Effect of Immobilization on Insoluble Collagen Concentration and Type I and Type III Collagen Isoforms of Rat Soleus Muscle

Focal Traumatic Brain Injury Impairs the Integrity of the Basement Membrane of Hindlimb Muscle Fibers Revealed by Extracellular Matrix Immunoreactivity

Traumatic brain injury (TBI) stands as a prominent global cause of disability, with motor deficits being a common consequence. Despite its widespread impact, the precise pathological mechanisms underlying motor deficits after TBI remain elusive. In this study, hindlimb postural asymmetry (HL-PA) development in rats subjected to focal TBI was investigated to explore the potential roles of collagen IV and laminin within the extracellular matrix (ECM) of selected hindlimb muscles in the emergence of motor deficits following TBI. A focal TBI was induced by ablating the left sensorimotor cortex in rats and motor deficits were assessed by measuring HL-PA. The expression of laminin and collagen IV in eight selected muscles on each side of the hindlimbs from both TBI- and sham-operated rats were studied using immunohistochemistry and semi-quantitatively analyzed. The results indicated that the TBI rats exhibited HL-PA, characterized by flexion of the contralateral (right) hindlimb. In the sham-operated rats, the immunoreactive components of laminin and collagen IV were evenly and smoothly distributed along the border of the muscle fibers in all the investigated muscles. In contrast, in the TBI rats, the pattern was broken into aggregated, granule-like, immunoreactive components. Such a labeling pattern was detected in all the investigated muscles both from the contra- and ipsilateral sides of the TBI rats. However, in TBI rats, most of the muscles from the contralateral hindlimb showed a significantly increased expression of these two proteins in comparison with those from the ipsilateral hindlimb. In comparison to sham-operated rats, there was a significant increase in laminin and collagen IV expression in various contralateral hindlimb muscles in the TBI rats. These findings suggest potential implications of laminin and collagen IV in the development of motor deficits following a focal TBI.

Rat Model of Quadriceps Contracture by Joint Immobilization

Muscle contracture is an abnormal pathologic process resulting in fibrosis and muscle atrophy, which can lead to limitation of joint motion. To establish a diagnostic method to detect muscle contracture and a method to control its progression, we investigated an appropriate method to create an animal model of quadriceps contracture using rats. Eighteen Wistar rats were divided into three groups, and bilateral hindlimbs were immobilized with either a cast (Group I), a Velcro hook-and-loop fastener (Group V), or steel wire (Group S) with the knee and ankle joints in extension position for two weeks. Five rats in a control group (Group C) were not immobilized. After two weeks, the progression of quadriceps contracture was assessed by measuring the range of joint motion and pathohistological changes. Muscle atrophy and fibrosis were observed in all immobilization groups. The knee joint range of motion, quadriceps muscle weight, and muscle fiber size decreased only in Group S compared to the other immobilization groups. Stress on rats due to immobilization was less in Group S. These results indicate that Group S is the superior quadriceps contracture model. This model aids research investigating diagnostic and therapeutic methods for muscle contracture in humans and animals.

Efficacy of Belt Electrode Skeletal Muscle Electrical Stimulation in the Postoperative Rest Period in Patients with Diabetes who Have Undergone minor Amputations: A Randomized Controlled Trial

This study aimed to investigate whether belt electrode skeletal muscle electrical stimulation (B-SES) would improve postoperative lower limb function and walking ability in patients with diabetes who have undergone minor amputations. Diabetic patients who had undergone minor amputations were assigned randomly to a B-SES or control group. The B-SES group underwent conventional physical therapy for 20 min and B-SES for 20 min. The control group underwent only the 20-min conventional physical therapy. In both groups, rehabilitation was introduced by the physical therapists for 14 days from postoperative day 1. The outcome measures were range of motion in the ankle joint, knee extension muscle strength, ambulation status, and quality of life score. All these were evaluated before the intervention and 2 and 4 weeks after the intervention. From the 84 patients initially assessed, 32 were assigned to either the B-SES (N = 16) or control (N = 16) group. Preoperatively, there were no significant differences in all endpoints. The B-SES group showed significant improvement in the ankle dorsiflexion angle at 2 weeks postoperatively and knee joint extension strength at 4 weeks postoperatively. Postoperative B-SES with standard physical therapy might improve the range of motion of dorsiflexion of the ankle joint and extensor strength of the knee joint in patients with diabetes who have undergone minor amputations. B-SES is a useful tool to improve postoperative physical function in diabetic patients who have undergone minor amputations. A multicenter study is needed to determine the effective B-SES combined with regular physiotherapy for minor amputation.

Transcutaneous application of carbon dioxide improves contractures after immobilization of rat knee joint

OBJECTIVE

Joint contractures are a major complication following joint immobilization. However, no fully effective treatment has yet been found. Recently, carbon dioxide (CO₂) therapy was developed and verified this therapeutic application in various disorders. We aimed to verify the efficacy of transcutaneous CO₂ therapy for immobilization-induced joint contracture.

METHOD

Twenty-two Wistar rats were randomly assigned to three groups: caged control, those untreated after joint immobilization, and those treated after joint immobilization. The rats were treated with CO₂ for 20 min once a daily either during immobilization, (prevention) or during remobilization after immobilization (treatment). Knee extension motion was measured with a goniometer, and the muscular and articular factors responsible for contractures were calculated. We evaluated muscle fibrosis, fibrosis-related genes (collagen Type 1α1 and TGF-β1) in muscles, synovial intima's length, and fibrosis-related proteins (Type I collagen and TGF-β1) in the joint capsules.

RESULTS

CO₂ therapy for prevention and treatment improved the knee extension motion. Muscular and articular factors decreased in rats of the treatment group. The muscular fibrosis of treated rats decreased in the treatment group. Although CO₂ therapy did not repress the increased expression of collagen Type 1α1, the therapy decreased the expression of TGF-β1 in the treatment group. CO₂ therapy for treatment improved the shortening of the synovial membrane after immobilization and decreased the immunolabeling of TGF-β1 in the joint capsules.

CONCLUSIONS

CO₂ therapy may prevent and treat contractures after joint immobilization, and appears to be more effective as a treatment strategy for the deterioration of contractures during remobilization.

Transcutaneous Carbon Dioxide Improves Contractures After Spinal Cord Injury in Rats

BACKGROUND

Joint contractures are a major complication in patients with spinal cord injuries. Positioning, stretching, and physical therapy are advocated to prevent and treat contractures; however, many patients still develop them. Joint motion (exercise) is crucial to correct contractures. Transcutaneous carbon dioxide (CO2) therapy was developed recently, and its effect is similar to that of exercise. This therapy may be an alternative or complementary approach to exercise.

QUESTION/PURPOSES

Using an established model of spinal cord injury in rats with knee flexion contractures, we sought to clarify whether transcutaneous CO2 altered (1) contracture, as measured by ROM; (2) muscular and articular factors contributing to the loss of ROM; (3) fibrosis and fibrosis-related gene expression in muscle; and (4) the morphology of and fibrosis-related protein expression in the joint capsule.

METHODS

Thirty-six Wistar rats were divided into three equal groups: caged control, those untreated after spinal cord injury, and those treated with CO2 after spinal cord injury. The rats were treated with CO2 from either the first day (prevention) or 15th day (treatment) after spinal cord injury for 2 or 4 weeks. The hindlimbs of rats in the treated group were exposed to CO2 gas for 20 minutes once daily. Knee extension ROM was measured with a goniometer and was measured again after myotomy. We calculated the muscular and articular factors responsible for contractures by subtracting the post-myotomy ROM from that before myotomy. We also quantified histologic muscle fibrosis and evaluated fibrosis-related genes (collagen Type 1, α1 and transforming growth factor beta) in the biceps femoris muscle with real-time polymerase chain reaction. The synovial intima's length was measured, and the distribution of fibrosis-related proteins (Type I collagen and transforming growth factor beta) in the joint capsule was observed with immunohistochemistry. Knee flexion contractures developed in rats after spinal cord injuries at all timepoints.

RESULTS

CO2 therapy improved limited-extension ROM in the prevention group at 2 weeks (22° ± 2°) and 4 weeks (29° ± 1°) and in the treatment group at 2 weeks (31° ± 1°) compared with untreated rats after spinal cord injuries (35° ± 2°, mean difference, 13°; 39° ± 1°, mean difference, 9°; and 38° ± 1°, mean difference, 7°, respectively) (95% CI, 10.50-14.86, 8.10-10.19, and 4.73-9.01, respectively; all p < 0.001). Muscular factors decreased in treated rats in the prevention group at 2 weeks (8° ± 2°) and 4 weeks (14°± 1°) and in the treatment group at 2 weeks (14 ± 1°) compared with untreated rats (15° ± 1°, 4.85-9.42; 16° ± 1°, 1.24-3.86; and 17° ± 2°, 1.16-5.34, respectively; all p < 0.05). The therapy improved articular factors in the prevention group at 2 weeks (4° ± 1°) and 4 weeks (6° ± 1°) and in the treatment group at 2 weeks (8° ± 1°) compared with untreated rats (10° ± 1°, 4.05-7.05; 12° ± 1°, 5.18-8.02; and 11° ± 2°, 1.73-5.50, respectively; all p < 0.05). CO2 therapy decreased muscle fibrosis in the prevention group at 2 weeks (p < 0.001). The expression of collagen Type 1, α1 mRNA in the biceps femoris decreased in treated rats in the prevention group at 2 and 4 weeks compared with untreated rat (p = 0.002 and p = 0.008, respectively), although there was little difference in the expression of transforming growth factor beta (p > 0.05). CO2 therapy did not improve shortening of the synovial intima at all timepoints (all p > 0.05). CO2 therapy decreased transforming growth factor beta immunolabeling in joint capsules in the rats in the prevention group at 2 weeks. The staining intensity and Type I collagen pattern showed no differences among all groups at all timepoints.

CONCLUSION

CO2 therapy may be useful for preventing and treating contractures after spinal cord injuries. CO2 therapy particularly appears to be more effective as a prevention and treatment strategy in early-stage contractures before irreversible degeneration occurs, as shown in a rat model.

CLINICAL RELEVANCE

Our findings support the idea that CO2 therapy may be able to improve the loss of ROM after spinal cord injury.

Relationship between extensibility and collagen expression in immobilized rat skeletal muscle

INTRODUCTION

This study investigated longitudinal changes in muscle extension and collagen expression in an immobilized rat soleus muscle, and assessed the relationship between both elements.

METHODS

Soleus muscles of the control and immobilization groups (1, 2, 4, 8, and 12 weeks) were used for analysis of muscle extensibility and collagen expression.

RESULTS

The slope value/physiological cross-sectional area (PCSA; a parameter for muscle extensibility) and hydroxyproline (a parameter for collagen expression) were significantly higher in the immobilization group than in the control group for all experimental time points. In the immobilization group, both factors were significantly higher at 4, 8, and 12 weeks than at 1 and 2 weeks after immobilization. A significant positive correlation was observed between the slope value/PCSA and hydroxyproline expression.

DISCUSSION

The present study indicated that a decrease in muscle extensibility depended on collagen overexpression in immobilized rat soleus muscles. Muscle Nerve 57: 672-678, 2018.

Astaxanthin supplementation attenuates immobilization-induced skeletal muscle fibrosis via suppression of oxidative stress

Immobilization induces skeletal muscle fibrosis characterized by increasing collagen synthesis in the perimysium and endomysium. Transforming growth factor-β1 (TGF-β1) is associated with this lesion via promoting differentiation of fibroblasts into myofibroblasts. In addition, reactive oxygen species (ROS) are shown to mediate TGF-β1-induced fibrosis in tissues. These reports suggest the importance of ROS reduction for attenuating skeletal muscle fibrosis. Astaxanthin, a powerful antioxidant, has been shown to reduce ROS production in disused muscle. Therefore, we investigated the effects of astaxanthin supplementation on muscle fibrosis under immobilization. In the present study, immobilization increased the collagen fiber area, the expression levels of TGF-β1, α-smooth muscle actin, and superoxide dismutase-1 protein and ROS production. However, these changes induced by immobilization were attenuated by astaxanthin supplementation. These results indicate the effectiveness of astaxanthin supplementation on skeletal muscle fibrosis induced by ankle joint immobilization.

Cyclic muscle twitch contraction inhibits immobilization-induced muscle contracture and fibrosis in rats

We investigated the effects of cyclic muscle twitch contraction caused by neuromuscular electrical stimulation (NMES) on immobilization-induced muscle contracture and fibrosis in rats. Twenty-nine rats were divided into control, immobilization, and immobilization with muscle contraction groups. The ankle joints of the immobilization and muscle contraction rats were fixed in full plantar flexion with a plaster cast for 4 weeks. In the muscle contraction group, cyclic muscle twitch contraction of the soleus muscle was induced using a commercial device (1 Hz, 4 ± 2 mA, 60 min/day, 5 times/week) with the ankle joint immobilized. The dorsiflexion range of ankle joint motion in the muscle contraction group was significantly greater than that in the immobilization group. The expressions of fibrosis-related genes (i.e., hypoxia inducible factor-1α, transforming growth factor-β1, α-smooth muscle actin, and types I and III collagen) were significantly decreased in the muscle contraction group compared to the immobilization group. The fluorescence intensities of type I and type III collagen in the perimysium and endomysium in the muscle contraction group were significantly decreased compared to the immobilization group. These results suggest that cyclic muscle twitch contraction induced by NMES might alleviate skeletal muscle fibrosis, reducing immobilization-induced muscle contracture.

Effects of joint immobilization and hindlimb unloading on collagen fibers of soleus muscles in rats

[Purpose] The purpose of this study was to determine whether collagen fibers cause a difference in a contracture resulting from a combination of joint fixation and hindlimb unloading as compared to joint fixation only. [Subjects and Methods] The subjects of this study were 21 female Wistar rats divided into 4 groups as follows: Control Group (CON, n=7); Joint Fixation Group (JF, n=7), Hindlimb Unloading Group (HU, n=7), Joint Fixation Plus Hindlimb Unloading Group (JF+HU, n=7). This study was conducted for 1-week. Ankle joint range of motion and positive areas of collagen using fluorescent stain were analyzed. [Results] Ankle joint range of motion in JF + HU showed an increase compared to that of JF. Positive areas of Type I collagen in JF+HU showed an increase as compared with that of JF. [Conclusion] The results of this study suggested that the difference in a contracture caused by only joint immobilization and by a combination of joint immobilization and hindlimb unloading were significantly associated with Type I collagen.

Stretching After Heat But Not After Cold Decreases Contractures After Spinal Cord Injury in Rats

BACKGROUND

Contractures are a prevalent and potentially severe complication in patients with neurologic disorders. Although heat, cold, and stretching are commonly used for treatment of contractures and/or spasticity (the cause of many contractures), the sequential effects of these modalities remain unclear.

QUESTIONS/PURPOSES

Using an established rat model with spinal cord injury with knee flexion contracture, we sought to determine what combination of heat or cold before stretching is the most effective for treatment of contractures derived from spastic paralyses and investigated which treatment leads to the best (1) improvement in the loss of ROM; (2) restoration of deterioration in the muscular and articular factors responsible for contractures; and (3) amelioration of histopathologic features such as muscular fibrosis in biceps femoris and shortening of the joint capsule.

METHODS

Forty-two adolescent male Wistar rats were used. After spasticity developed at 2 weeks postinjury, each animal with spinal cord injury underwent the treatment protocol daily for 1 week. Knee extension ROM was measured with a goniometer by two examiners blinded to each other's scores. The muscular and articular factors contributing to contractures were calculated by measuring ROM before and after the myotomies. We quantitatively measured the muscular fibrosis and the synovial intima length, and observed the distribution of collagen of skeletal muscle. The results were confirmed by a blinded observer.

RESULTS

The ROM of heat alone (34° ± 1°) and cold alone (34° ± 2°) rats were not different with the numbers available from that of rats with spinal cord injury (35° ± 2°) (p = 0.92 and 0.89, respectively). Stretching after heat (24° ± 1°) was more effective than stretching alone (27° ± 3°) at increasing ROM (p < 0.001). Contrastingly, there was no difference between stretching after cold (25° ± 1°) and stretching alone (p = 0.352). Stretching after heat was the most effective for percentage improvement of muscular (29%) and articular (50%) factors of contractures. Although quantification of muscular fibrosis in the rats with spinal cord injury (11% ± 1%) was higher than that of controls (9% ± 0.4%) (p = 0.01), no difference was found between spinal cord injury and each treatment protocol. The total synovial intima length of rats with spinal cord injury (5.9 ± 0.2 mm) became shorter than those of the controls (7.6 ± 0.2 mm) (p < 0.001), and those of stretching alone (6.9 ± 0.4 mm), stretching after heat (7.1 ± 0.3 mm), and stretching after cold (6.7 ± 0.4 mm) increased compared with rats with spinal cord injury (p = 0.01, p = 0.001, and p = 0.04, respectively). The staining intensity and pattern of collagen showed no difference among the treatment protocols.

CONCLUSIONS

This animal study implies that heat or cold alone is ineffective, and that stretching is helpful for the correction of contractures after spinal cord injury. In addition, we provide evidence that heat is more beneficial than cold to increase the effectiveness of stretching.

CLINICAL RELEVANCE

Our findings tend to support the idea that stretching after heat can improve the loss of ROM and histopathologic features of joint tissues. However, further studies are warranted to determine if our findings are clinically applicable.

An immunohistochemical study of the sciatic nerve in a rat knee immobilization model

[Purpose] This study was performed to immunohistochemically evaluate changes in the periphery of the sciatic nerve in a rat model of knee immobilization, and to assess the effects of range of motion exercise. [Subjects and Methods] Twenty-one male rats were divided randomly into three groups: control (C), immobilized (I), and exercise (E group). Rats in the I and E groups had the right knee joint immobilized for 2 weeks. In the E group, range of motion exercise was also performed. After the experimental period, the periphery of the sciatic nerve was immunohistochemically observed. [Results] Immunohistochemical staining revealed that the myelin sheath and the perineurium in all groups were laminin positive. In the C and E groups, all rats showed normal staining. In contrast, 4 rats in the I group exhibited weak labeling. [Conclusion] Our results suggest that immobilization alters the perineurium at a molecular level and the range of motion exercise is essential for maintaining the environment of the perineurium.

Effects of therapeutic ultrasound on joint mobility and collagen fibril arrangement in the endomysium of immobilized rat soleus muscle

This study examined effects of therapeutic ultrasound on joint mobility and collagen fibril arrangement in the endomysium of immobilized rat soleus muscle. Twenty-two male Wistar rats were divided randomly into control (n = 5) and experimental groups (n = 17). In the experimental group, bilateral ankle joints of each rat were fixed in full plantar flexion with a plaster cast over a 4-wk period. Five animals in the experimental group were immobilized throughout the 4-wk (immobilization group) period, whereas the remaining rats in the experimental group were randomly divided into the ultrasound (US, n = 6) and sham (n = 6) treatment groups. Under anesthesia, continuous ultrasonic energy (frequency, 1 MHz; intensity, 1.0 W/cm(2)) was delivered to the triceps surae muscle of the US group for 15 min per d, 6 d per wk over the 4-wk immobilization period. Ultrasonic energy was not delivered to the triceps surae muscle in sham animals; only the transducer head was moved. Ankle joint mobility on dorsiflexion in the immobilization, sham and US groups was significantly smaller than that of the control group, whereas in the US group, this parameter was significantly greater than in the immobilization and sham groups. Collagen fibril arrangement in the endomysium of the control and US groups was longitudinal to the axis of the muscle fibers; in contrast, it was circumferential in the immobilization and sham groups. Our findings revealed that joint immobilization induces decreased joint mobility and collagen fibril movement in the endomysium; furthermore, ultrasound treatment can prevent these changes. We hypothesized that therapeutic ultrasound during the immobilization process may inhibit deterioration of muscle contracture.