Adapatações da junção neuromuscular na isquemia cerebral e no diabetes mellitus

Abstract

Introduction: Chronic Noncommunicable Diseases (CNCDs) are the leading cause of mortality and premature disability in most countries of the American continent, including Brazil. Among CNCDs are Diabetes Mellitus (DM) and Cerebral Vascular Accident (CVA). Both DM and CVA can compromise upper limb (UL) function, decreasing motor performance by compromising the structure and function of muscle tissue. The Neuromuscular Junction (NMJ) is an important structure that relates the function of the central and peripheral nervous system to that of muscle tissue. Understanding NMJ changes in DM and CVA and its relation to UL function may help in understanding the pathophysiology of these diseases, as well as guide possible therapies. Objective: The objective of the two studies was to evaluate the plasticity of NMJ in animal models of DM and Brain Ischemia (BI) separately, as well as its relationship with motor skills in a reach and manipulation task. Method: For this, two studies were conducted. In study 1, 12 3-month-old Wistar rats, divided into two Control (C) and DM groups, were trained in reaching task, through habituation, dominance determination and reach task training. After these procedures, all animals were evaluated with the test of collecting tablets. In the animals of the DM group, the induction of DM was performed, with the injection of streptozotocin (STZ) dissolved in citrate buffer. In study 2, 12 3-month-old Wistar rats divided into 2 groups (C and BI) were also trained for the task of collecting tablets, as previously explained. In BI group, ischemia was induced with injection of Endothelin 1 (ET1) in the area of motor representation of forelimb. After 15 days, all animals of both groups were euthanized, extracting the biceps, triceps, fingers flexor and fingers extensor muscles. The cross-sectional muscle fiber area (CSA) the percentage of connective tissue and NMJ area were investigated in both studies. Correlations between morphometric variables and motor performance were performed. Results: In study 1, there was a decrease in the morphometric parameters of the NMJ, as well as an increase in the atrophy of the muscles of the DM group compared to the animals in C group. In study 2, there was a increase in the morphometric parameters of NMJ and an increase in muscle group atrophy of the BI group compared to the animals in C group. In the two studies, there was an important association between the NMJ parameters and the motor performance evaluated in the DM and BI. Conclusions: Both DM and BI generate changes in NMJ, muscular atrophy and fibrosis of the forelimb muscles. Such alterations are associated with performance in coordinated tasks of the forelimb of the animals.