title: Lipopolysaccharide induces proenkephalin gene expression in rat lymph nodes and adrenal glands.
abstract: The proenkephalin gene encodes a family of neuropeptides that was originally identified in brain tissue and adrenal glands. Recently, it was shown that proenkephalin is also expressed in cultured lymphoid cells. To elucidate the physiological significance of this expression, we examined the in vivo expression of proenkephalin in lymphoid tissues. We show here that exposing rats to the endotoxin lipopolysaccharide induces an intense and transient expression of proenkephalin in adrenal glands and lymph nodes. By using combined in situ hybridization and immunohistochemistry on tissue slices, we identified proenkephalin expression in macrophages located within the lymph nodes and in chromaffin cells within the adrenal glands. This in vivo expression of proenkephalin was enhanced by adrenaline. The present observations demonstrate that the immune system is a site of significant expression of proenkephalin and provide a basis for neuroimmune interactions.
authors.affiliation: Department of Molecular Virology, Hebrew University Hadassah Medical School, Jerusalem, Israel.
authors.forename: O
authors.initials: O
authors.lastname: Behar
authors.forename: H
authors.initials: H
authors.lastname: Ovadia
authors.forename: R D
authors.initials: RD
authors.lastname: Polakiewicz
authors.forename: H
authors.initials: H
authors.lastname: Rosen
mesh_terms: D000311:Adrenal Glands / Q000502:physiology*; D000818:Animals; D004745:Enkephalins / Q000235:genetics*; D004837:Epinephrine / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects*; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism; D007107:Immune System / Q000378:metabolism; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008198:Lymph Nodes / Q000502:physiology*; D008297:Male; D010913:Pituitary-Adrenal System / Q000378:metabolism; D011498:Protein Precursors / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D004745:Enkephalins; D008070:Lipopolysaccharides; D011498:Protein Precursors; D012333:RNA, Messenger; C029992:proenkephalin; D004837:Epinephrine