title: Contractile function recovery in severely injured gastrocnemius muscle of rats treated with either oleic or linoleic acid.
abstract: What is the central question of this study? Oleic and linoleic acids modulate fibroblast proliferation and myogenic differentiation in vitro. However, their in vivo effects on muscle regeneration have not yet been examined. We investigated the effects of either oleic or linoleic acid on a well-established model of muscle regeneration after severe laceration. What is the main finding and its importance? We found that linoleic acid increases fibrous tissue deposition and impairs muscle regeneration and recovery of contractile function, whereas oleic acid has the opposite effects in severely injured gastrocnemius muscle, suggesting that linoleic acid has a harmful effect and oleic acid a potential therapeutic effect on muscle regeneration. Oleic and linoleic acids control fibroblast proliferation and myogenic differentiation in vitro; however, there was no study in skeletal muscle in vivo. The aim of this study was to evaluate the effects of either oleic or linoleic acid on the fibrous tissue content (collagen deposition) of muscle and recovery of contractile function in rat gastrocnemius muscle after being severely injured by laceration. Rats were supplemented with either oleic or linoleic acid for 4 weeks after laceration [0.44 g (kg body weight)-1day-1]. Muscle injury led to an increase in oleic-to-stearic acid and palmitoleic-to-palmitic acid ratios, suggesting an increase in Δ9desaturase activity. Increased fibrous tissue deposition and reduced isotonic and tetanic specific forces and resistance to fatigue were observed in the injured muscle. Supplementation with linoleic acid increased the content of eicosadienoic (20:2, n-6) and arachidonic (20:4, n-6) acids, reduced muscle mass and fibre cross-sectional areas, increased fibrous tissue deposition and further reduced the isotonic and tetanic specific forces and resistance to fatigue induced by laceration. Supplementation with oleic acid increased the content of docosahexaenoic acid (22:6, n-3) and abolished the increase in fibrous tissue area and the decrease in isotonic and tetanic specific forces and resistance to fatigue induced by muscle injury. We concluded that supplementation with linoleic acid impairs muscle regeneration and increases fibrous tissue deposition, resulting in impaired recovery of contractile function. Oleic acid supplementation reduced fibrous tissue deposition and improved recovery of contractile function, attenuating the tissue damage caused by muscle injury.
authors: Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.
authors: Phablo
authors: P
authors: Abreu
authors: Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.
authors: Carlos H J
authors: CH
authors: Pinheiro
authors: Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.
authors: Kaio F
authors: KF
authors: Vitzel
authors: Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.
authors: Diogo A A
authors: DA
authors: Vasconcelos
authors: Faculty of Pharmaceutical Sciences, University of São Paulo, São Paulo, SP, Brazil.
authors: Rosângela P
authors: RP
authors: Torres
authors: Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.
authors: Marco S
authors: MS
authors: Fortes
authors: Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.
authors: Gabriel N
authors: GN
authors: Marzuca-Nassr
authors: Faculty of Pharmaceutical Sciences, University of São Paulo, São Paulo, SP, Brazil.
authors: Jorge
authors: J
authors: Mancini-Filho
authors: Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.|Institute of Physical Activity Sciences and Sports, Cruzeiro do Sul University, São Paulo, SP, Brazil.
authors: Sandro M
authors: SM
authors: Hirabara
authors: Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil. ruicuri@icb.usp.br.
authors: Rui
authors: R
authors: Curi
mesh_terms: D000818:Animals; D019787:Linoleic Acid / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000187:drug effects*; D019301:Oleic Acid / Q000494:pharmacology*; D019308:Palmitic Acid / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D020127:Recovery of Function / Q000187:drug effects*; D013229:Stearic Acids / Q000494:pharmacology
chemical_list: D013229:Stearic Acids; D019301:Oleic Acid; D019308:Palmitic Acid; C031183:stearic acid; D019787:Linoleic Acid
keywords: fatty acid composition; fatty acids; muscle contraction; muscle regeneration; skeletal muscle