CELL-SPECIFIC EXPRESSION OF PREPROENKEPHALIN INTRONIC HETERONUCLEAR RNA IN THE RAT FOREBRAIN

Using in situ hybridization with multiple probes to the rat preproenke phalin gene, we have identified a novel population of cells in the ret icular thalamic nucleus and basal forebrain which express RNA derived from the preproenkephalin gene. These cells contain nuclear RNA from d ownstream of an alternate transcription start site in intron A of the preproenkephalin gene (Kilpatrick et al., Mol. Cell Biol., 10 (1990) 3 717-3726), while in the same cells preproenkephalin exon 2 RNA is unde tectable. The results suggest that in this population of cells, prepro enkephalin gene transcription initiates from the intron A initiation s ite, and is regulated by an additional mechanism which results in the accumulation of nuclear preproenkephalin intron A-derived heteronuclea r RNA. The anatomical distribution of these cells indicates that they may be involved in the control of cerebral cortical function.