title: Dietary Genistein Rescues Reduced Basal Chloride Secretion in Diabetic Jejunum via Sex-Dependent Mechanisms.
abstract: OBJECTIVE
  The goal of this study was to determine the effect of dietary genistein (naturally occurring phytoestrogen) on jejunal secretory function in a clinically relevant model of diabetes and obesity, the leptin-defIcient ob/ob mouse.
  
  
  METHODS
  We measured transepithelial short circuit current (Isc), across freshly isolated segments of jejunum from 12-week old male and female ob/ob and lean C57Bl/6J mice fed a genistein diet (600 mg genistein/kg diet) for 4-weeks. Separate segments of jejunum were frozen for western blot determination of key proteins involved in secretory transport.
  
  
  RESULTS
  Basal Isc was signifIcantly decreased (by 33%, P<0.05) in ob/ob females versus leans, and genistein-diet reversed this. Similarly, in males, basal Isc was decreased (by 47%, P<0.05) in ob/ob mice versus leans, and genistein-diet reversed this. Inhibition with either clotrimazole (100 µM, bilateral) or ouabain (100 µM, basolateral) was signifIcantly reduced in ob/ob mice compared to leans (P<0.05), and genistein-diet reversed clotrimazole-sensitive inhibition in ob/ob females, and reversed the ouabain-sensitive inhibition in males (indicating sex-dependent mechanisms). Our data suggested that PDE3 levels were dysregulated in ob/ob females and genistein reversed this. Expression of total CFTR (normalized to actin) was signifIcantly decreased ∼80% (P<0.05) in all ob/ob mice compared to leans, and genistein-diet was without effect. Expression of total NKCC1 (normalized to actin) was signifIcantly decreased ∼80% (P<0.05) in ob/ob male mice versus leans, and genistein-diet reversed this.
  
  
  CONCLUSIONS
  Our data suggests that the reduced basal jejunal Isc in ob/ob female mice is a consequence of reduced CFTR expression, decreased activities of the basolateral KCa channel and Na+/K+-ATPase, and in male mice reduced basal jejunal Isc is a consequence of reduced CFTR and NKCC1 expression, along with decreased activities of the basolateral KCa channel and Na+/K+-ATPase. Genistein-diet has beneficial effects on basal Isc mediated by sex-dependent mechanisms in diabetic mice: in females via increased KCa-sensitive Isc and in males via increased Na+/K+-ATPase activity and increased NKCC1 expression. Improved understanding of intestinal dysfunctions in the ob/ob jejunum, may allow for the development of novel drug targets to treat obesity and diabetes, and may also be of benefit in CF-related diabetes.
authors.affiliation: Department of Physiology, Arizona College of Osteopathic Medicine, Midwestern University, Glendale, USA.
authors.forename: Shawn
authors.initials: S
authors.lastname: Catmull
authors.forename: Faisal
authors.initials: F
authors.lastname: Masood
authors.forename: Sydney
authors.initials: S
authors.lastname: Schacht
authors.forename: Robert
authors.initials: R
authors.lastname: Dolan
authors.forename: Daniel
authors.initials: D
authors.lastname: Stegman
authors.forename: Lana
authors.initials: L
authors.lastname: Leung
authors.forename: Layla
authors.initials: L
authors.lastname: Al-Nakkash
mesh_terms: D000818:Animals; D002712:Chlorides / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism* / Q000473:pathology; D004032:Diet; D004560:Electricity; D005260:Female; D019833:Genistein / Q000494:pharmacology*; D007583:Jejunum / Q000187:drug effects / Q000473:pathology; D008297:Male; D008810:Mice, Inbred C57BL; D008820:Mice, Obese; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D012727:Sex Characteristics; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D064506:Solute Carrier Family 12, Member 2 / Q000378:metabolism
chemical_list: D002712:Chlorides; D010726:Phosphodiesterase Inhibitors; C578878:Slc12a2 protein, mouse; D064506:Solute Carrier Family 12, Member 2; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D019833:Genistein; D000254:Sodium-Potassium-Exchanging ATPase