AUTHOR=Carvalho-Paulo Dario , de Morais Magalhães Nara G. , de Almeida Miranda Diego , Diniz Daniel G. , Henrique Ediely P. , Moraes Isis A. M. , Pereira Patrick D. C. , de Melo Mauro A. D. , de Lima Camila M. , de Oliveira Marcus A. , Guerreiro-Diniz Cristovam , Sherry David F. , Diniz Cristovam W. P. 

TITLE=Hippocampal Astrocytes in Migrating and Wintering Semipalmated Sandpiper Calidris pusilla

JOURNAL=Frontiers in Neuroanatomy

VOLUME=11

YEAR=2018

URL=https://www.frontiersin.org/journals/neuroanatomy/articles/10.3389/fnana.2017.00126

DOI=10.3389/fnana.2017.00126

ISSN=1662-5129

ABSTRACT=<p>Seasonal migratory birds return to the same breeding and wintering grounds year after year, and migratory long-distance shorebirds are good examples of this. These tasks require learning and long-term spatial memory abilities that are integrated into a navigational system for repeatedly locating breeding, wintering, and stopover sites. Previous investigations focused on the neurobiological basis of hippocampal plasticity and numerical estimates of hippocampal neurogenesis in birds but only a few studies investigated potential contributions of glial cells to hippocampal-dependent tasks related to migration. Here we hypothesized that the astrocytes of migrating and wintering birds may exhibit significant morphological and numerical differences connected to the long-distance flight. We used as a model the semipalmated sandpiper <italic>Calidris pusilla</italic>, that migrates from northern Canada and Alaska to South America. Before the transatlantic non-stop long-distance component of their flight, the birds make a stopover at the Bay of Fundy in Canada. To test our hypothesis, we estimated total numbers and compared the three-dimensional (3-D) morphological features of adult <italic>C. pusilla</italic> astrocytes captured in the Bay of Fundy (<italic>n</italic> = 249 cells) with those from birds captured in the coastal region of Bragança, Brazil, during the wintering period (<italic>n</italic> = 250 cells). Optical fractionator was used to estimate the number of astrocytes and for 3-D reconstructions we used hierarchical cluster analysis. Both morphological phenotypes showed reduced morphological complexity after the long-distance non-stop flight, but the reduction in complexity was much greater in Type I than in Type II astrocytes. Coherently, we also found a significant reduction in the total number of astrocytes after the transatlantic flight. Taken together these findings suggest that the long-distance non-stop flight altered significantly the astrocytes population and that morphologically distinct astrocytes may play different physiological roles during migration.</p>