- Exacerbated loss of cell survival, neuropeptide Y-immunoreactive (IR) cells, and serotonin-IR fiber lengths in the dorsal hippocampus of the aged flinders sensitive line "depressed" rat: Implications for the pathophysiology of depression? Husum, H., Aznar, S., H??yer-Hansen, S., Larsen, M.H., Mikkelsen, J.D., M??ller, A., Math??, A.A., W??rtwein, G. J. Neurosci. Res. (2006)