TGFB1 and major depressive disorder: To better understand the alterations of the TGF-β1 pathway in our model of adolescent depression, we carried out western blot analysis in hippocampus of control and PNS rats, also starting from the well-known evidence that TGF-β1 final activity is regulated not only at a transcriptional level, but also at a post-transcriptional level and primarily through the conversion of latent TGF-β1 to active TGF-β1 by a variety of proteases (Annes et al., 2003).