Manual therapy ameliorates delayed-onset muscle soreness and alters muscle metabolites in rats

Whole-body insulin resistance and energy expenditure indices, serum lipids, and skeletal muscle metabolome in a state of lipoprotein lipase overexpression

INTRODUCTION

Overexpression of lipoprotein lipase (LPL) protects against high-fat-diet (HFD)-induced obesity and insulin resistance in transgenic rabbits; however, the molecular mechanisms remain unclear. Skeletal muscle is a major organ responsible for insulin-stimulated glucose uptake and energy expenditure.

OBJECTIVES

The main purpose of the current study was to examine the effects of the overexpression of LPL on the skeletal muscle metabolomic profiles to test our hypothesis that the mitochondrial oxidative metabolism would be activated in the skeletal muscle of LPL transgenic rabbits and that the higher mitochondrial oxidative metabolism activity would confer better phenotypic metabolic outcomes.

METHODS

Under a HFD, insulin resistance index was measured using the intravenous glucose tolerance test, and total energy expenditure (TEE) was measured by doubly-labeled water in control and LPL transgenic rabbits (n = 12, each group). Serum lipids, such as triglycerides and free fatty acid, were also measured. The skeletal muscle metabolite profile was analyzed using capillary electrophoresis time-of flight mass spectrometry in the two groups (n = 9, each group). A metabolite set enrichment analysis (MSEA) with muscle metabolites and a false discovery rate q < 0.2 was performed to identify significantly different metabolic pathways between the 2 groups.

RESULTS

The triglycerides and free fatty acid levels and insulin resistance index were lower, whereas the TEE was higher in the LPL transgenic rabbits than in the control rabbits. Among 165 metabolites detected, the levels of 37 muscle metabolites were significantly different between the 2 groups after false discovery rate correction (q < 0.2). The MSEA revealed that the TCA cycle and proteinogenic amino acid metabolism pathways were significantly different between the 2 groups (P < 0.05). In the MSEA, all four selected metabolites for the TCA cycle (2-oxoglutaric acid, citric acid, malic acid, fumaric acid), as well as eight selected metabolites for proteinogenic amino acid metabolism (asparagine, proline, methionine, phenylalanine, histidine, arginine, leucine, isoleucine) were consistently increased in the transgenic rabbits compared with control rabbits, suggesting that these two metabolic pathways were activated in the transgenic rabbits. Some of the selected metabolites, such as citric acid and methionine, were significantly associated with serum lipids and insulin resistance (P < 0.05).

CONCLUSION

The current results suggest that the overexpression of LPL may lead to increased activities of TCA cycle and proteinogenic amino acid metabolism pathways in the skeletal muscle, and these enhancements may play an important role in the biological mechanisms underlying the anti-obesity/anti-diabetes features of LPL overexpression.

Distinct effects of thermal treatments after lengthening contraction on mechanical hyperalgesia and exercise-induced physiological changes in rat muscle

Delayed-onset muscle soreness (DOMS) is a common but displeasing event induced by excessive muscle use or unaccustomed exercise and characterized by tenderness and movement-related pain in the exercised muscle. Thermal therapies, either icing or heating applied to muscles immediately after exercise, have been used as therapeutic interventions for DOMS. However, the mechanisms of their analgesic effects, and physiological and metabolic changes in the muscle during thermal therapy, remain unclear. In the present study, we investigated the effects of both thermal treatments on mechanical hyperalgesia of DOMS and physiological and muscle metabolite changes using the rat DOMS model induced by lengthening contraction (LC) to the gastrocnemius muscle. Heating treatment just after LC induced analgesic effects, while rats with icing treatment showed mechanical hyperalgesia similar to that of the LC group. Furthermore, increased physiological responses (e.g., muscle temperature and blood flow) following the LC were significantly kept high only in the rats with heating treatment. In addition, heating treatment increased metabolites involved in the improvement of blood flow and oxidative metabolisms in the exercised muscle. The results indicated that heating treatment just after LC has analgesic effects on DOMS, which might be mediated partly through the improvement of muscle oxidative metabolisms by changes in metabolites and elevated physiological responses.NEW & NOTEWORTHY Physiological effects of thermal therapy in the muscle and its mechanisms of analgesic effects remain unclear. The results indicated that heating, but not icing, treatment just after lengthening contractions induced analgesic effects in the rat muscle. Increases in hemodynamics, muscle temperature, and metabolites such as nicotinamide were more prominent in heating treatment, consistent with improvement of muscle oxidative metabolisms, which might reduce chemical factors to induce mechanical hyperalgesia.

Effect of compression garments on delayed-onset muscle soreness and blood inflammatory markers after eccentric exercise: a randomized controlled trial

The purpose of this study was to investigate how compression garments, applied after eccentric exercise, can affect delayed onset muscle soreness (DOMS) and inflammatory markers. Sixteen healthy male university students enrolled in this study and were randomly assigned to either the compression garment group (CG, n=8) or control group (CON, n=8). All participants performed two sets of eccentric exercise using elbow flexor with 25 repetitions per set on a modified preacher curl machine. Maximal isometric strength was measured before exercise and immediately, 24, 48, 72, and 96 hr after eccentric exercise. Muscle soreness was measured before exercise and 24, 48, 72, and 96 hr after eccentric exercise. Creatine kinase (CK) activity and tumor necrosis factor-alpha (TNF-α) levels were also measured before exercise and 3, 6, 24, and 48 hr after exercise. A repeated measures analysis of variance was used for statistical analysis. The CG group reported faster recovery of maximal isometric strength following exercise (P<0.001) and lower muscle soreness during the recovery period than the control group (P<0.05). However, there were no significant differences in either CK activity or TNF-α levels between the two groups (P>0.05). In conclusion, wearing compression garments during the postexercise period can be an effective way to reduce DOMS and accelerate the recovery of muscle function.

Metabolome Profiling of Partial and Fully Reprogrammed Induced Pluripotent Stem Cells

Acquisition of proper metabolomic fate is required to convert somatic cells toward fully reprogrammed pluripotent stem cells. The majority of induced pluripotent stem cells (iPSCs) are partially reprogrammed and have a transcriptome different from that of the pluripotent stem cells. The metabolomic profile and mitochondrial metabolic functions required to achieve full reprogramming of somatic cells to iPSC status have not yet been elucidated. Clarification of the metabolites underlying reprogramming mechanisms should enable further optimization to enhance the efficiency of obtaining fully reprogrammed iPSCs. In this study, we characterized the metabolites of human fully reprogrammed iPSCs, partially reprogrammed iPSCs, and embryonic stem cells (ESCs). Using capillary electrophoresis time-of-flight mass spectrometry-based metabolomics, we found that 89% of analyzed metabolites were similarly expressed in fully reprogrammed iPSCs and human ESCs (hESCs), whereas partially reprogrammed iPSCs shared only 74% similarly expressed metabolites with hESCs. Metabolomic profiling analysis suggested that converting mitochondrial respiration to glycolytic flux is critical for reprogramming of somatic cells into fully reprogrammed iPSCs. This characterization of metabolic reprogramming in iPSCs may enable the development of new reprogramming parameters for enhancing the generation of fully reprogrammed human iPSCs.

A metabolic profile in Ruditapes philippinarum associated with growth-promoting effects of alginate hydrolysates

The aim of this study is to demonstrate the growth-promoting effect of alginate hydrolysates (AHs) on the Manila clam Ruditapes philippinarum, and to verify the physiological change occurring within a living R. philippinarum stimulated by AHs. We show that growth of clams was dramatically promoted by supplementing a diet of the diatom Chaetoceros neogracile with AHs at 4 mg/mL. Furthermore, metabolomics indicates that each state of starvation, food satiation, and sexual maturation have a characteristic pattern. In the groups given AHs in addition to C. neogracile in particular, excess carbohydrate was actively utilized for the development of reproductive tissue. In contrast, it appeared that clams in the groups given C. neogracile only were actively growing, utilizing their adequate carbohydrate resources. Meanwhile, the unfed groups have slowed growth because of the lack of an energy source. Hence, supplementation of AHs in addition to the algal diet may be an inexpensive way to shorten the rearing period of R. philippinarum. Moreover, metabolomics can evaluate the growth condition of R. philippinarum in a comprehensive way, and this approach is crucially important for not only the development of a mass culture method but also for the conservation of the clam resource in the field.

Manual therapy as an effective treatment for fibrosis in a rat model of upper extremity overuse injury

Key clinical features of carpal tunnel syndrome and other types of cumulative trauma disorders of the hand and wrist include pain and functional disabilities. Mechanistic details remain under investigation but may involve tissue inflammation and/or fibrosis. We examined the effectiveness of modeled manual therapy (MMT) as a treatment for sensorimotor behavior declines and increased fibrogenic processes occurring in forearm tissues of rats performing a high repetition high force (HRHF) reaching and grasping task for 12 weeks. Young adult, female rats were examined: food restricted control rats (FRC, n=12); rats that were trained for 6 weeks before performing the HRHF task for 12 weeks with no treatment (HRHF-CON, n=11); and HRHF task rats received modeled manual therapy (HRHF-MMT, n=5) for 5 days/week for the duration of the 12-week of task. Rats receiving the MMT expressed fewer discomfort-related behaviors, and performed progressively better in the HRHF task. Grip strength, while decreased after training, improved following MMT. Fibrotic nerve and connective tissue changes (increased collagen and TGF-β1 deposition) present in 12-week HRHF-CON rats were significantly decreased in 12-week HRHF-MMT rats. These observations support the investigation of manual therapy as a preventative for repetitive motion disorders.

Delayed onset muscle soreness: Involvement of neurotrophic factors

Delayed-onset muscle soreness (DOMS) is quite a common consequence of unaccustomed strenuous exercise, especially exercise containing eccentric contraction (lengthening contraction, LC). Its typical sign is mechanical hyperalgesia (tenderness and movement related pain). Its cause has been commonly believed to be micro-damage of the muscle and subsequent inflammation. Here we present a brief historical overview of the damage-inflammation theory followed by a discussion of our new findings. Different from previous observations, we have observed mechanical hyperalgesia in rats 1-3 days after LC without any apparent microscopic damage of the muscle or signs of inflammation. With our model we have found that two pathways are involved in inducing mechanical hyperalgesia after LC: activation of the B2 bradykinin receptor-nerve growth factor (NGF) pathway and activation of the COX-2-glial cell line-derived neurotrophic factor (GDNF) pathway. These neurotrophic factors were produced by muscle fibers and/or satellite cells. This means that muscle fiber damage is not essential, although it is sufficient, for induction of DOMS, instead, NGF and GDNF produced by muscle fibers/satellite cells play crucial roles in DOMS.