Fig. 4. Loss of TH-positive and CV-positive LC NA neurons in the TrkB null mutant mice. A-D show representative sections through the LC of wild-type (A), TrkB^-/- (B), TrkC^-/- (C) and TrkB^-/- TrkC^+/- (D) at P0 after TH immunohistochemistry. The graph in E describes the average number of TH-positive cells (±s.d.) in the LC of wild-type, TrkB^+/-, TrkB^-/-, TrkC^-/- and TrkB^-/- TrkC^+/- mice. TrkB^-/- was significantly different from wild-type and TrkB^+/- (*P<0.05), and TrkB^-/- TrkC^+/- was different from TrkB^+/- (^#P<0.05) as assessed by unpaired t-test (n=4-10). The number of TH-positive and CV-positive neurons in the LC was examined in adjacent sections of wild-type and TrkB null mutant mice at P0 (F). A decrease of 28.3% and 25.7% in the number of TH-positive and CV-positive neurons, respectively, was detected in the TrkB^-/- mice. (*P<0.05, paired t-test). Scale bar: 100 µm.