Mudanças morfológicas nos astrócitos hipocampais no período de invernada em Arenaria interpres

Abstract

Astrocytes are essential for lipid neuronal metabolism in long-distance uninterrupted migratory flights, when glucose is not available as the main source of energy. We previously demonstrated in Calidris pusilla that after uninterrupted 5 days transatlantic flight, astrocytes shrink and reduce its number in the hippocampal formation. Here we shifted our attention to the wintering period and tested the hypothesis that as the wintering progresses, hippocampal astrocytes morphological changes following Atlantic crossing, would be recovered. To that end we used Arenaria interpres, which also crosses the Atlantic Ocean and reaches the mangroves of the Amazon River estuary for wintering. Birds were captured in September/October (closer to the arrival in the coast of Bragança - Pará, Brazil for wintering) and in April/May (closer to the departure towards the breeding sites) and had their brains processed for selective GFAP-astrocyte immunolabeling. Three-dimensional reconstructions of the immunostained astrocytes were performed and morphological classification was done based on hierarchical cluster and discriminant analysis of multimodal morphometric features. We found two morphological phenotypes of astrocytes exhibiting distinct morphological complexities after the long-distance non-stop transatlantic flight. Although to a different extent, both morphotypes increased their complexities as wintering period progresses towards the pre-migration window. Taken together, our findings demonstrate that the long-distance non-stop flight and wintering period differentially affected the two astrocytes morphotypes, suggesting distinct physiological roles for these cells. We suggest that morphological recovering during the wintering period, may be part of the adaptive changes of the local hippocampal circuits of A. interpres in preparation for the long journey back to their breeding sites in the north hemisphere.