Expression of the cholecystokinin gene in organotypic slice cultures of immature rat somatosensory cortex.

The preprocholecystokinin gene is expressed in a subpopulation of cortical interneurons containing gamma-aminobutyric acid. Slices of neonatal rat cortex were cultivated for 12 +/- 2 days and examined for the presence and distribution of these neurons by in situ hybridization and immunocytochemistry. Like in situ, two layers of preprocholecystokinin-mRNA-expressing cells were present. Immunopositive fibers formed a dense network and established symmetric contacts on dendritic shafts and spines. It is concluded that cholecystokinin-expressing interneurons survive in cultured slices of rat cerebral cortex. These organotypic cultures may be useful to study the cellular interactions which regulate neuronal cholecystokinin expression.