Fig. 2. Properties of cortical neurons in a glia-free culture for 6 days (A and B) or after exposure to BDNF for 3 days (C-E). (A,B) Two neurons immunoreactive with anti-GABA (A) and TUJ1 (not shown) each possess a phosphorylated neurofilament-positive axon (B). (C,D) Cortical neurons in a glia-free culture in the presence of BDNF (5 µg/ml) for 3 days. Neurons were stained with antibodies to GABA (C) and to phosphorylated neurofilaments (D). The arrow in (C) indicates a GABA-positive neuron without an axon. The arrowhead in (D) indicates the highly branched axons of GABA-negative neurons. Bar, 100 µm. (E) Effect of BDNF on the intensity of GABA immunoreactivity in inhibitory neurons after 3 DIV. Data are means±s.d. for 36 neurons cultured with BDNF and 32 neurons cultured in its absence. *P<0.001 (Student's t-test).