Somatostatin- and Substance P-ergic neurons and Glial cell line-derived neurotrophic factor in the human archicortex.

By means of immunohistochemistry, the localization of Somatostatin (SOM)- and Substance P (SP)-ergic neuronal populations was compared to the occurrence of Glial cell line-derived neurotrophic factor (GDNF) in the human hippocampus from prenatal to adult life stages. The results obtained i) confirm previous reports on the distribution of SOM and SP; ii) show that GDNF-like immunoreactivity occurs in an ample population of hippocampal neurons, with a main location in the pyramidal cells; iii) identify regions of codistribution of either neuropeptide with GDNF-positive elements. Although coexistence of GDNF with SOM or SP was not detected, the possibility that the trophic factor may act on the neuropeptide-containing neurons can be envisaged and is worth further analysis.