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. 2018 Oct 30;7:e39945. doi: 10.7554/eLife.39945

Figure 3. Heroin activates NAc projecting DA neurons in the medial VTA.

Figure 3.

(a), Schematic of experiment for (b-e); (b), TH (left, red), cFos (middle, green) staining of VTA DA neurons and co-localization of TH- and cFos-expressing neurons (right) after one day of either saline (top) or heroin (bottom) self-administration. Mice were perfused 60 min after the end of a single self-administration session. Cell nuclei are stained with Hoechst (not shown). D, dorsal; L, lateral; v, ventral; m, medial. (c) , Location within the VTA of histologically identified DA neurons expressing cFos after one day of heroin self-administration. Each color of the markers represents one animal.( d), High magnification confocal pictures of TH and cFos staining in saline and heroin mice. (e), Quantification of the TH positive VTA DA neurons also expressing cFos after one day of saline or heroin self-administration (saline: 2102 cells from four mice, heroin: 1902 cells from four mice). (f), Schematic of experiment for (f–g). The retrograde tracers CTB, conjugated to either the fluorescent dye AlexaFluor 488 (green) or AlexaFluor 555 (red) were injected in the lateral NAc shell or the medial one, respectively. In addition, a catheter implantation was performed (see methods) in order to allow heroin self-administration.( f), Left, coronal images showing infections in the NAc shell. Right, coronal image of the VTA. (g), Quantification of CTB positive cells in the VTA. (h), Schematic for cFos staining in the medial and lateral VTA, projecting to the NAc medial and lateral. Coronal pictures of NAc injected with CTB-555 in the medial Shell and CTB-647 in the lateral Shell and corresponding pictures in the VTA with cFos staining. (i), High magnification confocal images of CTB-555 and 647 with Hoechst (left), cFos (middle, green) and cFos with CTBs (right, green/red/magenta) in the medial or lateral VTA neurons after one day of heroin self-administration. Mice were perfused 60 min after the end of the self-administration session and cell nuclei have also been stained with Hoechst (not shown).( j), Quantification of the cFos positive VTA neurons labelled with red or magenta CTB.