title: Characterization of weight loss and weight regain mechanisms after Roux-en-Y gastric bypass in rats.
abstract: Roux-en-Y gastric bypass (RYGB) is the most effective therapy for morbid obesity, but it has a approximately 20% failure rate. To test our hypothesis that outcome depends on differential modifications of several energy-related systems, we used our established RYGB model in Sprague-Dawley diet-induced obese (DIO) rats to determine mechanisms contributing to successful (RGYB-S) or failed (RYGB-F) RYGB. DIO rats were randomized to RYGB, sham-operated Obese, and sham-operated obese pair-fed linked to RYGB (PF) groups. Body weight (BW), caloric intake (CI), and fecal output (FO) were recorded daily for 90 days, food efficiency (FE) was calculated, and morphological changes were determined. d-Xylose and fat absorption were studied. Glucose-stimulated vagal efferent nerve firing rates of stomach were recorded. Gut, adipose, and thyroid hormones were measured in plasma. Mitochondrial respiratory complexes in skeletal muscle and expression of energy-related hypothalamic and fat peptides, receptors, and enzymes were quantified. A 25% failure rate occurred. RYGB-S, RYGB-F, and PF rats showed rapid BW decrease vs. Obese rats, followed by sustained BW loss in RYGB-S rats. RYGB-F and PF rats gradually increased BW. BW loss in RYGB-S rats is achieved not only by RYGB-induced decreased CI and increased FO, but also via sympathetic nervous system activation, driven by increased peptide YY, CRF, and orexin signaling, decreasing FE and energy storage, demonstrated by reduced fat mass associated with the upregulation of mitochondrial uncoupling protein-2 in fat. These events override the compensatory response to the drop in leptin levels aimed at conserving energy.
authors.affiliation: Dept. of Surgery, University Hospital, 750 East Adams St., Syracuse, NY 13210, USA.
authors.forename: Ana
authors.initials: A
authors.lastname: Guijarro
authors.forename: Susumu
authors.initials: S
authors.lastname: Suzuki
authors.forename: Chung
authors.initials: C
authors.lastname: Chen
authors.forename: Henriette
authors.initials: H
authors.lastname: Kirchner
authors.forename: Frank A
authors.initials: FA
authors.lastname: Middleton
authors.forename: Sergiy
authors.initials: S
authors.lastname: Nadtochiy
authors.forename: Paul S
authors.initials: PS
authors.lastname: Brookes
authors.forename: Akira
authors.initials: A
authors.lastname: Niijima
authors.forename: Akio
authors.initials: A
authors.lastname: Inui
authors.forename: Michael M
authors.initials: MM
authors.lastname: Meguid
mesh_terms: D000818:Animals; D001823:Body Composition / Q000502:physiology; D001835:Body Weight / Q000502:physiology*; D004063:Digestion / Q000502:physiology; D002149:Energy Intake / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology; D005243:Feces; D005247:Feeding Behavior; D015390:Gastric Bypass; D005786:Gene Expression Regulation; D007031:Hypothalamus / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal; D051381:Rats; D017207:Rats, Sprague-Dawley; D013270:Stomach / Q000294:innervation; D013997:Time Factors; D014630:Vagus Nerve / Q000502:physiology; D014994:Xylose / Q000378:metabolism
chemical_list: D014994:Xylose