Figure 1

A single infusion of recombinant glial cell line-derived neurotrophic factor (rGDNF) into the ventral tegmental area (VTA) produces a sustained induction of GDNF expression and phosphorylation of extracellular-regulated protein kinase 1/2 (ERK1/2). rGDNF (10 μg, unilateral) or vehicle was infused into the VTA of rats 12 h (a), 24 h (b) or 48 h (c) before the VTA dissection. GDNF and GAPDH mRNA levels were determined using semi-quantitative reverse transcription PCR. GAPDH levels were measured to standardize sample loading. Data are expressed as mean±s.e.m. of GDNF/GAPDH expression (t's>3.50, ^*P<0.05; n=3–5). (d) Shown is a dual-channel immunofluorescence for phospho-ERK1/2 (p-ERK1/2, red), tyrosine hydroxylase (TH, a marker for dopaminergic neurons, green), and overlay (yellow). Left panel: images depict ERK1/2 phosphorylation in the midbrain 24 h after rGDNF (left brain side) or PBS (right side) infusion into the VTA. Images are representative of results from four rats (six sections per rat), scale bar: 500 μm. Right panel: magnified image of the VTA infused with rGDNF, as marked in a white square in Figure 2a. The arrowheads point to cells immunostained for both p-ERK1/2 and TH, scale bar: 50 μm.