Fig. 3. All ICNs were immunoreactive for DBH and NET but these cells rarely showed VMAT2 immunoreactivity.

Double labeling for TH and DBH (A–C) and for TH and NET (D–F) showed that DBH and NET were present in TH-positive and TH-negative ICNs. (A–C) Arrows indicate examples of neurons that contained TH and DBH. The intensity of DBH staining was slightly higher in some TH-positive neurons compared to TH-negative neurons (B insert: line arrow indicates DBH in TH-positive neuron and open arrowhead indicates an adjacent TH-negative neuron with less intense DBH labeling). (D–F) Likewise, NET staining was evident in all neurons, including those that contained TH (open arrows), and was sometimes more intense when colocalized with TH (D insert, line arrow). (G–I) Double labeling for TH and VMAT2 showed that almost all ICNs lacked VMAT2, although weak VMAT2 staining was rarely observed in THIR neurons (arrowheads). This observation is demonstrated in (H insert), where the line arrow indicates an example of a TH-positive neuron with weak VMAT2 staining and the open arrowhead shows an adjacent cell not containing VMAT2. All panels contain maximum projection images compiled from confocal scans, with (A–C) spanning 5 µm, (D–F) spanning 10 µm, and (G–I) spanning 8 µm. Scale bars indicate 100 µm in (A–C), (D–F), and (G–I).