The role of ischemic preconditioning at the gracilis muscle of rats in the early phase of reperfusion injury

Preconditioning improves muscle regeneration after ischemia-reperfusion injury

Ischemia-reperfusion injury (IRI) is a critical condition associated with serious clinical manifestations. Extensive research has focused on the strategies increasing organ tolerance to IRI. Preconditioning (PC) has been shown to provide protection to various organs toward IRI. However, the underlying mechanisms remain unknown. This study aimed to evaluate the role of PC on muscle regeneration after IRI and the potential underlying mechanisms. Three-month-old male UCP-1 reporter mice underwent unilateral hindlimb IRI with or without PC, the tissue viability and injury index were measured at 24 h after IRI. Hindlimb gait, muscle contractility, muscle histology were analyzed at 2 weeks after IRI. In another group of animals, β3 adrenergic receptor (β3AR) agonist amibegron and β3AR antagonist SR-59230A were administrated before PC/IRI, the hindlimb function and muscle regeneration were evaluated at 2 weeks after IRI. Our results showed that PC has little effect on improving the tissue viability at the acute phase of IRI, but it showed a long-term beneficial role of improving hindlimb function and muscle regeneration as evidenced by increased central nuclei regenerating myofibers. The effects of PC are related to inducing muscle fibro-adipogenic progenitor (FAP) brown/beige-like adipocyte (BAT) differentiation. Amibegron treatment displayed a similar role of PC while SR-59230A abolished the effect of PC. This study suggests PC has a beneficial role in promoting muscle regeneration after IRI through β3AR signaling pathway-stimulated FAP-BAT differentiation.

Effects of kinesiotherapy in ischemic lesion and reperfusion in rats

OBJECTIVE

To investigate the effect of kinesiotherapy on the functionality of the pelvic limb of rats after ischemic and reperfusion injury.

METHODS

10 rats were divided into two groups, GI (control) and GII (kinesiotherapy). All the animals underwent ischemia for a period of three hours, followed by tissue reperfusion. In Group GII, non-resistive systemic kinesiotherapy was performed (swimming) in three weekly sessions of 50 minutes, over a period of four weeks, while the GI animals remained at rest. Functional analysis of motor behavior was evaluated weekly. The animals were then sacrificed, and the soleus and gastrocnemius muscles and the sciatic nerve removed for histopathological analysis.

RESULTS

There was a significant recovery of motor behavior with kinesiotherapeutic treatment during the four weeks of treatment. However, the histological examination of the tissues showed no morphological changes of cell injury and repair.

CONCLUSION

It was not possible to affirm that the exercise was effective in cell repair, because neither of the groups (control and experimental) showed any histological difference. On the other hand, systemic kinesiotherapy showed a beneficial effect on functional rehabilitation after ischemia and reperfusion. Level of evidence III, Case-Control Study .