Undernutrition regulates the expression of a novel splice variant of myostatin and insulin-like growth factor 1 in ovine skeletal muscle

Gene expression in the Longissimus dorsi muscle related to meat quality from tropical hair lambs

The present study describes the expression of genes in the Longissimus dorsi muscle related to meat quality of hair lambs finished in an Integration Crop-Livestock system. Twenty-eight non-castrated lambs of two breeds, Somalis Brasileira and Santa Inês, at 120 ± 15 days of age, with an average initial live weight of 18 ± 3.1 kg, were kept in a pasture-based finishing system with supplementation. Upon reaching 28 kg body weight, animals were sent for slaughter. Samples of the Longissimus dorsi and Biceps femoris muscle were harvested for analyses of gene expression and physicochemical properties. Significant differences were detected between the breeds for tissue and chemical composition, whereas the physical aspects did not differ. We observed the expression of six genes related to lipid synthesis (acetyl-CoA carboxylase [ACACA], fatty acid synthase [FAS], stearoyl-CoA desaturase [SCD], lipoprotein lipase [LPL], cell death-inducing DFFA-like effector A [CIDEA], and thyroid hormone responsive [THRSP]) and six genes related to molecular synthesis (myostatin [MSTN], growth differentiation factor 8 [GDF8], insulin-like growth factor 1 [IGF1], insulin-like growth factor 2 [IGF2], delta-like 1 homolog [DLK1], and growth hormone receptor [GHr]) in both breeds. The Santa Inês breed and the Somalis Brasileira showed similar expression patterns of genes related to lipogenesis and myogenesis of the Longissimus dorsi muscle, with the exception of the THRSP gene, in which the Somalis Brasileira have more receptors for the action of thyroid hormones, which resulted in greater thickness of fat in the carcass (subcutaneous fat) and higher lipid content in the chemical composition of the meat.

The Role of Crosstalk between Adipose Cells and Myocytes in the Pathogenesis of Sarcopenic Obesity in the Elderly

As a result of aging, body composition changes, with a decline in muscle mass and an increase in adipose tissue (AT), which reallocates from subcutaneous to visceral depots and stores ectopically in the liver, heart and muscles. Furthermore, with aging, muscle and AT, both of which have recognized endocrine activity, become dysfunctional and contribute, in the case of positive energy balance, to the development of sarcopenic obesity (SO). SO is defined as the co-existence of excess adiposity and low muscle mass and function, and its prevalence increases with age. SO is strongly associated with greater morbidity and mortality. The pathogenesis of SO is complex and multifactorial. This review focuses mainly on the role of crosstalk between age-related dysfunctional adipose and muscle cells as one of the mechanisms leading to SO. A better understanding of this mechanisms may be useful for development of prevention strategies and treatments aimed at reducing the occurrence of SO.

Correlation between insulin-like growth factor 1 gene expression and fennel (Foeniculum vulgare) seed powder consumption in muscle of sheep

It has been shown that addition of fennel in the diets of domestic animals has positive and beneficial effects on growth and meat production traits. Thus, the purpose of current study was to investigate the effect of adding fennel in the ration on growth characteristics and on insulin-like growth factor 1 (IGF1) gene expression in muscle tissue of Kermani lamb. Feeding of animals were performed with three levels of fennel including zero, 10 and 20 g/kg dry matter (DM) for 90 days. After slaughter, small pieces of tissues were removed and rapidly transferred to a nitrogen tank. Then, total RNA extracting and the Real-Time PCR reaction was performed. Results showed that as the level of fennel in the diet increases the amount of IGF1 gene expression also increases significantly in humeral muscle and femur (leg) muscle tissues (p < 0.05). In animals fed with fennel, femur muscle weight, back muscle weight, lean meat weight, final weight, warm carcass weight and live daily gain were greater than in animals fed with diet without fennel (p < 0.05). According to the findings of this investigation, it can be concluded that fennel, by creating positive effects on IGF1 gene expression can be used to improve muscle structure.

A variant associated to IGF-1 mRNA and protein expression in sheep

The insulin-like growth factor-1 (IGF-1), a key hormone in muscle development was investigated for single-nucleotide polymorphisms (SNPs) upstream of the IGF-1 gene and their effects upon its cognate mRNA and hormone levels in sheep. A 70 d feeding trial was conducted with 22 F1 (Dorper × Pelibuey) lambs, individually allocated and fed a diet with a forage-to-concentrate ratio of 36:64 and 17% crude protein. Sequence analyses of 265 bp upstream the IGF-1 gene revealed the variant NC_040254.1:g.[184028491G > C;184028493G > A]. These SNPs generate alleles A and B, with frequencies of 0.66 and 0.34 in F1 lambs and of 0.73 and 0.27 in 81 pure Dorper lambs, respectively. Females were grouped by genotype AA, AB and BB (n = 3). IGF-1 hormone concentrations at 14, 42 and 70 d were higher (p < 0.05) in AA lambs compared to AB + BB lambs. The IGF-1 mRNA level was 2.6-fold higher in AA animals (n = 5, p < 0.05) than in AB + BB lambs (n = 7). A DNA binding site for the Inhibitor of Growth family member 4 (ING4) was found in allele B but not in allele A, which could explain the lower mRNA and hormone expression levels for AB + BB animals. The variant reported here appears to function as an eQTL with a negative effect on the level of IGF-1.

The association of the serum levels of myostatin, follistatin, and interleukin-6 with sarcopenia, and their impacts on survival in patients with hepatocellular carcinoma

Background/Aims

The role of serum myokine levels in sarcopenia and the outcome of hepatocellular carcinoma (HCC) patients are not clear. This study investigated the serum levels of myostatin, follistatin, and interleukin-6 (IL-6) in HCC patients and their association with sarcopenia and survival.

Methods

Using prospectively collected pretreatment samples from 238 HCC patients in a hospital from 2012 to 2015, the serum levels of 3 myokines were determined and compared to 50 samples from age and sex-matched healthy controls. Sarcopenia was evaluated using the psoas muscle index (PMI) measured at the third lumbar level in the computed tomography, and clinical data were collected until 2017.

Results

The median levels of the 3 myokines for the male and female HCC patients were as follow: myostatin (3,979.3 and 2,976.3 pg/mL), follistatin (2,118.5 and 2,174.6 pg/mL), and IL-6 (2.5 and 2.7 pg/mL), respectively. Those in the HCC patients were all significantly higher than in the healthy controls. In the HCC patient, the median PMI was 4.43 (males) and 2.17 cm²/m² (females) with a sarcopenic prevalence of 56.4%. The serum levels of myostatin, IL-6 and follistatin in the HCC patients showed a positive, negative, and no correlation with PMI, respectively. The serum follistatin level was an independent factor for poor survival in HCC patients.

Conclusions

The serum levels of myostatin, follistatin, and IL-6 and their correlation with sarcopenia and survival were presented in HCC patients for the first time. The role of the serum follistatin level as a poor prognostic biomarker warrants further study.

Healthy community-living older men differ from women in associations between myostatin levels and skeletal muscle mass

BACKGROUND

Myostatin is a negative regulator of muscle growth but the relationship between serum myostatin levels and muscle mass is unclear. This study investigated the association between serum myostatin levels and skeletal muscle mass among healthy older community residents in Taiwan, to evaluate the potential of serum myostatin as a biomarker for diagnosing sarcopenia and/or evaluating the effect of its treatment.

METHODS

Study data were excerpted from a random subsample of the I-Lan Longitudinal Aging Study population. Serum myostatin levels were determined and categorized into tertiles (low, medium, high). Relative appendicular skeletal muscle mass (RASM) was calculated as appendicular lean body mass by dual-energy X-ray absorptiometry divided by height squared (kg/m² ). Low muscle mass was defined as recommended by the Asian Working Group for Sarcopenia.

RESULTS

The analytic study sample comprised 463 adults (mean age: 69.1 years; 49.5% men). Compared with subjects with normal RASM, those with lower RASM were older and frailer, with significantly higher prevalence of malnutrition, lower serum dehydroepiandrosterone (DHEA) levels, and were more likely to have low serum myostatin status. Multivariable logistic regression analysis showed that male sex (OR 3.60, 95% CI 1.30-9.92), malnutrition (OR 4.39, 95% CI 1.56-12.36), DHEA (OR 0.99, 95% CI 0.99-1.00), and low myostatin (OR 3.23, 95% CI 1.49-7.01) were all independent risk factors for low RASM (all P < 0.05). In men, DHEA (OR 0.99, 95% CI 0.98-1.00) and low myostatin (OR 4.89, 95% CI 1.79-13.37) were significantly associated with low RASM (both P < 0.05); however, only malnutrition was associated with low RASM in women (OR 13.59, 95% CI 2.22-83.25, P < 0.05).

CONCLUSIONS

Among healthy community-living older adults, low serum myostatin levels were associated with low skeletal muscle mass in men, but not in women. Our results do not support using serum myostatin levels to diagnose sarcopenia, or to monitor how it responds to treatments. Further research is needed to understand why men apparently differ from women in the interrelationship between their myostatin levels and muscle mass.

The effect of caloric restriction on the forelimb skeletal muscle fibers of the hypertrophic myostatin null mice

Skeletal muscle mass loss has a broad impact on body performance and physical activity. Muscle wasting occurs due to genetic mutation as in muscular dystrophy, age-related muscle loss (sarcopenia) as well as in chronic wasting disorders as in cancer cachexia. Food restriction reduces muscle mass underpinned by increased muscle protein break down. However the influence of dietary restriction on the morphometry and phenotype of forelimb muscles in a genetically modified myostatin null mice are not fully characterized. The effect of a five week dietary limitation on five anatomically and structurally different forelimb muscles was examined. C57/BL6 wild type (Mstn^+/+) and myostatin null (Mstn^-/-) mice were either given a standard rodent normal daily diet ad libitum (ND) or 60% food restriction (FR) for a 5 week period. M. triceps brachii Caput laterale (T.lateral), M. triceps brachii Caput longum (T.long), M. triceps brachii Caput mediale (T.medial), M. extensor carpi ulnaris (ECU) and M. flexor carpi ulnaris (FCU) were dissected, weighted and processed for immunohistochemistry. Muscle mass, fibers cross sectional areas (CSA) and myosin heavy chain types IIB, IIX, IIA and type I were analyzed. We provide evidence that caloric restriction results in muscle specific weight reduction with the fast myofibers being more prone to atrophy. We show that slow fibers are less liable to dietary restriction induced muscle atrophy. The effect of dietary restriction was more pronounced in Mstn^-/- muscles to implicate the oxidative fibers compared to Mstn^+/+. Furthermore, peripherally located myofibers are more susceptible to dietary induced reduction compared to deep fibers. We additionally report that dietary restriction alters the glycolytic phenotype of the Mstn^-/- into the oxidative form in a muscle dependent manner. In summary our study shows that calorie restriction alters muscle fiber profile of forelimb muscles of Myostatin null mice.