Muscle Wet Weight Research Articles

Therapeutic effects of diclofenac, pregabalin, and duloxetine on disuse-induced chronic musculoskeletal pain in rats

The aim of this study was to clarify the mechanism of disuse-induced muscle hyperalgesia through the evaluation of the pharmacological behaviour of muscle hyperalgesia profiles in chronic post-cast pain (CPCP) rats with acute and chronic-phase mirror-image muscle hyperalgesia treated with diclofenac (NSAID), pregabalin (an inhibitor of Ca2+ channel α2δ), and duloxetine (SNRI). After 2 weeks of cast immobilization, the peak cross-sectional area and muscle wet weight of the ipsilateral soleus and gastrocnemius muscles decreased more significantly in CPCP rats than in untreated rats. Histological findings revealed disuse-induced muscle atrophy in CPCP rats. The blood biochemical parameters of CPCP rats in acute and chronic phases did not differ significantly from those of untreated rats. The diclofenac and pregabalin-treated groups exhibited no improvement in acute or chronic muscle hyperalgesia. In contrast, the duloxetine-treated group exhibited an improvement in acute muscle hyperalgesia, but showed no apparent effect on chronic muscle hyperalgesia on ipsilateral or contralateral sides. However, the chronic muscle hyperalgesia was reversed by intrathecal administration of DAMGO (a μ-opioid receptor agonist). The results suggest that chronic muscle hyperalgesia in CPCP rats did not result from an inflammatory mechanism, and there is only a low probability that it’s caused by a neuropathic mechanism.

Developmental dosing with a MEK inhibitor (PD0325901) rescues myopathic features of the muscle-specific but not limb-specific Nf1 knockout mouse

Neurofibromatosis Type 1 (NF1) is a common autosomal dominant genetic disorder While NF1 is primarily associated with predisposition for tumor formation, muscle weakness has emerged as having a significant impact on quality of life. NF1 inactivation is linked with a canonical upregulation Ras-MEK-ERK signaling. This in this study we tested the capacity of the small molecule MEK inhibitor PD0325901 to influence the intramyocellular lipid accumulation associated with NF1 deficiency. Established murine models of tissue specific Nf1 deletion in skeletal muscle (Nf1MyoD−/−) and limb mesenchyme (Nf1Prx1−/−) were tested.Developmental PD0325901 dosing of dams pregnant with Nf1MyoD−/− progeny rescued the phenotype of day 3 pups including body weight and lipid accumulation by Oil Red O staining. In contrast, PD0325901 treatment of 4 week old Nf1Prx1−/− mice for 8 weeks had no impact on body weight, muscle wet weight, activity, or intramyocellular lipid. Examination of day 3 Nf1Prx1−/− pups showed differences between the two tissue-specific knockout strains, with lipid staining greatest in Nf1MyoD−/− mice, and fibrosis higher in Nf1Prx1−/− mice.These data show that a MEK/ERK dependent mechanism underlies NF1 muscle metabolism during development. However, crosstalk from Nf1-deficient non-muscle mesenchymal cells may impact upon muscle metabolism and fibrosis in neonatal and mature myofibers.

Thermally processed diet greatly affects profiles of amino acids rather than fatty acids in the muscle of carnivorous Silurus meridionalis

This study aimed to evaluate the effects of thermally processed diet (TD) on the muscle nutritional values of southern catfish in two experiments (named E1 and E2). Compared to non-thermally processed diet (ND), TD did not significantly affect proximate composition of southern catfish, but increased moisture content and decreased protein content in E1. Meanwhile, it had no effect on overall fatty acid profiles of the catfish rich in PUFA. Southern catfish had high proportions of indispensable amino acids (IAA, 44.6–46.4% of total fatty acids), with the highest contents of lysine (1551–1808 mg/100 g wet weight muscle). However, TD altered profiles of the IAA, particularly decreased 68.5% and 68.4% of methionine, and 9.5% and 10.7% of lysine in E1 and E2, respectively. Conversely, it increased 45.4% and 83.4% of dispensable fatty acid proline. These results suggest TD could affect the nutritional quality of protein rather than fat in farmed fish.

Hyperbaric oxygen reduces inflammation, oxygenates injured muscle, and regenerates skeletal muscle via macrophage and satellite cell activation

Hyperbaric oxygen treatment (HBO) promotes rapid recovery from soft tissue injuries. However, the healing mechanism is unclear. Here we assessed the effects of HBO on contused calf muscles in a rat skeletal muscle injury model. An experimental HBO chamber was developed and rats were treated with 100% oxygen, 2.5 atmospheres absolute for 2 h/day after injury. HBO reduced early lower limb volume and muscle wet weight in contused muscles, and promoted muscle isometric strength 7 days after injury. HBO suppressed the elevation of circulating macrophages in the acute phase and then accelerated macrophage invasion into the contused muscle. This environment also increased the number of proliferating and differentiating satellite cells and the amount of regenerated muscle fibers. In the early phase after injury, HBO stimulated the IL-6/STAT3 pathway in contused muscles. Our results demonstrate that HBO has a dual role in decreasing inflammation and accelerating myogenesis in muscle contusion injuries.

Validation of Isometric Tetanic Force as a Measure of Muscle Recovery After Nerve Injury in the Rabbit Biceps.

The purpose of this study was to describe and validate a technique for measurement of isometric tetanic force (ITF) in the rabbit biceps muscle. Eighteen New Zealand White rabbits were randomized to test either the right side or the left side first. Under propofol anesthesia, the brachial plexus and biceps brachii were exposed. The middle trunk (C6, C7) was secured in a bipolar electrode. Compound muscle action potential (CMAP) was measured. The proximal, tendinous portion of the biceps was severed at the shoulder and clamped in a custom-made force transducer. Muscle preload and electrical stimulation variables were optimized to obtain the highest tetanic muscle contraction. Wet muscle weight (WMW) and nerve histomorphometry were analyzed. Statistical analysis was performed to determine side-to-side equivalence. The rabbit biceps muscle force demonstrated side-to-side equivalence with overlapping 95% confidence intervals (95% CI). The right side, expressed as a percentage of the left, averaged 99.69% (95% CI, 88.89%-110.5%). The WMW of the right expressed as a percentage of the left was 98.9% (95% CI, 95.8%-102%). The ITF is equivalent from side to side in the rabbit as demonstrated by the high degree of overlap in the 95% CIs for each side. The width of the 95% CI implies that there is more variability in the rabbit upper extremity than for the lower extremity of the rabbit or rat models, and researchers should take this into account when performing sample size estimates in pre-experimental planning. The rabbit biceps muscle ITF measurements can be used to measure motor recovery in a rabbit model of brachial plexus injury and compared with the contralateral uninjured side.

Early electrical field stimulation prevents the loss of spinal cord anterior horn motoneurons and muscle atrophy following spinal cord injury.

Our previous study revealed that early application of electrical field stimulation (EFS) with the anode at the lesion and the cathode distal to the lesion reduced injury potential, inhibited secondary injury and was neuroprotective in the dorsal corticospinal tract after spinal cord injury (SCI). The objective of this study was to further evaluate the effect of EFS on protection of anterior horn motoneurons and their target musculature after SCI and its mechanism. Rats were randomized into three equal groups. The EFS group received EFS for 30 minutes immediately after injury at T10. SCI group rats were only subjected to SCI and sham group rats were only subjected to laminectomy. Luxol fast blue staining demonstrated that spinal cord tissue in the injury center was better protected; cross-sectional area and perimeter of injured tissue were significantly smaller in the EFS group than in the SCI group. Immunofluorescence and transmission electron microscopy showed that the number of spinal cord anterior horn motoneurons was greater and the number of abnormal neurons reduced in the EFS group compared with the SCI group. Wet weight and cross-sectional area of vastus lateralis muscles were smaller in the SCI group to in the sham group. However, EFS improved muscle atrophy and behavioral examination showed that EFS significantly increased the angle in the inclined plane test and Tarlov's motor grading score. The above results confirm that early EFS can effectively impede spinal cord anterior horn motoneuron loss, promote motor function recovery and reduce muscle atrophy in rats after SCI.

Comparison betweent the Effects of Swimming and Treadmill-Based Aerobic Training Protocols in Diabetic Rats

Abstract Background: Type 1 diabetes mellitus (DM1) can cause damage to several physiological systems. Objectives: To compare and characterize the effects of aerobic exercise training (ET) performed by swimming with those of ET performed on a treadmill on the skeletal muscle and heart of rats with DM1. Methods: 41 male Wistar rats were randomized into four groups: nondiabetic control (CTR), diabetic control (DMC), diabetic trained on the treadmill (DMT), and diabetic trained by swimming (DMS). The trained groups performed aerobic exercise training for 8 weeks, 5 times a week, 60 min per day. Exercise tolerance, blood glucose, body weight, wet weight of the skeletal muscles and left ventricle (LV), muscle glycogen, cross-sectional area of skeletal muscles, and cross-sectional diameter and collagen volume fraction of the LV were evaluated. Results: The results were expressed as mean ± standard deviation of the mean and submitted to two-way ANOVA with post-hoc Bonferroni test. Aerobic ET protocols applied to animals with DM1, regardless of the ergometer, showed satisfactory results (p < 0.05) when compared to the control groups: improved exercise tolerance, increased glycogen content of the soleus and extensor digitorum longus (EDL) muscles and increased cross-sectional diameter of the left ventricular cardiomyocytes. In some variables, such as exercise tolerance and cross-sectional area of the soleus and EDL muscles, DMT showed better results than DMS (p < 0.05). On the other hand, DMS showed increased cross-sectional diameter of cardiomyocytes when compared with the DMT group. Conclusion: Both aerobic ET protocols offered benefits to animals with diabetes; however, due to the specific characteristics of each modality, different physiological adaptations were observed between the trained groups.

Phrenic and intercostal nerves with rhythmic discharge can promote early nerve regeneration after brachial plexus repair in rats.

Exogenous discharge can positively promote nerve repair. We, therefore, hypothesized that endogenous discharges may have similar effects. The phrenic nerve and intercostal nerve, controlled by the respiratory center, can emit regular nerve impulses; therefore these endogenous automatically discharging nerves might promote nerve regeneration. Action potential discharge patterns were examined in the diaphragm, external intercostal and latissimus dorsi muscles of rats. The phrenic and intercostal nerves showed rhythmic clusters of discharge, which were consistent with breathing frequency. From the first to the third intercostal nerves, spontaneous discharge amplitude was gradually increased. There was no obvious rhythmic discharge in the thoracodorsal nerve. Four animal groups were performed in rats as the musculocutaneous nerve cut and repaired was bland control. The other three groups were followed by a side-to-side anastomosis with the phrenic nerve, intercostal nerve and thoracodorsal nerve. Compound muscle action potentials in the biceps muscle innervated by the musculocutaneous nerve were recorded with electrodes. The tetanic forces of ipsilateral and contralateral biceps muscles were detected by a force displacement transducer. Wet muscle weight recovery rate was measured and pathological changes were observed using hematoxylin-eosin staining. The number of nerve fibers was observed using toluidine blue staining and changes in nerve ultrastructure were observed using transmission electron microscopy. The compound muscle action potential amplitude was significantly higher at 1 month after surgery in phrenic and intercostal nerve groups compared with the thoracodorsal nerve and blank control groups. The recovery rate of tetanic tension and wet weight of the right biceps were significantly lower at 2 months after surgery in the phrenic nerve, intercostal nerve, and thoracodorsal nerve groups compared with the negative control group. The number of myelinated axons distal to the coaptation site of the musculocutaneous nerve at 1 month after surgery was significantly higher in phrenic and intercostal nerve groups than in thoracodorsal nerve and negative control groups. These results indicate that endogenous autonomic discharge from phrenic and intercostal nerves can promote nerve regeneration in early stages after brachial plexus injury.

Transcutaneous carbon dioxide application with hydrogel prevents muscle atrophy in a rat sciatic nerve crush model.

Transcutaneous CO2 application has the therapeutic potential to accelerate the recovery of muscle atrophy in peripheral nerve injury. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1653-1658, 2018.

The influence of isoflavone for denervation-induced muscle atrophy.

Decrease in activity stress induces skeletal muscle atrophy. A previous study showed that treatment with a high level (20%) of isoflavone inhibits muscle atrophy after short-term denervation (at 4days) in mice. The present study was designed to elucidate whether the dietary isoflavone aglycone (AglyMax) at a 0.6% prevents denervation-mediated muscle atrophy, based on the modulation of atrogin-1- or apoptosis-dependent signaling. Mice were fed either a normal diet or 0.6% AglyMax diet. One week later, the right sciatic nerve was cut. The wet weight, mean fiber area, amount of atrogin-1 and cleaved caspase-3 proteins, and the percentages of apoptotic nuclei were examined in the gastrocnemius muscle at 14days after denervation. The 0.6% AglyMax diet significantly attenuated denervation-induced decreases in fiber atrophy but not the muscle wet weight. In addition, dietary isoflavone suppressed the denervation-induced apoptosis in spite of there being no significant changes in the amount of cleaved caspase-3 protein. In contrast, the 0.6% AglyMax diet did not significantly modulate the protein expression of atrogin-1 in the denervated muscle of mice. The isoflavone aglycone (AglyMax) at a 0.6% significantly would modulate muscle atrophy after denervation in mice, probably due to the decrease in apoptosis-dependent signaling.

Effect of local administration of platelet-rich plasma (PRP) on peripheral nerve regeneration: An experimental study in the rabbit model.

Twenty-eight Japanese white rabbits were used. A 15-mm sciatic nerve defect was created on the left limb. The resected nerve was used as a reverse autologous nerve. The rabbits were randomly divided into two groups. In group A (n = 10), only nerve grafting was performed. In group B (n = 18), nerve grafting was performed with local PRP administration. Right limbs were used as control (group C, n = 28). The rabbits in each group were equally divided into two subgroups based on the evaluation period of 4 and 12 weeks after grafting. Electrophysiological evaluation, muscle wet-weight, histological evaluation, and multiple immunofluorescence staining were performed to investigate the regenerative effect of PRP. The mean regenerative axon diameter of the graft portion in group B (2.02 ± 0.22-μm) was significantly larger than that in group A (1.89 ± 0.16-μm) at 4 weeks. The regenerative axon number at the distal portion showed a greater increase in group B (9017 ± 2224/mm2 ) than in group A (4955 ± 3117/mm2 ) at 12 weeks. Electrophysiological evaluation and muscle wet-weight revealed no significant differences. On immunohistological evaluation, the number of activated SCs increased to a larger extent in group B (188 ± 90/mm2 ) than in group A (117 ± 51/mm2 ). Local PRP administration increases the regenerative axon diameter and the regenerative axon number at the distal portion. PRP accelerates SC proliferation in vivo.

Effects of rapid or slow body weight reduction on intramuscular protein degradation pathways during equivalent weight loss on rats.

The purpose of this study was to compare the effects of short-term fasting-induced rapid weight loss with those of slower but equivalent body weight loss induced by daily calorie restriction on muscle protein degradation pathways and muscle protein content. Male Fischer rats were subjected to either 30 % calorie restriction for 2 weeks to slowly decrease body weight (Slow) or 3-day fasting to rapidly decrease body weight by a comparable level of that of the Slow group (Rapid). The final body weights were about 15 % lower in both the Slow and Rapid groups than in the Con group (p<0.001). The total protein content and wet weight of fast-twitch plantaris muscle, but not slow-twitch soleus muscle, were significantly lower in the Rapid group compared with the control rats fed ad libitum. Substantial increases in the expression ratio of autophagosomal membrane proteins (LC3-II/-I ratio) and polyubiquitinated protein concentration, used as biomarkers of autophagy-lysosome and ubiquitin-proteasome activities, respectively, were observed in the plantaris muscle of the Rapid group. Moreover, the LC3-II/-I ratio and polyubiquitinated protein concentration were negatively correlated with the total protein content and wet weight of plantaris muscle. These results suggest that short-term fasting-induced rapid body weight loss activates autophagy-lysosome and ubiquitin-proteasome systems more strongly than calorie restriction-induced slower weight reduction, resulting in muscular atrophy in fast-twitch muscle.

Identification of the optimal dose and calpain system regulation of tetramethylpyrazine on the prevention of skeletal muscle atrophy in hindlimb unloading rats

Previous studies in our lab have shown that tetramethylpyrazine (TMP) could effectively attenuate disuse induced muscle atrophy. In order to screening out the optimal dose of tetramethylpyrazine (TMP) for protection against disuse induced muscle atrophy in hindlimb unloading (HLU) rats, in this study, we compared effects of 4 TMP doses on muscle wet weight (MWW), the ratios of muscle wet weight/body weight (MWW/BW) and muscle wet weight/dry weight (MWW/DW), fiber type composition, as well as cross-sectional area (CSA) in soleus (SOL) muscle. Consequently, we quantified optimal dose effects on both functional properties and protein expression (calpain-1, calpain-2, calpastatin and MuRF1) in SOL and extensor digitorum longus (EDL) muscles. Data indicated that the protective potential of TMP was dose-dependent: 60mg/kg TMP was most effective in terms of atrophy prevention. This dose reduced SOL MWW, MWW/BW and CSA muscle loss by 60, 60 and 54% (P<0.001), respectively. HLU-induced slow-to-fast fiber transition was reduced by 17% (P<0.01). 60mg/kg TMP also significantly lessened the decrease of contractile force, the increase of shorting velocity and fatigability induced by HLU. Besides, it also attenuated expressions of calpain-1 (SOL −8.6%, P<0.05; EDL −10.9%, P<0.05), calpain-2 (SOL −60%, P<0.001; EDL −32%, P<0.01) and MuRF1 expression (SOL −21%, P<0.001; EDL −10%, P<0.01), promoted the expression of calpastatin by 18% (P<0.05) in SOL muscle. Taken together, present study demonstrated that 60mg/kg body weight was the optimal dose of TMP against disuse induced muscle atrophy which effectively protected muscle function by inhibiting calpain-1, calpain-2 and MuRF1 expression, promoted calpastatin expression, especially in slow-twitch muscle.

Balanced Diet-Fed Fat-1 Transgenic Mice Exhibit Lower Hindlimb Suspension-Induced Soleus Muscle Atrophy.

The consequences of two-week hindlimb suspension (HS) on skeletal muscle atrophy were investigated in balanced diet-fed Fat-1 transgenic and C57BL/6 wild-type mice. Body composition and gastrocnemius fatty acid composition were measured. Skeletal muscle force, cross-sectional area (CSA), and signaling pathways associated with protein synthesis (protein kinase B, Akt; ribosomal protein S6, S6, eukaryotic translation initiation factor 4E-binding protein 1, 4EBP1; glycogen synthase kinase3-beta, GSK3-beta; and extracellular-signal-regulated kinases 1/2, ERK 1/2) and protein degradation (atrophy gene-1/muscle atrophy F-box, atrogin-1/MAFbx and muscle RING finger 1, MuRF1) were evaluated in the soleus muscle. HS decreased soleus muscle wet and dry weights (by 43% and 26%, respectively), muscle isotonic and tetanic force (by 29% and 18%, respectively), CSA of the soleus muscle (by 36%), and soleus muscle fibers (by 45%). Fat-1 transgenic mice had a decrease in the ω-6/ω-3 polyunsaturated fatty acids (PUFAs) ratio as compared with C57BL/6 wild-type mice (56%, p < 0.001). Fat-1 mice had lower soleus muscle dry mass loss (by 10%) and preserved absolute isotonic force (by 17%) and CSA of the soleus muscle (by 28%) after HS as compared with C57BL/6 wild-type mice. p-GSK3B/GSK3B ratio was increased (by 70%) and MuRF-1 content decreased (by 50%) in the soleus muscle of Fat-1 mice after HS. Balanced diet-fed Fat-1 mice are able to preserve in part the soleus muscle mass, absolute isotonic force and CSA of the soleus muscle in a disuse condition.

Effect of conjugated linoleic acids and omega-3 fatty acids with or without resistance training on muscle mass in high-fat diet-fed middle-aged mice.

What is the central question of this study? This study examined the effects of 20weeks of administration of conjugated linoleic acids/omega-3 fatty acids with or without programed resistance exercise training on body composition, skeletal muscle properties and functional capacity in middle-aged mice fed a high-fat diet. What is the main finding and its importance? Chronic daily administration of conjugated linoleic acids/omega-3 fatty acids with resistance exercise training can help to blunt fat gain, alleviate loss of myogenic capacity and sensorimotor function and lower tissue inflammation in middle-aged mice during chronic high-fat diet-induced catabolism. This study investigated the effects of 20weeks of combined conjugated linoleic acid (CLA)/omega-3 fatty acid (n-3) administration independently or combined with resistance exercise training (RET) on skeletal muscle in middle-aged mice consuming a high-fat diet (HFD). Nine-month-old C57BL/6 mice were randomly assigned into four experimental groups (H, high-fat diet; HE, H+RET; HCN, H+CLA/n-3; and HECN, H+CLA/n3+RET). Body composition and functional capacity were assessed pre- and post-intervention. Muscle tissues were collected at 14months of age. ANOVA was used, with significance set at P≤0.05. Fat mass significantly increased in H (+74%), HE (+142%) and HECN (+43%) but not in HCN. Muscle wet weights were significantly lower in H and HCN than in HE and HECN. Grip strength substantially declined in H (-15%) and HCN (-17%), whereas sensorimotor function significantly declined only in H (-11%). HECN exhibited improvement in strength (+22%) and sensorimotor coordination (+17%). In comparison to H, muscle tumour necrosis factor-α mRNA expression was significantly lower in HE (-39%), HCN (-24%) and HECN (-21%), respectively. Mean myofibre cross-sectional areas were markedly lower in H and HCN than in HE and HECN. H showed significantly lower satellite cell abundance and numbers of myonuclei than all other groups. Our findings suggest that long-term daily CLA/n-3 intake with resistance training improved sensorimotor function, ameliorated fat gain and prevented loss of myogenic capacity while lowering tumour necrosis factor-α expression during chronic HFD.

Comparison of age-related morphological changes in the masseter muscles of senescence-accelerated mouse (SAM)

ObjectiveAge-related morphological changes in the perioral muscles are still garnering attention today. We planned an experiment using a senescence-accelerated mouse (SAM) to compare age-related morphological changes in the masseter muscle in young and old mice. The masseter muscle in elderly mice (40 -week- old) of SAM-prone 8 (SAMP8) mice has been found to demonstrate greater muscle fiber atrophy than that in a control group of SAM-resistant 1(SAMR1) mice. In the present study, in order to assess age-related morphological changes in the masseter muscles of SAMP8 mice, we compared three groups of mice: young mice (12 -week- old), elderly mice (40 -week- old), and later-stage elderly mice (55 -week- old). Materials and methodsThe body weight, the masseter muscle wet weight and the serum albumin levels of each stages in SAMP8 mice were measured. Also, SAMR1 mice were measured as control. Frozen sections of sampled muscles were prepared and dyed with Hematoxylin-eosin (H-E) and immunohistochemical staining. ResultsThe mean cross-sectional area of muscle fibers decreased from 12- week- old to 40- week-old and from 12- week- old to 55- week- old. Immunohistochemical staining showed that the percentage(%) of MyHC-IIa increased from 12- week- old to 55- week- old, whereas that of MyHC-IIb decreased from 12- week- old to 55- week- old and 40- week- old to 55- week- old. ConclusionsIn the present study, it showed that atrophy of the masseter muscle had occurred by 40- week- old and that there were additional subsequent changes in contraction characteristics.

Bone marrow derived mesenchymal stem cell transplantation for treatment of denervated intrinsic paw muscular atrophy: an experimental research in rats

Objective To investigate the feasibility of bone marrow derived mesenchymal stem cell (BMSC) transplantation in the treatment of denervated intrinsic paw muscle atrophy. Methods Twelve adult male Sprague-Dawley rats (24 sides) were randomly divided into ulnar nerve transection group, stem cell transplantation group, culture medium injection group and normal control group. GFP-transfected BMSCs cultured in vitro were injected into the paw muscles of rats in the stem cell transplantation group. After 1 month, intrinsic paw muscles were tested by histology, immunofluorescence and PCR. Results The muscle wet weight and muscle fiber cross-sectional area of stem cell transplantation group were 66% and 63% of normal control group, respectively, and twice as much as that of ulnar nerve transection and culture medium injection groups (P<0.05). GFP-positive mesenchymal stem cells still could be detected at injection site. The expression of VEGF, HGF, CNTF, bFGF in stem cell transplantation group were higher than that in ulnar nerve transection and culture medium injection groups, and the apoptotic index (apoptotic cells/total cells) in stem cell transplantation group was smaller (P<0.05). Conclusion BMSCs can effectively delay the denervated intrinsic paw muscular atrophy. BMSCs may have the capbility of secreting neurotrophic factor and reducing muscle tissue apoptosis. Key words: Mesenchymal stem cell transplantation; Muscular atrophy; Intrinsic paw muscles; Animal experimentation

The influence of Toll-like recepter 4 activation to the skeletal muscle fibrosis mediated by transforming growth factor-beta1

Objective Obtain the Muscle derived stem cells from the mouse skeletal muscle and observe the influence of Toll-like receptor 4 (TLR4) activation to the skeletal muscle fibrosis mediated by transforming growth factor-beta1. Methods Cell culture: muscle-derived stem cells (MDSCs) from primary cultures of mouse skeletal muscle were isolated and purified by the preplate technique. Then, the MDSCs were divided into 3 average groups (A, B, C) at random. Group A is the control, Group B cultured in vitro with the transforming growth factor-β1 (TGF-β1), Group C cultured in vitro with the TGF-β1 and heat shock protein 60 (Hsp60)respectively for 3 days. At first, the level of Nuclear transcription factors κB (NF-κB)was tested by RT-PCR and Western blotting to make clear if the TLR4 was activated. Then the level of CTGF and collagen I in these three groups were tested by RT-PCR, Western blotting and immunofluorescence. Animal model: 24 adult male mouses (15-18 g) were divided into three groups (D, E, F) of 8 each at random. The saline, rhTGF-β1 solution and rhTGF-β1 with Hsp60 solution were injected into the left gastrocnemius medial head respectively per 7 days for four times. At the 28th day, the left gastrocnemius medial head was removed to test the wet weight of the muscles and Von Geison stain performed to observe the muscular fibrosis of each group. Results Cell culture: RT-PCR show that the relative expression of the NF-κB of group A, B and C were respectively 0.852±0.121, 0.987±0.084 and 1.304±0.171 (P=0.031). The CTGF of group A, B and C were respectively 0.756±0.205, 0.977±0.188, 1.308±0.302 (P=0.022). The collagen I of group A, B and C were respectively 0.767±0.148, 0.998±0.138, 1.261±0.327 (P=0.016). Western blotting show that the optical density ratio of the NF-κB of group A, B and C were respectively 0.784±0.133, 0.887±0.066, 0.994±0.171 (P=0.026). The CTGF of group A, B and C were respectively 0.644±0.125, 0.863±0.109, 0.998±0.512 (P=0.018). The collagen I of group A, B and C were respectively 0.347±0.133, 0.761±0.086, 0.868±0.167 (P=0.045). In response to the Western blotting, immunofluorescence showed that the expression of the CTGF and collagen I of group A, B and C were increased gradually and there was significance of all the tests statistically between each group (P=0.025, P=0.012). Animal model: The mean value of the wet weight of the left gastrocnemius medial head of group D, E and F are respectively (0.015±0.002), (0.014±0.002), (0.012±0.003) g (P=0.037), PD vs. E=0.033, PD vs. F=0.029, PE vs. F=0.016.The Von Geison stain obtained the integrated optical density ratio of D, E and F group were respectively 100.8±10.3, 112.7±11.1 and 131.9±12.5 (P=0.013, PD vs. E=0.041, PD vs. F=0.027, PE vs. F=0.010). Conclusion The activation TLR-4 of the mouse MDSCs can promote the skeletal muscular fibrosis mediated by TGF-β1. Key words: Muscle-derived stem cells; Ttransforming growth factor-β1; Tool-like receptor; Connective tissue growth factor; Fibrosis

Nerve growth factor and basic fibroblast growth factor promote reinnervation by nerve-muscle-endplate grafting.

This study was designed to test whether exogenous application of nerve growth factor (NGF) and basic fibroblast growth factor (FGF-2) to muscles reinnervated with nerve-muscle-endplate band grafting (NMEG) could promote specific outcomes. The right sternomastoid muscle in adult rats was experimentally denervated and immediately reinnervated by implanting an NMEG pedicle from the ipsilateral sternohyoid muscle. A fibrin sealant containing NGF and FGF-2 was focally applied to the implantation site. Maximal tetanic force, muscle weight, regenerated axons, and motor endplates were analyzed 3 months after treatment. Mean tetanic force, wet muscle weight, and number of regenerated axons in the treated muscles were 91%, 92%, and 84% of the contralateral controls, respectively. The majority of endplates (86%) in the treated muscles were reinnervated by regenerated axons. Focal administration of NGF and FGF-2 promotes efficacy of the NMEG technique. Muscle Nerve 57: 449-459, 2018.

Bridging the Gap

This study aims to compare engineered nerve conduits constructed from porcine-derived urinary bladder matrix (UBM) with the criterion-standard nerve autografts, for segmental loss peripheral nerve repairs. Forty-eight Sprague-Dawley rats were divided into 2 groups. All underwent a 10-mm sciatic nerve gap injury. This was repaired using either (1) reverse autograft-the 10-mm cut segment was oriented 180 degrees and used to coapt the proximal and distal stumps or (2) UBM conduit-the 10-mm nerve gap was bridged with UBM conduit. Behavior assessments such as sciatic function index and foot fault asymmetry scores were performed weekly. At 3- or 6-week time endpoints, the repaired nerves and bilateral gastrocnemius/soleus muscles were harvested from each animal. Nerves were evaluated using immunohistochemistry for motor and sensory axon staining and with diffusion tensor imaging. The net wet muscle weights were calculated to assess the degree of muscle atrophy. The UBM group demonstrated significantly improved foot fault asymmetry scores at 2 and 4 weeks, whereas there was no difference in sciatic function index. The net muscle weights were similar between both groups. Motor axon counts proximal/inside/distal to the conduit/graft were similar between UBM conduits and reverse autografts, whereas sensory axon counts within and distal to the conduit were significantly higher than those of the autograft at 6 weeks. Sensory axonal regeneration seemed to be adherent to the inner surface of the UBM conduit, whereas it had a scattered appearance in autografts. Diffusion tensor imaging parameters between groups were similar. Urinary bladder matrix conduits prove to be at least similar to nerve autografts for the repair of peripheral nerve injuries with a short gap. The matrix perhaps serves as a scaffold to augment sensory nerve growth. In a clinical setting, UBM may eliminate the donor site morbidity and increased operative time associated with nerve autografting.