Increase in ghrelin levels after weight loss in obese Zucker rats is prevented by gastric banding.
BACKGROUND
Gastric banding is thought to decrease appetite in addition to the mechanical effects of food restriction, although this has been difficult to demonstrate in human studies. Our aim was to investigate the changes in orexigenic signals in the obese Zucker rat after gastric banding.


METHODS
Obese Zucker rats (fa/fa) were submitted to gastric banding (GBP), sham gastric banding fed ad libitum (sham), or sham operation with food restriction, pair-fed to the gastric banding group (sham-PF). Lean Zucker rats (fa/+) were used as additional controls. Body weight and food intake were daily recorded for 21 days after surgery when epididymal fat was weighed and fasting ghrelin and hypothalamic NPY mRNA expression were measured.


RESULTS
Gastric banding in obese Zucker rats resulted in a significant decrease of cumulative body weight gain and food intake. Furthermore, gastric banded rats were leaner than Sham-PF, as expressed by a significantly lower epididymal fat weight. Ghrelin levels of gastric banded rats were not increased when compared to sham-operated animals fed ad libitum and were significantly lower than the levels of weight matched sham-PF rats (1116.9 +/- 103.3 g GBP vs 963.2 +/- 54.3 g sham, 3,079.5 +/- 221.6 sham-PF and 2,969.9 +/- 150.9 g lean rats, p < 0.001); hypothalamic NPY mRNA expression was not increased in GBP when compared to sham-operated rats.


CONCLUSIONS
In obese Zucker rats, GBP prevents the increase in orexigenic signals that occur during caloric deprivation. Our data support the hypothesis that sustained weight loss observed after gastric banding does not depend solely on food restriction.
Department of Anatomy and UMIB (Unit for Multidisciplinary Biomedical Research) of ICBAS (Abel Salazar Institute for the Biomedical Sciences), University of Porto, 4099-003 Porto, Portugal. mpmonteiro@icbas.up.pt
Mariana P
MP
Monteiro
Andreia H
AH
Ribeiro
Ana F
AF
Nunes
Mónica M
MM
Sousa
J Duarte
JD
Monteiro
Artur P
AP
Aguas
M Helena
MH
Cardoso
D050154:Adiposity; D000818:Animals; D001786:Blood Glucose; D001835:Body Weight; D031204:Caloric Restriction; D005247:Feeding Behavior; D005768:Gastrointestinal Hormones / Q000097:blood; D015391:Gastroplasty; D015870:Gene Expression; D054439:Ghrelin / Q000097:blood*; D007031:Hypothalamus / Q000378:metabolism; D007328:Insulin / Q000097:blood; D020738:Leptin / Q000097:blood; D008297:Male; D009478:Neuropeptide Y / Q000235:genetics / Q000378:metabolism; D009765:Obesity / Q000178:diet therapy / Q000378:metabolism* / Q000601:surgery*; D012333:RNA, Messenger / Q000378:metabolism; D011863:Radioimmunoassay; D011897:Random Allocation; D051381:Rats; D011924:Rats, Zucker; D014280:Triglycerides / Q000097:blood
D001786:Blood Glucose; D005768:Gastrointestinal Hormones; D054439:Ghrelin; D007328:Insulin; D020738:Leptin; D009478:Neuropeptide Y; D012333:RNA, Messenger; D014280:Triglycerides