GABAergic septohippocampal neurons contain parvalbumin.

Septal axons were visualized in the hippocampus by anterograde transport of Phaseolus vulgaris leucoagglutinin (PHAL) injected into the medial septal region, which contains large numbers of parvalbumin (PV)-immunoreactive somata. A proportion of the PHAL-labelled afferents in the hippocampus were shown to be immunoreactive for PV by immunostaining alternate sections. This population of septohippocampal axons alone was found to be immunoreactive for gamma-aminobutyric acid (GABA) following post-embedding immunogold staining of ultrathin sections cut from the same material.