Figure 3.

In top graph panels, immunofluorescence results from VTA showing the percent PRV+ cells co-expressing WFA at either 45 min (Panel A) or 72 hr (Panel B) after the last saline or nicotine self-administration session; **represents significant difference from saline control, p<0.01. In second row of graph panels, intensity of WFA+ labelling at either 45 min (Panel C) or 72 hr (Panel D) after the last self-administration session; *represents significant difference in percent faint intensity labelling compared to saline control, p<0.05. In third row of graph panels, number of c-Fos+ cells/mm² at either 45 min (Panel E) or 72 hr (Panel F) after the last self-administration session; ***represents significant difference from saline control, p<0.001. In bottom row of graph panels, percentage of WFA+ cells co-expressing c-Fos at either 45 min (Panel G) or 72 hr (Panel H) after the last self-administration session. Data represent mean +SEM. (I) Confocal images showing representative fluorescent cells in VTA 45 min after the last session. Images show VTA cells expressing PRV or WFA alone, as well as the merge showing co-expression of PRV and WFA. (J) Confocal images showing representative fluorescent cells in VTA 45 min after the last session. Images show VTA cells expressing c-Fos or WFA alone, as well as the merge showing co-expression of c-Fos and WFA. Scale bar represents 20 μm. Images were acquired with a 40x lens with a digital zoom of 2x (80x).