Abstract
BackgroundDietary fish oil (DFO) has been identified as a micronutrient supplement with the potential to improve musculoskeletal health in old age. Few data are available for effects of DFO on muscle contractility, despite the significant negative impact of muscle weakness on age-related health outcomes. Accordingly, the effects of a DFO intervention on the contractile function and proteomic profile of adult and aged in an animal model of aging were investigated.MethodsThis preliminary study evaluated 14 adult (8 months) and 12 aged (22 months) male, Sprague-Dawley rats consuming a DFO-supplemented diet or a control diet for 8 weeks (7 adult and 6 aged/dietary group). Animal weight, food intake and grip strength were assessed at the start and end of the FO intervention. In situ force and contractile properties were measured in the medial gastrocnemius muscle following the intervention and muscles were processed for 2-D gel electrophoresis and proteomic analysis via liquid chromatography with tandem mass spectrometry, confirmed by immunoblotting. Effects of age, diet and age x diet interaction were evaluated by 2-way ANOVA.ResultsA significant (P = 0.022) main effect for DFO to increase (~ 15%) muscle contractile force was observed, without changes in muscle mass. Proteomic analysis revealed a small number of proteins that differed across age and dietary groups at least 2-fold, most of which related to metabolism and oxidative stress. In seven of these proteins (creatine kinase, triosephosphate isomerase, pyruvate kinase, parvalbumin, beta-enolase, NADH dehydrogenase and Parkin7/DJ1), immunoblotting corroborated these findings. Parvalbumin showed only an effect of diet (increased with DFO) (P = 0.003). Significant age x diet interactions were observed in the other proteins, generally demonstrating increased expression in adult and decreased expression aged rats consuming DFO (all P > 0.011). However, correlational analyses revealed no significant associations between contractile parameters and protein abundances.ConclusionsResults of this preliminary study support the hypothesis that DFO can enhance musculoskeletal health in adult and aged muscles, given the observed improvement in contractile function. The fish oil supplement also alters protein expression in an age-specific manner, but the relationship between proteomic and contractile responses remains unclear. Further investigation to better understand the magnitude and mechanisms muscular effects of DFO in aged populations is warranted.
Highlights
Impairment of muscular function has significant negative consequences for older adults, as age-associated muscle weakness contributes to multiple chronic medical conditions [1], mortality [2], loss of independent function [3], frailty and risk of falls [4, 5]
A number of anti-inflammatory effects known to reduce oxidative injury have been ascribed to Dietary fish oil (DFO) and it has been suggested that it reduces the ageassociated accumulation of markers of inflammation and oxidative injury in skeletal muscle, where they may contribute to loss of mass and force production [16,17,18]
Body mass and food intake Body mass was assessed at the start and the completion of the dietary intervention
Summary
Impairment of muscular function has significant negative consequences for older adults, as age-associated muscle weakness contributes to multiple chronic medical conditions [1], mortality [2], loss of independent function [3], frailty and risk of falls [4, 5]. In addition to exercise- and pharmacologically-based interventions for improving aged muscle function, dietary supplements may hold some promise as alternative or adjunctive strategies. One such dietary intervention that has received substantial attention in recent years is dietary fish oil (DFO). Though increased longevity has not been linked to DFO, a recent scoping review identified DFO as one of only 16 micronutrient supplements with the potential to improve musculoskeletal health in old age [10]. Dietary fish oil (DFO) has been identified as a micronutrient supplement with the potential to improve musculoskeletal health in old age. The effects of a DFO intervention on the contractile function and proteomic profile of adult and aged in an animal model of aging were investigated
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