Distribution of parvalbumin-containing neurons and lectin-binding perineuronal nets in the rat basal forebrain

In sections of rat brain treated for Wisteria floribunda agglutinin (WFA) labelling the occurrence of parvalbumin (PARV)-, calbindin (CALB)- or choline acetyltransferase (ChAT) immunoreactivity was analyzed in the basal forebrain using dual-peroxidase and double-fluorescence methods. Only PARV-immunoreactive (-ir) neurons were surrounded by WFA-labelled, i.e. N-acetylgalactosamine-containing, perineuronal lattice-like structures known as perineuronal nets. The distribution of these nets and PARV-ir cells in the rat basal forebrain was documented to obtain detailed data on their co-existence. A remarkable diversity in distribution of both markers was observed, as PARV-ir neurons are only associated with nets in the medial septal nucleus, the nuclei of the diagonal band and the magnocellular preoptic nucleus, but not in the ventral pallidum or the substantia innominata/nucleus basalis complex. These differences in the neuronal microenvironment may reflect system-related specializations of neurons within the basal forebrain nuclei.