Granule cells in the rat olfactory tubercle accumulate3H-γ-aminobutyric acid

Publisher Website
Google Scholar
Abstract
The rat olfactory tubercle contains high concentrations of γ‐aminobu‐tyric acid (GABA) and its synthetic enzyme, glutamic acid decarboxylase (GAD). We previously demonstrated that GABA and GAD are most concen‐trated in the polymorphic layer of the tubercle and relatively absent from the plexiform and pyramidal layers. Here we report that the granule cells (the islands of Calleja) in the polymorphic layer.accumulate 3H‐GABA. 3H‐GABA Ci/mmole; 1.5 μ1 was injected trie tubercle and an hour later the rat was perfused with a mixture of paraformaldehyde and glu‐taraldehyde. The tissue was osmicated, dehydrated, and embedded in epon. Silver grains were sparse over the pyramidal and polymorphic cell bodies but numerous over the granule cell bodies in the islands of Callejaanddendrites in the surrounding.neuropjl. Grain densities for the granule cells were 41/100 μm3 compared to 4.2 for pyramidal and polymorphic cells. Witnm the island, all the granule cells appeared to be labeled. These results, com‐bined with previous demonstrations of the presence in this region of endo‐genous GABA and GAD, suggest that the granule neurons of the rat olfac‐tory tubercle are GABA‐ergic. These neurons also appear to receive dopamine input and therefore form part of a circuit that includes targets for both major and minor tranquilizers.