Astrocytic GDNF and GFRα-1 expression following increases in neurotrophic factors in vivo and in vitro. (A, B) Western blot (A) and immunohistochemical (B) analysis for GDNF and GFRα-1 expression in the hippocampus of AAV1-Rheb(S16H)-injected rat brains, with or without neutralizing antibodies (NA; 200 ng) against BDNF or GDNF. Differences among groups were evaluated by one-way analysis of variance and Tukey’s post-hoc analysis [*p<0.05 vs. Rheb(S16H) alone; n=3 per group]. Scale bar, 100 μm. (C, D) Quantitative RT-PCR analyses for GFRα-1 in primary astrocyte cultures showed significant increases in GFRα-1 expression in the GDNF (100 ng/ml; C)-treated astrocyte cultures compared to vehicle-treated controls (CON), but no change in response to treatment with BDNF (100 ng/ml; D). Differences among groups were evaluated by t-test analysis (*p<0.001 vs. CON; n=3 per group).