BDNF and bronchopulmonary dysplasia: In addition, our results demonstrated that the expression of CDK5 protein in the hippocampus of BPD mice was greatly increased compared with the control group at P14 and P70 (Figure 2D–F; t = 3.093, p = 0.0213 in Figure 2E; t = 5.503, p = 0.0015 in Figure 2F), while the expression of BDNF protein in the hippocampus of BPD mice was remarkably decreased (Figure 2G–I; t = 3.753, p = 0.0095 in Figure 2H; t = 4.850, p = 0.0029 in Figure 2I).