The morphological and functional effects of exercise in the aquatic environment, performed before and/or after sciatic nerve compression in Wistar rats

The potential protective effects of pre-injury exercise on neuroimmune responses following experimentally-induced traumatic neuropathy: a systematic review with meta-analysis

Pre-clinical evidence shows that neuropathy is associated with complex neuroimmune responses, which in turn are associated with increased intensity and persistence of neuropathic pain. Routine exercise has the potential to mitigate complications of future nerve damage and persistence of pain through neuroimmune regulation. This systematic review aimed to explore the effect of pre-injury exercise on neuroimmune responses, and other physiological and behavioural reactions following peripheral neuropathy in animals. Three electronic databases were searched from inception to July 2022. All controlled animal studies assessing the influence of an active exercise program prior to experimentally-induced traumatic peripheral neuropathy compared to a non-exercise control group on neuroimmune, physiological and behavioural outcomes were selected. The search identified 17,431 records. After screening, 11 articles were included. Meta-analyses showed that pre-injury exercise significantly reduced levels of IL-1β (SMD: -1.06, 95% CI: -1.99 to -0.13, n=40), but not iNOS (SMD: -0.71 95% CI: -1.66 to 0.25, n=82). From 72 comparisons of different neuroimmune outcomes at different anatomical locations, vote counting revealed reductions in 23 pro-inflammatory and increases in 6 anti-inflammatory neuroimmune outcomes. For physiological outcomes, meta-analyses revealed that pre-injury exercise improved one out of six nerve morphometric related outcomes (G-ratio; SMD: 1.95, 95%CI: 0.77 to 3.12, n=20) and one out of two muscle morphometric outcomes (muscle fibre cross-sectional area; SMD: 0.91, 95%CI: 0.27 to 1.54, n=48). For behavioural outcomes, mechanical allodynia was significantly less in the pre-injury exercise group (SMD -1.24, 95%CI: -1.87 to -0.61) whereas no overall effect was seen for sciatic function index. Post hoc subgroup analysis suggests that timing of outcome measurement may influence the effect of pre-injury exercise on mechanical allodynia. Risk of bias was unclear in most studies, as the design and conduct of the included experiments were poorly reported. Preventative exercise may have potential neuroprotective and immunoregulatory effects limiting the sequalae of nerve injury, but more research in this field is urgently needed.

The timing point of exercise intervention regulates neuropathic pain-related molecules in the ipsilateral dorsal root ganglion neurons after sciatic nerve injury

The purpose of this study was to determine whether the timing of tread-mill exercise application can control expression levels of neuropathic pain- and regeneration-related proteins in the ipsilateral lumbar 4 (L4) to 6 (L6) dorsal root ganglion cells (DRG) after sciatic nerve injury (SNI). The experimental rats were randomly divided into five groups: the normal control, SNI+sedentary (IS), exercise+SNI (EI), SNI+exercise (IE), exercise+SNI+exercise (EIE) groups. The rats in exercise groups per-formed treadmill exercise at a speed of 8 m/min for 30 min once a day during 14 days before and/or after SNI. For investigating the expression of specific neuropathic pain and regeneration-related proteins in DRG, we prepared L4 to L6 DRG in the ipsilateral side. In the quantitative analysis, growth associated protein 43 (GAP-43) and brain-derived neurotrophic factor levels were further increased in the ipsilateral DRG at all treadmill exercise groups than those in IS group. In the histological findings, GAP-43 was qualitatively increased IE and EIE groups than IS group at DRG. Wnt3a and β-catenin were dramatically downregulated in EIE and IE groups than IS groups. In addition, nuclear factor kappa-light-chain-enhancer of activated B cells and tumor necrosis factor-α were significantly decreased in IE and EIE groups than IS group in the ipsilateral DRG. Our findings suggested novel information that regular low-intensity exercise before and/or after SNI might be a therapeutic and preventive approaches for relieving neuropathic pain and improving axonal elongation after peripheral nerve injury.

Resistance exercise promotes functional test via sciatic nerve regeneration, and muscle atrophy improvement through GAP-43 regulation in animal model of traumatic nerve injuries

Resistance training improves muscle strength through a combination of neural plasticity and muscle hypertrophy. This study aimed to evaluate the effects of resistance exercise on sciatic nerve regeneration and histology, growth-associated protein 43 (GAP-43) expressions, and soleus muscle atrophy following traumatic nerve injuries in Wistar rats. In the present study, 40 male Wistar rats were randomly assigned into four groups: healthy control (HC) as a sham group was exposed to the surgical procedures without any sciatic nerve compression, lesioned control (LC), resistance training (RT,non-lesioned), and lesioned rats+RT (LRT) (n=10 in each). The RT group performed a resistance-training program 5 days/week for 4 weeks. Sciatic functional index (SFI) score, beam score and Basso, Beattie, and Bresnahan (BBB) score decreased and the hot plate time increased significantly in the LC‌ group compared to the HC (p<0.05) group. However, the LRT‌ group showed a significant increase in the SFI score (p=0.001) and a significant decrease in hot plate time (p=0.0232) compared to the LC group. The LC group also showed neurological morphological damage and muscle atrophy and a decrease in GAP-43 in nerve tissue. In comparison to the LC group, a significant increase in sciatic nerve caliber, diameter, number of muscle fibers, and the expression of GAP-43‌ (p<0.05) was observed in the LRT group. Doing resistance training even for four weeks seems to affect sciatic nerve lesions and injuries. It can also repair and regenerate nerve tissue by upregulating GAP-43 expression‌, improving motor behavioral tests, and controlling muscle atrophy.

Negative neuromuscular and functional repercussion of forced swimming after axonotmesis

Peripheral nerve injuries are cause of sensory disturbances and in functional abilities, and are associated personal and social costs. Strategies that maximize nerve regeneration and functional recovery are necessary, the exercise is an option. This study evaluated the effects of forced swimming exercise on neuromuscular histomorphometry and on functional recovery in a median nerve crush model. Sixteen Wistar rats underwent median nerve crush and were divided into control group (CG) and swimming group (SG). The forced swimming protocol started one week after the injury and was performed for 1 hr a day, 5 days per week, for 2 weeks. The rats swam with an overload of 5% and 10% of body weight in the first and second week, respectively. The functional recovery was assessed in three moments using the grasping test. On day 21, fragments of the median nerve and of the forearm flexors muscles were removed for histomorphometric analysis. The SG had functional recovery impaired (P<0.001) and presented lower myelinated fibers number, fiber and axon minimal diameter, myelin thickness and g-ratio in the proximal e distal segments of the median nerve (P<0.005) and area muscle fiber (P<0.005) than CG. Also, the SG presented a number of capillaries in the proximal segments of the median nerve greater than CG (P<0.005). The exercise protocol used in this study impaired the regeneration of the median nerve and negatively influenced the functional recovery.

Ladder-based resistance training elicited similar ultrastructural adjustments in forelimb and hindlimb peripheral nerves of young adult Wistar rats

To analyze the morphological response induced by high-volume, high-intensity ladder-based resistance training (LRT) on the ultrastructure of the radial (forelimb) and sciatic (hindlimb) nerves of adults Wistar rats. Twenty rats were equally distributed into groups: sedentary (SED) and LRT. After the rodents were subjected to the maximum load (ML) carrying test, the LRT group performed 6-8 progressive climbs (2 × 50% ML, 2 × 75% ML, 2 × 100% ML, and 2 × 100% ML + 30 g) three times per week. After 8 weeks, the radial and sciatic nerves were removed and prepared for transmission electron microscopy. In the radial nerve, myelinated axons cross-sectional area (CSA), unmyelinated axons CSA, myelin sheath thickness, and Schwann cells nuclei area were statistically larger in the LRT group than SED (p < 0.05). Also, the number of microtubules and neurofilaments per field were statistically higher in the LRT group than in SED (p < 0.01). For sciatic nerve, myelinated fibers CSA, unmyelinated axons CSA, myelin sheath thickness, Schwann cells nuclei area, and the number of neurofilaments per field were statistically larger in the LRT group compared to the SED group (p < 0.05). LRT with high-volume and high-intensity effectively induce similar changes in adult Wistar rats' radial and sciatic nerves' ultrastructure.

The Effect of Aerobic Physical Activity in Adrenaline Level in White Laboratory Rats

Introduction

Physical activity is one important factor in the nervous system of animals, it may affect the structure also the function of the brain. Regular aerobic exercises have a good effect on the whole body and thus improves the sense of well-being.

Aim

The aim of this experiment was to evaluate the effect of aerobic physical activity in white laboratory rats for 21 days.

Methods

The experimental animals used were twenty Wistar rats, divided into 2 groups of 10 animals they were subjected to forced swim test for 21 days for 60-90 min swim. The evaluation of levels of Adrenaline was performed on 1st, 7th, 14th day and on the last day of the experiment day 21 using ELISA kit protocol, also body mass was compared between groups.

Results

Our results showed that inducing aerobic physical activity for 21 days on the rats affects their levels of adrenaline. Comparatively, the control group of rats had significantly higher levels of adrenalin compared with day 21 (p=0.435) but lower compared with day 7 and 14 (p=0.231). There was also a difference in body mass which demonstrates adaptability to the surroundings and better coping with physical stress.

Conclusion

Regular aerobic activity for 21 days, for 60-90 min swim has a positive impact on adrenaline level also this aerobic exercise protocol could have a positive impact on reducing and maintaining body weight, thus preventing overweight.

Recovery of sensory function after the implantation of oriented-collagen tube into the resected rat sciatic nerve

Introduction

In the present study, we examined the effect of oriented collagen tube (OCT) implantation on the recovery of sensory function of the resected rat sciatic nerve.

Materials and methods

After a 10-mm long portion of the sciatic nerve of a rat was resected, an OCT was placed in the site of nerve defect. Recovery of the sensory function was evaluated using Von Frey test every 3 days after surgery. The regenerated tissue were histologically and ultrastructurally analyzed 2 and 4 weeks after the surgery.

Results

The sensory reflexes of the OCT group were restored to the level of that of the intact group after 15 days. Hematoxylin and eosin staining revealed the cross-linking between the proximal and distal stumps after 2 weeks. After 4 weeks, Luxol Fast Blue and immunohistochemical staining revealed the presence of myelin sheath from the proximal to distal region of the regenerated tissue and S100B staining confirmed the presence of Schwann cells. Interestingly, no myelin sheath was ultrastructurally observed around the regenerated axons at the central region after 2 weeks.

Conclusions

These results suggest that OCTs facilitate the recovery of sensory function. Additionally, the non-myelinated axons contributed to the recovery of the sensory function.

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Von Frey test results in the OCT group on POD 15 were comparable at the sham group.

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OCT group showed regeneration of unmyelinated axons in 2 weeks.

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Myelination was observed from proximal to distal after 4 weeks OCT implantation.

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In the OCT group, a large number of blood vessels were observed in nerve in 2 weeks.

Effects of two intensities of treadmill exercise on neuromuscular recovery after median nerve crush injury in Wistar rats

Considering the potential action of exercise on neuroplasticity and the need to adapt protocols to enhance functional recovery after nerve injury, this study evaluated the effects of two intensities of treadmill exercise on nervous and muscular tissues and functional recovery after nerve crush injury. Wistar rats were distributed into sedentary group (SED), and 10 m/min (EG10) and 17 m/min (EG17) exercise groups. The exercise started one week after the injury. Ten daily sessions were performed with a 2-day interval after the fifth day. The flexor digitorum muscle and two segments of the median nerve were analysed histomorphometrically by light microscopy and computer analysis. Function was evaluated by grasping test, in 3 moments. Approval number: 016/2013. In the proximal segments of the median nerve, the diameter of myelinated fibres and axon, the myelin sheath thickness and the ratio of axon diameter to fibre diameter (g ratio) were significantly larger (P<0.05) in the EG10. The number of myelinated fibres was lesser in the EG17 than the other groups (P<0.05). No difference in the number of myelinated fibres among groups was observed in the distal segments, but the SED presented significantly larger axon and fibre diameters than those that performed exercise. The EG10 presented greater area and diameter of muscle fibres (P<0.05) and functional improvement observed on the 21st day after injury (P<0.05) compared with the EG17 and SED. Continuous exercise at 10 m/min accentuates nerve regeneration, accelerating functional recovery and preventing muscle atrophy.

Scolopendra subspinipes mutilans Extract Suppresses Inflammatory and Neuropathic Pain In Vitro and In Vivo

Background

Sciatic nerve injury develops from a variety of pathological causes, including traumatic injury and neuroinflammatory disorders, which are accompanied by pathological changes that have a critical impact on neuropathic pain and locomotor activity. Extracts of Scolopendra subspinipes mutilans (SSM) are used in traditional medicine for the treatment of a wide range of neuropathic diseases, including lower back pain, peripheral neuropathy, and sciatic nerve injury. Although SSM shows anti-inflammatory, antibacterial, and anticonvulsant activities, its diverse mechanisms of action remain unclear. Thus, the present study examined the effects of SSM in vitro and in vivo.

Methods

To estimate the anti-inflammatory effects of SSM, inflammatory conditions were induced using lipopolysaccharide (LPS) in RAW 264.7 cells, and inflammatory-related factors were evaluated by enzyme-linked immunosorbent assay (ELISA) and western blotting analyses. Sciatic nerve crush injury (SNCI) was induced in rats using a surgical clip instrument. The effects of SSM in the SNCI model were evaluated in behavioral tests by calculating the sciatic functional index (SFI) and measuring thermal hyperalgesia sensitivity and by monitoring inflammatory factors expression in western blotting analyses.

Results

We observed the anti-inflammatory effects of SSM treatment both in vitro and in vivo. The PGE₂ and NO production were suppressed by SSM. Protein analyses indicated that expression of NF-κB and degradation of IκBα were suppressed by SSM treatment. In addition, the levels of iNOS, TNF-α, IL-6, and COX-2 expression were reduced by SSM treatment in RAW 264.7 cells and in the SNCI-induced animals. In behavioral studies, SSM treatment enhanced the SFI and improved the thermal sensitivity test results.

Conclusions

Our results suggest that SSM suppresses the production of inflammatory factors via the NF-κB pathway and accelerates the morphological and functional recovery of the peripheral nervous system. Hence, SSM may be a useful therapeutic candidate for treatment of neuropathic pain diseases.