Distribuição dos grupamentos neuronais colinérgicos no encéfalo do mocó (Kerodon rupestris)

Abstract

The acetylcholine (Ach) was the first discovered neurotransmitter, in the somatic motor neurons and autonomic neurons, and then observed in several neuronal clusters in the central nervous system, in the form of interneurons and large projection neurons. In the central nervous system, Ach is involved in the control of certain motor activities and processes to learning and memory. The aim of this study was to cytoarchitectonicly and by cholineacetyltransferase (ChAT)-immunohistochemistry delimit the cholinergic groups in the encephalon of the rock cavy (Kerodon rupestris), a crepuscular Caviidae rodent from Brazilian Northeast. For this, threeyoung adult animals were anesthetized and transcardially perfused. The encephala were frozen-cut in the coronal plane, obtaining 6 series of 30 µm sections. The sections from one series were subjected to Nissl staining. Another series was subjected to immunohistochemistry to develop the acetylcholine putatively present in diverse neural centers of the rock cavy, using the synthesizing enzyme ChAT as marker. The slides were analyzed under light microscope and the results documented by description and digital photomicrographs. ChAT-immunoreactive neurons were identified in the telencephalon (nucleus accumbens, caudate-putamen, globus pallidus, entopeduncular nucleus and ventral globus pallidus, olfatory tubercle and Islands of Calleja, diagonal band of Broca nucleus, nucleus basalisand medial septal nucleus), diencephalon (ventrolateral preoptic, hypothalamic ventrolateralandmedial habenularnuclei) and brainstem (parabigeminal, laterodorsal tegmental and pedunculopontine tegmental nuclei). These findings are discussed in a functional and phylogenetic perspective, because although there are similarities between the species previously studied, in our work it was possible to observe differences and new results previously not described in other species of mammals.