title: Adaptation of ghrelin levels to limit body weight gain in the obese Zucker rat.
abstract: In this study, we measured the ghrelin, leptin, and insulin variations in lean and obese Zucker fa/fa rats during the acute phase of body weight gain. At 2 months of age, plasma insulin and leptin concentrations in fa/fa rats were, respectively, 470% and 3700% higher than in lean rats (p <0.0001). Plasma ghrelin was significantly lower (-24.6%; p <0.02) than in lean rats. At 6 months of age, ghrelin increased in both genotypes but the difference was no more significant. The inverse correlations existing between ghrelin and either body weight (BW), insulin or leptin at 2 months of age were no more observable in 6-month-old rats. At 6 months of age, the lean rats had the same body weight as the 2-month-old obese rats. In these body weight-matched rats, ghrelin was not correlated with BW but it remained negatively correlated with insulin and leptin. At the same body weight, obese rats had a much lower plasma ghrelin than lean rats (717+/-42 vs. 1754+/-83 pg/ml; p <0.0001). These data indicate that body composition rather than body weight is the primary factor for the down-regulation of the ghrelin system. This down-regulation constitutes a mechanism of defense of the organism against the development of obesity at least during the first part of life.
authors.affiliation: UHP/EA 3453-IFR 111-Systèmes Neuromodulateurs des Comportements Ingestifs-38, rue Lionnois, 54000 Nancy, France. Bernard.Beck@nancy.inserm.fr
authors.forename: Bernard
authors.initials: B
authors.lastname: Beck
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Max
authors.forename: Brigitte
authors.initials: B
authors.lastname: Fernette
authors.forename: Sébastien
authors.initials: S
authors.lastname: Richy
mesh_terms: D000818:Animals; D001835:Body Weight / Q000502:physiology; D004435:Eating / Q000502:physiology; D054439:Ghrelin; D006720:Homozygote; D007328:Insulin / Q000097:blood; D020738:Leptin / Q000097:blood; D008137:Longitudinal Studies; D036361:Peptide Hormones / Q000097:blood*; D011863:Radioimmunoassay; D051381:Rats; D011924:Rats, Zucker; D012044:Regression Analysis; D015430:Weight Gain / Q000502:physiology*
chemical_list: D054439:Ghrelin; D007328:Insulin; D020738:Leptin; D036361:Peptide Hormones