DIFFERENTIAL REGULATION OF C-FOS, PROENKEPHALIN AND TYROSINE-HYDROXYLASE GENE-EXPRESSION BY METRAZOLE IN THE HAMSTER ADRENAL AND HIPPOCAMPUS

Metrazole (MTZ) induces sequential activation of c-fos, proenkephalin (Penk) and tyrosine hydroxylase (TH) gene expression in the rat adrena l and c-fos and Penk gene expression in the rat hippocampus. As in the rat, MTZ produced a dose-dependent induction of c-fos mRNA in the ham ster adrenal and hippocampus together with an increase in adrenal TH m RNA. Although MTZ-induction of preproenkephalin (PPenk) mRNA was obser ved in the hippocampus of the hamster, the same treatment failed to in duce PPenk mRNA in the hamster adrenal. These results indicate that Pe nk gene expression in the hamster is differentially regulated in the a drenal and hippocampus. Furthermore, the regulation of adrenal Penk ge ne expression differs significantly when rat and hamster are compared.