title: Leptin regulates gallbladder genes related to gallstone pathogenesis in leptin-deficient mice.
abstract: BACKGROUND
  Little is known about the genetic factors that cause alterations in gallbladder motility, cholesterol crystal nucleation, biliary lipids, and, ultimately, cholesterol gallstones. Obese, leptin-deficient (Lep(ob)) mice have large gallbladder volumes with decreased contraction in vitro and are predisposed to cholesterol crystal formation. Leptin administration to these mice causes weight loss and restores gallbladder function. We hypothesize that administration of leptin to Lep(ob) mice would cause weight loss, decrease gallbladder volume, and change gallbladder genes related to gallbladder motility, nucleating factors, and lipid metabolism.
  
  
  METHODS
  Twenty-four 8-week-old Lep(ob) mice were fed a nonlithogenic diet for 4 weeks. Twelve mice received daily IP saline injections, and 12 received 5 mug/g recombinant leptin. Gallbladder mRNA was pooled and analyzed on murine genome microarray chips. Selected genes were confirmed by real-time polymerase chain reaction (PCR) in a second group of mice treated by the same protocol.
  
  
  RESULTS
  Leptin-deficient mice given leptin had significant weight loss and reductions in gallbladder volume. These mice had upregulation of the leptin receptor (p = 0.007; PCR = 1.1-fold increase) but downregulation of leptin (p = 0.003; PCR = 13.5-fold decrease). Leptin upregulated the cholecystokinin A receptor (p < 0.001; PCR = 3.1-fold increase), acetylcholine beta2 receptor (p = 0.005), and the Ca+-calmodulin-dependent protein kinase (p = 0.002) genes. Leptin also altered immunoglobulin heavy chain 4 (p = 0.005; PCR = 17.7-fold increase), mucin 3 (p = 0.006), and carboxylesterase (p = 0.016; PCR = 2.5-fold decrease) genes. Leptin downregulated 3-hydroxy 3-methylglutaryl coenzyme A reductase (p = 0.006; PCR = 2.5-fold decrease) and LDL receptor (p = 0.003).
  
  
  CONCLUSIONS
  Leptin modulates obesity and regulates gallbladder genes related to cholesterol gallstone pathogenesis.
authors.affiliation: Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, USA.
authors.forename: Shannon J
authors.initials: SJ
authors.lastname: Graewin
authors.forename: James M
authors.initials: JM
authors.lastname: Kiely
authors.forename: Debao
authors.initials: D
authors.lastname: Lu
authors.forename: Carol L
authors.initials: CL
authors.lastname: Svatek
authors.forename: Hayder H
authors.initials: HH
authors.lastname: Al-Azzawi
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Swartz-Basile
authors.forename: Henry A
authors.initials: HA
authors.lastname: Pitt
mesh_terms: D000818:Animals; D005260:Female; D005704:Gallbladder / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D042882:Gallstones / Q000235:genetics*; D020738:Leptin / Q000494:pharmacology*; D051379:Mice; D008820:Mice, Obese; D009765:Obesity / Q000150:complications / Q000378:metabolism* / Q000473:pathology*; D020411:Oligonucleotide Array Sequence Analysis; D009929:Organ Size / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D015431:Weight Loss / Q000187:drug effects
chemical_list: D020738:Leptin; D012333:RNA, Messenger