Figure 5.

PACAP enhances cortical precursor differentiation. Precursors were incubated in control or PACAP-containing medium and were analyzed for trkB expression (a–c) and neurite outgrowth (d–f). (a) Brightfield photomicrograph of trkB immunoreactive precursors at 24 h: only a subset express trkB, localized to cytoplasm (arrows; arrowhead = negative cell; Santa Cruz Biotechnology antiserum). (b) Similar staining was observed with a different antiserum (D. Kaplan, Montreal University). (c) PACAP increased trkB-positive cells by 30%. Data are expressed as percentage control ± SEM. Range of positive cells: control = 36–67%; PACAP = 57–84% (4 expts using both antisera); n = 14; ∗, P < 0.01. (d and e) Phase photomicrographs of control (d) and PACAP-treated cultures at 48 h (e). (f) PACAP doubled the percentage of cells with neurites that were ≥2 cell soma diameters. Data are expressed as mean ± SEM (5 expts); n = 15; ∗, P < 0.007. (g) DbcAMP and forskolin elicited a 4-fold increase in neurite-bearing cells (2 expts); n = 6; ∗, P < 0.001. (Bar = 50 μm.) Con, control.