Estudo morfoquantitativo do Complexo Olivar Inferior de morcegos (Artibeus planirostris): descrição da marcação serotoninérgica

Abstract

The inferior olivary complex (IOC) is a set of pre-cerebellar nuclei with organized subdivisions and topographical olivocerebellar connections, essential for motor integration and coordination. There are important cytoarchitectural differences between mammals in relation to the IOC. This study uses the bat species Artibeus planirostris, characterized by its flattened snout and wide geographical distribution throughout the tropical zones of several countries located in the northern half of South America. In the literature, several studies address serotoninergic distribution, either in the cell nucleus or in serotoninergic fibers, especially in the IOC of rats, cats and monkeys. Serotonin (5-HT) is an important neurotransmitter that acts in processes such as cognition, attention, emotion, pain regulation and sleep. Serotonin plays a crucial role in this complex by acting to regulate rhythmic oscillations and activities in living organisms. No studies have been found that specifically explore serotonin labeling in the IOC of bats. Therefore, the aim of this study was to carry out a morphometric analysis of the inferior olivary complex of A. planirostris bats in order to describe its serotoninergic markings. Together, the morphology, morphometry and serotonin marking pattern of the IOC of four specimens of A. planirostris bats were observed, in accordance with SISBIO license No. 25233-2 and CEUA protocol number 009/2012. To carry out the work, the following procedures were carried out: capture, anesthesia, euthanasia, transcardiac perfusion, removal of the brains, microtomy, Nissl staining, immunohistochemistry and obtaining images of coronal sections to quantify cells and average cell areas between the IOC nuclei in order to carry out the statistical analysis. The Shapiro-Wilk and Kruskal-Wallis statistical tests, respectively, carried out using GraphPad Prism software, revealed that the data analyzed did not have a normal distribution and showed significant variation between the mean cell areas of the animals. In terms of morphology, it was observed that the cytoarchitecture of the IOC of A. planirostris is defined bilaterally by the dorsal and medial accessory inferior olivary nuclei and the main inferior olivary nucleus. In addition, rounded and oval cells were observed, with distinct predominance between the nuclei. The morphometric analysis showed that there are differences between the mean cell areas of the nuclei of the animals analyzed. As for serotonin, it is characterized by a distribution with different concentration patterns between the rostral, middle and caudal levels between the coronal sections observed.