DEVELOPMENTAL DISTRIBUTION OF GFAP AND VIMENTIN IN THE BRAZILIAN OPOSSUM BRAIN

Cells of glial origin are involved in the morphogenesis of the mammali an central nervous system (CNS). Characterization of glial-associated proteins during neurogenesis and differentiation may aid in understand ing the complexity of CNS development. We have utilized immunoblotting and immunohistochemistry to characterize the developmental profiles o f glial fibrillary acidic protein (GFAP) and vimentin (VIM) in the bra in of the Brazilian opossum, Monodelphis domestica. Typical of marsupi als, CNS morphogenesis and neurogenesis in the opossum extend well int o the postnatal period. Opossum GFAP and VIM were found as single band s at molecular weights consistent with those reported for other specie s, thus indicating conservation of the VIM and GFAP proteins through m ammalian evolution. Differential developmental trends were observed fo r both proteins with relative VIM levels decreasing and GFAP levels in creasing with age. Vimentin-like immunoreactivity (VIM-IR) was present at day 1 of postnatal life throughout the brain. The density of VIM-I R was maximal at 10 and 15 days postnatal (especially in radial glial elements) and decreased slightly by 25 days postnatal. In the adult br ain, VIM-IR was markedly reduced compared to that of younger ages. In contrast, GFAP-like immunoreactivity (GFAP-IR) in the brain of Monodel phis increased dramatically with age. No GFAP-IR was observed in the 1 and 5 day postnatal brains. By 25 days postnatal, the pattern of GFAP -IR in the brainstem resembled that of the adult. In the forebrain, mo re GFAP-IR was present than at younger ages. The adult distribution of GFAP-IR was very similar to that reported for other mammalian species . These results indicate that GFAP and VIM are reciprocally related du ring periods of morphogenesis and differentiation of the opossum brain . (C) 1994 Wiley-Liss, Inc.