Fig 6.
Retrograde labelling from the lateral parabrachial (LPb) area combined with intraspinal injection to label substance P cells in a Tac1Cre mouse. Cholera toxin B (CTb) was injected into the LPb on one side and AAV.flex.eGFP into the L5 dorsal horn on the contralateral side. (A) A transverse section through the L5 segment (corresponding to the intraspinal injection site) that has been immunostained to reveal CTb (magenta) and eGFP (green). Numerous eGFP-positive cells are present throughout the superficial laminae and scattered cells are present in the deeper part. CTb-positive cells, which have been retrogradely labelled from the LPb, are most numerous in lamina I and the lateral spinal nucleus (LSN). Some of these are also positive for eGFP (one shown with an arrow) and others lack eGFP (one shown with an arrowhead). (B–D) A detail from the region shown in the box in (A). A double-labelled cell is indicated with an arrow, two CTb-positive/eGFP-negative cells with arrowheads and a CTb-negative/eGFP-positive cell with an asterisk. The thicker dashed line in (A) outlines the dorsal horn, and the thinner dashed lines indicates the medial edge of the AAV.flex.eGFP injection site. (E) Positions of retrogradely-labelled superficial dorsal horn neurons that were eGFP+ (filled symbols) and eGFP- (open symbols) in one of the two experiments, plotted onto an outline of the grey matter. The dashed lines represent the approximate positions for the borders of lamina II. Images in (A) and (B–D) were from 10 and 4 optical sections at 1 μm z-spacing, respectively. Scale bars: A = 100 μm; B–D = 25 μm.