMD) patients and is exacerbated in the benign mdx mouse model by in vivo treadmill exercise. We hypothesized a different threshold for functional adaptation of mdx muscles in response to the duration of the exercise protocol. In vivo weakness was confirmed by grip strength after 4, 8, and 12 wk of exercise in mdx mice. Torque measurements revealed that exercise-related weakness in mdx mice correlated with the duration of the protocol, while wild-type (WT) mice were stronger. Twitch and tetanic forces of isolated diaphragm and extensor digitorum longus (EDL) muscles were lower in mdx compared with WT mice. In mdx, both muscle types exhibited greater weakness after a single exercise bout, but only in EDL after a long exercise protocol. As opposite to WT muscles, mdx EDL ones did not show any exercise-induced adaptations against eccentric contraction force drop. qRT-PCR analysis confirmed the maladaptation of genes involved in metabolic and structural remodeling, while damage-related genes remained significantly upregulated and angiogenesis impaired. Phosphorylated AMP kinase level increased only in exercised WT muscle. The severe histopathology and the high levels of muscular TGF-β1 and of plasma matrix metalloproteinase-9 confirmed the persistence of muscle damage in mdx mice. Therefore, dystrophic muscles showed a partial degree of functional adaptation to chronic exercise, although not sufficient to overcome weakness nor signs of damage. The improved understanding of the complex mechanisms underlying maladaptation of dystrophic muscle paves the way to a better managment of DMD patients.NEW & NOTEWORTHY We focused on the adaptation/maladaptation of dystrophic mdx mouse muscles to a standard protocol of exercise to provide guidance in the development of more effective drug and physical therapies in Duchenne muscular dystrophy. The mdx muscles showed a modest functional adaptation to chronic exercise, but it was not sufficient to overcome the progressive in vivo weakness, nor to counter signs of muscle damage. Therefore, a complex involvement of multiple systems underlies the maladaptive response of dystrophic muscle.
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Affiliation(s)
- Roberta Francesca Capogrosso
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "Aldo Moro," Bari, Italy.,Department of Chemical, Toxicological and Pharmacological Drug Studies, Catholic University "Our Lady of Good Counsel," Tirana, Albany
| | - Paola Mantuano
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "Aldo Moro," Bari, Italy
| | - Anna Cozzoli
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "Aldo Moro," Bari, Italy
| | - Francesca Sanarica
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "Aldo Moro," Bari, Italy
| | - Ada Maria Massari
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "Aldo Moro," Bari, Italy
| | - Elena Conte
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "Aldo Moro," Bari, Italy
| | - Adriano Fonzino
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "Aldo Moro," Bari, Italy
| | - Arcangela Giustino
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari "Aldo Moro," Bari, Italy
| | - Jean-Francois Rolland
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "Aldo Moro," Bari, Italy
| | - Angelo Quaranta
- Department of Veterinary Medicine, University of Bari "Aldo Moro," Valenzano (BA), Italy
| | - Michela De Bellis
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "Aldo Moro," Bari, Italy
| | - Giulia Maria Camerino
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "Aldo Moro," Bari, Italy
| | - Robert W Grange
- Department of Human Nutrition, Foods, and Exercise, Virginia Tech University, Blacksburg, Virginia; and
| | - Annamaria De Luca
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "Aldo Moro," Bari, Italy;
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