title: Differential expression of the neurotensin gene in the developing rat and human gastrointestinal tract.
abstract: Neurotensin (NT) is an important hormone regulating gut motility, secretion, and growth. The purpose of this study was to determine the developmental expression of the NT/neuromedin N gene (NT/N) in the gut and pancreas of rats and humans. We found that NT/N expression, initially low in the fetal rat jejunum and ileum, is increased by postnatal day 3. This increase is independent of contact with luminal nutrients as demonstrated by elevated NT/N expression in rat jejunoileal grafts implanted in nude mice. NT/N expression reaches maximal levels in the small bowel by postnatal day 14. After postnatal day 28, NT/N mRNA levels remain constant in the ileum but decrease in the jejunum. Transient NT/N expression is found in the colon of fetal and postnatal rats. Similar to the rat, NT/N expression is low in the human fetal ileum but increases in the adult. In the human colon, NT/N is transiently expressed in the fetus at midgestation but disappears by birth and, similarly, is not apparent in the adult. We conclude the following. 1) The NT/N gene demonstrates a complex pattern of tissue-specific expression; the jejunum and ileum show a similar pattern of expression until the end of the fourth postnatal week, when NT/N levels decrease in the jejunum to assume the distinctive adult topographical distribution with NT/N increasing along the jejunoileal axis. 2) NT/N is transiently expressed in the colon of rats and humans during a developmental stage characterized by morphological and functional similarities to the small bowel; therefore, NT/N may provide a useful endocrine marker to further define the complex differentiation pathway leading to small bowel and colonic phenotypes.
authors.affiliation: Department of Surgery, University of Texas Medical Branch, Galveston 77555.
authors.forename: B M
authors.initials: BM
authors.lastname: Evers
authors.forename: S
authors.initials: S
authors.lastname: Rajaraman
authors.forename: D H
authors.initials: DH
authors.lastname: Chung
authors.forename: C M
authors.initials: CM
authors.lastname: Townsend
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.forename: K
authors.initials: K
authors.lastname: Graves
authors.forename: J C
authors.initials: JC
authors.lastname: Thompson
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology*; D000818:Animals; D004064:Digestive System / Q000196:embryology / Q000254:growth & development*; D004068:Digestive System Physiological Phenomena; D005314:Embryonic and Fetal Development; D005333:Fetus / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D007082:Ileum / Q000196:embryology / Q000378:metabolism; D007583:Jejunum / Q000196:embryology / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D009496:Neurotensin / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D014018:Tissue Distribution
chemical_list: D012333:RNA, Messenger; D009496:Neurotensin