Eicosapentaenoic acid enhances skeletal muscle hypertrophy without altering the protein anabolic signaling pathway.

This study aimed to examine the effect of eicosapentaenoic acid (EPA) on skeletal muscle hypertrophy induced by muscle overload and the associated intracellular signaling pathways. Male C57BL/6J mice were randomly assigned to oral treatment with either EPA or corn oil for 6 weeks. After 4 weeks of treatment, the gastrocnemius muscle of the right hindlimb was surgically removed to overload the plantaris and soleus muscles for 1 or 2 weeks. We examined the effect of EPA on the signaling pathway associated with protein synthesis using the soleus muscles. According to our analysis of the compensatory muscle growth, EPA administration enhanced hypertrophy of the soleus muscle but not hypertrophy of the plantaris muscle. Nevertheless, EPA administration did not enhance the expression or phosphorylation of Akt, mechanistic target of rapamycin (mTOR), or S6 kinase (S6K) in the soleus muscle. In conclusion, EPA enhances skeletal muscle hypertrophy, which can be independent of changes in the AKT-mTOR-S6K pathway.

Effect of prior chronic aerobic exercise on overload-induced skeletal muscle hypertrophy in mice.

This study aimed to examine how regular aerobic training can affect the muscle hypertrophy induced by overloading. Male C57BL/6J mice were randomly divided into three groups: rest group, low-intensity aerobic exercise group, and high-intensity aerobic exercise group. Mice in the exercise groups were assigned to run at a speed of 10 m/min (low-intensity) or 25 m/min (high-intensity) for 30 min/day, five days/week, for four weeks. Then, the right hind leg gastrocnemius muscles were surgically removed to overload the plantaris and soleus muscles, while the left hind leg was subjected to a sham-operation. Both the plantaris and soleus muscles grew larger in the overloaded legs than those in the sham-operated legs. Muscle growth increased in the plantaris muscles in the low-intensity exercise group compared to that in the rest or high-intensity exercise groups at one and two weeks after overloading. This enhancement was not observed in the soleus muscles. Consistently, we observed changes in the expression of proteins involved in anabolic intracellular signaling, including Akt, mechanistic target of rapamycin (mTOR), and p70S6K, in the plantaris muscles. Our data showed for the first time that chronic low-intensity aerobic exercise precipitates overload-induced muscle growth.

Molecular phylogeny of the Bactrian camel based on mitochondrial Cytochrome b gene sequences.

The Bactrian camel is an important domesticated animal providing milk, meat, and other products in desert countries. In this study, 111 individuals representing 11 domestic Bactrian camel breeds from China, Mongolia, Russia, and one wild Bactrian camel group from Mongolia were selected for the preparation of mitochondrial DNA. The 1140-bp fragments of the cytochrome b gene (Cytb) were amplified by polymerase chain reaction and sequenced directly. Sequences of the 92 domestic and 19 wild Bactrian camel samples were analyzed with DNASTAR, and a phylogenic tree was constructed using MEGA. The analysis revealed sixteen haplotypes among the samples that were divided into two haplogroups: a domestic haplogroup (H1-H13, H15, and H16) and a wild haplogroup (H14). Haplotype diversity values were from 0.356 in the HosZogdort, to 0.889 in the Sunit Bactrian camel breed. The Sunit breed displayed the highest nucleotide diversity value (0.00115), and the HosZogdort breed had the lowest value (0.00031). All domestic Bactrian camels formed a single monophyletic lineage that is the sister group to wild Bactrian camels, a finding consistent with a single domestication event and independent maternal inheritance since domestication. In addition, the most common mitochondrial haplotypes (H1, H3, and H4) were shared between Chinese, Mongolian, and Russian domestic Bactrian camels, which indicated that there was no distinguishing geographic structure among the domestic breeds from these three regions. These findings provide important insights into patterns of relatedness among Bactrian camels from the Chinese, Mongolian, and Russian regions.