Association of sericin and swimming on the phenotype, motor plate, and functionality of the denervated plantar muscle of Wistar rats

Abstract

Physical exercise may help maintain muscle properties and functional improvement after peripheral nerve lesion, which may be enhanced by using biocompatible substances, such as sericin. The aim of this study was analyse the effect of sericin associated with swimming exercise on the phenotype, innervation, and functionality of the plantar muscle of Wistar rats. Forty randomly divided adult rats were used in five groups of eight animals: control, injury, sericin, exercise, exercise and sericin. The application of sericin was done on the spot, 100 μL, shortly after nerve compression. Three days after sciatic nerve compression, the swimming and swimming and sericin groups were submitted to physical swimming exercise for 21 days. Afterwards, the animals were euthanised and the plantar muscle was dissected and submitted to histochemical and histoenzymological techniques. The grip strength test did not show alterations in muscular functionality, and the control presented greater muscle mass in relation to the other groups, the same did not occur for muscle length. Polymorphic neuromuscular junctions were detected in the groups, although without significant morphometric alterations of the area, major and minor diameters. The percentage of type I fibres was lower in the lesion group and there was no difference in fibres IIa and IIb between groups. The area of fibres I, IIa and IIb remained constant between groups. Sericin biopolymer combined with swimming exercise did not affect plantar muscle function, submitted to experimental axonotmosis, whose contractile properties were altered by nerve injury.

Swimming Exercise Ameliorates Symptoms of MOG-Induced Experimental Autoimmune Encephalomyelitis by Inhibiting Inflammation and Demyelination in Rats

“…The forelimb strength was measured by the grip strength test using the grip strength meter 47200 (UgoBasile, Varese, Italy) according to the previous described method [11]. The rat was placed in front of the T-bar to hold the T-bar with the forefoot.…”

“…Regular exercise can contribute to suppressing pathogenic infections by enhancing antigen-specific immune responses [9,10]. Swimming exercise improves muscle endurance, pro-motes anti-inflammatory action and has a neuroprotective effect [11,12]. Compared to running, swimming can improve molecular adaptation, causing more neuroprotective effects [13].…”

Comparação de diferentes comprimentos de onda do laser de baixa potência no sóleo de ratos Wistar após lesão nervosa

“…Regarding morphometric analysis, by the measurements of area and smaller diameter, it is evident that all injury groups presented atrophy of muscle fibers. Santana et al 1,15 observed, in a similar model of nerve injury, muscle fibers characteristics of tropism, with reduction in strength and phenotypic changes. In our study, only the group using 830 nm obtained a higher result than the injury group for the area of muscle fibers, observing a small evolution.…”

Negative neuromuscular and functional repercussion of forced swimming after axonotmesis

“…The assessment of the muscular weight, fibers type and protein concentration indicates that the intense swimming (2 hr day, 5 days week during 3 weeks with load) was not able to improve the reinnervation repair in a denervated muscle after sciatic crush model ( Herbison et al, 1974 ). Swimming exercise stated on the 3rd day after sciatic crush, during 3 weeks and progressive time of 15, 20, and 25 min with an overload of 10% of the BW, did not affect the area of muscle fibers and neuromuscular junctions of the plantar muscle ( Santana et al, 2018 ).…”