SummaryThe leucine metabolite b-hydroxy-b-methylbutyrate (HMB) has been studied by many researchers over the last two decades. In particular, the utility of HMB supplementation in animals has been shown in numerous studies, which have demonstrated enhanced body weight gain and carcass yield in slaughter animals; positive immunostimulatory effect; decreased mortality; attenuation of sarcopenia in elderly animals; and potential use in pathological conditions such as glucocorticoid-induced muscle loss. The aim of this study was to summarize the body of research on HMB supplementation in animals and to examine possible mechanisms of HMB action. Furthermore, while the safety of HMB supplementation in animals is well documented, studies demonstrating efficacy are less clear. The possible reasons for differences in these findings will also be examined.

Recent studies have shown that naturally occurring substances found in the food of the daily human diet are important for preventing chronic non-communicable diseases. One of them is beta-glucan, which is a natural polysaccharide, occurring in plant cell walls, mainly oats, barley and wheat. It is also present in baker’s yeast cells, fungal cell walls, and some microorganisms. Beta-glucan belongs to one of the dietary fiber fractions, which are attributed a number of beneficial health properties, including the prevention and treatment of certain digestive diseases and supporting the immune system. This compound has biological activity that depends on the size, molecular weight, conformation, frequency of bonds, solubility and changes in structure. Beta-glucan reduces cholesterol and glucose concentrations in the blood, which reduces the risk of cardiovascular disease and diabetes. In addition to its effects on lipid levels and glucose metabolism, beta-glucan also exhibits antioxidant properties by scavenging reactive oxygen species, thereby reducing the risk of diseases, including atherosclerosis, cardiovascular diseases, neurodegenerative diseases, diabetes, and cancer. Immunostimulatory and antitumor effects have also been reported. The immunostimulatory activity of beta-glucan occurs as a result of its attachment to specific receptors present on the immune cell surface. Beta-glucan belongs to the group of prebiotics which stimulate the growth and activity of the desired natural intestinal microbiota, while inhibiting the growth of pathogens. It plays an important role in the proper functioning of the gastrointestinal tract and preventing inflammation as well as colon cancer. Such a number of health benefits resulting from the properties of beta-glucan may play a key role in improving health and preventing chronic non-communicable diseases, such as diabetes, hypercholesterolemia, obesity, cardiovascular diseases, and cancer.

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SummaryGamma-oryzanol (GO) is an abundant dietary antioxidant that is considered to have beneficial effects in cardiovascular disease, cancer and diabetes. Other potential properties of GO include inhibition of gastric acid secretion and decreased post-exercise muscle fatigue. GO is a unique mixture of triterpene alcohol and sterol ferulates present in rice bran oil, a byproduct of rice processing. GO has been studied by many researchers over the last three decades. In particular, the utility of GO supplementation has been documented in numerous animal models. A large variety of species was examined, and various experimental methodologies and targets were applied. The aim of this study was to summarize the body of research on GO supplementation in animals and to examine possible mechanisms of GO action. Furthermore, while the safety of GO supplementation in animals has been well documented, studies demonstrating pharmacokinetics, pharmacodynamics and efficiency are less clear. The observed differences in these findings are also discussed.

Myostatin (GDF-8) is a key protein responsible for skeletal muscle growth and development, thus mutations in the mstn gene can have major economic and breeding consequences. The aim of the present study was to investigate myostatin gene expression and transcriptional profile in skeletal muscle of Holstein-Friesian (Black-and-White) bulls carrying a polymorphism in the 5'-flanking region of the mstn gene (G/C transversion at position -7828). Real-time qRT-PCR and cDNA microarray revealed significantly lower mstn expression in muscle of bulls with the CC genotype, as compared to GG and GC genotypes. The direct comparison of skeletal muscle transcriptional profiles between the CC genotype and GG and GC genotypes resulted in identification of genes, of which at least some can be putative targets for myostatin. Using cDNA microarray, we identified 43 common genes (including mstn) with significantly different expression in skeletal muscle of bulls with the CC genotype, as compared to GG and GC genotypes, 15 of which were upregulated and 28 were downregulated in the CC genotype. Classification of molecular function of differentially expressed genes revealed the highest number of genes involved in the expression of cytoskeleton proteins (9), extracellular matrix proteins (4), nucleic acid-binding proteins (4), calcium-binding proteins (4), and transcription factors (4). The biological functions of the largest number of genes involved: protein metabolism and modification (10), signal transduction (10), cell structure (8), and developmental processes (8). The main identified signaling pathways were: Wnt (4), chemokines and cytokines (4), integrin (4), nicotine receptor for acetylocholine (3), TGF-beta (2), and cytoskeleton regulation by Rho GTPase (2). We identified previously unrecognized putatively myostatin-dependent genes, encoding transcription factors (EGR1, Nf1b, ILF1), components of the proteasomal complex (PSMB7, PSMD13) and proteins with some other molecular function in skeletal muscle (ITGB1BP3, Pla2g1b, ISYNA1, TNFAIP6, MST1, TNNT1, CALB3, CACYBP, and CTNNA1).

A cDNA microarray (18 263 probes) was used for transcriptome analysis of bovine skeletal muscle (m. semitendinosus) in 12-month-old bulls of the beef breed Limousin (LIM) and the typical dairy breed Holstein-Friesian (HF, used as a reference). We aimed to identify the genes whose expression may reflect the muscle phenotype of beef bulls. A comparison of muscle transcriptional profiles revealed significant differences in expression of 393 genes between HF and LIM. We classified biological functions of 117 genes with over 2-fold differences in expression between the examined breeds. Among them, 72 genes were up-regulated and 45 genes were down-regulated in LIM vs. HF. The genes were involved in protein metabolism and modifications (22 genes), signal transduction (15), nucleoside, nucleotide and nucleic acid metabolism (13), cell cycle (9), cell structure and motility (9), developmental processes (9), intracellular protein traffic (7), cell proliferation and differentiation (6), cell adhesion (6), lipid, fatty acid and steroid metabolism (5), transport (5), and other processes. For the purpose of microarray data validation, we randomly selected 4 genes: trip12, mrps30, pycrl, and c-erbb3. Real-time RT-PCR results showed similar trends in gene expression changes as those observed in microarray studies. Basing on results of the present study, we proposed a model of the regulation of skeletal muscle growth and differentiation, with a principal role of the somatotropic pathway. It may explain at least in part the development of muscle phenotype in LIM bulls. We assume that the growth hormone directly or indirectly (through IGF-1) activates the calcium-signaling pathway with calcineurin, which stimulates myogenic regulatory factors (MRFs) and inhibits early growth response gene. The inhibition results in indirect activation of MRFs and impaired activation of TGF-beta1 and myostatin, which finally facilitates terminal muscle differentiation.

BackgroundSkeletal muscle in livestock develops into meat, an important source of protein and other nutrients for human consumption. The muscle is largely composed of a fixed number of multinucleated myofibers determined during late gestation and remains constant postnatally. A population of postnatal muscle stem cells, called satellite cells, gives rise to myoblast cells that can fuse with the existing myofibers, thus increasing their size. This requires a delicate balance of transcription and growth factors and specific microRNA (miRNA) expressed by satellite cells and their supporting cells from the muscle stem cell niche. The role of transcription and growth factors in bovine myogenesis is well-characterized; however, very little is known about the miRNA activity during this process. We have hypothesized that the expression of miRNA can vary between primary cultures of skeletal muscle cells isolated from the semitendinosus muscles of different cattle breeds and subjected to myogenic differentiation.ResultsAfter a 6-day myogenic differentiation of cells isolated from the muscles of the examined cattle breeds, we found statistically significant differences in the number of myotubes between Hereford (HER)/Limousine (LIM) beef breeds and the Holstein-Friesian (HF) dairy breed (p ≤ 0.001). The microarray analysis revealed differences in the expression of 23 miRNA among the aforementioned primary cultures. On the basis of a functional analysis, we assigned 9 miRNA as molecules responsible for differentiation progression (miR-1, -128a, -133a, -133b, -139, -206, -222, -486, and -503). The target gene prediction and functional analysis revealed 59 miRNA-related genes belonging to the muscle organ development process.ConclusionThe number of myotubes and the miRNA expression in the primary cultures of skeletal muscle cells derived from the semitendinosus muscles of the HER/LIM beef cattle breeds and the HF dairy breed vary when cells are subjected to myogenic differentiation. The net effect of the identified miRNA and their target gene action should be considered the result of the breed-dependent activity of satellite cells and muscle stem cell niche cells and their mutual interactions, which putatively can be engaged in the formation of a larger number of myotubes in beef cattle-related cells (HER/LIM) during in vitro myogenesis.Electronic supplementary materialThe online version of this article (10.1186/s12864-018-4492-5) contains supplementary material, which is available to authorized users.