Análise comparativa da denervação no sistema nervoso entérico no megaesôfago chagásico versus idiopático na cárdia e nos terços esofágicos, em relação ao número total de neurônios e à proporção de neurônios SP+ (excitatórios) e NOS+ (inibitórios)

Abstract

Introduction/objective: Clinical studies suggest that inhibitory innervation injury would prevail in the idiopathic megaesophagus (IME), while in the chagasic megaesophagus (CME) there would be impairment of both inhibitory and excitatory innervation. The aim of this study was to analyze intramural denervation in relation to the total number of neurons and to the proportion of excitatory and inhibitory neurons, in the cardia (Cd) and in the esophageal thirds, between CME, IME and chagasic with no megaesophagus (CNME) groups, in relation to the non-chagasic control (NC). Material and methods: In the first step, for the general assessment of denervation, the neurons were counted in the myenteric plexus of 87 esophagus, 62 of necropsies and 25 esophagectomies (NC = 19; IME = 18; CME = 22 e CNME = 28 cases) in 5 HE-staggered cuts in a ring of the lower third (LT), medium third (MT) and upper third (UT), and in 5 longitudinal cuts on each side of the Cd. In the second step, 28 cases (NC = 6, IME = 7, CME = 7 and CNME = 8) were analyzed by immunohistochemistry to assess the proportion of inhibitory neurons (NOS +) versus excitatory (SP +). Results: There was no statistically significant difference between the denervation in the CME x IME in any region, with frequent aganglionosis. These groups showed significant denervation in relation to NC in all regions. The CME group showed significant denervation in relation to CNME in all regions; however, IME differed from CNME only in Cd and LT. Some cases of IME still had frequent neurons, predominantly in MT and UT. In the CNME group the denervation was very variable, being significant in relation to the NC in the LT, MT and UT, but not in the Cd. These data suggest that denervation in Cd may be more important for triggering megaesophagus, as well as dysphagia, that was present in two cases of CNME with denervation greater than 95% only in Cd. A case of discrete and recent CME also had intense denervation only in Cd. There was no evidence of selective denervation in relation to NOS or SP neurons in any group; however, in a case of IME with less intense denervation and in a CNME with dysphagia, there was a greater loss of NOS neurons than SP ones. Discussion/Conclusion: In megas the neuronal destruction was total (aganglionose), or almost total, of the two types of neurons. The intense denervation in the distal part seems to be the main factor for the pathogenesis of the megaesophagus; however, it is possible that the imbalance between inhibitory and excitatory neurons may contribute to motor dysfunction in15 some cases, especially in the cardia, as seems to have occurred in a case of IME with less intense denervation than usual and in a CNME with dysphagia.