Fig. 7.

Neurite outgrowth from E19 primary hippocampal neurons is increased when neurons are cultured in the presence of media derived from GFAP-apoE3-secreting astrocytes. E19 primary hippocampal neurons (C57Bl6) were plated onto poly-d-lysine-coated coverslips and after attachment were incubated in the presence (but not in direct contact with) confluent astrocyte monolayers derived from the forebrain of P1 GFAP-apoE3 line 2 (C, D), GFAP-apoE4 line 22 (B), or apoE−/− (A) littermate pups. After 44 hr in culture, neurites, here identified by MAP-2-IR but also identified by phase-contrast microscopy, were on average longer in the presence of the apoE3-secreting astrocytes than in the presence of the apoE4 or apoE−/− astrocytes. The increase in neurite outgrowth seen in the presence of apoE3 was blocked by anti-LRP IgG (D). The tips of two axons are identified witharrows in C. Scale bar, 35 μm.