EN
Matrix metalloproteinases (MMPs) are considered to play a pivotal role in remodeling of the extracellular matrix in health and disease. Recent studies suggest that MMP-9 plays an important role in synaptic plasticity, learning and memory. It was shown that MMP-9 occurs in postsynaptic part of hippocampal synapses, where the amount and activity of MMP-9 were increased by stimulation leading plasticity changes. At the neuromuscular junction, a role, related to the turnover of agrin, has been demonstrated for MMP-3. Although MMP-9 has been localized to NMJ, neither its role nor precise distribution in relation to synaptic elements is established unequivocally. Here, we have carried out the investigation of the gelatinolytic activity of NMJ in rats, in order to establish whether high-intensity exercise can promote expression of MMP-9 at the NMJ. Our fi nding of the present work is that training increases the gelatinolytic activity of the NMJ in the extensor digitorium longus and soleus muscles. The 4-week endurance training program elicited alterations at the presynaptic side of the NMJ, where the increasing gelatinolytic activity was localized in the Schwann cells. These data shows that endurance training infl uences on the gelatinolytic activity of NMJ, possibly through synaptic transmission.