O núcleo supraquiasmático e o folheto intergenicula do do morcego (Artibeus planirostris): projeção retiniana e caracterização neuroquímica

Abstract

The circadian timing system (CTS) comprises a set of neural structures that include input pathways, such retinal projections, which allow the synchronization of the biological rhythms to environmental cycles; a central circadian pacemaker, which generates the circadian signal and output pathways connecting the pacemaker to the behavioral effectors. Among the major components of the STC, highlight the suprachiasmatic nucleus (SCN), classically known as the neural structure that governs biological rhythmicity, and the intergeniculate leaflet (FIG) of the thalamic lateral geniculate complex, modulator pacemaker. In this study, both circadian centers were evaluated in respect to their cytoarchiteture, pattern of the retinal innervations and chemical content with a Nissl stain, neural tracer and imunohistochemical techniques in bat Artibeus planirostris, common microchiropteran in Brazil. Based on these techniques was observed in rostral sections, the SCN had an approximately triangular shape and in middle and caudal sections, this nucleus assumed an ellipsoidal contour. It receives bilateral retinal in nervations, with discrete contralateral predominance and contains vasopressin (VP), vasoactive intestinal polypeptide (VIP), calbindin (CB) e calretinin (CR) immunoreactive cell bodies; neuropeptide Y (NPY) and serotonin (5-HT) imunopositive fibers/ terminals, besides to glial fibrillary acidic protein (GFAP) labeling. The IGL contains NPY, CB and CR immunoreactive perikarya and receives a bilateral retinal projection. The rostral and middle IGL had a leaflet shape between the DLG and VLG. At a caudal level it had a descending portions which outlines de VLG medially. This is the first report examining the CTS of these species of chiropteran. The results indicate that retinal input and chemical content of the SCN and IGL in Artibeus planirostris are similar other mammalian species. In contrast, the SCN of these bat transcend the classical organizational schemes proposed in the scientific literature. Hodological and molecular studies are needed to stablish a specific division of this structure in these species of chiropteran.