Efeito da criolesão no remodelamento da matriz extracelular em músculo esquelético de rato

Abstract

The aim of the present study was to investigate components of extracellular matrix (ECM) during the skeletal muscle regeneration after cryolesion in rats. Sixty adult Wistar rats were used. The animals were divided into 4 groups: 1, 7, 14 and 21 days post-injury (10animls/group). One of the tibialis anterior muscles was cryolesioned and the contralateral muscle was used as the control. One sham group, in which animals received only the surgical procedure and one group of control animals that do not receive any intervention were included. The muscles were submitted to hematoxylin-eosin and immunohistochemistry staining for collagen IV, MMP-2 and MMP-9 detection. The MMP enzymatic activity was verified by zymography. The control muscles showed normal morphology and the sham group exhibited an inflammatory infiltrated. After 1 day, the cryolesioned group exhibit moderate inflammatory infiltrated and necrosis areas. At 7 and 14 days a significant reduction of the inflammatory process, absence of necrosis and presence of immature muscular cells could be observed. The injured group revealed total remodeling after the 21 days. Collagen IV showed a disordered distribution pattern after 1 day of injury and gradually it was reorganized during the 21 days of the muscle regeneration. The MMP-2 and MMP-9 immunolabeling, as well, the MMP-2 activity were related to the phase of skeletal muscle repair. After 1 day, an increase on MMP-2 and MMP-9 labeling and MMP-2 activity were observed. In conclusion, the increase and decrease of immunolabeling and activity of MMP were related to the break down and accumulation of collagen IV during the skeletal muscle remodeling.