Adapatações da junção neuromuscular na isquemia cerebral e no diabetes mellitus
Resumo
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.