Beneficial Effects of a Mixture of Algae and Extra Virgin Olive Oils on the Age-Induced Alterations of Rodent Skeletal Muscle: Role of HDAC-4

Abstract

Aging is associated with a progressive decline in skeletal muscle mass, strength and function (sarcopenia). We have investigated whether a mixture of algae oil (25%) and extra virgin olive oil (75%) could exert beneficial effects on sarcopenia. Young (3 months) and old (24 months) male Wistar rats were treated with vehicle or with the oil mixture (OM) (2.5 mL/kg) for 21 days. Aging decreased gastrocnemius weight, total protein, and myosin heavy chain mRNA. Treatment with the OM prevented these effects. Concomitantly, OM administration decreased the inflammatory state in muscle; it prevented the increase of pro-inflammatory interleukin-6 (IL-6) and the decrease in anti-inflammatory interleukin-10 (IL-10) in aged rats. The OM was not able to prevent aging-induced alterations in either the insulin-like growth factor I/protein kinase B (IGF-I/Akt) pathway or in the increased expression of atrogenes in the gastrocnemius. However, the OM prevented decreased autophagy activity (ratio protein 1A/1B-light chain 3 (LC3b) II/I) induced by aging and increased expression of factors related with muscle senescence such as histone deacetylase 4 (HDAC-4), myogenin, and IGF-I binding protein 5 (IGFBP-5). These data suggest that the beneficial effects of the OM on muscle can be secondary to its anti-inflammatory effect and to the normalization of HDAC-4 and myogenin levels, making this treatment an alternative therapeutic tool for sarcopenia.

Keywords: HDAC-4; aging; atrogenes; autophagy; extra virgin olive oil; omega 3 fatty acids; sarcopenia.

Figure 1

Beneficial effects of oil mixture on body weight gain (A), gastrocnemius muscle relative weight (B), gastrocnemius muscle protein concentration (C), and gastrocnemius mRNA levels of myosin heavy chain isoforms (MHC) I and IIa (D). Values are represented as mean ± standard error of the mean (SEM) of young rats (n = 11), old rats (n = 8), and old rats treated for 21 days with the oil mixture (OLD + OILS, n = 5). Statistics: ** p < 0.01 and * p < 0.05 vs. Young; ^## p < 0.01 and ^# p < 0.05 vs. Old, by least-significant difference post hoc analysis after significant one-way analysis of variance (ANOVA).

Figure 2

Oil mixture treatment improved the inflammatory profile and the expression of metabolic regulators in old gastrocnemius muscle. Figures show the mRNA levels of (A) interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), IL-1β and interleukin-6 (IL-10), (B) peroxisome proliferator-activated receptor alpha (PPAR-α), and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) of young rats (n = 11), old rats (n = 8), and old rats treated for 21 days with the oil mixture (OLD + OILS, n = 5). Values are represented as mean ± standard error of the mean (SEM). Statistics: ** p < 0.01 and * p < 0.05 vs. Young; ^## p < 0.01 and ^# p < 0.05 vs. Old, by least-significant difference post hoc analysis after significant one-way analysis of variance (ANOVA).

Figure 3

Oil mixture treatment did not prevent the age-induced decrease of IGF-I serum levels and the muscle Akt signaling pathway, although it did prevent increased expression of muscle IGFBP-5. Figures show (A) insulin-like growth factor (IGF-I) serum levels; (B) gastrocnemius IGF-I, IGF-I receptor (IGF-IR), IGF-I binding protein 3 (IGFBP-3), and 5 (IGFBP-5) mRNA levels; (C) gastrocnemius protein levels and ratio between phospho Akt (pAkt) and Akt of young rats (n = 11), old rats (n = 8) and old rats treated for 21 days with the oil mixture (OLD + OILS, n = 5). Values are represented as mean ± standard error of the mean (SEM). Statistics: ** p < 0.01 and * p < 0.05 vs. Young, by least-significant difference post hoc analysis after significant one-way analysis of variance (ANOVA).

Figure 4

Oil mixture treatment did not prevent age-induced alterations in the expression of atrogenes and Bnip, although it did prevent a decrease in autophagy activity (ratio LC3b II/I) in skeletal muscle. Figures show gastrocnemius (A) muscle RING-finger protein-1 (MuRF1) and atrogin-1; (B) BCL2/adenovirus E1B 19 kDa interacting protein (Bnip) and 1A/1B-light chain 3 (LC3b) mRNA levels; (C) gastrocnemius protein levels and ratio between LC3b I and II of young rats (n = 11), old rats (n = 8) and old rats treated for 21 days with the oil mixture (OLD + OILS, n = 5). Values are represented as mean ± standard error of the mean (SEM). Statistics: ** p < 0.01 and * p < 0.05 vs. Young; ^## p < 0.01 and ^# p < 0.05 vs. Old, by least-significant difference post hoc analysis after significant one-way analysis of variance (ANOVA).

Figure 5

Oil mixture treatment prevented the age-induced activation of the HADC-4-myogenin axis in skeletal muscle. Figures show gastrocnemius mRNA levels of (A) histone deacetylase 4 (HDAC-4) and myogenin and (B) HDAC-4 protein levels of young rats (n = 11), old rats (n = 8) and old rats treated for 21 days with the oil mixture (OLD + OILS, n = 5). Values are represented as mean ± standard error of the mean (SEM). Statistics: ** p < 0.01 and * p< 0.05 vs. Young; ^## p < 0.01 and ^# p < 0.05 vs. Old, by least-significant difference post hoc analysis after significant one-way analysis of variance (ANOVA).

Figure 6

Schematic representation of the effects of the oil mixture on the main aged-induced alterations in skeletal muscle. Oil mixture administration prevented the age-induced increase of HDAC-4. This effect, together with the decrease in inflammatory mediators, may have beneficial consequences such as the prevention of the fiber senescence and muscle atrophy, restoration of autophagy equilibrium, increase in mitochondriogenesis, fatty acid oxidation rate, and protein synthesis. All these effects help to prevent the development of sarcopenia (see Discussion for further details). Abbreviations: BP-5 (insulin-like growth factor I binding protein 5); HDAC-4 (histone deacetylase 4); IL (interleukin); LC3 (1A/1B-light chain 3); MHC (myosin heavy chain); PGC-1α (peroxisome proliferator-activated receptor gamma coactivator 1-alpha); PPAR-α (proliferator-activated receptor alpha).