ATF-3 como marcador de lesão e de padrões topográficos em neurônios autonômicos do núcleo dorsal motor do nervo vago após axotomia periférica

Abstract

The topographical distribution of vagal efferent neurons has been studied mainly by the use of retrograde tracers applied to specific segments of organs or proximal part of severed nerves. The aim of this study was to evaluate whether the induced expression of lesion markers can be used to study the distribution and the chemical code of dorsal motor nucleus of vagus nerve (DMV). To this end, rats were submitted to section of one of the three branches of the anterior subdiaphragmatic vagus. Five days after axotomy, rats were perfused and immunofluorescence reactions performed for lesions markers: activating transcriptional factor 3 (ATF-3), nestin and Growth associated proteins 43 (GAP-43), as well as for neuronal markers: choline acetyltransferase (ChAT), tyrosine hydroxylase (TH) and neuronal nitric oxide synthase (nNOS). Peripheral vagotomy resulted in a rapid increase in ATF-3 expression but not for nestin or GAP-43. Using the retrograde tracer choleric toxin  subunit it was estimated that 95.2 ± 0.7% of DMV neurons respond to vagotomy with an increase in antiATF-3 labeling. The anterior gastric, hepatic and accessory celiac branch neurons reached a maximum number at the level 33, 3 and 121 m, respectively. The anterior gastric branch is represented medially, the accessory celiac laterally and the hepatic branch homogeneously at DMV. The anti-TH labeling occurred exclusively in anterior gastric projecting neurons. It was observed a significant increase in the percentage of positive nNOS neurons after axotomy. Therefore, the induced expression of ATF-3 is a useful tool for analysis of distribution of unmyelinated autonomic neurons.