Avaliação de marcadores de neurônios entéricos Dogiel tipo II: caracterização neuroquímica dos neurônios aferentes primários intrínsecos (IPANs) no SNE do cólon humano

Abstract

The enteric nervous system (ENS) consists of a network of millions of interconnected neurons that are responsible for the autonomic innervation of the entire gastrointestinal tract. The advent of new laboratory techniques, such as immunohistochemistry with confocal microscopy, enabled the identification and characterization of several components of the ENS that were previously unknown. Among these components, there are IPANs (intrinsic primary afferent neurons), which are the representation of the sensitive neurons of the entire gastrointestinal tract. IPANs are transducers of physiological stimuli, including villous movement or mucosal distortion, intestinal muscle contraction and changes in the chemistry of the intestinal lumen content. In the intestine, IPANs have Dogiel type II morphology, that is, they are large round or oval neurons with multiple dendrites, some of which end near the luminal surface of the intestine and some of which form synapses with enteric interneurons, motor neurons and other IPANs. The objective of this work is to characterize the best combination of identification of neuromarkers capable of characterizing IPANs by immunohistochemistry, and thus contribute to more accurate, rapid and effective diagnoses in several pathologies. For that, we used the calcium channel markers calretinin and calbindin in association with nitric oxide synthase (NOS), choline acetyltransferase (cChAT) and vasoactive intestinal peptide (VIP). Statistical differences were determined using the one-way ANOVA test of the Minitab v.13 statistical program and considered p <0.05. The results showed that the best combination for identifying IPANs was calretinin with cChAT, reaching positivity of 73% in the myenteric plexus and 82% in the submucosal plexus. We believe that future studies that aim to evaluate the neurochemical marking of IPANs may reach higher levels of positivity, by adding, for example, a third marker. These identification studies are important to optimize the early diagnosis of several pathologies that afflict the gastrointestinal tract.