Caracterização citoarquitetônica e morfoquantitativa dos núcleos talâmicos da linha média e intralaminares e sua população neuronal glutamatérgica em Mocós (Kerodon rupestris)

Abstract

The thalamocortical projections are fundamental to regulate the flow of sensory information, as well as the relation of the integration of this information with the cortex. Glutamate (Glu) is a fundamental neurotransmitter in the processing of sensory functions, development and maintenance of cognitive functions, and therefore constitutes the main neurotransmitter of the pathways related to the thalamic-cortical-thalamic projections. The midline/intralaminar (LM/IL) nuclei form a significant portion of the thalamus and have a global influence on cortical functioning. With this, we aim to characterize the LM and IL nuclei, through morphology and stereology, of the rock cavy thalamus (Kerodon rupestris), a typical rodent of the Brazilian Northeast, as well as morphological aspects of its glutamatergic neuronal population. Our study is the pioneer in the stereological analysis of the LM / IL nuclei as well as the IR-Glu cells in them. We used 6 young adult rock cavies, whose brains were submitted to Nissl technique and immunohistochemistry for Glu. Similar nuclear organization in LM/IL was observed in comparison with other species. We estimated the reference volume (Vref) of LM and IL, which presented statistical difference between them, with IL 54% bulkier than LM. The volume density (Vv) of neurons reactive to Glu (IR-Glu) between LM/IL did not present statistical difference. The total volume (VTot) occupied by neurons in IL is 51% statistically higher than in LM. The neuronal bodies IR-Glu visualized between the LM nuclei were characterized predominantly rounded and ovoid. In addition, the mean cell area was 10% statistically lower in the LM nuclei when compared to IL. There are no quantitative studies relating the stereology with IR-Glu in the nuclei studied. The morphometric and stereological differences of the IR-Glu cell bodies in the rock cavie can be related to the diversity of the glutamatergic phylogenetic routes of the LM/IL complex and its consequent influence on the cortical function between the species.