Effects of exercise on muscle reinnervation and plasticity of spinal circuits in rat sciatic nerve crush injury models with different numbers of crushes

Abstract

Introduction/Aims: Motor function recovery is frequently poor after peripheral nerve injury. The effect of different numbers of nerve crushes and exercise on motor function recovery is unknown. We aimed to examine how different numbers of crushes of the rat sciatic nerve affects muscle reinnervation and plasticity of spinal circuits and the effect of exercise intervention.Methods: Single and multiple sciatic nerve crush models with different numbers of crushes were created in rats. Treadmill exercise was performed at 10 m/min for 60 min, five times a week. Muscle reinnervation and synaptic changes in L4-5 motor neurons were examined by immunofluorescence staining. Behavioral tests were the sciatic functional index (SFI) and the pinprick tests. Results:The percentage of soleus muscle reinnervation was not significantly increased by the presence of exercise in single or multiple crushes. Exercise after a single crush increased the contact of motor neurons with VGLUT1-containing structures (Exercised vs. Unexercised, 12.9% vs. 8.7%; p < .01), but after multiple crushes, it decreased with or without exercise (8.1% vs. 8.6%). Exercise after a single crush significantly improved SFI values from 14 to 24 days, and exercise after multiple crushes from 21 to 35 days (all p < .05). The pinprick test showed no difference in recovery depending on the number of crushes or whether or not exercised.Discussion: Different numbers of sciatic nerve crushes affect muscle reinnervation and motor neuron synaptic changes differently, but motor function recovery may improve with exercise regardless of the number of crushes.

The Impact of Treadmill Training on Tissue Integrity, Axon Growth, and Astrocyte Modulation

“…Higher expression of vGlut1 + -motoneurons was reported in rats trained on a treadmill after spinal cord transection [39] and in mice with contusive SCI [40]. Treadmill exercises also increased synaptic coverage of vGlut1 + terminals on motoneurons after sciatic nerve transection [41]. The increase in vGlut1 + profiles suggests an increase in presynaptic terminals and glutamatergic synapses.…”

Yüzme Egzersizinin Siyatik Sinir Hasarı Sonrasında Elektrofizyolojik Parametreler Üzerindeki İyileştirici Etkisi

“…Low-intensity treadmill exercises (8 m/min/30 min/5 days) in the acute period after nerve damage and high-intensity treadmill exercises (20 m/min/30 min/5 days) in the late period provide motor functional improvement by increasing SFI values (Cai et al, 2015). Treadmill exercises performed after single and multiple sciatic nerve crush injuries (60 min/week 5 days/10 m/min) statistically improved SFI values on the 14th to 21st days for single nerve crush injury and on the 21st to 35th days for multiple nerve crush injury (Minegishi et al, 2022;Tsai et al, 2012). Treadmill exercises (10 min/5m/min for the first 2 weeks, 15 min/10 m/min for the 3rd and 4th weeks, 20 min/m/min for the 5th and 6th weeks) started at the 3rd week after sciatic nerve damage and repair, improved SFI values, similar results were obtained to the control group, nerve graft, and nerve repair after damage and repair of the sciatic nerve by nerve graft they stated that the graft+exercise groups did not improve the SFI values and did not modify nerve regeneration (Figueiredo et al, 2022).…”

“…The types of sciatic nerve damage (Goulart et al, 2014;Andrade et al, 2020), type of exercise and duration of application affect SFI values in different ways (Pollari et al, 2018;Debastiani, Santana, Ribeiro, Brancalhão and Bertolini, 2019;Rosa Junior et al, 2016;Arabzadeh at al., 2022). Different exercise practices ; swimming exercises (Ozocak, 2022, Pollari et al, 2018Debastiani et al, 2019;Rosa Junior et al,2016;Arabzadeh at al., 2022), resistance exercises (Bobinski et al, 2011), treadmill exercises (Udina et al, 2011;Goulart et al, 2014;Bobinski et al, Cai, Na and Hwangbo, 2015;Minegishi et al, 2022;Tsai et al, 2012), endurance exercises (Ilha et al, 2008), balance and coordination exercises (Bonetti et al, 2011), eccentric exercises (Martins et al, 2018), active and passive cycling exercises (Oliveira et al, 2008), the intensity of exercise (low intensity-30min/ 5 days a week/2 and 4 weeks-10m/min)and high intensity improve nerve regeneration and functional recovery by increasing the SFI values (Bobinski et al, 2011;Cai et al, 2015). Low-intensity treadmill exercises (8 m/min/30 min/5 days) in the acute period after nerve damage and high-intensity treadmill exercises (20 m/min/30 min/5 days) in the late period provide motor functional improvement by increasing SFI values (Cai et al, 2015).…”

Comparative neuroprotective effects of Cerebrolysin, dexamethasone, and ascorbic acid on sciatic nerve injury model: Behavioral and histopathological study

“…Unlike the central nervous system, the peripheral nervous system is gifted to repair and regenerate after injury, but this capability is functionally limited and slow with subsequent vulnerability to permanent disabilities. Overall the process of peripheral nerve recovery is far from being satisfactory ( Minegishi et al, 2022 ).…”