title: The regulation of proenkephalin expression in a distinct population of glial cells.
abstract: The expression of opioid genes was examined in isolated populations of glial cells in primary culture. Northern blot analysis of purified type I astrocytes, oligodendrocytes and mixed oligodendrocyte-type-2-astrocyte lineage cells derived from cerebral cortex demonstrated robust expression of proenkephalin mRNA exclusively in type I astrocytes. The expression of proenkephalin mRNA was stimulated by the beta-adrenergic agonist isoproterenol, and 8-(4-chlorophenyl thio)adenosine 3'-5'-cyclic monophosphate (cpt-cAMP). Both of these compounds regulated a proenkephalin-chloramphenicol acetyltransferase fusion gene transiently transfected into type I astrocytes. HPLC and immunoassay of the cell culture media revealed significant levels of unprocessed proenkephalin secreted by the cell and this secretion was stimulated by isoproterenol and cpt-cAMP. The relatively high levels of proenkephalin expressed suggest that enhanced expression in astrocytes may be important during neural development, in trauma-induced gliosis and in neuroimmune interactions.
authors.affiliation: Division of Reproductive Biology, Oregon Regional Primate Research Center, Beaverton 97006.
authors.forename: M H
authors.initials: MH
authors.lastname: Melner
authors.forename: K G
authors.initials: KG
authors.lastname: Low
authors.forename: R G
authors.initials: RG
authors.lastname: Allen
authors.forename: C P
authors.initials: CP
authors.lastname: Nielsen
authors.forename: S L
authors.initials: SL
authors.lastname: Young
authors.forename: R P
authors.initials: RP
authors.lastname: Saneto
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000378:metabolism*; D015152:Blotting, Northern; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000378:metabolism*; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular; D004745:Enkephalins / Q000032:analysis / Q000235:genetics* / Q000302:isolation & purification; D005786:Gene Expression Regulation; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D009457:Neuroglia / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011498:Protein Precursors / Q000032:analysis / Q000235:genetics* / Q000302:isolation & purification; D012333:RNA, Messenger / Q000235:genetics*; D011863:Radioimmunoassay; D051381:Rats; D014162:Transfection
chemical_list: D004745:Enkephalins; D011498:Protein Precursors; D012333:RNA, Messenger; C029992:proenkephalin; D015500:Chloramphenicol O-Acetyltransferase; D007545:Isoproterenol