title: Genistein stimulates jejunum chloride secretion via an Akt-mediated pathway in intact female mice.
abstract: OBJECTIVE
  We have previously shown that daily subcutaneous injections with the naturally occurring phytoestrogen genistein (600 mg genistein/kg body weight/day, 600G) results in a significantly increased basal intestinal chloride, Cl(-), secretion (Isc, a measure of transepithelial secretion) in intact C57BL/6J female mice after 1-week of treatment, compared to controls (DMSO vehicle injected). Removal of endogenous estrogen via ovariectomy (OVX) had no effect on the 600G-mediated increase in basal Isc.
  
  
  METHODS
  Given the estrogen-like characteristics of genistein, we compared the effects of daily estradiol (E2) injections (10 mg E2/kg body weight/day, 10E2) on basal Isc in intact and OVX mice. In intact mice, 10E2 was without effect on basal Isc, however, in OVX mice, 10E2 significantly increased basal Isc (mimicked 600G). The goal of the current study was to characterize the intracellular signaling pathways responsible for mediating 600G- or 10E2-stimulated increases in basal Isc in intact female or OVX mice.
  
  
  RESULTS
  We measured total protein expression in isolated segments of jejunum using western blot from the following six groups of mice; intact or OVX with; 600G, 10E2 or control. The proteins of interest were: Akt, p-Akt, p-PDK1, p-PTEN, p-c-Raf, p-GSK-3β, rap-1 and ERK1/2. All blots were normalized to GAPDH levels (n = 6-18/group).
  
  
  CONCLUSIONS
  These data suggest that the presence of the endogenous sex steroid, estrogen, modifies the intracellular signaling pathway required to mediate Cl(-) secretion when the intestine is exposed to exogenous 600G or E2. These studies may have relevance for designing pharmacological tools for women with intestinal chloride secretory dysfunctions.
authors.affiliation: Department of Physiology, Midwestern University, Glendale, AZ, USA.
authors.forename: Lana
authors.initials: L
authors.lastname: Leung
authors.forename: Ashesh
authors.initials: A
authors.lastname: Bhakta
authors.forename: Katherine
authors.initials: K
authors.lastname: Cotangco
authors.forename: Layla
authors.initials: L
authors.lastname: Al-Nakkash
mesh_terms: D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D015153:Blotting, Western; D002712:Chlorides / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D019833:Genistein / Q000494:pharmacology*; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D007583:Jejunum / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010052:Ovariectomy; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D015398:Signal Transduction / Q000187:drug effects*; D020827:rap1 GTP-Binding Proteins / Q000378:metabolism
chemical_list: D016588:Anticarcinogenic Agents; D002712:Chlorides; C000631433:Pdk1 protein, mouse; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D004958:Estradiol; D019833:Genistein; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D019908:Proto-Oncogene Proteins c-raf; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D038362:Glycogen Synthase Kinase 3; D020827:rap1 GTP-Binding Proteins