title: Effect of epidermal growth factor on the developing rat renal papilla.
abstract: BACKGROUND
  Apoptosis plays an important role in the morphogenesis of the renal papilla. During kidney development, ATL is derived from the TAL in the inner medulla by apoptotic deletion of a fraction of TAL cells and the transformation of the remaining TAL cells. EGF is an important regulator of apoptosis in the kidney.
  
  
  OBJECTIVE
  Exogenously administered EGF in postnatal rat affects renal papilla growth with cell proliferation and apoptosis in the loop of Henle.
  
  
  METHODS
  Rat pups received subcutaneous injections of EGF (0.3 microg/g body weight) or saline four times a day from after birth. Rats were sacrificed and the kidneys were preserved for immunohistochemistry on day 4 and day 7. The TAL was identified with antibody directed against Na-K-ATPase or BSC1, and type A intercalated cells were identified with antibody to anion exchanger 1 (AE1). Apoptosis was detected with TUNEL method, and cell proliferation with immunostaining for PCNA. RESULTS--PRIMARY AND SECONDARY: EGF treatment resulted in the following: (1) reduced kidney weight; (2) shortened length of renal papilla; (3) delayed transformation of the cuboidal epithelium into the squamous epithelium of the ATL; (4) delayed elimination of type A intercalated cells in the medullary collecting duct; (5) decreased both apoptotic index and PCNA-positive cells in the TAL and the collecting duct of the renal medulla.
  
  
  CONCLUSIONS
  These findings suggest that exogenous EGF delays the development of loop of Henle in the renal papilla by reducing both apoptosis and cell proliferation.
authors.affiliation: Department of Internal Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Seung-Hun
authors.initials: SH
authors.lastname: Lee
authors.forename: Ju-Young
authors.initials: JY
authors.lastname: Jung
authors.forename: Ki-Hwan
authors.initials: KH
authors.lastname: Han
authors.forename: Chul-Woo
authors.initials: CW
authors.lastname: Yang
authors.forename: Kyu-Bok
authors.initials: KB
authors.lastname: Choi
authors.forename: Jin
authors.initials: J
authors.lastname: Kim
mesh_terms: D000818:Animals; D017209:Apoptosis; D002455:Cell Division; D004815:Epidermal Growth Factor / Q000502:physiology*; D020287:In Situ Nick-End Labeling; D007668:Kidney / Q000254:growth & development*; D008138:Loop of Henle / Q000166:cytology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004815:Epidermal Growth Factor