Figure 4.

In the top graph panels, immunofluorescence results from NAc shell showing the number of pDARPP-32 cells per mm² at either 45 min (Panel A) or 72 hr (Panel B) after the last session. In the middle row of graph panels, immunofluorescence results showing the number of c-Fos+ cells per mm² either 45 min (Panel C) or 72 hr (Panel D) after the last saline or nicotine self-administration session; *represents significant difference from saline control p<0.05, ***represents significant difference from saline control p<0.001. In the bottom row of graph panels, percentage of pDARRP-32+ cells co-expressing c-Fos at either 45 min (Panel E) or 72 hr (Panel F) after the last session; ***represents significant difference compared to saline control, p<0.001. Data represent mean+SEM. (G) Confocal microscope images showing representative fluorescent cells in NAc shell 45 min after the last session. Images show NAc cells expressing pDARPP-32 or c-Fos alone, as well as the merge showing co-expression of pDARPP-32 and c-Fos. (H) Confocal microscope images showing representative fluorescent cells in NAc 72 hr after the last session. Images show NAc cells expressing pDARPP-32 or c-Fos alone, as well as the merge showing co-expression of pDARPP-32 and c-Fos. For panels (G) and (H), scale bar represents 20 μm and images were acquired with a 20x lens with a digital zoom of 2.5x (50x). (I) Representative photoimage showing NAc shell and core subregions relative to anterior commissure (AC).