Figure 4.

Switch experiments. E12 sympathetic explants were cultured with NGF or NT3 for 4 days in parallel cultures. Subsequently the ganglia were either kept for 4 further days with the same neurotrophin reapplied, or factors were switched. In cultures in which NT3 had replaced NGF, TH (5 ± 3:1) and NET (8 ± 2:1) expression levels were strongly reduced, while at the same time CHAT (1:10 ± 3) and VIP (1:8 ± 3) levels were elevated compared with cells kept with NGF for 8 consecutive days. The reverse phenomenon was observed when previously NT3-treated cells were switched to NGF. In this case TH (1:5 ± 2) and NET (1:12 ± 2) transcripts were induced, whereas CHAT (8 ± 2:1) and VIP (12 ± 2:1) expression levels decreased compared with cultures continuously grown with NT3.