PMC

BDA injection site in the area of the mZI, including the A13 cell group. Images from fluorescent microscopy show neurons containing the anterograde tracer (in red) and TH in (green). Double-labeled cells are indicated by arrows and appear in yellow. Scale bar is 30 μm.

BDA-labeled terminals and terminal boutons in the dlPAG originating from the A13 dopaminergic cell group. Upper panel: images from confocal microscopy showing BDA- (in green) and TH-labeled fibers (in red) in the dlPAG. Arrowheads indicate double-labeled processes. Middle and lower panels: high magnification images of double-labeled processes. Arrowheads indicate double labeling. Scale bar is 10 μm.

Double-labeled neurons in the A11 dopaminergic cell group projecting to the dlPAG. (A) Distribution of CTb/TH-positive cells in the A11 cell group, cases R22 (black dots) and R30 (red dots). Figures modified from Paxinos and Watson (). (B) Fluorescence micrographs showing TH-labeled (green) and CTb-labeled neurons (red) in the A11 group in case R22. Double-labeled neurons appear yellow in the merged image (white arrows). Scale bar is 50 μm.

Distribution of TH and DBH immunoreactivity in the PAG. (A) Schematic representation of the PAG and adjacent nuclei. (B) Micrograph of a coronal section showing TH-labeled fibers and terminals in the PAG and deep layers of the SC. The dlPAG is outlined in red; the subdivisions of the PAG are depicted in yellow. (C) Micrograph of a coronal section showing DBH-labeled fibers and terminals in the PAG and deep layers of the SC. The dlPAG is outlined in red. Comparison between Figures suggests that dopamine is more abundant than noradrenaline in the dlPAG. Scale bar is 200 μm. For abbreviations, see list.

Double-labeled neurons in the A13 dopaminergic cell group projecting to the dlPAG. (A) Diagrammatic representation of the distribution of CTb/TH-positive cells in the A13 cell group, cases R22 (black dots) and R30 (red dots). Figures modified from Paxinos and Watson (). (B) Fluorescence micrographs showing TH-labeled (green) and CTb-labeled neurons (red) in the A13 group in case R22. Double-labeled neurons appear yellow in the merged image (white arrows). Scale bar is 60 μm.

Injection sites of retrograde tracer experiments. (A) Schematic drawings representing CTb deposits by pressure injections along the rostro-caudal extent of the dlPAG and the SC. The four cases are represented by different colors (R22 in red, R23 in brown, R25 in green and R26 in blue). (B) Schematic representation of CTb iontophoresis deposits in the dlPAG. R30 is in purple and R29 in dark brown. The injection made in case R29 was placed in the deep layers of the SC and did not include the dlPAG. This case was used as a control injection. For abbreviations, see list.

Double-labeled neurons in the A10 dopaminergic cell group projecting to the dlPAG. (A) Distribution of CTb/TH-positive cells in the posterior hypothalamic area (PHA), case R22 (black dots) and R30 (red dots). Figures modified from Paxinos and Watson (). (B) Distribution of double-labeled neurons in the rostral linear nucleus of the raphe and the ventral PAG. Figures modified from Paxinos and Watson (). (C) Fluorescence micrographs showing TH-labeled (green) and CTb-labeled neurons (red) in the rostral linear nucleus in case R22. Double-labeled neurons appear yellow in the merged image (white arrows). Scale bar is 100 μm.