Appearance of β-dystroglycan precedes the formation of glio-vascular end-feet in developing rat brain

Abstract

Dystroglycan has an important role in binding of perivascular glial end-feet tothe basal lamina. Its β-subunit is localized in the glial end-feet. The investigation period lasted from E(embryonic day)12 to E20. Laminin and β-dystroglycan were detected by immunohistochemistry, the glial localization of the latter one was supported by electron microscopy. The immatureglial structures were visualized by the immunostaining of nestin. The β-dystroglycan immunoreactivity appeared at E16 following the laminin of basal lamina but preceding the perivascular processes of radial glia (E18) and astrocyte-like cells (E20). It occurred in cell bodies which attached to the vessels directly but not with vascular processes and end-feet. The presence of β-dystroglycan in such immature cells may promote their differentiation to perivascular astrocytes and influence the formation of the glio-vascular processes.

Keywords: Brain development; dystroglycan; glial end-feet; glio-vascular; nestin..

Figure 1.

Appearance of -dystroglycan immunoreactivity delineates vessels. a,b) E14(embryonic day), rat dorsolateral pallium, double immunostaining for -dystroglycan and laminin; laminin immunostaining visualizes the cerebral vasculature and the pial (P) basal lamina; arrows and double arrows label identical points in the parallel photos; V, ventricle. c,d) E16, double immunostaining for -dystroglycan and laminin; both -dystroglycan and laminin immunoreactivities delineate the same vessels (arrows and double arrows label identical points in the parallel photos); P, pial surface; V, ventricle. e,f ) E16, rat dorsolateral pallium, electron microscopic immunoperoxidase reaction for -dystroglycan; the -dystroglycan immunoreactivity (arrowheads) is localized in vessel-contact cell bodies; asterisks, capillary lumen; N, nucleus; EC, endothelial cell; ery, erythrocyte. Inset: an enlarged detail pointed by arrow at the right border of the vessel. Scale bars: a-d) 60 m; e,f ) 5 m; inset, 2 m.

Figure 2.

Appearance of glial vascular end-feet. Confocal photomicrographs following double labeling of nestin (red) and laminin (green). a) E16: despite of the vicinity of vessels, no glial end-feet have been visualized; arrows point to laminin-immunoreactive vessels; P, pial surface; scale bar: 20 m. b) E18: several endings of glial processes on vessels (arrowheads). Arrow points a bifurcating process with two endings (see enlarged in inset); scale bar: 30 m; inset: 20 m. c) E18: large end-feet-like widenings at the ends of two processes (arrow) on a vessel; the close contacts (yellow color), however, have not yet been generalized; arrowheads point to lesser end-feet of other glial processes on the vessel; scale bar: 20 m. d) E20: nestin-immunoreactive astrocyte-like structure extends a process with endfoot (arrowhead) to a vessel; scale bar: 10 m. e) A vessel at E20, electron microscopic immunoperoxidase reaction for -dystroglycan (arrowheads); besides the nucleus (N)-containing cell bodies there are small profiles: endings of glial processes (#; arrows: their cell borders); asterisks: capillary lumen; EC, endothelial cell; ery, erythrocyte; scale bar: 2 m.